Determinants of morbidity and mortality after coronary artery bypass graft surgery: a single-center experience

Background: Coronary artery disease remains to be a major public health concern worldwide, and because of this, coronary artery bypass graft surgery evolved to become one of the most important treatment modalities to address this concern. Local data is wanting with regards to the predictors of outcomes of this procedure, with most of the bases for the currently established guidelines coming from international studies.

Objective: To describe the outcome and determine the predictors of morbidity and mortality among patients who underwent coronary artery bypass graft surgery at St. Luke’s Medical Center, QC.

Study design: Retrospective cohort study

Participants: Patients diagnosed with coronary artery disease that underwent coronary artery bypass graft surgery at St. Luke’s Medical Center, QC from January 2010 to December 2014.

Outcome measures: The primary outcomes measured are mortality, perioperative myocardial infarction and post-operative stroke. The secondary outcomes measured are post-operative atrial fibrillation, bleeding and acute kidney injury.

Results: A total of 114 subjects were included in the study. The mortality rate was 5.6%, and the incidence rates of perioperative MI and post-operative stroke are 0.7% and 4.2%, respectively. The incidence rate of post-operative AF was 39.6%, post-operative bleeding was 10.4%, and acute kidney injury was 18.8%. A lower mortality rate was seen among patients on pre-operative beta blockers (p=0.009), while an increased rate was seen with longer ischemic (p=0.039) and bypass time (p=0.001). Patients with a high serum creatinine pre-operatively had increased mortality rates (p=0.044). Increased rates of stroke were seen in patients with multi-vessel CAD (p=0.034) and diabetes (p=0.046). Higher rates of acute kidney injury were seen among patients with a history of chronic kidney disease (p=0). Post-operative bleeding was seen among patients with multi-vessel CAD (p=0.009). AF was increased in patients with left main CAD (p=0.010).

Conclusion:

The mortality rate after coronary artery bypass graft surgery noted in this study is higher compared to previous local and international data, although the small sample size could have contributed significantly to this disparity. The determinants of increased mortality include elevated pre-operative serum creatinine levels, prolonged ischemic time and prolonged bypass time. Multi-vessel CAD and a history of diabetes mellitus were determined to increase the post-operative stroke rate. Left main CAD is predictive of the occurrence of post-operative AF, as is the presence of chronic kidney disease in the development of post-operative acute kidney injury. Multi-vessel CAD predicts the increased occurrence of post-operative bleeding.