Right ventricular dysfunction and impaired right ventricular-pulmonary arterial coupling in paradoxical low-flow,...

Paradoxical low-flow, low-gradient aortic stenosis (pLFLG AS) may represent a diagnostic challenge, and its pathophysiology is complex. While left ventricular (LV) systolic function is preserved, right ventricular dysfunction (RVD) and consecutive LV underfilling may contribute to low-flow and reduced stroke volume index, and to adverse outcomes following transcatheter aortic valve implantation (TAVI). The aim of this study was to evaluate the potential role of RVD in pLFLG AS, and to assess the impact of pre-procedural RVD on clinical outcomes after TAVI in patients with pLFLG AS.

Out of 2739 native AS patients, who received TAVI at the University of Cologne Heart Center between March 2013 and June 2021, 114 patients displayed pLFLG AS and were included in this study. Right ventricular (RV) function was assessed by transthoracic echocardiography, and a fractional area change (FAC) ≤35% and/or a tricuspid annular plane systolic excursion (TAPSE) <18 mm determined RVD. In addition, the TAPSE/systolic pulmonary artery pressure ratio (TAPSE/sPAP) was monitored as a measure of RV-pulmonary arterial (PA) coupling. An impaired FAC and TAPSE was present in 21.9% and 45.6% of patients, respectively, identifying RVD in 50.0%. RVD (p = 0.016), reduced FAC (p = 0.049), reduced TAPSE (p = 0.035) and impaired RV-PA coupling (TAPSE/sPAP ratio <0.31 mm/mmHg; p = 0.009) were associated with significantly higher all-cause mortality compared to patients with normal RV function. After adjustment for sex, age, body mass index, EuroSCORE II, previous myocardial infarction and mitral regurgitation, independent predictors for all-cause mortality were FAC, sPAP, TAPSE/sPAP ratio, right atrial area, RV diameter and tricuspid regurgitation.

Adverse RV remodelling, RVD and impaired RV-PA coupling provide an explanation for low-flow and reduced stroke volume index in a subset of patients with pLFLG AS, and are associated with excess mortality after TAVI.