BackgroundFunctional tricuspid regurgitation (FTR) is common in left-sided heart pathology involving the mitral valve. The incidence, clinical impact, risk factors, and natural history of FTR in the setting of ischemic mitral regurgitation (IMR) are less known.MethodWe conducted a cohort study based on data collected from January 2012 to December 2014. Patients diagnosed with IMR were eligible for the study. The median follow-up was 5 years. The primary outcome is defined as FTR developing at any stage.ResultsAmong the 134 IMR patients eligible for the study, FTR was detected in 29.9% (N = 40, 20.0% mild, 62.5% moderate, and 17.5% severe). In the FTR group, the average age was 60.7 ± 9.2 years (25% females), the mean LV ejection fraction (LVEF) was 37.3 ± 6.45 [%], LA area 46.4 ± 8.06 (mm2), LV internal diastolic diameter (LVIDD) 59.6 ± 3.94 (mm), RV fractional area change 22.3 ± 4.36 (%), systolic pulmonary artery pressure (SPAP) 48.4 ± 9.45 (mmHg). Independent variables associated with FTR development were age ≥ 65y [OR 1.2], failed revascularization, LA area ≥ 42.5 (mm2) [OR 17.1], LVEF ≤ 24% [OR 32.5], MR of moderate and severe grade [OR 419.4], moderate RV dysfunction [OR 91.6] and pulmonary artery pressure of a moderate or severe grade [OR 33.6]. During follow-up, FTR progressed in 39 (97.5%) patients. Covariates independently associated with FTR progression were lower LVEF, RV dysfunction, and PHT of moderate severity. LA area and LVIDD were at the margin of statistical significance (p = 0.06 and p = 0.05, respectively).ConclusionIn our cohort study, FTR development and progression due to IMR was a common finding. Elderly patients with ischemic MR following unsuccessful PCI are at higher risk. FTR development and severity are directly proportional to LV ejection fraction, to the extent of mitral regurgitation, and SPAP. FTR tends to deteriorate in the majority of patients over a mean of 5-y follow-up.