Right Ventricular and Pulmonary Computed Tomography Assessments in Paradoxical Low-Flow Low-Gradient Aortic Stenosis Undergoing Transcatheter Aortic Valve Replacement

Abstract

BackgroundPatients with paradoxical low-flow low-gradient aortic stenosis (pLFLG AS) have high mortality and a high degree of transcatheter aortic valve replacement (TAVR) futility. Computed tomography (CT) enables accurate simultaneous right ventricular (RV) and parenchymal lung disease evaluation, which may provide useful objective markers of AS severity, concomitant pulmonary comorbidities, and TAVR improvement. However, the prevalence of RV dysfunction and its association with pulmonary disease in pLFLG AS are unknown. The study objective was to test the hypothesis that pLFLG AS patients undergoing TAVR have decreased RV function without a significant parenchymal lung disease. MethodsBetween August 2016 and March 2020, 194 consecutive AS patients completed high-resolution CT imaging for TAVR evaluation. Subjects were stratified based on echocardiographic criteria as the study group, pLFLG (n = 27), and 2 consecutive control groups: classic severe, normal-flow, high-gradient (n = 27) and normal-flow, low-gradient (NFLG) (n = 27) AS. Blinded biventricular function and lung parenchymal disease assessments were obtained by high-resolution CT imaging. ResultsPatient demographics were similar between groups. pLFLG AS had a lower RV ejection fraction (49 ± 10%) than both classic severe (58 ± 7%, p < 0.001) and NFLG AS (55 ± 65%, p = 0.02). There were no significant differences on lung emphysema (p = 0.19), air fraction (p = 0.58), or pulmonary disease presence (p = 0.94) and severity (p = 0.67) between groups. ConclusionspLFLG AS patients have lower RV ejection fraction than classic severe and NFLG AS patients in the absence of significant parenchymal lung disease on CT imaging. These findings support the direct importance of RV function in the pathophysiology of aortic valve disease.