Functional Mitral Regurgitation in HFrEF
Does medical management alter the severity of functional mitral regurgitation (FMR) and its prognosis in patients who have heart failure with reduced ejection fraction (HFrEF)?
The study cohort was comprised of 163 consecutive HFrEF patients (left ventricular EF [LVEF] <40%) who were followed-up in the HF clinic at the Antwerp University Hospital, Belgium, between January 2007 and December 2013. The extent of FMR was assessed at baseline and after a median follow-up period of 50 months in this cohort. The study investigators defined severe FMR as MR grade 3-4. All of the patients received the maximal tolerable doses of their HF medications. The primary study endpoint was freedom from major adverse cardiac events (MACE) defined as a composite of all-cause death, the need for cardiac transplantation, and hospitalization for HF or malignant arrhythmias.
At baseline, 31% of the cohort (n = 50) had severe MR. During the follow-up period, 38% of the severe FMR patients showed an improvement to nonsevere FMR (MR grade <3), whereas 18% of the nonsevere FMR patients developed severe FMR despite optimal HF treatment. Ninety-two patients who had nonsevere FMR at the time of inclusion remained nonsevere (period between both echocardiograms, 1,441 days). Twenty-one patients had nonsevere FMR at baseline, but deteriorated to severe FMR (period between both echocardiograms, 1,400 days). Nineteen patients had severe FMR at baseline and improved to nonsevere FMR (period between both echocardiograms, 1,501 days). Thirty-one patients had severe FMR at the time of inclusion and maintained a severe FMR (period between both echocardiograms, 1,060 days). Cox regression analysis revealed that the presence of sustained severe FMR or worsening of FMR was the most important independent prognostic determinant with an adjusted odds ratio of 2.5 (95% confidence interval, 1.5-4.3; MACE 83% vs. 43%). In addition, those patients showed a 13% increase in LV end-diastolic volume index (LVEDVI), whereas the patients with improvement in their severe MR showed a 2% decrease in LVEDVI (p = 0.01).
The authors concluded that severe FMR was successfully treated with medication in almost 40% and was associated with prevention of LV adverse remodeling and with an improved long-term prognosis.
This is an important study because it suggests that medical therapy can ameliorate severe MR, suggesting that surgery should be considered only after guideline-directed medical therapy is not successful in doing so. The findings of this study should be evaluated in a larger cohort, particularly because the natural history of FMR is variable.
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