PTCA IN ACUTE MYOCARDIAL-INFARCTION - DIRECT, IMMEDIATE, DELAYED OR ELECTIVE

With intravenous thrombolysis mortality of acute myocardial infarction can be significantly reduced, not only in the first hours after the onset of symptoms, but also up to 24 hours. The open infarct related coronary artery is important concerning long-term clinical outcome. If thrombolysis can be administered within the first three to six hours, limitation of infarct size and preservation of left ventricular function contribute to an impressive reduction in mortality. Long-term assessments of clinical outcome have surprisingly shown that the prognosis is much more dependent upon patency of the infarct related artery than from the time to treatment. Since a correlation is suspected between the degree of residual stenosis and the clinical course, recurrence of ischemia, reinfarction, hemodynamic instability and death, and the fact that mortality is highest within the first three days after thrombolysis the emphasis of numerous investigations has been on possibilities of PTCA in the acute stage of myocardial infarction. The application of interventional techniques was tested at different times within the progression of myocardial infarction. PTCA can be applied as primary, direct therapy without thrombolysis, immediately and during intravenous thrombolysis, following successful pharmacological recanalisation, as rescue-PTCA for failed thrombolytic therapy, delayed and as a prophylactic measure up to until days after the infarction or later when accompanied by careful observation of the patient, when limited to few indications with spontaneous or stress-related angina pectoris, hemodynamic instability or predetermined angiographic criteria. Important results have been gathered by the larger studies of the last few years, TAMI, ECSG, and TIMI as well as by numerous smaller investigations, about the phathophysiology and treatment of myocardial infarction. Despite different study design, the three larger trials have come to the same conclusion regarding PTCA and rt-PA thrombolysis, early PTCA is without advantage compared to a deferred treatment; the acute results are usually worse and the clinical course more complicated. It must be mentioned however, that major problems still remain unresolved: primary or direct angioplasty, PTCA in combination with non-fibrin specific plasminogen activators, as well as rescue-PTCA after failed thrombolysis. Specially, 90 minutes after thrombolysis 23 to 44% of the coronaries are still occluded, depending on the plasminogen activator, and there is no non-invasive procedure to detect this patient-group and to advise further treatment. Due to the high mortality rate within the first three days attempts of treatment are concentrated on this timespan. Myocardial reperfusion is still called for, preferably within the first few hours, it is however unclear, whether recanalisation with PTCA should be performed within 24 hours or later, due to the importance of the open infarct-related vessel concept. The excellent results of thrombolysis with patency rates of over 90% for rt-PA after 90 minutes and reinfarction rates of less than 6 to 10% can hardly be improved upon. Since however, only 20% of all infarct patients are suitable for thrombolysis, other treatment possibilities, especially PTCA, have a growing importance for those remaining patients.