The right ventricle as the Achilles' heel: tricuspid regurgitation and right heart failure in the era of mechanical circulatory support

Across the mechanical circulatory support (MCS) spectrum, from temporary devices in acute cardiogenic shock to durable left ventricular assist devices, the right ventricle (RV) and tricuspid valve are often underestimated determinants of outcome. This narrative review centers on the RV–tricuspid unit across advanced heart failure and cardiogenic shock, with MCS—temporary and durable and left-, right-, or biventricular—as its principal setting; transcatheter tricuspid trials conducted largely outside MCS are used as the best available causal evidence on whether correcting tricuspid regurgitation changes symptoms and events, and are explicitly distinguished from MCS-specific observational data. Three fields have advanced largely in isolation: transcatheter tricuspid intervention, right ventricular failure risk stratification, and mechanical support of the failing right heart. This review synthesizes the pathophysiology of the RV–tricuspid unit and its prognostic role in durable LVAD therapy and acute shock. It appraises the arrival of transcatheter tricuspid repair and replacement and the limits of the supporting evidence. It also confronts three persistent controversies: concomitant tricuspid surgery at LVAD implantation, the split between symptom and survival benefit after tricuspid intervention, and the timing of right ventricular support. Throughout, we distinguish established evidence from reasonable inference and untested hypothesis. We propose a unified, RV-first framework (assess the unit, stage the ventricle, time the intervention) that recasts these controversies as testable hypotheses, and we present its treatment triggers as research propositions for stage-stratified trials rather than as validated clinical recommendations.