Late angioplasty after thrombolysis for myocardial infarction
ACP J Club. 1993 May-June;118:75. doi:10.7326/ACPJC-1993-118-3-075
Ellis SG, Mooney MR, George BS, et al. Randomized trial of late elective angioplasty versus conservative management for patients with residual stenoses after thrombolytic treatment of myocardial infarction. Circulation. 1992 Nov; 86:1400-6.
To determine whether percutaneous transluminal coronary angioplasty (PTCA) done 4 to 14 days after myocardial infarction (MI) improves left ventricular function and survival in patients with residual stenoses.
1-year randomized controlled trial.
6 tertiary care hospitals in the United States and Brazil.
Patients who had elective cardiac catheterization 4 to 14 days after acute MI were enrolled if they had infarct-artery stenosis of ≥ 50% and were candidates for PTCA, had no previous Q-wave infarction in the same territory, had received thrombolytic therapy within 6 hours of symptom onset, had no postinfarction angina, and had a negative or equivocal stress test ≥ 4 days after infarction. Exclusion criteria were an indeterminate infarct artery or other illnesses thought to limit survival. All 87 patients (mean age 57 y, 73 men) were followed for 1 year.
42 patients were randomized to PTCA of the infarct artery with treatment of any other severe stenoses left to the discretion of the cardiologist. PTCA was judged successful if a final diameter stenosis < 50% was obtained with no major ischemic complications. 45 patients were assigned to conservative treatment. Both groups received aspirin, 80 to 975 mg/d for at least 6 months, and cardioactive agents at the discretion of their cardiologist.
Main outcome measures
An exercise test at 6 weeks and left ventricular ejection fraction (by gated blood-pool scintigraphy). Data on survival, clinical events, interventions, and functional status were collected through chart audit, a clinic visit at 6 weeks, and mailed or telephone questionnaires.
PTCA was successful in 38 of 42 patients; 1 lesion could not be crossed, and 3 patients had non-Q-wave infarcts despite intracoronary thrombolytics. No difference was seen in 6-week left ventricular ejection fractions at rest or with exercise, or in mean duration of exercise or maximum heart rate. There was a trend toward better 12-month infarct-free survival in the patients treated conservatively (98% vs. 90%; P = 0.07).
Routine percutaneous transluminal coronary angioplasty done 4 to 14 days after myocardial infarction did not improve left ventricular function or clinical outcome compared with medical treatment alone.
Source of funding: Not stated.
For article reprint: Dr. S.G. Ellis, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Desk F25, Cleveland, OH 44195-5066, USA. FAX 216-445-6714.
Thrombolytic therapy works by dissolving an occlusive coronary artery thrombus but leaving the underlying atherosclerotic plaque unchanged. Cardiologists have commonly used coronary angiography to document the effects of thrombolysis on the infarct artery and to decide if they should do further mechanical revascularization. The rationale for angiography after thrombolysis has been the supposition that the recently ruptured plaque was inherently unstable and would benefit from mechanical intervention to ensure sustained patency.
Several randomized studies have evaluated aggressive approaches to angiography or angioplasty after thrombolysis for acute MI. These trials differ in important details, but the findings are remarkably consistent: Patients who are treated aggressively tend to have worse outcomes than patients who are treated conservatively. This result, although initially surprising, is now believed to occur because angioplasty of an unstable coronary plaque has a higher rate of complication. Most previous studies examined the strategy of early (18 to 48 hours) angiography and angioplasty, whereas the study by Ellis and colleagues examined a strategy of delayed angioplasty (4 to 14 days), an interval that was hoped to be sufficient to allow the recently ruptured coronary plaque to stabilize. The results, again, show no advantage for angioplasty patients, even on exercise testing at 6-week follow-up.
These findings raise the broader issue of patient selection for coronary angiography after acute MI. Angiography can improve outcome only if it improves selection of therapy, particularly the use of mechanical revascularization. The randomized trials can be interpreted as showing that routine angioplasty after thrombolysis does not reduce the frequency of subsequent death or re-infarction, and they, therefore, strongly suggest that routine angiography will not be beneficial. Patients with recurrent myocardial ischemia after MI, however, are at increased risk for adverse outcomes, and the consensus of experts is that they have coronary angiography if they are candidates for myocardial revascularization (1).
Mark A. Hlatky, MD
Stanford University School of Medicine Stanford, California, USA