Twenty-Five-Year Follow-Up of Quantified Mitral Regurgitation.

Abstract

IMPORTANCE: Current guidelines recommend consideration of surgical treatment for asymptomatic patients with severe mitral valve regurgitation, but the long-term prognosis and optimal treatment of those with moderate mitral regurgitation (MR) remain uncertain. OBJECTIVE: To evaluate the long-term prognostic value of baseline MR severity and the association of surgery with survival outcomes in asymptomatic patients. DESIGN, SETTING, AND PARTICIPANTS: This was a prospective cohort study with extended follow-up among 449 asymptomatic patients with holosystolic degenerative MR enrolled between January 1991 and November 2000 and followed up with through May 2025 (median [IQR] follow-up, 26 [14-29] years; maximum, 34 years) at a single tertiary referral center (the Mayo Clinic, Rochester, Minnesota). EXPOSURE: Baseline MR severity quantified by effective regurgitant orifice area (ERO). Patients were monitored under medical therapy and, when applicable, after subsequent surgical correction. MAIN OUTCOMES AND MEASURES: All-cause mortality, assessed according to baseline ERO using Cox proportional hazards models adjusted for cardiovascular risk factors. RESULTS: Among the 449 patients included, the mean (SD) age was 64 (14) years, and 278 participants (62%) were male. At baseline, 127 patients (28%) had ERO <20 mm2, 128 (28%) had ERO 20-39 mm2, and 194 (43%) had ERO ≥40 mm2. During follow-up, 254 patients (57%) underwent mitral valve surgery. Ten-year cumulative incidence of surgery was 18% for ERO <20 mm2, 64% for 20-39 mm2, and 88% for ≥40 mm2. Survival of medically treated patients declined progressively with increasing ERO category (5-year rate: 88% [<20 mm2], 72% [20-39 mm2], and 55% [≥40 mm2]; P = .01), and multivariable analysis confirmed the incremental risk of higher ERO on a continuous scale (adjusted hazard ratio per IQR increase, 2.53; 95% CI, 1.30-4.93; P = .01). When extending the analysis through subsequent surgical follow-up, the survival difference between patients who did vs did not undergo operation widened with ERO (χ23 = 8.4; interaction P = .04), starting at values above 30 mm2. CONCLUSIONS AND RELEVANCE: In this 25-year follow-up cohort study, increasing ERO was associated with an increase in risk of mortality under medical therapy. Patients with upper-moderate MR (ERO 30-39 mm2) at baseline demonstrated a significant association between surgical treatment and improved long-term survival.