Reperfusion Strategies in Acute ST-Elevation Myocardial Infarction: An Overview of Current Status

Abstract

Several randomized trials and meta-analyses have shown that primary angioplasty is superior to thrombolysis in the treatment of ST-segment elevation myocardial infarction (MI) in terms of death, reinfarction, and stroke. However, primary angioplasty should be regarded as the preferred strategy as long as it can not be applied with a reasonable time delay to treatment, as compared with the administration of thrombolysis. In fact, time-to-treatment has been shown to be a determinant of survival not only for thrombolysis but also for primary angioplasty. Recent guidelines consider a time from first medical contact to PCI of 90 minutes or a PCI-related delay of 60 minutes as reasonable cutoffs to identify the best reperfusion strategy. The beneficial effects of primary angioplasty could be expected particularly after the first 3 hours from symptom onset, when thrombolysis, particularly streptokinase, may be less effective, whereas within the first 3 hours, thrombolysis (started in the prehospital setting, preferably) may represent a valid therapeutic option. Because the survival benefits of primary angioplasty depends on the patient's risk profile and timely application of reperfusion, we would suggest, among patients in the first hours from symptom onset, a strategy of early pharmacologic reperfusion and transfer to primary PCI centers, where the decision of performing angiography acutely may be based on the assessment of myocardial reperfusion and risk profile, whereas after the first 3 hours from symptoms onset, primary angioplasty should be considered the preferred strategy if applicable, particularly in regions when streptokinase still represents the only available lytic therapy. However, even though primary angioplasty is able to achieve thrombolysis and TIMI 3 flow in most patients, a still relevant proportion of patients experience poor myocardial reperfusion, with negative impact on acute and long-term survival. The use of platelet glycoprotein IIb/IIIa complex inhibitors has significantly improved survival, with additional benefits obtained by early administration aiming at early reperfusion, which are to be recommended, particularly among high-risk patients and those presenting within the first hours from symptom onset. The use of adjunctive mechanical devices has reduced the incidence of distal embolization without any apparent benefit in survival. Until the results of larger randomized trials become available, these devices may be considered in patients at high risk for distal embolization, such as those with large thrombotic burden. The use of coronary stenting has significantly reduced restenosis, as compared with balloon angioplasty. Several randomized trials have recently been conducted on drug-eluting stents in ST-segment elevation MI, showing the safety and significant benefits of these devices in terms of restenosis, as compared with bare metal stents (BMSs). However, because of unpredictable compliance to long-term double oral antiplatelet therapy in acute patients, caution should be taken with extensive use of drug-eluting stents in primary angioplasty.