Prognostic value of cardiac magnetic resonance imaging in patients with aortic regurgitation

Abstract

Evaluation of: Myerson SG, d’Arcy J, Mohiaddin R et al. Aortic regurgitation quantification using cardiovascular magnetic resonance: association with clinical outcome. Circulation 126(12), 1452–1460 (2012). Guidelines on valve replacement recommend aortic valve replacement for patients with severe aortic regurgitation (AR) with symptoms or left ventricular (LV) dysfunction. However, the optimal timing of surgery for asymptomatic AR patients without LV dilation or dysfunction is not known. There are data to suggest that excess volume load imposed by AR may not only produce subclinical LV dysfunction, but produce neurohormonal activation similar to the heart failure syndrome resulting in reduced survival. The study by Myerson et al. is the first to investigate the predictive ability of cardiac MRI (CMR) for the outcome of asymptomatic patients with AR. They studied 113 asymptomatic patients with moderate-to-severe AR on echocardiography in four centers. A total of 39 (35%) patients developed symptoms or an indication for surgery over a mean follow-up period of 2.6 years. AR volume, AR regurgitant fraction, LV end-diastolic and end-systolic volumes had high discriminatory powers (area under curve of 0.96, 0.93, 0.88 and 0.78, respectively) to predict these events. Higher association with the outcome was observed when LV end-diastolic volume and regurgitant fraction were combined. A significantly higher number of patients with regurgitant fraction >33% were likely to progress to surgery compared with patients with a regurgitant fraction of <33% (85 vs 8%; p < 0.001). These results demonstrate a potential role for CMR for risk stratification of patients with asymptomatic moderate or severe AR, given the ability of CMR to accurately quantify AR and LV volumes. Based on the data presented, it is possible that we may be waiting too long to offer surgery in patients with severe AR.