Postoperative Atrial Fibrillation after Coronary Artery Bypass Grafting: Risk factors and clinical outcome

  • Date:
  • Location: Robergsalen, Akademiska sjukhuset, Ing 40, 4 tr, Uppsala
  • Doctoral student: Thorén, Emma
  • About the dissertation
  • Organiser: Thoraxkirurgi
  • Contact person: Thorén, Emma
  • Disputation

Postoperative atrial fibrillation (POAF) is a common complication after coronary artery bypass grafting (CABG), and more knowledge is needed regarding prediction of POAF, the extent of early atrial fibrillation (AF) recurrence after discharge, and the associations between POAF and short and long-term overall and cause-specific mortality and morbidity.

After CABG, 31-32% of all patients developed POAF. Several independent risk factors were identified, including increasing age, preoperative S-creatinine ≥150 µmol/l, male gender, NYHA class III/IV, current smoking, prior myocardial infarction (MI), and absence of hyperlipidaemia. The discriminatory ability of the final prediction model was moderate. POAF patients had a higher incidence of early postoperative complications, including stroke and heart failure (HF) and longer hospital stays. In-hospital mortality did not differ between groups.

In long-term follow-up, POAF was independently associated with increased risk of late cardiac mortality after CABG. Examining both underlying and contributing causes of death, POAF was associated with death related to arrhythmia, cerebrovascular disease and HF. The associations remained for more than 8 years.

Observation of heart rhythm during the 30 days following discharge after CABG revealed that 30% of all patients experienced episodes of post-discharge AF. Of all patients with AF, 35% did not experience any symptoms. Patients with POAF had a higher incidence of post-discharge AF, but high incidences were recorded both for patients with POAF (58%) and with sinus rhythm (19%) in-hospital.

POAF was associated with increased long-term risk of overall, cardiac and cerebrovascular mortality, ischemic stroke and HF, and displayed higher incidence rates of these morbidities after CABG. Furthermore, POAF was recognised as a recurrent condition where AF in relation to surgery was a precursor to both first and subsequent events of AF during follow-up. Occurrence of AF, HF, MI and ischemic stroke during follow-up further increased overall mortality.

In conclusion, POAF is common after CABG and remains hard to accurately predict. POAF patients experience more postoperative complications, a higher incidence of post-discharge AF and a recurrent pattern of AF long-term. POAF is also associated with an increased risk of cardiovascular-related mortality, and ischemic stroke and HF in long-term follow-up.