Late myocardial salvage: Time to recognize its reality in the reperfusion therapy of acute myocardial infarction

The prevailing opinion in the reperfusion therapy of patients with acute myocardial infarction (AMI) is that the benefit of reperfusion is mostly confined to the first 12 h after the symptom onset. This opinion is based on the results of the prior megatrials of thrombolytic therapy and the experimental studies. Thrombolytic studies have unequivocally proven that the efficacy of thrombolysis to salvage ischaemic myocardium is drastically reduced with the increase in the time-to-treatment interval. A relatively large number of patients present beyond the limit efficacy of thrombolysis and are considered ineligible for this reperfusion modality. Recent experimental and clinical evidence indicates that a large amount of viable myocardium is still present in the area at risk in patients with AMI presenting late after symptom onset and considered ineligible for thrombolysis. In this review, we summarized the existing data demonstrating that this viable myocardium is salvageable given the primary percutaneous coronary intervention (PCI) is used as a reperfusion therapy. By emphasizing this fact, we do not mean to contest the concept of time dependence of myocardial necrosis following coronary occlusion and time dependence of efficacy of interventions performed early (within 2-3 h) after symptom onset or to dissuade the early coronary interventions in patients with AMI. Instead, we strongly recommend the primary PCI in patients with AMI presenting late after onset of myocardial ischaemia.