Transcatheter Aortic Valve Replacement in Patients With Low-Flow, Low-Gradient Aortic Stenosis: The TOPAS-TAVI Registry

Background: Few data exist on patients with low-flow, low-gradient aortic stenosis (LFLG-AS) undergoing transcatheter aortic valve replacement (TAVR). Also, very scarce data exist on the usefulness of dobutamine stress echocardiography (DSE) before TAVR in these patients. Objectives: The authors sought to evaluate clinical outcomes and changes in left ventricular ejection fraction (LVEF) following TAVR in patients with classical LFLG-AS. Methods: This multicenter registry included 287 patients with LFLG-AS undergoing TAVR. DSE was performed before TAVR in 234 patients and the presence of contractile reserve was defined as an increase of ≥20% in stroke volume. Transthoracic echocardiography was repeated at hospital discharge and at 1-year follow-up. Clinical follow-up was obtained at 1 and 12 months, and yearly thereafter. Results: The median Society of Thoracic Surgeons score of the study population was 7.7% (interquartile range 5.3% to 12.0%), and the mean LVEF and transvalvular gradient were 30.1 ± 9.7% and 25.4 ± 6.6 mm Hg, respectively. The presence of contractile reserve was observed in 45% of patients at DSE. Mortality rates were 3.8%, 20.1%, and 32.3% at 30 days, 1 year, and 2 years, respectively. On multivariable analysis, chronic obstructive pulmonary disease (p = 0.022) and lower hemoglobin values (p < 0.001) were associated with all-cause mortality. Lower hemoglobin values (p = 0.004) and moderate-to-severe aortic regurgitation post-TAVR (p = 0.018) were predictors of the composite of mortality and rehospitalization due to heart failure. LVEF increased by 8.3% (95% confidence interval: 6% to 11%) at 1-year follow-up, and the lack of prior coronary artery bypass graft (p = 0.004), a lower LVEF at baseline (p < 0.001), and a lower stroke volume index at baseline (p = 0.019) were associated with greater increase in LVEF. The absence of contractile reserve at baseline DSE was not associated with any negative effect on clinical outcomes or LVEF changes at follow-up. Conclusions: TAVR was associated with good periprocedural outcomes in patients with LFLG-AS. However, approximately one-third of LFLG-AS TAVR recipients died at 2-year follow-up, with pulmonary disease, anemia, and residual paravalvular leaks associated with poorer outcomes. LVEF improved following TAVR, but DSE failed to predict clinical outcomes or LVEF changes over time.