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Postoperative AF after CABG decreases thromboembolic risk
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Patients who underwent CABG and developed new-onset postoperative atrial fibrillation had a lower long-term risk for thromboembolism compared with patients who developed nonsurgical, nonvalvular AF, according to a study published in JAMA Cardiology.
“Our data do not support the notion that new-onset [postoperative] AF should be regarded as similar to primary [nonsurgical, nonvalvular] AF in terms of long-term thromboembolic risk,” Jawad H. Butt, MD, of the department of cardiology at Copenhagen University Hospital in Denmark, and colleagues wrote.
CABG, AF in Denmark
In this retrospective cohort study, researchers analyzed data from 2,108 patients (median age, 69 years; 82% men) who underwent first-time isolated CABG and developed postoperative AF during hospitalization between 2000 and June 2015. Patients did not have a history of AF, deep vein thrombosis or pulmonary embolism before surgery, were alive at discharge and did not have a prescription for oral anticoagulation 6 months before surgery.
Patients with postoperative AF were matched by sex, age, year of index date and CHA2DS2-VASc score with 8,432 patients (median age, 69 years; 82% men) with nonsurgical, nonvalvular AF.
The primary outcome was thromboembolism, which was a composite of transient cerebral ischemia, ischemic stroke and embolism or thrombosis in peripheral arteries. Secondary outcomes included all-cause mortality and recurrent AF hospitalization.
Follow-up was conducted from the index date until the outcome of interest occurred, 10 years after the index date, a patient moved out of Denmark or December 2015, whichever came first.
Within 30 days after the index date, oral anticoagulation therapy was initiated in 8.4% of patients in the postoperative AF group and 42.9% of those in the nonvalvular AF group.
Risk for thromboembolism
Patients with postoperative AF had a lower risk for thromboembolism (18.3 events per 1,000 person-years; 95% CI, 16-20.9) compared with those with nonvalvular AF (29.7 events per 1,000 person-years; 95% CI, 28-31.5; adjusted HR = 0.67; 95% CI, 0.55-0.81).
Oral anticoagulation therapy reduced the risk for thromboembolic events in the postoperative AF group (aHR = 0.55; 95% CI, 0.32-0.95) and the nonvalvular AF group (aHR = 0.59; 95% CI, 0.51-0.68) vs. patients who did not receive the therapy.
Compared with patients who did not develop postoperative AF after CABG, those who developed the condition had an increased risk for rehospitalization for AF (aHR = 2.27; 95% CI, 1.84-2.8) and all-cause mortality (aHR = 1.32; 95% CI, 1.18-1.47), although the risk for thromboembolism was similar in both groups (aHR = 1.11; 95% CI, 0.94-1.32).
“Given that [postoperative] AF is one of the most common complications of cardiac surgery, more studies specifically addressing the role of [oral anticoagulation] therapy in patients with [postoperative] AF are warranted to examine the efficacy, safety, timing and duration of [oral anticoagulation] therapy in this setting, preferably in a randomized clinical trial,” Butt and colleagues wrote.
In a related editorial, Jeff S. Healey, MD, MSc, FRCPC, from the Population Health Research Institute at McMaster University in Ontario, Canada, and colleagues wrote: “This has important implications for how clinicians should treat patients with this common problem. It is likely that some AF following cardiac surgery is indeed transient and caused by inflammation, while in other cases, it is typical clinical AF in an at-risk individual that happens to receive a diagnosis for the first time in the postoperative setting. Identifying this latter group who may be at higher risk of AF recurrence and stroke is not yet possible and should be a priority.” – by Darlene Dobkowski
Disclosures: Butt reports no relevant financial disclosures. Healey reports he received research grants from Bristol-Myers Squibb and Pfizer. Please see the study for all other authors’ relevant financial disclosures.
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