Disproportionate Left Ventricular Enlargement in Mitral Valve Prolapse: Prevalence, Predictors, and Association With Outcomes.

Background: Left ventricular (LV) end-systolic enlargement in severe degenerative mitral-regurgitation (MR) is a class I surgical trigger. Whether it occurs disproportionately to less-than-severe MR due to mitral valve prolapse and is associated with mortality are unknown. We aimed to analyze prevalence and association with survival of disproportionate LV enlargement in less-than-severe MR.

Methods: A multicenter cohort international study enrolled 2848 consecutive patients (52% women, 69±16 years) with degenerative MR prospectively quantified and graded mild or moderate. Primary end point was survival under medical management. Secondary outcome was survival throughout follow-up stratified by performance of early mitral surgery within 3 months postdiagnosis.

Results: Among LV remodeling parameters (abnormal end-diastolic diameter, LV end-systolic diameter [LVESD] absolute and indexed), LVESD ≥40 mm (present in 12.4%) was the sole independent associate of reduced survival (5-year 70±3 versus 76±9%; =0.009). LVESD ≥40 mm was independently linked to larger body surface area, effective regurgitant orifice, and left atrium, and to male sex and diabetes. With multivariable comprehensive adjustment, LVESD ≥40 mm (adjusted hazard ratio [aHR], 1.25 [95% CI, 1.005-1.53]; =0.04) remained associated with excess mortality under medical management, even after adjustment for lowered ejection fraction (aHR, 1.49 [95% CI, 1.13-1.95]; =0.004) and in all patient subsets. Among patients with moderate degenerative MR and LVESD ≥40 mm, 22% underwent mitral surgery within 3 months, which was associated with superior survival, even after comprehensive adjustment (aHR, 0.11 [95% CI, 0.005-0.51]; =0.002).

Conclusions: Disproportionate LV enlargement in patients with less-than-severe degenerative MR is common, particularly with larger bodies, regurgitation, and overall cardiac remodeling. LVESD ≥40 mm is associated with worse survival independent of all baseline characteristics, even lowered ejection fraction, and represents a marker for risk stratification of patients who are generally not yet considered for medical or surgical/interventional treatment.