Incremental prognosis by left atrial functional assessment: The left atrial coupling index in patients with floppy mitral valves

Abstract

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 LAC I≥ 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 ( Fig. 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