Right Ventricular–Pulmonary Artery Coupling by TAPSE/PASP in Tricuspid Regurgitation: A Narrative Review

Severe tricuspid regurgitation (TR) is increasingly recognized as an independent determinant of morbidity and mortality, and the rapid growth of transcatheter tricuspid valve interventions (TTVIs) has created an urgent need for reliable tools to identify patients who will benefit from treatment before right ventricular (RV) decompensation becomes irreversible. Right ventricular–pulmonary artery (RV–PA) coupling, most commonly estimated non-invasively as the ratio between tricuspid annular plane systolic excursion (TAPSE) and pulmonary artery systolic pressure (PASP), has been proposed as a pragmatic candidate surrogate for the invasive end-systolic elastance/effective arterial elastance (Ees/Ea) ratio and has been associated with adverse outcomes in observational cohorts of conservatively managed, transcatheter-treated and surgically treated patients with TR, with modest discrimination where reported and cutoffs ranging widely (approximately 0.26–0.49 mm/mmHg). However, the correspondence between TAPSE/PASP and invasive Ees/Ea has so far been demonstrated only in pulmonary hypertension and has not been shown in TR, where the ratio is applied by extrapolation. Evidence was identified by a structured narrative search. This narrative review synthesizes the pathophysiological rationale for RV–PA coupling in TR, summarizes the prognostic evidence from medical, transcatheter and surgical cohorts, and critically examines the central methodological limitation of the construct: the unreliability of Doppler-derived PASP as TR severity increases, sometimes referred to as the “denominator problem”, compounded by the tendency of severe TR to amplify TAPSE itself by increasing the systolic excursion of the tricuspid annulus. We then review the growing family of alternative and multiparametric coupling indices—strain-based ratios, three-dimensional echocardiographic and cardiac magnetic resonance (CMR) surrogates, and composite morphology–load–function scores—that have been proposed to overcome these limitations, and we discuss the hypothesis-generating suggestion that RV–PA coupling might, beyond prognosis, help to identify patients who benefit most from intervention, which currently rests on a single retrospective propensity-matched analysis. We conclude by outlining the principal research gaps that must be addressed before RV–PA coupling can be safely incorporated into routine clinical decision pathways for TR.