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Quantitation of Degenerative Mitral Regurgitation
Study Questions:
Does echocardiographic quantitation of degenerative mitral regurgitation (MR) severity performed in routine clinical practice by multiple practitioners independently predict long-term survival?
Methods:
Patients diagnosed with isolated mitral valve prolapse between 2003 and 2011 at the Mayo Clinic in Rochester, MN, with any degree of MR quantified by any physician/sonographer in routine clinical practice were included in a retrospective analysis. Clinical/echocardiographic data acquired at diagnosis were retrieved electronically. MR severity was assessed for a relationship with outcome, with an endpoint of mortality during medical treatment analyzed by Kaplan-Meier method and proportional-hazard models.
Results:
The study cohort included 3,914 patients (55% male) aged 62 ± 17 years, with left ventricular ejection fraction (LVEF) 63 ± 8% and effective regurgitant orifice area (EROA) 19 [0–40] mm2. During follow-up (6.7 ± 3.1 years), 696 patients died during medical management and 1,263 underwent mitral surgery. In multivariate analysis, EROA was associated with mortality (adjusted hazard ratio, 1.19 [1.13–1.24]; p < 0.0001 per 10 mm2) independent of LVEF and end-systolic diameter, symptoms, age, and comorbidities. The association between routinely measured EROA and mortality persisted with competitive risk modeling (adjusted hazard ratio, 1.15 [1.10–1.20] per 10 mm2; p < 0.0001); in patients without guideline-based indications for intervention (adjusted hazard ratio, 1.19 [1.10–1.28] per 10 mm2; p < 0.0001); and in all other subgroups examined, including end-systolic diameter <40 mm or ≥40 mm, and LVEF ≥60% or <60% (all p < 0.01). Spline curve analysis showed that, compared with mortality in a general population, excess mortality was apparent with moderate degenerative MR (EROA ≥20 mm2) and steadily increased with higher EROA levels.
Conclusions:
The authors concluded that the echocardiographic quantitation of degenerative MR is scalable to routine practice, and is independently associated with clinical outcome. Because excess mortality compared to a general population first appears in association with moderate degenerative MR, the authors propose that EROA values should be integrated into therapeutic decisions in addition to categorical grading of MR severity.
Perspective:
Current guidelines recommend the quantitation of MR, with an integrative approach in the overall assessment of MR severity. The group at the Mayo Clinic previously has published data demonstrating a correlation between the quantitative assessment of degenerative MR severity and all-cause mortality, using a small number of expert readers for the quantitation of MR. This study suggests that the quantitative assessment of degenerative MR severity in routine clinical practice also has independent association with mortality. The quantitative assessment of MR is important and should be more broadly implemented in routine clinical practice. Perhaps the most provocative finding of this study (and past studies from the same group) is the demonstrated association between moderate MR and excess all-cause mortality. Data are lacking as to whether intervention on moderate MR affects mortality, but these findings raise questions regarding thresholds for intervention for degenerative MR.
Keywords: Cardiac Surgical Procedures, Diagnostic Imaging, Echocardiography, Heart Valve Diseases, Mitral Valve Insufficiency, Mitral Valve Prolapse, Stroke Volume, Survival, Ventricular Function, Left
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