Meta-Analysis of Outcomes of Transcatheter Aortic Valve Implantation Among Patients With Low Gradient Severe Aortic Stenosis

Abstract

Transcatheter aortic valve implantation (TAVI) has emerged as an effective therapy for patients with severe aortic stenosis (AS). However, data on TAVI outcomes in patients with low gradient (LG) AS are limited. We performed a meta-analysis of studies comparing TAVI outcomes between patients with classic high gradient (HG) and LG AS through November 2018. The 30-day mortality, mid-term all-cause, and cardiovascular mortality at maximum follow-up were compared between patients with HG and LG AS (Pairwise meta-analysis), and between the three distinct groups of AS including HG, paradoxical low-flow low-gradient and low gradient with reduced ejection fraction (rEF-LG) (Network meta-analysis). Nineteen studies (n = 27,204 patients) met the inclusion criteria. The HG group had less 30-day, mid-term all-cause and cardiovascular mortality compared with the low-gradient AS group overall, (6% vs 7.5%, OR 0.76, 95% CI 0.66 to 0.87, I2 = 18%), (21% vs 29%, OR 0.59, 95% CI 0.52 to 0.67, I2 = 62%), and (12.6% vs 18.7%, OR 0.61, 95% CI 0.49 to 0.76, I2 = 62%), respectively, p <0.0001. These outcomes were confirmed in a trial sequential analysis in which the cumulative Z-curve crossed the conventional test boundary as well as the trial sequential monitoring boundary for all outcomes. The network meta-analysis revealed that patients with rEF-LG had similar outcomes to those with pLFLG, and both had worse outcomes than patients with classic HG AS. In conclusion patients with classic HG have better 30-day mortality, mid-term all-cause and cardiovascular mortality compared with LG patients following TAVI. Among patients with LG severe AS, TAVI outcomes were similar in patients with rEF-LG and pLFLG.