Optimal timing of coronary artery bypass after acute myocardial infarction: A review of California discharge data

Objective

The optimal timing for coronary artery bypass grafting after acute myocardial infarction is not well established. The California Discharge Database facilitates the study of this issue by providing data from a large patient cohort free of institutional bias. We examine the timing of coronary artery bypass grafting after acute myocardial infarction on short-term outcomes.

Methods

We reviewed California Discharge Data to identify 40,159 patients who were hospitalized for acute myocardial infarction (day 0) and underwent subsequent coronary artery bypass grafting. Patients were stratified by the timing of coronary artery bypass grafting to “early” (days 0–2) and “late” groups (day 3 or later). The primary outcome variable was all-cause hospital mortality. Multiple logistic and linear regression and propensity analyses assessed the risk of adverse events, controlling for factors associated with preoperative clinical acuity, including the Charlson Comorbidity Index, shock, mechanical ventilation, and the use of intra-aortic balloon counterpulsation.

Results

Of 9476 patients identified, 4676 (49%) were in the early coronary artery bypass grafting group and 4800 (51%) were in the late coronary artery bypass grafting group. A total of 444 patients (4.7%) died during hospitalization, with a peak mortality rate of 8.2% among patients undergoing coronary artery bypass grafting on day 0, declining to a nadir of 3.0% among patients undergoing coronary artery bypass grafting on day 3. The mean time to coronary artery bypass grafting was 3.2 days. Patients undergoing early coronary artery bypass grafting experienced a higher mortality rate than those undergoing late coronary artery bypass grafting (5.6% vs 3.8%, P < .001). Early coronary artery bypass grafting was an independent predictor of mortality after controlling for clinical acuity and on propensity analysis (odds ratio 1.43, P = .003).

Conclusion

Patients undergoing coronary artery bypass grafting within 2 days of hospitalization for acute myocardial infarction experienced higher mortality rates than those undergoing coronary artery bypass grafting 3 or more days after acute myocardial infarction, independently of clinical acuity. This suggests that coronary artery bypass grafting may best be deferred for 3 or more days after admission for acute myocardial infarction in nonurgent cases.

CTSNet classification: 20, 23

Abbreviations and Acronyms: AMI, acute myocardial infarction, CABG, coronary artery bypass graft, IABP, intra-aortic balloon pump, ICD-9-CM, International Classification of Diseases, Ninth Revision, Clinical Modification, OR, odds ratio, PCI, percutaneous coronary intervention