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Perioperative myocardial infarction with coronary artery surgery: diagnosis, incidence and consequences
M J Gardner1, D E Johnstone, L Lalonde
1Division of Cardiology, Victoria General Hospital, Halifax, Nova Scotia.
Insights
Diagnosing perioperative myocardial infarction after coronary artery bypass surgery is challenging. However, early diagnosis and treatment do not impact long-term patient outcomes.
Area of Science:
- Cardiology
- Cardiac Surgery
Background:
- Perioperative myocardial infarction (MI) is a serious complication following coronary artery bypass grafting (CABG).
- Accurate diagnosis of perioperative MI is complicated by postoperative symptoms and nonspecific diagnostic markers.
Purpose of the Study:
- To evaluate the diagnostic methods for perioperative MI after CABG.
- To assess the impact of perioperative MI on early and long-term left ventricular function.
- To determine the long-term functional status of patients who experience perioperative MI.
Main Methods:
- A combination of electrocardiogram, creatine kinase-MB (CK-MB) analysis, and technetium pyrophosphate scanning was used for diagnosis.
- Left ventricular ejection fraction (LVEF) was measured preoperatively and postoperatively.
- Long-term follow-up assessed functional and work status at two years.
Main Results:
- The incidence of perioperative MI was 6%.
- Perioperative MI significantly reduced early postoperative LVEF (63% to 54%, P<0.05).
- Long-term LVEF, functional, and work status at two years were similar between patients with and without perioperative MI.
Conclusions:
- A multimodal diagnostic approach improves perioperative MI detection.
- While early LVEF is affected, perioperative MI does not compromise long-term cardiac function or overall patient status.
- Survivors of perioperative MI achieve comparable long-term functional recovery to those without MI.
Abstract:
Perioperative myocardial infarction is a potential consequence of coronary artery bypass surgery. The diagnosis is difficult due to multiple factors including postoperative chest discomfort, serum enzyme elevations and nonspecific electrocardiographic changes. No one test is reliable, but a combination of electrocardiogram, MBCK serum enzyme analysis and technetium pyrophosphate scanning should increase the probability of correct diagnosis. Using this method, the incidence of perioperative myocardial infarction in this study was six out of 100. Left ventricular function in the early postoperative period was adversely affected by perioperative myocardial infarction with a reduction in left ventricular ejection fraction (63 +/- 9% preoperative to 54 +/- 12% postoperative; P less than 0.05), whereas left ventricular ejection fraction was unchanged in the absence of perioperative myocardial infarction. The long term left ventricular function, however, appears to recover, and at two years after surgery there was no difference in rest or exercise left ventricular function between patients who suffered perioperative myocardial infarction versus those who did not. All patients with perioperative myocardial infarction survived to be discharged from hospital, and all returned for follow-up at two years. Their functional and work status was no different from those without perioperative myocardial infarction. This would suggest that, if patients survive a perioperative myocardial infarction, their long term functional status is no different from those patients without perioperative myocardial infarction.