Postoperative arrhythmias (heart irregularities) are one of the most common complications after cardiac surgery and are associated with increased morbidity and mortality. Preoperative depression may be an important co-factor in the generation of postoperative arrhythmias due to sympathetic hyperactivity evident in patients with depression. Objectives: To determine the effect of preoperative depression on postoperative arrhythmia in patients undergoing elective coronary artery bypass graft (CABG) surgery. Prospective observational study, 120 patients undergoing elective CABG surgery ECG will be preformed preoperatively on all patients. All patients will be assessed for signs of depression using the Prime MD Patient Health Questionnaire (Prime MD PHQ) one week before surgery and 6 weeks postoperatively.Based on the Prime MD PHQ results, patients will be divided into two groups: those with or without signs of depression. Heart rate and rhythm monitoring with Holter will be performed for 3 days postoperatively in order to compare the incidence of postoperative arrhythmias between groups.

The primary outcome is the number of patients with and without depression suffering from ventricular and/or supraventricular arrhythmias. Secondary outcomes include all cause mortality, non-fatal myocardial infarction, cardiac arrest, and congestive heart failure. CABG surgery is the most common operative procedure in North America and arrhythmias are one of the most common postoperative complication. It is estimated that about a third of these cardiac patients suffer from preoperative depression and therefore may be exposed to a higher risk of perioperative morbidity and mortality.

If an association between preoperative depression and postoperative arrhythmia is found, treatment modalities may be indicated to reduce the prevalence of perioperative arrhythmia in patients with preoperative depression undergoing cardiac surgery.