Epidemiology and prognostic impact of FMR
FMR is one of the most common valvular diseases in the developed world, with an incidence in the United States estimated less than 1% before age 55 years but rising to 9.3% in those greater than 75 years of age.18 Moreover, approximately 20-35% of patients after AMI have ischemic MR (IMR) that is considered to be clinically meaningful, and in up to 50% in patients with HF of either ischemic (>70% cases) or non-ischemic origin.2-6The prevalence of symptomatic HF is estimated to range from 1-2% in the general European population.19 Moderate/severe MR is common after HF and AMI, which was reported in 16-43% of patients.20-23 In China, 4 million people had been estimated to be living with HF and by 2030 the country is estimated to have over 23 million patients with AMIs each year (nearly 3 times as many as those in 2010).24-26 In HF and AMI cohorts, moderate or severe FMR affects up to 30% of patients.25,26 Given an aging population and lifestyle changes that are associated with increases in hypertension, body mass index, and metabolic syndrome, combined with improved survival of patients with coronary artery disease, the burden of FMR is expected to increase substantially in China.27
Closely related to poor prognosis, FMR is an independent predictor of mortality with more than 2.5 times higher than that of community patients.6 In patients with ischemic cardiomyopathy, the presence of MR of any grade results in worse long-term prognosis while severe IMR is even an indicator of short-term mortality. In a retrospective study of 4005 ST-segment elevation myocardial infarction (STEMI) patients in the United States, 9.5% of them presented with moderate/severe FMR. The 1-year mortality rates of moderate, moderate-severe, and severe FMR were 20.8%, 37.4%, and 37.1%, respectively.28 In another hospital-based cohort in Japan, among a total of 1701 symptomatic HF patients while 104 FMR patients (who had moderate to severe FMR) and 1597 non-FMR patients (who had no or mild FMR) were compared, Kaplan–Meier curves and Cox regression analysis revealed that significant FMR was associated with higher incidence of all-cause death, cardiovascular death, and repeated admissions for HF.29 An effective regurgitant orifice area (EROA) >20 mm2 has also been shown to be a predictor of adverse outcomes in patients with FMR. In an observational study in Europe, 138 adult patients were subjected to echocardiography evaluation after AMI whereas moderate/severe MR was found in 70% of patients.30 Five-year mortality in patients with moderate/severe FMR were higher than that in those with mild FMR, while mortality in patients with EROA≥20 mm2was also higher than that in those with EROA <20 mm2.30 In another multivariable analysis that included parameters such as LV volume, LV ejection fraction (LVEF), renal function, etc., FMR was an independent predictor of adverse prognosis.9