LAUSR

Rubbio et al. have retrospectively analyzed a single‐center cohort undergoing MitraClip (Abbott Vascular) to test the hypothesis that right ventricular (RV) function is a significant determinant of survival. Assessment of RV function was performed using RV strain and RV systolic pressure (RVSP) ratio, with a cutoff of 0.36 as determined from prior heart failure studies. Even after adjusting for covariates, TAPSE/PASP ≤ 0.36 predicted 1‐year mortality and hospitalizations with a nearly four‐fold increase in mortality compared to those with better RV function. Assessment of RV function has long been a source of debate for clinicians. Measurement of the ratio of longitudinal RV strain to Doppler estimated pulmonary artery systolic pressure (PASP) is a relatively practical means to evaluate RV function. There have been other measures: pulmonary artery pressure index (PAPi), cardiac magnetic resonance imaging, 2‐dimensional (2D) echocardiographic fractional shortening, RV end‐systolic elastance/arterial elastance ratio, cardiopulmonary exercise testing to just name a few. This illustrates the struggles of measuring RV function as many of the techniques are difficult to implement in daily clinical practice. Therefore, while the concept of RV assessment permeates cardiology, the logistics of measuring and interpreting RV function are clearly more research‐oriented and clinical application remains under utilized. The concept of RV/PA uncoupling was first discussed in the context of pulmonary hypertension but has now been extrapolated to heart failure and valvular heart disease. Resistance of the pulmonary vascular bed can change over time. The challenge for the RV is to remain coupled to afterload and in end‐stage disease, the RV cannot overcome the pulmonary vascular resistance (PVR) resulting in decreasing stroke volume. Loss of RV/PA coupling indicates end‐stage RV failure and the challenge for clinicians is to interpret pulmonary pressures in the context of a dysfunctional RV. Furthermore, can we discriminate patients with primary RV myopathy from end‐stage myopathy from elevated pulmonary pressures? Rubbio et al.'s study is consistent with a broader experience observed in the COAPT study. In this analysis, the same measure of RV/PA coupling in functional mitral regurgitation (MR) patients. RV/ PA uncoupling with a threshold of ≤0.5%/mmHg independently identified patients with an increased hazard for 2‐year mortality (hazard ratio [HR]: 2.57) and finding was consistent in patients randomized to both medical therapy and MitraClip. Given the reproducibility of results, RV/PA coupling is here to stay as a prognostic variable. Ultimately, assessment of RV function and accurate prognostication will be vital to patient selection for surgical and percutaneous procedures. Perhaps there are more sensitive and provocative tests that can further improve prognostication such as the exercise of pharmacologic testing. Certainly, this analysis confirms the unforgiving nature of RV dysfunction and gives hope of improving the process of patient selection.