ABSTRACT
Introduction Since the early eighties many trials have tried to determine the role of different treatment strategies for acute myocardial infarction (AMI). The use of aspirin,1 beta-blockers,2 and angiotensin-converting enzyme (ACE) inhibitors3 have all contributed to a reduction of mortality. Restoring antegrade flow through the infarct-related vessel (IRV) by means of reperfusion therapy has also been successful in infarct treatment, especially in those patients who present within 12 hours of symptom onset with ST-elevation on the ECG. Reperfusion therapy is defined as the first therapy used to restore blood flow through a suspected or known occluded coronary artery immediately at diagnosis. It includes intravenous thrombolysis, intracoronary thrombolysis, primary coronary angioplasty, or immediate coronary artery bypass surgery.1,4-16 Currently available thrombolytic agents are all associated with certain limitations: half or more of the patients will fail to achieve early and complete reperfusion with the current regimens. The mortality rate is at least 6 to 8%, and possibly higher.5,9,13
Reinfarction, bleeding risk (including intracranial haemorrhage), and the potential need for transfusion continue to pose concerns. Recent studies have determined the role of primary coronary angioplasty: primary angioplasty results in higher patency rates, a better preservation of left ventricular function and a reduction of mortality and recurrent infarction when compared to thrombolytic therapy.11,14-16
On the other hand, thrombolytic therapy has the major advantage that it can be administered in all hospitals while primary angioplasty can only be applied in hospitals with facilities for interventional cardiology. Therefore, in many patients with acute infarction the choice has to be made for treatment with thrombolytic therapy in the community hospital (or even in the prehospital phase), or transfer to a tertiary centre with interventional cardiology equipment, or a combination of 17-19
Thrombolytic therapy and timing of coronary angioplasty Reocclusion at the site of the often critical residual coronary vessel stenosis within the following days after myocardial infarction led several cardiologists to perform percutaneous transluminal coronary angioplasty at varying intervals after thrombolysis and as early as 1982, Meyer and colleagues reported very encouraging results of this combination strategy.20 Others were soon to follow.21-23 Several studies on the combination of thrombolytic therapy and coronary angioplasty have been published.24-27
Definitions 1: Immediate PTCA After or while starting a thrombolytic agent, angioplasty is performed as soon as possible. Despite the attractive concept of reducing the underlying stenosis while the thrombus is lysed, the toll that has to be paid for this combination procedure is considerable. The complication rates are higher, there is no beneficial effect on left ventricular function or mortality and the costs of this combination approach have lead to the conclusion that immediate PTCA is not the treatment of choice.24-27
Angioplasty produces a localized injury to the arterial wall leading to plaque splitting, stretching of the arterial wall, plaque compression, thrombus ‘squeezing’ with release of many vasoactive mediators, and denudation of the endothelium. This can be regarded as an ideal ‘target’ for rethrombosis. In combination with thrombolytic agents and their potential to activate thrombin and platelets, these factors may contribute to the high
incidence of complications of immediate PTCA.28-30 However, if reocclusion can be prevented, immediate angioplasty may be beneficial in selected patients.31
