Key result
CABG fails to reduce 10-year MI incidence versus medical therapy but lowers post-MI mortality.
Why the study?
Does coronary artery bypass surgery reduce the incidence of myocardial infarction and post-infarction mortality compared to medical treatment in patients with stable angina?
RCT (n=686)
Yes
Does coronary artery bypass surgery reduce the incidence of myocardial infarction and post-infarction mortality compared to medical treatment in patients with stable angina?
In patients with stable angina, coronary artery bypass surgery does not reduce the overall 10-year incidence of myocardial infarction but significantly reduces the risk of mortality if an infarction occurs, particularly within the first 30 days.
Answers are grounded in this paper and cite their sources.
CABG should not be selected to reduce MI incidence in stable angina; extends evidence that its mortality benefit occurs after infarction.
BACKGROUND: The 10-year incidence of myocardial infarction (fatal and nonfatal) and the prognosis after infarction were evaluated in 686 patients with stable angina who were randomly assigned to medical or surgical treatment in the Veterans Administration Cooperative Study of Coronary Artery Bypass Surgery. METHODS AND RESULTS: Myocardial infarction was defined by either new Q wave findings or clinical symptoms compatible with myocardial infarction accompanied by serum enzyme elevations with or without electrocardiographic findings. Treatment comparisons were made according to original treatment assignment; 35% of the medical cohort had bypass surgery during the 10-year follow-up period. The overall cumulative infarction rate was somewhat higher in patients assigned to surgery (36%) than in medical patients (31%) (p = 0.13) due to perioperative infarctions (13%) and an accelerated infarction rate after the fifth year of follow-up (average, 2.4%/yr in the surgical group versus 1.4%/yr in the medical group). The 10-year cumulative incidence of death or myocardial infarction was also higher in surgical (54%) than in medical (49%) patients (p = 0.20). According to the Cox model, the estimated risk of death after infarction was 59% lower in surgical than in medical patients (p less than 0.0001). The reduction in postinfarction mortality with surgery was most striking in the first month after the event: 99% in the first month (p less than 0.0001) and 49% subsequently (p less than 0.0001). The estimated risk of death in the absence of infarction was nearly identical regardless of treatment (p = 0.75). Exclusion of perioperative infarctions did not alter the findings. CONCLUSIONS: Although surgery does not reduce the incidence of myocardial infarction overall, it does reduce the risk of mortality after infarction, particularly in the first 30 days after the event (fatal infarctions).
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Peduzzi et al. (1991) conducted an RCT in Stable angina (n=686). Coronary artery bypass surgery vs. Medical treatment was evaluated on 10-year incidence of myocardial infarction (fatal and nonfatal) (p=0.13). Coronary artery bypass surgery did not reduce the 10-year incidence of myocardial infarction compared to medical therapy, but reduced post-infarction mortality.
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