Percutaneous transluminal coronary angioplasty during acute myocardial infarction

Intravenous thrombolytic therapy with streptokinase in the setting of acute MI has been shown to be effective in improving left ventricular function, limiting infarct size, and improving early mortality. The benefit of this therapy is greatest when administered within 3 hours and is of minimal benefit when given more than 6 hours from symptom onset. Newer second generation thrombolytic agents such as intravenous r-TPA have been shown to be more effective at establishing patency of acutely thrombosed coronary arteries. TPA treatment produces patency rates similar to those observed with intracoronary administration of streptokinase (65 to 75 per cent). This agent will probably become standard therapy for patients with acute MI. Unfortunately, there are significant problems with systemic thrombolytic therapy. The potential for bleeding complications contraindicates the use of this therapy in patients with recent cerebrovascular events, recent surgery, or other possible bleeding problems. Acute angioplasty of the infarct-related artery has been shown to be effective in restoring blood flow in 85 per cent of patients with acute MI. Preliminary studies have suggested that this therapy, when administered within 4 hours from symptom onset, improves global and regional left ventricular function to a greater degree than intracoronary streptokinase. Patients receiving acute PTCA as a primary reperfusion modality have a lower incidence of post-infarction angina and provokable ischemia by exercise testing. If facilities and skilled personnel are available to perform PTCA within 4 hours from symptom onset, this therapy remains an alternative revascularization modality in patients with acute infarction and contraindications to systemic thrombolytic therapy. However, the benefit of PTCA with regard to reduction in mortality when used in this manner is unproven. PTCA can also be used as an adjunctive therapy administered at some time following systemic thrombolytic therapy. Performing PTCA acutely offers the potential to restore blood flow in 90 per cent of the patients that initially fail thrombolytic therapy. However, despite the use of PTCA in this subgroup, benefits with regard to improved ventricular function and decreased mortality have yet to be conclusively demonstrated. Performing acute PTCA following systemic thrombolytic therapy also incurs a high incidence of bleeding complications. If initial thrombolytic therapy reestablishes vessel patency, similar improvements in ventricular function can be expected even if PTCA is deferred until clinically indicated by evidence of recurrent ischemia.(ABSTRACT TRUNCATED AT 400 WORDS)