Introduction

Rheumatic heart disease (RHD) remains the leading acquired cardiovascular disease among children and young adults in low-income and middle-income countries and in some at-risk populations living in high-income countries1,2. RHD results from cumulative valvular damage that is largely preventable by secondary antibiotic prophylaxis (SAP)3,4. Given that clinically detectable RHD might present after years of subclinical disease, the detection of early RHD by echocardiography and the subsequent initiation of SAP, alongside other established strategies, may reduce the global burden of RHD5. Echocardiography is vastly superior to auscultation for detecting RHD6. In 2012, the World Heart Federation (WHF) published the first evidence-based guidelines for the echocardiographic diagnosis of RHD7 (referred to in this article as the WHF 2012 guidelines). These guidelines included the minimum criteria required to diagnose RHD, harmonized the diagnosis and classification approach for RHD across global regions and were especially useful for epidemiological studies. Although the WHF 2012 guidelines were research-oriented, they have since become a frequently used tool in clinical settings for diagnosing RHD. However, research and real-world experience with the WHF 2012 guidelines have led to the identification of some limitations in the criteria. This includes the heterogeneous outcomes of echocardiography-detected RHD and the practical challenges in applying the criteria in the busy settings in which RHD active case finding occurs8,9.

Over the past decade, the RHD research community has made important strides in understanding the natural history of RHD8 and risk factors for its progression10. Concurrently, the management strategies for the early stages of RHD were assessed, including the efficacy of SAP4. Furthermore, there has been an increasing appreciation of hand-held echocardiography and task sharing for active case finding in resource-limited settings11,12,13. The evidence and experience accrued over the past decade have thus prompted this revision. The WHF 2023 guidelines incorporate evidence gathered from a scoping review, an expert panel and end-user feedback obtained through a global survey on the utility of the WHF 2012 guidelines7. In these updated guidelines, we provide the revised minimum echocardiographic criteria for the definitive diagnosis of RHD; a new classification of RHD that is dependent on the risk of disease progression; a two-step echocardiography algorithm for RHD active case finding, including screening criteria for detecting suspected cases and confirmatory criteria for the definitive diagnosis of RHD; management recommendations for early-stage RHD; and guidance for task sharing and the use of hand-held echocardiography in RHD active case finding.

These WHF 2023 guidelines, endorsed by globally representative societies (Box 1), are a pragmatic, contemporary and relevant reference tool that can be utilized for clinical and research applications in RHD-endemic regions across the world. They provide an evidence-based guide for the standardization of disease definitions, diagnostic criteria, risk assessment strategies and management approaches for patients with varying severities of RHD.

Revising the guidelines

Changes to the WHF 2012 guidelines

In the revised WHF 2023 guidelines, we have introduced a new set of echocardiographic criteria — the ‘screening criteria’ — to facilitate task sharing in active case-finding programmes. We have also formulated a stage-based classification system for RHD that reflects the continuous spectrum of the disease and risk of progression, as opposed to the discreet classification system used in the WHF 2012 guidelines7. These developments are summarized in Boxes 2 and 3.

Aim

These WHF 2023 guidelines aim to define the minimum echocardiographic criteria for diagnosing RHD according to the best-available evidence. These guidelines do not describe all rheumatic valvular lesions and the spectrum of diseases, nor do they intend to provide comprehensive management guidance on the different presentations of valvular heart disease (these topics are discussed in other clinical practice guidelines14,15,16). The focus of this document on the echocardiographic diagnosis of RHD complements, but does not overlap with, the 2023 American Society of Echocardiography report that focuses on providing recommendations for advanced RHD14. The current guidelines are designed to provide diagnostic guidance for health-care practitioners and researchers conducting active case-finding programmes, for opportunistic case detection in clinical settings, and for health-care practitioners who detect possible RHD cases as part of routine care.

Methods

An international panel of experts in the screening and echocardiographic imaging of RHD were involved in revising the WHF 2012 guidelines to develop this updated, evidence-based version7. A scoping review (not yet published) will summarize the available evidence on the performance of the WHF 2012 criteria, including the specificity (in low-prevalence populations), the inter-rater reliability and various modifications of the criteria for diagnostic simplicity. The panel of experts also conducted an end-user survey to assess the applicability and usability of the WHF 2012 guidelines. The evidence gathered from the scoping review, alongside end-user feedback from the survey, generated three main conclusions: first, the important role of task sharing and the need for a simplified set of criteria that health-care practitioners with limited training using hand-held devices could adopt; second, that the WHF 2012 criteria did not take into account the continuum of early rheumatic valvular changes that might regress, progress and overlap with normal valve morphology; and third, that certain aspects of the WHF 2012 criteria were subjective and difficult to replicate, especially in the clinical setting. Of note, the WHF 2012 criteria were primarily written for use by research teams performing epidemiological studies. However these criteria have now also been widely incorporated into clinical use in RHD-endemic and non-endemic settings. This includes the development of task-sharing and active case-finding programmes for the echocardiographic detection of RHD. Consequently, an updated version of the guidelines was necessary to improve the utility across these various applications.

Grading of evidence

The classification of recommendations and levels of evidence are expressed in accordance with the 2016 ACC/AHA grading system17.

Summary of recommendations

Figure 1 summarizes the steps from screening to confirmatory echocardiography and subsequent care plans for children and young adults diagnosed with RHD through active case-finding programmes. In addition, Table 1 summarizes the recommendations for RHD care pathways by disease stage, and Table 2 provides an overview of recommendations for at-risk populations, equipment use, task sharing for active case-finding and technology for RHD screening to improve RHD care in endemic regions.

Fig. 1: The approach to active case finding, classification and care implications for rheumatic heart disease in endemic regions.
figure 1

a, Screening for rheumatic heart disease (RHD). aAlthough confirmatory echocardiography is recommended before the initiation of secondary antibiotic prophylaxis (SAP), in settings in which confirmatory echocardiography cannot be performed immediately, SAP can be initiated in patients while waiting for  a confirmatory study. The final decision should be made by or in consultation with a clinician with expertise in RHD diagnosis. b, Classification of RHD. bThese criteria can be achieved in two separate views or from two separate continuous-wave Doppler measures. c, Staging and care recommendations. cStage A only applies to individuals aged 20 years or less. dEvidence from a randomized, controlled trial showed that SAP reduces the risk of RHD progression in children aged 5–17 years with stage A or stage B RHD4. However, SAP is also associated with adverse effects, including allergy and anaphylaxis, and numerous health-system factors should be considered before the roll-out of large-scale SAP programmes. Consequently, there is a need to consider family and clinician decisions, as well as health-system factors before recommending SAP in individuals aged ≤ 20 years with stage A RHD who are at low risk of RHD progression. However, all children with stage A disease must have access to follow-up echocardiography and longitudinal clinical evaluation to monitor for disease progression. AR, aortic regurgitation; ARF, acute rheumatic fever; AS, aortic stenosis; AV, aortic valve; LV, left ventricular; MR, mitral regurgitation; MS, mitral stenosis; MV, mitral valve.

Full size image
Table 1 Recommendations for care pathways for rheumatic heart disease by disease stage
Full size table
Table 2 Recommendations for at-risk populations, equipment use and task sharing for rheumatic heart disease screening
Full size table

Echocardiographic criteria and staging of RHD

Two sets of criteria are presented that can be integrated into the stage-based diagnostic strategy, including a new set of ‘screening criteria’ as well as ‘confirmatory criteria’. The latter are largely similar to the original WHF 2012 criteria, but with minor modifications. The WHF 2023 guidelines also present a staging process for RHD diagnosis on the basis of the risk of disease progression.

The two-step screening criteria and confirmatory criteria have been developed predominantly to assist in coordinated population-based screening programmes that might or might not involve task sharing. In terms of task sharing, non-experts can use the screening criteria to conduct screening echocardiograms, but the same steps can also be performed by experts to save time during screening or in clinical settings, or when the appropriate equipment for applying the confirmatory set of criteria is not available. Confirmatory echocardiograms can be performed in individuals who have a positive screening result, or as a single step in individuals without a history of acute rheumatic fever (ARF) or RHD by experts who have ready access to the necessary echocardiography equipment.

Screening criteria for the echocardiographic detection of RHD

The screening criteria are intended to rapidly detect possible disease in settings in which RHD is highly prevalent and in which equipment and health-care providers are limited (Box 4). They are only applicable to individuals aged 20 years or less. They can also be applied in high-volume screening programmes that use task sharing and hand-held devices. The criteria have been selected on the basis of the best-known evidence to provide greater sensitivity, as a screening test, at the expense of specificity. The two-step screening strategy should be adopted whenever possible (Fig. 1a).

Following up a screening echocardiogram with a confirmatory echocardiogram might not be possible in certain high-risk populations from resource-limited regions. In some circumstances, a diagnosis on the basis of the screening criteria in combination with clinical features and a high pre-test probability of disease might be reasonable, with the final decision to be made by or in consultation with a clinician with expertise in diagnosing RHD.

Rationale and evidence

The screening criteria proposed were derived from an analysis of numerous studies that have evaluated abbreviated (modified) versions of the WHF 2012 criteria18,19,20,21,22. Although the modified criteria and the echocardiography protocols have varied between studies, the sensitivity of modified criteria compared with the WHF 2012 criteria across these studies has been satisfactory12,18,23,24. Most of these studies have utilized valvular regurgitation alone, excluding morphological features, to screen for RHD, which is reflected in the screening criteria presented in this guideline.

In the current guidelines, the definitions of mitral and aortic regurgitation have been simplified by excluding the need for spectral Doppler imaging. This simplification will enable the application of the screening criteria using hand-held devices that do not have spectral Doppler capacity and allows ease of application in settings with large volume, active case-finding programmes or task sharing.

The detection of mitral regurgitation has demonstrated substantial-to-almost-perfect inter-reviewer reliability for the diagnosis of RHD8,25,26 and is the most common lesion detected when screening for RHD. Therefore, mitral regurgitation forms the basis of the abbreviated criteria. Several reports have analysed various combinations of mitral and aortic jet lengths from expert-performed and task-sharing echocardiographic screening studies to determine the optimal sensitivity and specificity20,27,28. Reporting minimal mitral regurgitation jet lengths as a positive screen has been shown to have a high sensitivity for detecting RHD18,21,22,27,28. However, the high rates of false positives that this protocol would produce in clinical practice (requiring confirmatory echocardiography) make this strategy impractical12. Available data support a mitral valve jet length of 1.5–2.0 cm as having the best balance between sensitivity (73–81%) and specificity (75–100%) for the detection of RHD18,20,22. A study that assessed the inter-rater reliability and individual reviewer performance of the 2012 WHF guidelines demonstrated the highest β-coefficient using a mitral regurgitation jet length of ≥2.0 cm26. The two jet lengths for different weight cut-offs presented in these guidelines were proposed by our panel of experts to ensure a high sensitivity of the criteria in the younger paediatric population. Studies that have assessed the WHF 2012 guidelines in populations with a low prevalence of RHD have demonstrated low rates (0.5–0.8%) of pathological mitral regurgitation, presumably representing the upper limit of normal physiological mitral regurgitation29,30,31. The requirement for the regurgitant jet to be observed in more than one consecutive frame can provide a surrogate for spectral Doppler imaging. A jet that is observed in more than one consecutive frame is less likely to be a closing volume than one that is observed in only one frame and is more consistent with pan-systolic regurgitation21.

As defined by the WHF 2012 criteria, pathological aortic regurgitation has been reported in two studies to have almost perfect inter-reviewer reliability for the detection of RHD (κ = 0.86 and 0.95)26,32. The sensitivity and specificity of reducing aortic regurgitation from a minimum jet length of 10 mm to any detected regurgitation have been described in numerous studies and remain adequate as screening criteria10,18,20,21. In addition, in a 2019 study, aortic regurgitation remained one of the highly significant variables in a point-based score (β-coefficient = 4.8) used to predict unfavourable outcomes10. Ensuring that the regurgitation jet is observed in more than one frame again excludes closing volumes and physiological regurgitation21.

Confirmatory criteria for the echocardiographic detection of RHD

The criteria for the detection of RHD using pathological valvular regurgitation and mitral stenosis are indicated in Box 5 and those for RHD-defining morphological features are in Box 6.

Rationale and evidence

The confirmatory criteria, which involve the use of 2D imaging, colour Doppler and continuous-wave Doppler echocardiography, aim to discriminate between physiological and pathological changes in the valves with reasonable accuracy and inter-rater reliability10. Differentiating between individual morphological features can be challenging, which is especially true when trying to distinguish between two features of mitral apparatus thickening (anterior leaflet and chordal thickening) and the two features of abnormal mitral valve motion (restrictive leaflet motion and excessive motion of the anterior leaflet tip). In each case, the paired abnormalities probably reflect a similar pathological finding10. Furthermore, the abnormalities within the two categories of morphological changes are continuous and often coexist. Accordingly, these features have a lower inter-rater reliability than pathological valvular regurgitation33,34. Analyses in multiple populations have led to the development of a risk prediction score that performs well in distinguishing between a low risk of disease progression and a moderate or severe risk of disease progression and includes the criterion of one morphological feature in addition to pathological regurgitation of the associated valve in individuals aged ≤20 years10. Additional data from a randomized trial and several natural history studies have shown an increased risk of developing RHD in patients with pathological mitral or aortic regurgitation and at least one morphological feature4,35. Given that mild valve thickening is common in adults, two morphological features are still required to diagnose those aged >20 years.

These WHF 2023 guidelines simplify the morphological features needed for the diagnosis and have created two morphological categories for the mitral valve: the thickening of the valvular apparatus (defined by the presence of either or both valvular and chordal thickening) and valve mobility (defined by the presence of either or both restricted and excessive leaflet motion). The morphological features of the aortic valve have not been combined because individual features are more specific for RHD. However, only one morphological feature is needed together with the presence of pathological aortic regurgitation for a diagnosis of mild RHD.

Staging of RHD based on the risk of disease progression

The natural history of early RHD is heterogeneous, and studies have demonstrated that the echocardiographic features of RHD might regress, remain unchanged or progress over time4,8. The GOAL study4 showed that treating early-stage RHD with SAP reduced disease progression at 2 years of follow-up. However, the study also highlighted the heterogeneous nature of early disease, with 50% of borderline and 30% of mild cases regressing spontaneously (without the need for SAP). In high-risk populations, some individuals with mild valvular changes do indeed have RHD (and are at risk of disease progression), whereas the mild changes in other individuals might be classified as being normal. Of note, individuals might oscillate between these two classifications. The stage-based criteria outlined in these guidelines acknowledge the spectrum of early echocardiographic rheumatic changes by incorporating the assessment of the risk of progression and replacing the previously described borderline and definite categories7 (Fig. 1 and Box 3).

A prediction score reported in 2019 using the parameters in the WHF 2012 echocardiographic criteria (anterior mitral valve thickening, excessive mitral leaflet motion, regurgitant mitral jet >2.0 cm, irregular aortic valve thickening and any aortic regurgitation) showed good discrimination and calibration for a diagnosis of RHD (c-statistic of 0.998 and 0.994, respectively) and good discrimination for predicting disease progression (c-statistic of 0.811)10. The score has been externally validated in international cohorts and has been recalibrated for refinement. The scoring system assigned point values to different variables that were proportional to their regression coefficients and stratified the sum of these values into low (0–6), intermediate (7–9) and high (≥10) risk categories of early RHD progression10. By risk-stratifying individuals with RHD at diagnosis, the score has potential value for deciding which patients will benefit most from close clinical monitoring and SAP36,37. In keeping with the features of this score and the corresponding level of risk of disease progression, as well as to reflect early RHD as a continuum instead of using distinct diagnostic categories, we present a staging system (stages A–D) for RHD as detected by echocardiography. The criteria to meet these stages and the risk of disease progression are shown in Box 7.

Stage A

Stage A indicates the presence of early valvular changes that meet the minimum diagnostic criteria for RHD in a high-prevalence population. Stage A is only applicable to individuals aged 20 years or less. On the basis of the risk score, individuals with stage A disease might be at risk of developing valvular heart disease, but are considered to have a low risk of disease progression. This stage A category corresponds to the disease stage previously known as ‘borderline RHD’7, but better acknowledges the continuum of echocardiographic features from normal variant to mild RHD. Of note, the presence of morphological features alone, without valvular regurgitation, does not qualify individuals for stage A disease, given that the presence of morphological features alone is observed only in a small number of individuals and is considered unlikely to be associated with the development of RHD.

Stage B

Stage B indicates mild RHD with the presence of both pathological regurgitation and morphological features. The presence of both aortic and mitral pathological regurgitation, but without morphological features, is also classified as stage B, given that the concurrence of pathological mitral and aortic regurgitation is probably indicative of true pathology. Patients with stage B disease are considered to have a moderate or high risk of disease progression on the basis of the risk score10 and correspond to the previous category named ‘definite RHD’ (Box 3).

Stage C

Stage C indicates established valvular disease detected by echocardiography, and patients with stage C disease are at risk of developing complications and might require medical treatment or surgical intervention. Mitral stenosis of any severity is included in this category.

Stage D

Stage D indicates established valvular disease detected by echocardiography (the same as stage C), but with overt clinical complications (such as heart failure, arrhythmia, stroke or the need for cardiac surgery).

Limitations of diagnostic criteria

Screening criteria

The screening criteria have been developed for ease and speed of application and are highly sensitive, but have a lower specificity than the confirmatory criteria. This compromise is acceptable for a screening test, given the need for a simplified set of criteria that can easily be applied in settings with limited resources and poor access to specialized care and advanced imaging modalities.

Confirmatory criteria

The limitations of the current confirmatory criteria are essentially unchanged from those described by the WHF 2012 guidelines7. However, the challenge of applying morphological features as a criterion has been addressed in this revision. The addition of the body weight-based measurements also addresses concerns about the under-reporting of pathological mitral regurgitation in younger children. The confirmatory criteria are detailed and are best applied by experts with advanced training on RHD diagnosis and with access to full-capacity echocardiogram machines. Although these criteria are appropriate for use in well-resourced settings, their application in certain resource-poor, RHD-endemic regions might be limited.

Furthermore, the comprehensive criteria do not include quantitative severity grading using measurements such as vena contracta, the proximal isovelocity surface area and the effective regurgitant orifice area. These measurements can be challenging to obtain in rheumatic valve lesions with eccentric regurgitant jets14. Any quantitative or qualitative evaluation of severity should remain in line with international guidelines on the echocardiographic assessment of valvular heart disease15,16.

Exclusion of aortic stenosis and right-sided valve lesions from the diagnostic criteria

Neither the screening criteria nor the comprehensive criteria include the presence of aortic stenosis or right-sided cardiac valve lesions. As stated in the WHF 2012 guidelines7, rheumatic aortic valve stenosis is rare in isolation, especially in the absence of mitral valve involvement38,39,40. Similarly, isolated involvement of right-sided cardiac valves — most notably tricuspid regurgitation — in the absence of mitral valve disease that leads to right ventricular dysfunction is an equally unusual finding, especially during screening41. Consequently, we have maintained the decision not to include these valve lesions in the minimum diagnostic criteria outlined in these guidelines.

Age-based and weight-based cut-offs for mitral regurgitation jet length

There are limited data on the use of mitral regurgitation jet length as a diagnostic criterion for RHD because it is not routinely included in paediatric echocardiography guidelines. However, in studies comparing left atrial size with body surface area and reporting on nomograms that have compared patient age and weight with body surface area, there is a demonstrable inflexion point where body surface area = 1 m2, which corresponds closely to an age of 9.5 years and weight of 27–30 kg42,43. These data have resulted in a consensus decision to use weight < 30 kg or age < 10 years as thresholds for a smaller mitral regurgitation length cut-off. Ideally, mitral regurgitation jet length should correlate with patient size or left atrial size as a continuous variable, but this criterion is not practical for guidelines in RHD-endemic settings. Therefore, these guidelines recommend the use of 1.5 cm as the cut-off value for patients weighing <30 kg or aged <10 years, for whom shorter mitral regurgitation jet lengths might indicate true rheumatic involvement, especially when smaller atrial sizes are anticipated. Our expert opinion is that the lower cut-off value will prevent the underdiagnosis of RHD in patients weighing < 30 kg or aged <10 years who would otherwise meet the criteria for pathological mitral regurgitation. We believe that the underdiagnosis of younger patients is a more pressing concern than overdiagnosis in RHD-endemic regions.

RHD care implications

The care pathways in these guidelines have been differentiated according to the disease stage, using best-available evidence. Data from a randomized, controlled trial demonstrated that SAP reduced the risk of RHD progression in children aged 5–17 years with stage A or stage B disease4, with the number needed to treat to prevent one case of RHD progression being 13. However, the adverse effects associated with SAP, including stigmatization, reduced quality of life, allergic reactions and anaphylaxis44,45, in addition to numerous health-system factors, should be considered before the roll-out of large-scale treatment programmes4. Consequently, there is a need to account for family and clinician decisions and health-system factors before recommending SAP in individuals aged ≤20 years with stage A RHD who are at low risk of RHD progression. However, all children with stage A disease must have access to follow-up echocardiography and longitudinal clinical evaluation to monitor for disease progression. We recommend that SAP be continued until a follow-up echocardiogram has been obtained. SAP is recommended for all individuals aged ≤20 years with stage B disease, who have a moderate-to-high risk of disease progression. Finally, SAP is recommended for all individuals with stage C or stage D disease and the treatment regimen should follow relevant local RHD management guidelines. In certain circumstances, such as for individuals without access to a comprehensive echocardiogram report, SAP can be commenced after the criteria for a positive screen have been fulfilled. However, the decision on whether to start SAP should be made with advice from a clinician with RHD experience and all efforts should be made to receive a formal diagnosis with a confirmatory criteria echocardiogram as soon as feasibly possible. These recommendations are summarized in Table 1.

Active case finding

Active case finding refers to active surveillance or screening for disease in at-risk populations within and outside health-care facilities46,47. Active case finding for RHD encompasses both coordinated population-based screening programmes and opportunistic case detection in clinical settings. Active case finding for RHD uses echocardiography to identify valvular changes that are consistent with RHD in individuals without a history of ARF and/or RHD. Active case finding can identify a spectrum of valvular changes that are associated with a variable risk of disease progression. Over the past decade, the RHD clinical and research communities have recognized the importance of active case finding to detect mild disease in patients who might benefit from the commencement of SAP and close clinical follow-up4, as well as patients with moderate or severe disease who require advanced medical and surgical interventions.

RHD meets much of the criteria necessary for conducting population-based screening33,48,49, albeit with some limitations (Table 3). Population-based echocardiography screening for RHD is resource-demanding. All prospective screening programmes should consider the economic and ethical considerations relevant to that specific jurisdiction, including the effect of the programme on other strategies aimed at addressing the burden of RHD50. The current guidelines specifically provide evidence-based guidance on diagnosing RHD by echocardiography that is relevant to various active case-finding strategies. However, the ultimate decision to conduct population-based screening should take into account all other relevant factors and be made by local government and health organizations. Further guidance on population-based screening is outlined subsequently.

Table 3 Suitability of population screening for rheumatic heart disease using echocardiography
Full size table

Population-based screening for RHD

Candidates

Echocardiography-based screening should be considered only in high-risk populations, as defined by a prevalence of more than 2 cases per 1,000 persons for RHD (all ages) or an incidence of more than 30 cases per 100,000 persons aged 5–14 years annually for ARF3,51. Children with no history of ARF (but a presumed subclinical episode) who have developed RHD have the most to gain from the prevention of disease progression. Therefore, most screening programmes for RHD in endemic regions have been undertaken in children and young adults aged 5–20 years2,6,34,52. Targeted screening of individuals at an increased risk of RHD, such as siblings (aged 5–20 years) and parents of index cases with ARF or RHD, might also be appropriate53,54,55. The screening of young adults could still be justified for local disease burden management, especially in socially vulnerable and high-prevalence settings. Given the substantial risk of undiagnosed RHD to pregnant women and the fetus, echocardiography screening is also reasonable in pregnant women at high risk of RHD, including those living in endemic regions56. These recommendations are summarized in Table 2.

Ethical considerations

Evidence shows that echocardiographic screening combined with SAP for early-stage RHD is more cost-effective than the use of primary prophylaxis for ARF57. However, the decision to invest in echocardiographic RHD active case-finding programmes at the expense of other competing health problems with robust evidence-based interventions remains an ethical dilemma, particularly in resource-limited settings58. Population-based screening could lead to increased utilization of the already overstretched infrastructure and requires providers to care for more individuals, as well as affecting the quality of life of patients and their families59. Although a negative screening result seems to have no adverse effect, a positive screen that might actually be a misdiagnosis can result in stigmatization, unnecessary anxiety, inappropriate SAP use, changes in physical activity levels and a reduction in the quality of life of the individual and their family60,61. With these potential harms in mind, implementing population-based screening programmes necessitates the education of health-care professionals about the potential risks and benefits of screening. All programmes should ensure sustainability and the availability of recommended treatment, including SAP and clinical follow-up, for all high-risk individuals, regardless of socio-economic status. This requirement might be even more important in low-resource settings, in which clinical care is prioritized on the basis of disease risk. Furthermore, individuals should be enrolled in a local RHD registry, if available, and the cost of screening should be balanced against potential expenditure on medical care and its effect on other public health strategies57,62,63.

Echocardiography in acute carditis

Diagnosis of carditis in an index ARF case

A detailed description of echocardiographic findings in ARF is outside the scope of these guidelines and has been reviewed previously51. Carditis in the setting of ARF has been described as pancarditis involving the endocardium, myocardium and pericardium. Only endocarditis and, more specifically, valve dysfunction (valvulitis) are considered major criteria for the diagnosis of carditis51. To meet the diagnostic definitions for a major criterion of carditis, pathological mitral and/or aortic regurgitation must be present (as defined in Box 5). Valvular regurgitation in ARF is attributable to various mechanisms, including valvulitis, mitral annular dilatation, leaflet prolapse and chordal elongation or rupture, all of which can be detected on echocardiography64. The morphological changes associated with RHD often develop at a later stage of disease or might never transpire and thus are not required for the diagnosis of acute carditis in the setting of ARF.

Diagnosis of acute carditis in the setting of RHD

The differentiation between acute valvulitis and established RHD can pose a clinical dilemma. No evidence exists for the use of echocardiography to differentiate between acute-on-chronic valvulitis and chronic RHD. Echocardiography cannot accurately measure when the rheumatic changes occurred, but a comparison with previous echocardiograms to assess the severity and progression of the valve lesions might be useful in determining whether there is acute valve inflammation in the setting of an ARF recurrence.

Echocardiography equipment

Hand-held echocardiogram devices

The development of hand-held echocardiography devices and improvements in their image quality and functionality have resulted in hand-held devices being a credible option for echocardiographic diagnosis of RHD65. All available hand-held devices allow for standard 2D and colour Doppler imaging. The probes of the hand-held devices weigh approximately 130–400 g, making them light enough for comfortable use in clinical practice and active case-finding settings. The phased array (cardiac) probe ‘footprint’ is small enough to obtain images from most acoustic windows. The hand-held machines can have high frame rates: approximately 40–50 frames/s for 2D imaging and up to 30 frames/s for colour Doppler imaging, depending on the image optimization capacity. The depth (up to 30 cm) and field of view of hand-held devices are adequate for appropriate image acquisition and analysis, and some devices now feature pulsed-wave and continuous-wave Doppler. In addition, certain devices now provide built-in training software, such as artificial intelligence (AI)-guided image acquisition or options to provide real-time teleguidance66,67.

However, hand-held devices have numerous limitations, including minimal manual image optimization capacity (with most devices now allowing harmonic imaging to be manually turned off), low colour scale and the absence of spectral Doppler imaging. Of note, all these factors associated with hand-held devices can impede the application of the WHF 2023 criteria. Furthermore, the functionality of the hand-held devices varies depending on the specific device characteristics, including battery life, recharge time, memory capabilities, cloud-based file-sharing capacity and the standardization of file types and temperature.

Hand-held echocardiography devices are substantially cheaper than portable ultrasonography machines and currently cost between US $2,000 and US $10,000. Many hand-held devices are sold as stand-alone probes that use widely available, non-brand-specific tablets, allowing operators to use larger screens, which improves disease detection. Finally, hand-held devices are now capable of secure image upload and storage. Some brands will host their specific study storage options, with limited and proprietary file formats, whereas most devices can upload Digital Imaging and Communications in Medicine (DICOM) formats to non-brand-specific image storage servers.

Portable echocardiogram machines with complete functionality

Portable echocardiography machines are still the mainstay in many RHD active case-finding programmes. Unfortunately, these machines are expensive and thus not accessible in resource-limited settings. In addition to producing high-quality 2D, colour Doppler and continuous-wave Doppler imaging, these portable devices have many extra functions (including global longitudinal strain, automated ejection fraction, stress and 3D imaging), which might not be necessary for RHD detection alone. The recommendations regarding equipment for RHD screening are summarized in Table 2.

Task sharing in RHD-endemic regions

RHD remains prevalent in many low-income and middle-income regions, where there are relatively few cardiologists and cardiac sonographers per capita compared with high-income countries, as well as a substantial disparity in health-care resources between rural and urban regions. An alternative workforce is crucial to the success of population-based active case-finding programmes for RHD in these areas. Task sharing involves strategically redistributing skills or tasks among teams and personnel. Task sharing for RHD active case-finding using echocardiography has been shown to be successful27,28 and might be a realistic and cost-effective alternative strategy for active case finding. Studies have shown that non-experts can acquire and interpret basic echocardiographic images after brief standardized training, even using limited single-view protocols, and achieve a moderate-to-high sensitivity and specificity18,28,65,68. A structured, coordinated and preferably regionally accredited training programme for task sharing is recommended. Furthermore, continuous monitoring and evaluation are vital to the task-sharing process. Discussions with health authorities and medical councils might also be required, given that the regulations in some locations might limit the task sharing of ultrasonography responsibilities to non-physicians. The recommendations for task sharing for active case finding in RHD-endemic regions are summarized in Table 2.

New and emerging technology

RHD active case-finding programmes can benefit from advances in medical technology. Echocardiographic images have been successfully transmitted to experts at an off-site location for analysis and interpretation using cloud-based image storage and viewing platforms (tele-echocardiography)69. Task sharing in screening programmes has also been improved by the miniaturization of ultrasonography devices, the increase in image quality and battery life, and the incorporation of dedicated cloud applications and advances features, such as Doppler and probe guidance applications and live videoconferencing70. In addition, a clinical trial has tested the utility of smartphone-connected, wireless devices, including pocket echocardiography, in a mobile health clinic to improve outcomes for patients with RHD and other structural heart diseases71. Compared with standard care, initial mobile health assessment resulted in a shorter time to diagnosis, increased the probability of referral for advanced surgical care and reduced the risk of adverse outcomes (hospitalization or death) at follow-up71. These findings show the potential of integrating technological devices for point-of-care management, especially in resource-limited settings71.

Preliminary data have been published on the use of AI technology to improve automated RHD diagnosis in clinical practice. A Brazilian study showed that a deep learning approach had moderate accuracy (72.8%, 95% CI 69.3–76.3%) for flagging latent RHD in screening images acquired using hand-held devices, with better accuracy for definite RHD72,73. AI algorithms have also successfully identified and quantified mitral regurgitation in children, a key feature for RHD diagnosis in screening studies74. A novel AI approach for computer-assisted auscultation showed low sensitivity (4.0%) but reasonable specificity (93.7%) for RHD detection compared with echocardiography22. Finally, AI-based software has been newly incorporated into echocardiogram devices to guide optimal probe positioning and to facilitate imaging acquisition66, and AI systems are currently being trained specifically to diagnose RHD. Therefore, although data are still scarce, AI technology holds promise for future development and incorporation into RHD diagnostic flowcharts. A list of recommendations for the use of new technology to detect RHD is presented in Table 2.

Future directions

Validation studies are essential to determine the utility of the new WHF 2023 criteria in communities. Although the abbreviated criteria aim to simplify the echocardiographic screening of RHD, an adequate balance of sensitivity and specificity must be maintained. Therefore, a series of studies are essential to assess whether these criteria are sensitive enough to detect most RHD and, at the same time, maintain adequate specificity. In addition, research is needed to validate and strengthen the age-specific and size-specific recommendations and further characterize the use of rheumatic regurgitant jet length as a criterion, to improve our capacity to distinguish pathology from physiology. Furthermore, continued efforts are required to ensure that the diagnostic criteria can best identify those individuals who will benefit the most from SAP.

In addition, the performance of the newer portable echocardiography devices should also be evaluated, as well as the new applications for imaging guidance, off-site review of images and automated flagging of abnormalities. AI technology for the diagnosis of RHD should continue to be developed.

Finally, cost–effectiveness and implementation research are required to determine the sustainability of various models of RHD active case finding. Guidance on the threshold for implementing active case finding is needed, as well as guidance on the ideal age for screening children. Furthermore, active case-finding programmes might have a role in evaluating vaccine efficacy and safety.

Conclusions

The WHF 2023 guidelines for the echocardiographic diagnosis of RHD provides a contemporary resource for researchers and health-care practitioners in RHD-endemic regions around the world. These guidelines provide an updated, evidence-based set of criteria for diagnosing RHD, which empowers clinicians to make management decisions on the basis of the risk of an individual of disease progression. These diagnostic criteria support the growing demand for task sharing, particularly in resource-limited settings, and complement local, national and international RHD treatment recommendations. In revising the guidelines, we have also identified areas for future research, including continued evaluation of the applicability of this new set of criteria in research and clinical settings to ensure that it remains relevant to end-users.