Background: Atrial fibrillation accounts for 15-50% of all the complications after a coronary artery bypass operation, making it the most common cause of mortality and morbidity. Off-pump CABG reduces the development of new onset atrial fibrillation by decreasing the inflammatory reaction, tissue trauma, and necrosis. Increased serum lactate levels are a direct marker for poor prognosis in post-operative bypass patients. In Pakistan, there is a scarcity of data related to off-pump CABG and new onset AF. Hence, there is a need to evaluate the incidence, causes, and effects of off-pump CABG on POAF.

Objective: The objective of this study was to determine the frequency of new-onset atrial fibrillation in post-operative off-pump coronary artery bypass patients and compare the frequency of POAF in patients with and without hyperlactatemia.

Methodology: This descriptive case study was carried out in the adult cardiac surgery operation theatre and ICU at the Armed Forces Institute of Cardiology/National Institute of Heart Diseases. It was carried out over a period of six months from 27-12-2018 to 26-06-2019. A total of 100 patients were included in the study. Their serum lactate levels were checked pre and post-procedure. Statistical analysis was used to determine the frequency of developing AF in the first 48 hours and its relation with lactate levels.

Results: The mean age of the patients was 59.1±7.8 years. 78% of the patients were males, while females were only 22%. The mean BMI was 28.4±3.0 kg/m². The majority of patients suffered from triple vessel disease (79%). LMS was found to be in 18 patients (18%). Atrial fibrillation was found in 16 patients (16%). Post-operative hyperlactatemia in the first 24 hours was present in 51 patients (51%).

Conclusion: Through this study, we established that off-pump CABG is a safer procedure as it can reduce the incidence of new-onset atrial fibrillation in post-operative patients.

Keywords: Atrial fibrillation, High serum lactate levels, Off-pump coronary artery bypass