Use of the PFA-100™ closure time to predict cardiovascular events in aspirin-treated cardiovascular patients:: a systematic review and meta-analysis

Background: PFA-100 (TM) is a point-of-care assay that evaluates platelet reactivity in high-shear-stress conditions by measuring the closure time (CT) of a membrane aperture. When determined with a collagen/epinephrine cartridge (CEPI), the CT is usually prolonged by aspirin. Studies of the predictive value of a short PFA-100 (TM) CTCEPI for ischemic events in aspirin-treated patients have given variable results. Objectives: To conduct a systematic review and meta-analysis of studies on the clinical predictive value of a short PFA-100 (TM) CTCEPI in aspirin-treated cardiovascular patients. Patients and methods: Relevant studies were identified by scanning electronic databases. Studies were selected if they included aspirin-treated patients with symptomatic atherosclerosis, measured the PFA-100 (TM) CTCEPI, used a CT cut-off value to define aspirin 'responders' and 'non-responders', and reported ischemic events. Results: We selected seven non-prospective studies (1466 patients) and eight prospective studies (1227 patients). In non-prospective studies, the PFA-100 (TM) CTCEPI was performed after the ischemic clinical endpoint, and a publication bias was identified. In prospective studies, the global odds ratio (OR) for the recurrence of an ischemic event in 'aspirin non-responders' relative to 'aspirin responders' was 2.1 [95% confidence interval (CI) 1.4-3.4, P < 0.001]. Pooled analysis with a random effect model revealed no heterogeneity (Q Cochran P = 0.36 and I-2 = 9.4%). Conclusions: A short PFA-100 (TM) CTCEPI is associated with increased recurrence of ischemic events in aspirin-treated cardiovascular patients. This finding needs to be confirmed in stable ischemic patients, and the PFA-100 (TM) CTCEPI cut-off needs to be refined in these patients.