Abstract 9545: Indexing Mitral Regurgitant Volume to Left Ventricular Cavity Size Improves Prognostication of Mortality

Abstract

Background: Indexing mitral regurgitation (MR) regurgitation volume (RVol) for left ventricular (LV) cavity size accounts for concomitant LV remodeling, but whether it improves prognostication of mortality is uncertain. Methods: The ratio of RVol to LV end-diastolic diameter (LVDD) was measured in 399 individuals (mean age 70.1 ±16.4 years, 51.1% female) with any MR (mean RVol 49.2 ± 27.7 mL) undergoing echocardiography (TTE). Individuals with prior mitral valve interventions were excluded. The relationship between RVol/LVDD and all-cause mortality was examined. The incremental predictive value of RVol/LVDD was compared to RVol alone. Results: Over a median (interquartile range) of 8.8 (3.4-10.5) years follow-up, there were 101 deaths (25.3%). Amongst those treated medically (N = 348), a lower ratio was associated with higher mortality (HR per 1-mL/cm decrease, 1.04, 95% CI 1.01-1.10, p = 0.04), despite a lesser degree of MR (low vs. high RVol/LVDD group, mean RVol, 30.3 ± 11.7 mL vs. 68.1 ± 26.3 mL, p < 0.001), with an inflection for increased risk < 8.4 mL/cm ( Figure ). By contrast, amongst those treated surgically (N = 41), no association was observed (p = 0.69) between RVol/LVDD and mortality, though death was less frequent. This association with risk was observed only amongst individuals with a reduced LVEF and was independent of etiology of MR (e.g. secondary vs. primary). Compared to RVol alone, indexing for LV cavity size improved the prognostication of death (p < 0.001). Conclusions: Amongst patients with MR with a reduced LVEF, treated medically, survival was significantly worse amongst individuals with lower RVol/LVDD ratios. Furthermore, indexing for LV cavity size improved prediction of mortality compared to RVol alone. These results overall suggest that RVol should be routinely indexed for LV size to improve prognostication of risk. Moreover, they suggest a threshold may exist where LV size predominates risk in individuals with MR, treated medically.