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Risk analysis of coronary bypass surgery after acute myocardial infarction
J H Lee1, H K Murrell, J Strony
1Division of Cardiothoracic Surgery, Case Western Reserve University School of Medicine, University Hospitals of Cleveland, Ohio 44106, USA.
Insights
Coronary bypass surgery after myocardial infarction (MI) is safe for stable patients, with outcomes comparable to elective procedures. Delaying surgery for stabilization is unnecessary and may increase risks.
Area of Science:
- Cardiology
- Cardiac Surgery
- Clinical Research
Background:
- Current acute myocardial infarction (MI) management includes thrombolysis, angioplasty, and coronary bypass surgery.
- This study identified contemporary risk factors for coronary bypass surgery in high-risk MI patients.
Purpose of the Study:
- To identify risk factors for coronary bypass surgery in patients with acute myocardial infarction (MI).
- To evaluate the safety and outcomes of early coronary bypass surgery following MI.
Main Methods:
- 1181 patients underwent isolated coronary bypass surgery between June 1992 and December 1995.
- 316 patients had surgery within 21 days of MI, categorized by clinical status (stable angina, unstable angina, intraaortic balloon counterpulsation, cardiogenic shock).
Main Results:
- In-hospital mortality was 5.1% for early bypass surgery post-MI, higher than surgery without recent MI (2.5%).
- Mortality increased with preoperative clinical severity: 1.2% (stable), 3.7% (unstable), 20.0% (balloon pump), 26.0% (cardiogenic shock).
- Independent mortality predictors included intraaortic balloon counterpulsation, left ventricular dysfunction, and renal insufficiency.
Conclusions:
- Coronary bypass surgery is safe for stable patients any time after acute MI, with operative mortality similar to elective surgery.
- Prolonged stabilization attempts delaying surgery are not indicated in the current healthcare cost environment.
Background:
Current strategies for management of acute myocardial infarction (MI) include thrombolysis, angioplasty, and coronary bypass surgery singly or in combination. This study was designed to identify contemporary risk factors for coronary bypass surgery among patients in this high-risk group.
Methods:
Between June 1992 and December 1995, 1181 consecutive patients underwent isolated coronary bypass surgery. Of these, 316 underwent coronary bypass surgery within 21 days of MI. Mean age was 65 years (range, 33 to 87 years), and 73% were male. There were 166 patients with stable angina (group 1), 107 patients with unstable angina requiring intravenous nitroglycerin for a control of ischemia (group 2), 20 patients with angina requiring intraaortic balloon counterpulsation for stabilization (group 3), and 23 patients with severe postinfarction ischemia complicated by cardiogenic shock (group 4).
Results:
The overall in-hospital mortality rate was 5.1% (16 of 316), which was higher (p < 0.05) than the 2.5% (22 of 865) among patients undergoing coronary bypass surgery without recent myocardial infarction. Mortality increased with severity of clinical preoperative status and was 1.2% in group 1, 3.7% in group 2, 20.0% in group 3, and 26% in group 4. Serious postoperative morbidity occurred in 7.3% of patients. Multivariate logistic regression analysis identified preoperative intraaortic balloon counterpulsation, left ventricular dysfunction, and renal insufficiency as the only independent correlates of mortality.
Conclusions:
Coronary bypass surgery can be safely performed in stable patients at any time after acute MI, with an operative mortality similar to elective surgery. Thus, in this era of medical cost containment, there is no apparent indication for prolonged stabilization attempts that delay surgery.