4058Effects of selective and nonselective beta-blockers on platelet aggregation in patients with acute coronary syndrome: the PLATE-BLOCK study

Abstract

Background: Platelet aggregation plays a pivotal role in the pathogenesis of acute coronary syndromes (ACS). In this setting, beta‐blockers (BB) are used to counteract catecholamines effects on heart. Circulating catecholamines can also potentiate platelet reactivity, mainly through α2‐ and β2‐adrenoceptors on human platelets surface, thus BB may affect platelet aggregation. However, the effects of different BB on platelet aggregation in contemporary treated ACS patients have been poorly investigated. Purpose: The aim of the present study is to investigate the effects of of selective and nonselective BB on platelet aggregation in ACS patients treated with aspirin and ticagrelor. Methods: One hundred ACS patients, on dual antiplatelet therapy (DAPT) with aspirin and ticagrelor, were randomized to receive treatment with carvedilol, a nonselective β‐blocker (n=50), or metoprolol, a selective β1‐blocker (n=50), at maximum tolerated dose. Light Transmittance Aggregometry was performed at randomization (T0) and at 30‐day follow up (T30), and results were expressed as a percentage of maximum platelet aggregation (MPA). The primary endpoint was epinephrine‐induced MPA at 30‐day. Secondary endpoints were the evaluation of ADP‐induced platelet aggregation (both 10 μM and 20 μM) and clinical adverse events, including ischemic and bleeding complications at 30 days. Results: Patients were predominantly males (80%) and mean age was 57.3±9.7 years. The two randomized groups were well‐balanced for baseline characteristics. At T0, mean MPA was similar between the groups (18.96±9.05 vs 18.32±9.21 with epinephrine 10 μM, 14.42±9.43 vs 15.98±10.08 with ADP 20 μM and 13.26±9.83 vs 14.30±9.40 with ADP 10 μM for carvedilol and metoprolol, respectively, all p=NS). At 30 days, platelet aggregation induced by epinephrine was significantly lower in carvedilol group than in metoprolol group (23.52±10.25 vs 28.72±14.37, p=0.04) with a trend toward the lower values of ADP‐induced MPA (ADP 20 μM: 19.42±13.84 vs 24.16±13.62, p=0.09; ADP 10 μM: 19.12±12.40 vs 22.57±13.59, p=0.19). No ischemic and major bleeding events were reported. Conclusions: Carvedilol, a nonselective BB, reduces residual platelet reactivity in ACS patients compared to the selective BB metoprolol.