Prognostic impact of significant mitral regurgitation in patients with severe low flow, low gradient aortic stenosis undergoing transcatheter aortic valve replacement

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Aim The aim of this study was to determine the prevalence and prognostic implications of MR severity in patients with LFLG-AS undergoing TAVR, and to evaluate whether the improvement of MR after procedure could influence 1-year outcome. Methods All consecutive patients with severe LFLG-AS undergoing TAVR in two high-volume Italian centres from 2017 to 2022 were prospectively included. LFLG-AS was defined as indexed aortic valve area (AVAì) ≤0.6 cm2/m2; mean gradient <40 mmHg and stroke volume index <36 ml/m2. LFLG-AS was classified as classical if LVEF was <50%, and paradoxical if LVEF was >50%. Dobutamine stress-echo was systematically performed in patients with LVEF<50% in order or exclude pseudo-severe AS. The study population was divided into two groups according to the baseline MR severity: ≤2+ (moderate or less than moderate) and >2+ (moderately-severe or severe) and reassessed after TAVR. The primary outcome was the composite of all-cause death and hospitalization for HF up to 1 year. The secondary outcomes were the single components of the primary outcome. Results The study included 268 patients [81±6 years; 53% females]; of them, 57 (21.3%) patients showed MR>2+ at hospital admission. Patients with MR>2+ showed a significantly higher NYHA class at admission (p = 0.001); higher EuroSCORE II (p<0.001); lower LVEF at baseline (p = 0.003); higher RV dysfunction (p = 0.003) compared with those with MR≤2+. Death was reported in 2 (0.7%) patients, vascular complications in 8 (3%), and permanent pacemaker implantation in 23 (8.5%). The primary outcome was reported in 55 (20.5%) patients; all-cause death was reported in 29 (10.8%) patients, and HF hospitalization in 34 (12.7%). At one year, patients with MR>2+ showed a significantly higher percentage of the primary outcome (p <0.001) and of all-cause mortality (p<0.001), which was related to cardiovascular cause in the majority of cases, and of HF rehospitalization (p<0.001). The survival free from the primary and secondary outcome was significantly lower in patients with MR>2+ compared with those with MR≤2+ (Log-Rank <0.001; Figure 1). The absence of MR improvement after TAVR was associated with higher percentage of the primary outcome (p = 0.020), all-cause death (p = 0.044), and HF rehospitalization (p = 0.030) at one year. The one-year survival free from the primary and secondary outcome was significantly higher in patients with MR improvement than in those without (Log-Rank = 0.009; Figure 2). Conclusion MR>2+ was reported in about 20% of patients with LFLG-AS undergoing TAVR, portend a worse clinical outcome up to one year. TAVR may improve MR severity, resulting in a potential outcome benefit after discharge. Our study suggests that both, the presence and the persistence of moderately-severe or severe MR, are of utmost importance for patient prognostic stratification, and should be carefully and systematically assessed in the very high-risk clinical scenario of LFLG-AS undergoing TAVR.