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.