To define the incremental prognostic value of the left atrial coupling-index (LACI), calculated as ratio of left atrial volume-index (LAVI) to Tissue-Doppler-Imaging a’ (TDI-a’), in a large cohort of patients with isolated floppy mitral valve (FMV).

All consecutive 4792 patients (61±16 years, 48% women) with isolated FMV in sinus rhythm diagnosed at Mayo Clinic 2003-2011, comprehensively characterized and with prospectively measured LAVI and TDI-a’ in routine practice, were enrolled and their long-term survival analyzed.

Overall LACI was 5.8±3.7 and was <5 in 2422 vs. ≥5 in 2370. LACI was independently higher with older age, more mitral regurgitation and with diastolic and systolic left-ventricular (LV) dysfunction (all P≤0.0001). At diagnosis higher LACI was associated with more severe presentation (P≤0.0001) independently of age, sex, comorbidity-index, ventricular function and MR-severity. During 7.0±3.0 years follow-up, 1146 underwent mitral-valve surgery (94% repair-6% replacement) and 880 died, 780 under medical management. In spline-curve analysis LACI≥5 was identified as threshold for excess-mortality, with much reduced 10-year survival under medical management (60±2% vs. 85±1% for LACI <5, P<0.0001), even after comprehensive adjustment (adjusted-hazard-ratio 1.30[1.10–1.53] for LACI≥5, P=0.002). Association of LACI≥5 with higher mortality persisted, stratifying by mitral-regurgitation severity of LA enlargement grade (all P<0.001). Nested-models confirmed LACI incremental prognosis (P<0.0001) with net-reclassification-improvement vs. LAVI 0.21±0.02, P<0.0001 (Figure 1).

LA functional assessment by LACI is strongly, independently and incrementally determinant of outcome, demonstrating the crucial importance of LA functional response to the mitral valve disease, achievable using conventional Doppler-echocardiographic measurements