Post-Surgery Atrial Fibrillation in Hospitalized Patients Is Associated with Increased Stroke Risk

New research suggests that patients who develop seemingly temporary cases of atrial fibrillation (AF) immediately after most types of surgery are dramatically more likely to suffer subsequent strokes.

The study used medical records to follow 1.7 million people for an average of 2.1 years after inpatient procedures and determine whether such “perioperative AF” is a transient response to surgical stress or a warning sign of ongoing problems.

Overall, 24,700 (1.5%) of the patients received a new diagnosis of AF while they were hospitalized for their initial surgery, and nearly 14,000 (0.81%) of them suffered an ischemic stroke at some time after the surgery.

Cumulative stroke rates a year after cardiac surgery were 0.99% (95% confidence interval [CI], 0.81%-1.20%) for patients who experienced perioperative AF and 0.83% (95% CI, 0.76%-0.91%) in those who did not. Cumulative stroke rates a year after all other types of surgery were 1.47% (95% CI, 1.24%-1.75%) for patients who experienced perioperative AF and 0.36% (95% CI, 0.35%-0.37%) for those who did not.

A Cox proportional hazards analysis accounting for potential confounders concluded that perioperative AF was associated with a 30% greater risk of future stroke for patients who underwent cardiac surgery (95% CI, 1.1-1.6) and a 100% greater risk of future strokes for patients who underwent any other type of surgery (95% CI, 1.7-2.3).

"Our results may have significant implications for the care of perioperative patients,” the study authors wrote in the Journal of the American Medical Association.

“The associations we found suggest that while many cases of perioperative AF after cardiac surgery may be an isolated response to the stress of surgery, perioperative AF after noncardiac surgery may be similar to other etiologies of AF in regard to future thromboembolic risk.”

Typically, a little more than 1% of all people who undergo inpatient surgery experience at least one incident of AF during their stay at the hospital. The rate, however, is much higher for people who undergo cardiac surgery. As many as a third of them experience perioperative AF.

Unlike chronic AF, which has long been known to elevate a patient’s stroke risk roughly threefold, such apparently temporary cases of the disease have generally been regarded as isolated incidents for almost all patients.

The study authors suggested several possible explanations for their findings. Many of the patients who were first diagnosed with AF after their surgeries may have unknowingly developed the paroxysmal form of the disease beforehand. Others may have been healthy until the surgery but developed an ongoing problem after the initial episode.

Either way, subsequent problems with irregular heartbeat may well have gone unnoticed after patients underwent surgery. Neither surgeons nor general practitioners typically check for AF in the months after a procedure, and several recent studies indicate that many people with sporadic AF often fail to recognize the problem.

“Our results,” the study authors wrote, “suggest the need for future studies involving long-term ambulatory cardiac monitoring to better delineate the risk associated with transient vs persistent perioperative AF, as well as randomized clinical trials to determine optimal strategies for antithrombotic therapy in patients with perioperative AF and a significant burden of other risk factors for stroke.”