Incidence, predictors and cerebrovascular consequences of leaflet thrombosis after transcatheter aortic valve implantation: A systematic review and meta-analysis

OBJECTIVES: We examined the incidence, the impact of subsequent cerebrovascular events and the clinical or procedural predictors of leaflet thrombosis (LT) in patients undergoing transcatheter aortic valve implantation (TAVI). METHODS: MEDLINE/PubMed was systematically screened for studies reporting on LT in TAVI patients. Incidence [both clinical and subclinical, i.e. detected with computed tomography (CT)] of LT was the primary end point of the study. Predictors of LT evaluated at multivariable analysis and impact of LT on stroke were the secondary ones. RESULTS: Eighteen studies encompassing 11 124 patients evaluating incidence of LT were included. Pooled incidence of LT was 0.43% per month [5.16% per year, 95% confidence interval (CI) 0.21-0.72, I² = 98%]. Pooled incidence of subclinical LT was 1.36% per month (16.32% per year, 95% CI 0.71-2.19, I² = 94%). Clinical LT was less frequent (0.04% per month, 0.48% per year, 95% CI 0.00-0.19, I² = 93%). LT increased the risk of stroke [odds ratio (OR) 4.21, 95% CI 1.27-13.98], and was more frequent in patients with a valve diameter of 28-mm (OR 2.89: 1.55-5.8), for balloon-expandable (OR 8: 2.1-9.7) or after valve-in-valve procedures (OR 17.1: 3.1-84.9). Oral anticoagulation therapy reduced the risk of LT (OR 0.43, 95% CI: 0.22-0.84, I² = 64%), as well as the mean transvalvular gradient. CONCLUSIONS: LT represents an infrequent event after TAVI, despite increasing risk of stroke. Given its full reversal with warfarin, in high-risk patients (those with valve-in-valve procedures, balloon expandable or large-sized devices), a protocol which includes a control CT appears reasonable.