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RV Function in Ischemic Cardiomyopathy
Study Questions:
What is the association between mitral regurgitation (MR) and right ventricular ejection fraction (RVEF) in ischemic cardiomyopathy?
Methods:
The study cohort was comprised of 588 patients with ischemic cardiomyopathy who underwent cardiac magnetic resonance imaging (MRI) (mean age 63 ± 11 years; 75% male; 57% had a history of hypertension, 55% had a history of hyperlipidemia, 52% had a history of prior revascularization, and 40% had a history of diabetes mellitus). In the analysis assessing predictors of RVEF, the study authors only included patients who had an echocardiogram within 6 months of the cardiac MRI. The study authors assessed baseline characteristics, left ventricular ejection fraction (LVEF), severity of MR, treatment modality, scar burden, and RVEF. They utilized Cox proportional hazards and multivariable linear regression models to assess the association between RVEF and mortality and MR and RVEF, respectively.
Results:
The study investigators found that MR severity was independently associated with RVEF, after adjusting for age, gender, LVEF, right bundle branch block (RBBB), and RV scar—the RVEF in patients with significant MR (effective regurgitant orifice [ERO] >0.2) was significantly lower than in patients with less MR (39% vs. 46%, p < 0.001). During the median follow-up period of 5.7 years, there were 240 deaths. And there was a 17% risk of mortality (p = 0.008) for every 10% decrease in RVEF, after multivariable adjustment. Although decreasing RVEF was associated with a poor prognosis in the non-repair group (hazard ratio [HR], 1.28 [1.12-1.47]; p < 0.001), it was not associated with death in the mitral valve (MV) repair or replacement group (p for interaction 0.046). In those who did undergo MV surgery, decreasing RVEF was no longer significantly associated with increased mortality (adjusted HR, 0.90 [0.71-1.13]; p = 0.354). The patients who underwent MV surgery were slightly older (mean age 65 vs. 62 years, p = 0.016), had a significantly lower mean RVEF (39% vs. 44%, p = 0.004), and mean LVEF (22% vs. 25%, p = 0.006), and had a higher mean ERO (0.28 vs. 0.12, p < 0.001). The patients who underwent MV repair or replacement also were more likely to undergo coronary revascularization with percutaneous coronary intervention or coronary artery bypass grafting (86% vs. 51%, p < 0.001). There was no significant difference in the two groups in terms of LV scar (p = 0.25) and RV scar (p = 0.71).
Conclusions:
The authors concluded that MR severity was found to be an independent predictor of RVEF, as were RBBB, LVEF, and the presence of RV scar. Decreasing RVEF is associated with increased mortality in patients with ischemic cardiomyopathy; however, this association may be mitigated in patients who undergo MV repair or replacement.
Perspective:
This retrospective study suggests that MR is an independent predictor of RV function and the latter was associated with increased mortality. More importantly, MV repair or replacement mitigated this increased mortality. It is unclear whether sleep apnea or coronary revascularization contributed to RV dysfunction and consequently to mortality. Prospective studies are needed to validate the important findings of this study.
Keywords: Bundle-Branch Block, Cardiac Surgical Procedures, Cardiomyopathies, Diagnostic Imaging, Echocardiography, Heart Failure, Hypertension, Magnetic Resonance Imaging, Mitral Valve Insufficiency, Myocardial Revascularization, Stroke Volume, Ventricular Function, Right
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