Patients with postoperative atrial fibrillation (AF) after coronary artery bypass graft (CABG) surgery are at a higher risk of cerebrovascular accidents (CVAs) up to 10 years after the procedure, a study published in Circulation has found. The authors of the study, Umberto Benedetto (Bristol Heart Institute, University of Bristol, Bristol, UK) et al, suggest that the findings highlight the need to revisit the notion that postoperative AF is a transient, benign complication, and that patients with postoperative AF should be considered for stricter surveillance and heart rhythm monitoring.
The study, a post hoc analysis of 10-year outcomes of the ART (Arterial Revascularization Trial), analysed 3,023 patients to have undergone surgical coronary revascularisation, of whom 734 developed postoperative AF. The study’s primary endpoint was the incidence of CVAs that occurred after discharge during the 10-year follow-up. Secondary endpoints were 10-year cardiovascular and all-cause mortality.
Benedetto and colleagues write that the incidence of postoperative AF after CABG surgery ranges between 20–40%, and typically develops within the first week after surgery, at a median time of two days after the operation. Typically, they note, it resolves with or without medication, and most patients are discharged in sinus rhythm (SR). “Although postoperative AF has traditionally been considered a transient and benign complication of CABG, more recent studies have reported an association between postoperative AF and increased early mortality and morbidity, including stroke, renal and respiratory failure, and a prolonged intensive care unit duration,” they write, adding that although postoperative AF may not be directly responsible for these poor outcomes, it is likely to contribute to increased morbidity and mortality after cardiac surgery.
The study team reports that the incidence of CVA among the study cohort during index admission was 14 (1.9%) and 23 (1%) in the pAF (postoperative AF) and SR (sinus rhythm) groups, respectively. Hospital mortality was 13 (1.8%) and 16 (0.7%) in the pAF and SR groups, respectively. In 676 patients (92.1%) in the pAF group, stable SR was restored before discharge. In the SR group, 20 patients presented with new onset of AF within six weeks after discharge.
During the 10-year follow-up, a total of 46 CVAs (6.3%) were recorded—23 ischaemic, 4 haemorrhagic and 19 of unknown cause—in the pAF group, while a total of 83 CVAs (3.6%) were recorded in the SR group—55 ischaemic, 7 haemorrhagic, and 21 unknown. The cumulative incidence of CVA at 10 years was 6.3% (4.6%–8.1%) versus 3.7% (2.9%–4.5%) in the pAF and SR groups, respectively.
With univariable and multivariable Cox regression, pAF was found to be an independent predictor of CVA at 10 years (HR, 1.53 [95% CI, 1.06–2.23]). CVA was reported as cause of death in 21 (9.7%) of 216 total deaths and in 15 (3.8%) of 394 total deaths in the pAF and SR groups, respectively. At 10 years, the cumulative incidence of cardiovascular and all-cause mortality was 11.1% (8.8%–13.4%) versus 6.4% (5.3%–7.4%) and 30.2% (26.8%–33.6%) versus 18% (16.4%–19.6%) in the pAF and SR groups, respectively.
Discussing the findings, Benedetto and colleagues note that in this cohort of patients undergoing CABG surgery, they identified a “significant association between postoperative AF and the risk of CVA at 10 years, and this association continued after controlling for potential confounders. They add: “Postoperative AF has long been considered a benign, self-limiting condition that converts to SR before hospital discharge in most cases. However, recent evidence suggests that the occurrence of postoperative AF is associated with patients with a larger burden of comorbidities, so causality between postoperative AF and long-term mortality remains unclear.”
In conclusion, the study team writes: “In the ART, the occurrence of pAF after CABG was associated with an increased 10-year risk of CVA and mortality. This association highlights the need to revisit the notion that pAF is a transient, benign condition. In particular, special consideration should be given to patients at higher baseline risk of CVA who develop postoperative AF.”