Non-invasive right ventricular myocardial work in patients with significant tricuspid regurgitation: association with etiology and outcome

Background/Introduction Right ventricular (RV) function is a key factor in risk stratification of patients with tricuspid regurgitation (TR). Right ventricular myocardial work (RVMW) has been proposed as a novel echocardiographic method to assess RV function, integrating myocardial deformation and afterload. However, data on its application in patients with significant TR, particularly in relation to long-term outcomes, remain limited. Purpose To evaluate RVMW parameters in patients with significant TR in relation to etiology and outcome. Methods Patients with significant (at least moderate-to-severe) secondary TR (STR) diagnosed between 2000 and 2016 were included. Patients without sinus rhythm or with a triangular-shaped early-peaking TR jet at the index echocardiography were excluded to ensure reliable measurements. Patients were classified as having atrial or ventricular STR according to current definitions. RVMW was calculated from RV pressure-strain loops, combining RV longitudinal strain and echo-estimated pulmonary artery pressure. Four RVMW parameters were assessed: RV global constructive work (RVGCW), RV global work index (RVGWI), RV global wasted work (RVGWW), and RV global work efficiency (RVGWE). The study endpoint was all-cause mortality. Results A total of 344 patients were included. Patients with atrial STR (n=69) showed significantly lower RVGWW and higher RVGWE than those with ventricular STR (n=275) (38.0 [21.0-61.0] vs 68.0 [37.0-122.5] mmHg%, P<0.001; 94 [90-96] vs 88 [80-93]%, P<0.001, respectively) (Figure 1). In contrast, RVGWI and RVGCW were comparable between the two etiologies (593.9±182.7 vs 532.3±258.6 mmHg%, P=0.06; 692.5±191.8 vs 667.9±289.3 mmHg%, P=0.50, respectively). During a median follow-up of 7.5 (IQR: 2.5-10.3) years, all-cause death occurred in 161 patients. Restricted cubic spline analyses identified cut-off values of 41 mmHg% for RVGWW and 90% for RVGWE, where the risk of all-cause death began to increase consistently. Patients with RVGWW≥41 mmHg% and RVGWE<90% had significantly higher all-cause mortality (Log-rank P<0.001 for both) (Figure 2). After adjusting for potential confounders based on univariate Cox regression analysis, both RVGWW≥41 mmHg% and RVGWE<90% remained independently associated with poor prognosis (adjusted HR [95%CI]: 1.94 [1.25-3.00], P=0.003, and 1.55 [1.02-2.35], P=0.04, respectively), whereas conventional indices of RV dysfunction such as TAPSE<17 mm and FAC<35% were not independently associated with all-cause death (adjusted HR [95%CI]: 1.14 [0.76-1.71], P=0.54, and 1.01 [0.67-1.52], P=0.95, respectively). Conclusions In patients with significant STR, RVMW parameters, specifically RVGWE and RVGWW, are more impaired in patients with ventricular etiology and are associated with worse outcome. In these patients, where the RV is subject to increased workload, loss of efficiency and increased wasted work may be useful for improving risk stratification.