Early thrombolytic therapy reduces the risk of cardiac rupture but delayed thrombolysis may increase this risk, despite improving overall survival. The mechanism appears to be related to both unsuccessful early reperfusion and haemorrhagic transformation following delayed reperfusion. The effect of antiplatelet therapy with glycoprotein IIb-IIIa receptor blockers (abciximab) on cardiac rupture is unknown. It is possible that they may contribute to cardiac rupture by promoting haemorrhagic transformation of the infarcted area. In this report we describe a 57 year old man who underwent emergency coronary angioplasty and stenting following failed thrombolytic therapy for an acute anterior myocardial infarction. A suboptimal result was obtained which necessitated an intravenous bolus of abciximab followed by an infusion. He abruptly developed electromechanical dissociation. Echocardiogram confirmed pericardial tamponade and a pericardial drain was inserted but the patient could not be resuscitated. Postmortem examination confirmed a large transmural rupture of the infarcted anterior wall which had undergone haemorrhagic transformation.