Interventional Treatment of Acute Myocardial Infarction: Is The Thrombolysis Era Coming to an End?

Abstract

For more than 10 years, intravenous thrombolysis has been regarded as a reference treatment in patients with myocardial infarction of < 12 hours’onset. Its proven efficacy in reducing mortality and its fast and easy implementation constitute its main advantages. However, this treatment has several limitations: < 50% of patients can be treated, TIMI 3 flow can only be obtained in 55% of cases at best, and in cases of reperfusion failure, clinical and electrocardiographic signs are not very reliable. Several studies are underway to determine whether combination with glycoprotein IIb/IIIa inhibitors may result in a higher reperfusion rate. Conversely, primary PTCA, which is a more recent treatment, has been proven superior to thrombolysis in achieving coronary reperfusion and reducing the rates of death and recurrent ischemia, especially in high risk patients. However, primary balloon PTCA is a more complex treatment strategy, which requires a well‐trained team available 24 hours a day and is associated with a number of limitations: 10%‐15% recurrent ischemia rate, 10%‐15% 6‐month reocclusion rate, and 40% restenosis rate. The good results obtained with stenting combined with antiplatelet treatments have completely modified our routine practice of PTCA to the extent that stents are now commonly used in the management of myocardial infarction. As early as 1995, a study was carried out on the French registry (Coronary Stenting Without Coumadin) including 2,900 patients. Eighty‐five of these patients had been included at the acute phase of myocardial infarction. The recurrent ischemia rate was 2.4%, and death rate at 1 month was 5.9%. In 1996, 269 patients were enrolled in the first registry on stenting at the acute phase of myocardial infarction (STENTIM). Angiographic success rate was 96% with a 3% subocclusion rate and 5.2% death rate at 1 month. More recently, a prospective trial including 312 consecutive patients was carried out in the United States by Gregg Stone. Stenting was performed in 240 (77%) patients with a 98% angiographic success rate, 1.3% subacute occlusion rate, and 1% death rate at 1 month. In the PAMI registry, a preamble to the randomized trial PAMI stent, 100 patients were treated with a Palmaz‐Schatz heparin‐coated stent with a 97% angiographic success rate, 2% death rate, and 18% angiographic restenosis rate including 3% reocclusion. Since then, a number of randomized studies have been initiated (ZWOLLE, FRESCO, GRAMI, STENTIM 2) and have shown similar outcomes, that is, a lower recurrent ischemia rate in stented patients and two to three times lower repeat target revascularization rate at 6 months. The 12‐month follow‐up results of the Stent PAMI trial are now available and show an 11.6% rate of target vessel revascularization in the stent group versus 21% in the balloon group (P < 0.0001) and 17% versus 25% rate of major cardiac events in the two groups, respectively (P < 0.01). One of the main limitations of these trials is that they involve selected patients, which does not accurately reflect everyday practice. Consequently, we have set up a prospective registry in our institution including all the patients admitted within 24 hours after the onset of myocardial infarction. Nine hundred twenty‐six patients were included between January 1995 and May 1999. Procedural success rate was 97% and stenting was performed in 89%. Overall in‐hospital mortality was 10% (5% in patients admitted with Killip 1, 2, or 3) and the recurrent ischemia rate was 2.4%. The complementarity of thrombolysis and PTCA is well illustrated in the 150 patients who received prehospital thrombolysis. In these patients, angiographic success was 98.7%, recurrent ischemia 1.3%, and in‐hospital mortality 4.7%. We also studied the subgroup of 448patients who could have been eligible for thrombolysis. In these patients, procedural success was 96.6%, recurrent ischemia 3.4%, and in‐hospital mortality 3.2%. The main issue in acute myocardial infarction (AMI) is to obtain TIMI 3 flow as quickly as possible. Thus, in patients likely to be quickly transferred to an experienced interventional cardiology center, the optimal strategy seems to be PTCA with stenting. In patients remote from a catheterization laboratory, thrombolysis may be the first choice treatment. The ideal strategy, however, is to transfer AMI patients to a reference center to perform a coronary angiogram allowing fast assessment of TIMI flow and severity of coronary disease followed by PTCA in the case of suboptimal or even TIMI 3 flow.