More Evidence for Early Surgery for Asymptomatic Primary Mitral Regurgitation

Authors: Borer JS., J Am Coll Cardiol 2014 Jun 10; 63:2408

A Korean registry study provides valuable long-term outcomes data in a large cohort, although important limitations constrain its impact on clinical practice.

Management of severe primary (degenerative) mitral regurgitation (MR) in asymptomatic patients with preserved left ventricular function is controversial. Current U.S. and European guidelines differ on whether to recommend surgery when repair is likely or to pursue a watchful-waiting strategy. To address this disagreement, investigators used registry data to compare outcomes in 235 patients undergoing early surgery and 375 patients treated conventionally at two centers in Korea between 1996 and 2009. All patients (mean age, 50; 60% men) had severe MR, defined as an effective regurgitant orifice area greater than 0.4 cm2.

The rate of repair (vs. replacement) in the early-surgery group was 94%, compared with 82% in the 26% of conventional-treatment patients who underwent late surgery (mean, 4.4 years after enrollment). With a median follow-up of about 8 years, estimated 12-year mortality was 9% in the early-surgery group and 12% in the conventional-treatment group, a nonsignificant difference. The estimated 12-year rate of cardiac events — a composite of operative mortality, cardiac death, repeat surgery, and hospitalization for heart failure — was significantly higher in the conventional-treatment group than in the early-surgery group (18% vs. 5%). In a propensity-score analysis involving 207 matched pairs of patients with similar baseline characteristics, cardiac mortality was significantly lower with early surgery than with conventional treatment (1% vs. 6%). In subgroup analysis, this difference persisted only in patients aged greater than 50.

Comment

These results support findings from smaller studies suggesting that early surgical repair is associated with reduced late cardiac mortality and cardiac events. Nonetheless, as an editorialist notes, this study suffers from the general limitations of observational comparisons as well as specific limitations related to the adequacy of follow-up in the conventional-treatment group and between-group differences in the use of drug therapy. In the absence of a randomized trial, this study moves the needle slightly further toward early surgery.