The effect of exercise on RV-PC coupling in asymptomatic patients with significant primary mitral regurgitation

Abstract Background Right ventricular–pulmonary circulation (RV-PC coupling) serves as an index to evaluate RV function in relation to underlying RV afterload. Although impaired RV-PC coupling has been proposed as a predictor of adverse outcomes in heart failure (HF) patients with secondary mitral regurgitation (MR), there is limited data available for patients with primary MR. Purpose The objective of this study was to assess and compare alterations in RV-PC coupling during exercise with bicycle stress echocardiography in individuals with asymptomatic moderate to severe primary MR (MR group) and normal subjects (Control group). Μethods All patients and controls underwent stress echocardiography with a supine bicycle. RV systolic function was evaluated with TAPSE and S’. The non-invasively measured RV-PC coupling was evaluated by indexing TAPSE and S’ to right ventricular systolic pressure (RVSP) during baseline echocardiogram and peak workload stages of bicycle SE. Results Among the 48 patients in the MR group (mean age 53.5±15.16 years, 58.3% female), 39 patients had moderate MR(81.3%), 5 patients had moderate-to-severe MR(10.4%), and 4 patients had severe MR(8.3%). The duration of stress echocardiogram was significantly shorter in the MR group compared to control group (8.11±2.39 min vs 10.5±1.05 min, respectively; p<.001). Left Ventricular Ejection Fraction (LVEF) was within normal limits in both groups {70.7±11.9 % vs 72.6±12.1 %(p=NS} and the dimensions of left ventricular cavity (end-diastolic and end-systolic diameters) were significantly larger in the MR group compared to control group (49.25±5.21 mm vs 45.6±4.08mm (p .016) and 31.81±4.27mm vs 29.07±4.21mm (p .033) respectively}. TAPSE and RVSP increased from baseline to peak dose [23.48 ±3.05mm vs 29.94±3.48mm (p < .001), 8.54±4.56mmHg vs 43.79±5.27mmHg (p < .001), respectively]. There were no significant differences in TAPSE/RVSP and S’/RVSP between the two groups at rest. However, a significantly steady decrease was observed from baseline to peak dose (0.84±0.16 mm/mmHg vs 0.72±0.19mm/mmHg (p <.001) and 0.52±0.11 cm/sec/mmHg vs 0.50±0.15 cm/sec/mmHg (p .004), respectively). Conversely, these parameters did not exhibit a significant decrease in the control group. Finally, there was no significant correlation observed between the changes in the index TAPSE/RVSP , ratio E/E’ and systolic blood pressure. Conclusions RV-PC coupling decreases during exercise in asymptomatic patients with moderate to severe MR, independently of left ventricular dynamic changes. In contrast , there is no significant change in RV-PC coupling observed in the control group. Therefore, future studies should aim to evaluate the incremental role of this novel index not only in the assessment and evaluation of patients with MR but also as a potential prognostic marker.TAPSE/RVSP GraphTable of echocardiographic measurements