New AF in Noncardiac Surgery Tied to One-Year Stroke Risk

Marlene Busko

August 14, 2014

NEW YORK, NY — New-onset perioperative atrial fibrillation during surgery—especially noncardiac surgery—was linked to an increased risk of stroke within a year, in a new study[1]. This large retrospective cohort study based on data from California hospitals highlights that even if AF is provoked only by the stress of surgery, it could be a harbinger of stroke.

"Our results may have significant implications for the care of perioperative patients," Dr Gino Gialdini (Cornell Medical College, New York, NY) and colleagues write. "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."

They call for future studies to better characterize stroke risk and therapeutic strategies for transient vs persistent perioperative AF. "Our results 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," Gialdini and colleagues say.

The study is published in the August 13, 2014 issue of the Journal of the American Medical Association.

Perioperative AF and Odds of Future Stroke

"It is important to fully elucidate the clinical burden of perioperative AF because approximately 200 million operations are performed worldwide every year," the researchers write. New-onset AF is estimated to occur in 1% to 40% of surgeries and is often considered to be a transient response to stress.

Perioperative AF during cardiac surgery has repeatedly been linked with an increased risk of perioperative stroke. However, the risk of ischemic stroke in the long term after new-onset AF during cardiac and noncardiac surgery is unclear.

To investigate this, the researchers performed a cohort study of patients who underwent major surgery in nonfederal, acute-care hospitals in California between 2007 and 2011.

Of the 1 729 360 eligible patients they identified, 24 711 (1.43%) had new-onset perioperative AF during the index hospitalization and 13 952 (0.81%) experienced an ischemic stroke after discharge, during a mean follow-up of 2.1 years.

Perioperative AF during both cardiac and noncardiac surgery was associated with a greater long-term risk of stroke after accounting for age, sex, race, insurance status, and cardiovascular comorbidities that up risk of stroke or perioperative AF (hypertension, type 2 diabetes, coronary heart disease, congestive heart failure, peripheral vascular disease, chronic kidney disease, and chronic obstructive pulmonary disease).

However, the association of perioperative AF with stroke was significantly stronger with noncardiac vs cardiac surgery (p<0.001 for interaction).

Risk of Stroke One Year After Hospitalization in Patients With vs Without Perioperative AF

Surgery type Stroke rate (%), patients with perioperative AF Stroke rate (%), patients without perioperative AF HR (95%CI)
Noncardiac 1.47 0.36 2.0 (1.7–2.3)
Cardiac 0.99 0.83 1.3 (1.1–1.6)

Several other studies support the validity of this study, the researchers note. An analysis of patients with recently implanted pacemakers or defibrillators found that a single six-minute episode of subclinical AF increased the risk of subsequent stroke. Another study showed that new-onset AF in patients hospitalized with severe sepsis has been associated with short-term and long-term risk of stroke.

"These . . . are consistent with our finding of a significantly stronger association between perioperative AF and stroke in patients undergoing noncardiac surgery than in those undergoing cardiac surgery," they write.

Gialdini has no conflicts of interest. Disclosures for the coauthors are listed in the article.

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