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

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.

To evaluate the long-term prognostic value of baseline MR severity and the association of surgery with survival outcomes in asymptomatic patients.

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).

Baseline MR severity quantified by effective regurgitant orifice area (ERO). Patients were monitored under medical therapy and, when applicable, after subsequent surgical correction.

All-cause mortality, assessed according to baseline ERO using Cox proportional hazards models adjusted for cardiovascular risk factors.

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.

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.