Myocardial damage during percutaneous interventions for non-ST-elevation acute coronary syndromes

The prognostic significance and pathophysiological mechanisms underlying elevations in cardiac enzymes in patients with non-ST-segment elevation acute coronary syndromes (ACS) post-percutaneous coronary intervention (PCI) is a matter of debate. The few available data, derived mainly from sub-analyses of large randomized trials and from small prospective observational studies, suggest that patients with ACS who undergo PCI have an increased risk for procedural myocardial damage which, in turn, is associated with an adverse clinical outcome. Although the pathophysiology of post-PCI myocardial damage is multifactorial, the embolization of debris or calcified plaque material, or exposure of thrombogenic material at intravascular sites seems to play a key role, as shown by mechanistic studies that demonstrate a close relationship between post-procedural enzyme release and abnormal tissue perfusion. Several pre-procedural treatment strategies using antithrombotic therapies have evolved in an attempt to lower the rate of myocardial damage related to the performance of PCI in ACS patients. Major trials that evaluated the use of glycoprotein (GP) IIb/IIIa inhibitors during PCI in patients with ACS have suggested that maximum benefit is obtained in patients with increased troponin levels and in patients undergoing PCI, reducing the incidence of cardiac enzyme release after the procedure. However, a number of lingering unsolved issues concerning which agent should be used and the most appropriate timing and dosage remain to be explored. Mechanistic and clinical findings suggest that an early invasive strategy with upstream GP IIb/IIIa inhibitors may yield more favourable outcomes than downstream strategies.