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Use of Coronary Stents Plus Angioplasty After Acute MI
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Am Fam Physician. 2000 Jun 15;61(12):3718-3720.
Treatment with coronary angioplasty after acute myocardial infarction (MI) has been shown to be superior to thrombolytic therapy, with a lower incidence of restenosis, recurrent ischemia, reinfarction and death. However, inherent complications are associated with angioplasty. Six-month follow-up data have shown that arteries will reocclude in 10 to 15 percent of patients, and restenosis occurs in 35 to 40 percent of patients. The implantation of coronary stents following angioplasty has been promoted as a way to prevent re-occlusion and improve long-term patency, but data to support this premise are lacking. Grines and colleagues performed a multicenter, randomized trial to compare the benefit of primary angioplasty alone with angioplasty plus implantation of a coronary stent.
Patients were eligible for the study if they were 18 years of age or older and presented with symptoms of acute MI that had begun less than 12 hours before. Participants had to have ST-segment elevation of at least 1 mm in two or more contiguous electrocardiographic (ECG) leads or a nondiagnostic ECG with documentation of acute MI in the catheterization laboratory. Patients were excluded from the study if they had received thrombolytic therapy, were in cardiogenic shock, were currently taking warfarin, had a stroke within the past month or had a history of renal failure.
All patients received aspirin, ticlopidine, intravenous heparin and a beta blocker as part of acute management in the emergency department. Then they were taken to the catheterization laboratory to undergo left ventriculography and coronary arteriography. After blood flow was reestablished in these patients, the infarct-related vessel had to have a diameter of 3.0 to 4.5 mm and one or more lesions that could accommodate one or two coronary stents that were 15 mm in length. Patients who did not meet these criteria or who the physician felt would be better treated medically or with surgery were subsequently excluded from the study.
Eligible patients were then randomized to receive angioplasty alone or placement of heparin-coated coronary stents. To assess the degree of coronary perfusion, repeat angiography was performed immediately after the initial procedures and again at 6.5 months. The primary end point of the study was the composite incidence of death, nonfatal reinfarction, disabling stroke or target-vessel revascularization for the treatment of ischemia with repeat angioplasty or surgery during the six-month follow-up period. Secondary end points included the percentage of stenosis and the minimal luminal diameter.
During the 11-month enrollment period, 1,458 patients with acute MI were screened for the study at 62 different sites. From this group, 448 patients were randomized to treatment with angioplasty alone, and 452 patients were randomized to receive angioplasty plus coronary stent implantation. The patients were 60 years of age on average, and about 75 percent were men. Evaluation of the angiograms that were done immediately after the procedure revealed that the patients who received coronary stents had a larger minimal luminal diameter, less residual stenosis and fewer dissections than the patients in the simple angioplasty group. However, the overall rates of defined “success” (less than 50 percent residual stenosis) were the same in both groups (about 99 percent). During hospitalization and the first month after treatment, the lengths of hospital stay were identical, and the rates of bleeding and recurrent ischemia were similar in both groups. Target-vessel revascularization was needed to treat ischemia in 1.3 percent of the stent group compared with 3.8 percent of the angioplasty group.
During the first six months of follow-up, the rates of the combined primary end point were 12.6 percent in the stent recipients and 20.1 percent in the angioplasty group. The incidence of angina was 11.3 percent in the stent group and 16.9 percent in the angioplasty group. At 6.5 months, follow-up angiograms showed that the stent patients had a larger minimal luminal diameter (1.81 versus 1.57 mm) than the angioplasty patients, and the rates of restenosis were 20.3 and 33.5 percent, respectively. Lastly, reocclusion of the infarct-related vessel occurred in 5.1 percent of the stent patients and 9.3 percent of the angioplasty patients. The rates of reinfarction between the two groups were similar at one month and again at six months.
The authors conclude that, in patients with acute MI, primary angioplasty combined with routine stent placement is superior to treatment with angioplasty alone in reducing the incidence of ischemia and the need for revascularization. However, further studies are needed to determine if the empiric use of coronary stents will reduce the incidence of reinfarction, death and stroke.
Grines CL, et al. Coronary angioplasty with or without stent implantation for acute myocardial infarction. N Engl J Med. December 23, 1999;341:1949–56.
Copyright © 2000 by the American Academy of Family Physicians.
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