Platelet reactivity in comatose survivors of cardiac arrest undergoing percutaneous coronary intervention and hypothermia

AIMS: To investigate the effects of clopidogrel and eptifibatide on platelet reactivity in patients resuscitated from cardiac arrest undergoing percutaneous coronary intervention (PCI) and hypothermia. METHODS AND RESULTS: VerifyNow® and Multiplate® aggregometry were used before, and 4, 12, 22 and 48 hours after 600 mg clopidogrel treatment in 28 post-cardiac arrest hypothermic patients and in 14 normothermic patients with acute coronary syndrome. Basal platelet reactivity after stimulation with iso-thrombin receptor-activating peptide (TRAP) and PAR4-activating peptide (BASE) was significantly lower in the post-cardiac arrest group and persisted up to 48 hours. The antiplatelet effect of clopidogrel measured by VerifyNow and expressed as % inhibition was significantly lower in the post-cardiac arrest group. It was close to zero with an increase to only around 10% after 48 hours. Post-cardiac arrest patients receiving eptifibatide showed profound platelet inhibition measured by both VerifyNow IIb/IIIa and Multiplate TRAP tests for at least 22 hours after administration. CONCLUSIONS: Post-resuscitation syndrome with ongoing hypothermia is associated with decreased platelet reactivity. Clopidogrel loading does not significantly affect platelet function during the first 48 hours. This is in contrast with eptifibatide which produces profound platelet inhibition, and may be used to bridge insufficient inhibition by clopidogrel.