Prognostic implications of right ventricular-pulmonary arterial coupling derived from right ventricular strain in secondary tricuspid regurgitation

Abstract Background Right ventricular (RV)-pulmonary arterial (PA) coupling is a key determinant of prognosis in moderate and severe secondary tricuspid regurgitation (TR), reflecting the complex interplay between RV contractility and afterload. The tricuspid annular plane systolic excursion (TAPSE)/pulmonary artery systolic pressure (PASP) ratio is widely used as a surrogate for RV-PA coupling; however, TAPSE remains an angle- and load-dependent parameter that does not directly assess myocardial contractility. Myocardial deformation indices such as RV free wall longitudinal strain (RVFWLS), provide a less angle- and load-dependent estimation of RV contractility. Purpose This study aimed to evaluate the prognostic utility of the RVFWLS/PASP ratio in secondary TR and determine whether it provides incremental prognostic value beyond the established TAPSE/PASP ratio. Methods A total of 1,007 patients (71 IQR 62-78 years, 51% male) were followed up for the endpoint of all-cause mortality from the date of diagnosis of moderate or severe secondary TR. RVFWLS was evaluated by speckle-tracking echocardiography and the absolute value was indexed to PASP. Results Over a median follow-up of 59 (IQR 19 to 100) months, a total of 564 (56%) patients died. Kaplan-Meier survival analysis revealed a stepwise increase in mortality across RVFWLS/PASP ratio tertiles, with the highest risk observed in the lowest tertile (Figure 1). In a comprehensive, multivariable Cox regression model with adjustment for age, sex, heart failure symptoms, left ventricular ejection fraction, atrial fibrillation, TR effective regurgitant orifice area, renal function, diabetes mellitus and smoking status, the RVFWLS/PASP ratio remained independently associated with all-cause mortality (adjusted HR 1.13 per 0.10 decrease below 0.60, 95% CI 1.07 to 1.19, P0.0001). Spline curve analysis demonstrated that mortality, compared to the general population, was elevated across all RVFWLS/PASP ratios, but the risk increased disproportionately below a ratio of approximately 0.50, suggesting a critical inflection point beyond which further RV-PA uncoupling may substantially worsen outcomes (Figure 2). The LR χ2 test for nested models demonstrated that the RVFWLS/PASP ratio added statistically significant prognostic value to multivariable models including the TAPSE/PASP ratio (P0.0001), while the TAPSE/PASP ratio did not add incremental value to models including the RVFWLS/PASP ratio. Conclusion The RVFWLS/PASP ratio is independently associated with mortality in patients with moderate or severe secondary TR. Importantly, it adds incremental prognostic value over the TAPSE/PASP ratio, highlighting its potential as a more precise non-invasive marker of RV-PA coupling.Figure 1:Kaplan Meier Survival Curves Figure 2:RR vs General Population