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Active Surveillance in Severe Asymptomatic MR
Study Questions:
What are the long-term outcomes of patients with asymptomatic severe primary mitral regurgitation (MR) who are followed with active surveillance (“watchful waiting”)?
Methods:
Between 1997-2015, 280 consecutive patients with severe asymptomatic primary MR and left ventricular ejection fraction (LVEF) ≥60%, LV end-systolic diameter <45 mm, and estimated pulmonary arterial systolic pressure ≤50 mm Hg were enrolled in the heart valve clinic follow-up program at a single large medical center. Patients were prospectively followed with clinical and echocardiographic exams every 6 months until Class I or Class IIa surgical criteria were reached. Event-free survival and overall survival compared to the age- and gender-matched general population were assessed.
Results:
During a median potential follow-up of 93.4 months (quartiles 55.3-152.9 months), 161 patients developed an indication for surgery and 13 patients died. Event-free survival rates were 78.0% (95% confidence interval, 73.2-83.2%) at 2 years, 52.2% (46.3-59.0%) at 6 years, 35.5% (29.3-43.1%) at 10 years, and 18.7% (12.3-28.5%) at 15 years. Overall survival was 99.6% (95% confidence interval, 98.9-100%) at 2 years, 94.6% (91.7-97.6%) at 6 years, 85.6% (80.3-91.2%) at 10 years, and 74.5% (66.6-83.4%) at 15 years. Overall survival of patients managed according to an active surveillance strategy was comparable to the expected cumulative survival, and early survival rates were even better in the study population (standardized mortality ratio, 0.667; 95% confidence interval, 0.463-0.963; p = 0.013).
Conclusions:
Patients with severe asymptomatic primary MR may remain free of indications for surgery for extensive periods of time. In such patients, active surveillance performed in experienced centers is associated with a favorable prognosis, resulting in timely referral to surgery, excellent long-term survival, and good surgical outcomes.
Perspective:
Debate continues regarding the mortality of asymptomatic patients with primary MR and no Class I indication for surgery (preserved LV size and systolic function). With no prospective, randomized trials to address the issue, and with some observational data suggesting an increased risk compared to the general population, some clinicians argue for early or ‘prophylactic’ mitral valve repair among such patients, with this view reflected in progressively lower thresholds for mitral repair in American Heart Association/American College of Cardiology valvular heart disease guidelines. This study suggests that, when patients are followed with careful surveillance in a dedicated heart valve clinic, mortality is not different from the general population. Although debate will continue as long as prospective, randomized data are not available, a take-home message from this study may be that outcomes among patients followed with ‘watchful waiting’ might be related to how and by whom those patients are watched.
Keywords: Blood Pressure, Cardiac Surgical Procedures, Diagnostic Imaging, Echocardiography, Heart Valve Diseases, Mitral Valve Insufficiency, Stroke Volume, Survival Rate, Systole, Treatment Outcome, Ventricular Function, Left
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