Cardiac MRI reveals the clinical importance of LV mass in hypertrophic cardiomyopathy

Olivotto I et al. (2008) Assessment and significance of left ventricular mass by cardiovascular magnetic resonance in hypertrophic cardiomyopathy. J Am Coll Cardiol 52: 559–566

Hypertrophic cardiomyopathy (HCM) has a heterogeneous phenotype that is not easily defined by two-dimensional echocardiography alone. In this multicenter study, Olivotto et al. used cardiac MRI to measure and compare the left ventricular (LV) dimensions of 606 healthy individuals with those of 264 patients with HCM. Their investigation provides new insights into the clinical correlates and importance of LV mass in patients with this condition.

In general, individuals with HCM had a higher LV mass index than healthy participants (104 ± 40 g/m² vs 61 ± 10 g/m² in men and 89 ± 33 g/m² vs 47 ± 7 g/m² in women; P <0.0001 for both). Notably, however, LV mass index was within the normal range in 20% of patients with HCM and only moderately elevated in 16%. Multivariate analysis revealed that male sex and outflow obstruction were independent predictors of increased LV mass index (P <0.001 for both). Increased maximal wall thickness and increased LV mass index were weakly, but significantly, correlated. Patients who died from HCM had a higher mean LV mass index than those who survived (P = 0.02). Sensitivity for prediction of HCM-related mortality was 100% for increased LV mass index (>91 g/m² in men and >69 g/m² in women) and 90% for maximal LV wall thickness >30 mm. The authors suggest that, contrary to popular belief, the presence of increased LV mass is not required for a diagnosis of HCM to be made.