Predicting outcome in patients with asymptomatic mitral regurgitation

Enriquez-Sarano M et al. (2005) Quantitative determinants of the outcome of asymptomatic mitral regurgitation. New Engl J Med 352: 875–883

The timing of surgery in asymptomatic patients with mitral regurgitation is a matter of debate, not least because high-risk subgroups are poorly defined. A new study by Enriquez-Sarano et al. has examined the effect of quantitative grading of patients with this condition.

A total of 456 patients with asymptomatic, organic mitral regurgitation and ejection fraction higher than 50% were included in this prospective study. Participants were divided into three groups according to the effective regurgitant orifice (<20 mm², 20–39 mm², and ≥40 mm²). The mean duration of follow-up was 2.7 years for those managed medically, and 5.1 years for those who also underwent surgical treatment.

Age, diabetes and increasing effective regurgitant orifice emerged as independent determinants of survival. Those with an effective regurgitant orifice of 40 mm² or above were at almost three times the risk of death compared with those with an orifice of less than 20 mm² (adjusted risk ratio 2.90, 95% CI 1.33–6.32, P <0.01). In addition, the risk of cardiac events and of death from cardiac causes were each increased more than fivefold in these patients; furthermore, survival was significantly better in those who underwent cardiac surgery than in those who did not (adjusted risk ratio 0.28, 95% 0.14–0.55, P <0.01).

The study clearly illustrates the benefits of quantitative grading of patients with mitral regurgitation. Because those with an effective regurgitant orifice of 40 mm² or above are at increased risk of cardiac events and death, and appear to benefit considerably from surgery, the authors advise that these patients “should promptly be considered for cardiac surgery”.