Independent Prognostic Value of Functional Mitral Regurgitation in Patients With Heart Failure. A Quantitative Analysis of 1256 Patients With Ischaemic and Non-Ischaemic Dilated Cardiomyopathy
What is the prognostic value of functional mitral regurgitation (MR) in patients with heart failure (HF)?
Patients with HF due to ischemic and nonischemic dilated cardiomyopathy (DCM) were retrospectively recruited. The clinical endpoint was a composite of all-cause mortality and hospitalization for worsening HF. Functional MR was quantitatively determined by measuring vena contracta or effective regurgitant orifice or regurgitant volume. Severe functional MR was defined as effective regurgitant orifice >0.2 cm2 or regurgitant volume >30 ml or vena contracta >0.4 cm. Restrictive mitral filling pattern was defined as E-wave deceleration time <140 ms.
The study population comprised 1,256 patients (mean age 67 ± 11 years; 78% male) with HF due to DCM: 27% had no functional MR, 49% had mild to moderate functional MR, and 24% had severe functional MR. There was a powerful association between severe functional MR and prognosis (hazard ratio [HR], 2.0; 95% confidence interval [CI], 1.5-2.6; p < 0.0001) after adjustment of left ventricular (LV) ejection fraction and restrictive mitral filling pattern. The independent association of severe functional MR with prognosis was confirmed in patients with ischemic DCM (HR, 2.0; 95% CI, 1.4-2.7; p < 0.0001) and nonischemic DCM (HR, 1.9; 95% CI, 1.3-2.9; p = 0.002).
In a large patient population, quantitatively defined functional MR was strongly associated with the outcome of patients with HF, independent of LV function.
Functional MR is a common finding among patients with ischemic or nonischemic DCM and HF. Previous smaller studies have suggested a strong association between functional MR and adverse outcome, confirmed in this larger study that used quantitative means to assess MR severity. Although the study demonstrated an association between MR and outcome that was independent of LV ejection fraction and restrictive filling pattern, both measures are affected by MR; it remains open to question whether functional MR is a marker of a worse ventricle, or is the primary cause of poor outcome. More importantly, a prospective randomized study would be necessary to determine whether intervention for functional MR affects outcome.
Keywords: Myocardial Ischemia, Ventricular Function, Left, Mitral Valve Insufficiency, Systole, Deceleration, Prognosis, Biological Markers, Heart Failure, Stroke Volume, Confidence Intervals, Ventricular Dysfunction, Left, Heart Ventricles, Cardiomyopathy, Dilated
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