Impact of disproportionality in severe secondary mitral regurgitation according to disease etiology

Aims Disproportionality in secondary mitral regurgitation (MR) provides insight into MR quantification in transcatheter edge-to-edge repair (TEER) candidates. Although secondary MR has two major etiologies, ischemic cardiomyopathy (ICMP) and dilated cardiomyopathy (DCMP), distinguishing analysis between these two etiologies has been insufficient. We sought to determine the prognosis of disproportional MR in each disease etiology and analyze the baseline characteristics. Methods and results From 2009 to 2019, in Samsung Medical Center, South Korea, 207 patients with severe secondary MR (median age 69 years old, median left ventricular ejection fraction [LVEF] 27.3%) were collected. The cut-off point for disproportional MR was the median value of regurgitant volume (RV)/left ventricular end-diastolic volume (LVEDV), which was 0.17. The primary endpoint was all-cause death. In this study, we analyzed 1) the prognosis of severe secondary MR based on proportional and disproportional MR and 2) the prognosis of disproportional MR based on etiology of dilated cardiomyopathy or ischemic cardiomyopathy. In survival analysis, the disproportional MR group had a worse prognosis in all-cause death (hazard ratio [HR] 2.013, 95% CI [1.254 - 3.230], log-rank p -value = 0.004). In subgroup analysis based on etiology, the disproportional MR group showed a significantly higher risk of all-cause death (HR 3.493, 95% CI [1.457 - 8.375], log-rank p -value = 0.005) in DCMP. On the other hand, there was no significant difference in all-cause death according to disproportionality in ICMP. Conclusion In severe secondary MR, disproportional MR has a worse prognosis than proportional MR due to age and comorbidities, and this difference is more prominent in DCMP than ICMP.