Perioperative AF: Not as Innocuous as It Seems

“Lone atrial fibrillation (AF),” a term that has been used to describe isolated episodes of AF, was previously thought to be innocuous, conferring no increased risk of thromboembolic complications. This was especially thought to be the case in occurrences of perioperative AF, which were previously presumed to be benign cardiac arrhythmias in response to physiologic stress.

However, a recent study published in the Journal of the American Medical Association questions these findings and reports that perioperative AF may indeed confer a higher long-term stroke risk. Patients without preexisting AF who were hospitalized for surgery (as defined by surgical diagnosis related group codes) between 2007 and 2011 in California hospitals, and discharged alive without stroke, as defined by ICD-9 codes, were included in this observational retrospective cohort study. Patients were censored from the study cohort if they had subsequent emergency or inpatient visits for AF and cardiac surgery patients were analyzed separately.

Among the 1,729,360 patients, there were 24,117 cases of perioperative AF (1.43%) with a higher event rate after cardiac vs noncardiac surgery (16.1% vs 0.78%). There were 13,952 (0.81% of patients) who had a documented ischemic stroke following discharge. After multivariate adjustment, perioperative AF was associated with a 1.3 times higher hazard ratio (HR) for stroke at 1 year after cardiac surgery and a 2 times higher HR for at 1 year after non-cardiac surgery. The risk for stroke conferred by perioperative AF was much higher for non-cardiac surgery than for cardiac surgery (P<.001 for interaction).

This large observational study establishes that perioperative AF associated with non-cardiac surgery is definitely a risk factor for ischemic stroke in the future. The mechanism of this relationship is most likely related to occult episodes of paroxysmal AF. But whether the presence of perioperative AF should change the clinical management of patients with respect to the decision to anticoagulate remains to be studied. For now, patients with AF in the perioperative period should be screened aggressively for occult AF in the ambulatory setting and their AF risk factors should be aggressively controlled.

References:

Gialdini G, Nearing K, Bhave PD, et al. Perioperative atrial fibrillation and the long-term risk of ischemic stroke.  JAMA. 2014;312(6):616-622. doi:10.1001/jama.2014.9143.