Risk Factors Identified for Prolonged AF After Surgical Aortic Valve Replacement

Atrial fibrillation (AF) is one of the most common postoperative complications of surgical aortic valve replacement (SAVR). Multiple studies show that in a reported 11% to 28% of cases, AF persists beyond 30 days and the patient requires long-term anticoagulation, incurring its associated risks of bleeding and stroke.

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Interventions such as left atrial appendage amputation/ligation, Cox maze and pulmonary vein isolation can be added to the valve replacement procedure to help prevent AF. These procedures add cost and operative risk, though, and many studies have tried to determine which patients are the best candidates. Most of that research has focused on the 30-day postoperative period.

By conducting a longer-term retrospective study, clinical surgical fellow Andrea L. Axtell, MD, MPH, Thoralf M. Sundt III, MD, chief of Cardiac Surgery at the Corrigan Minehan Heart Center at Massachusetts General Hospital, and colleagues identified older age and left atrial enlargement as factors that put patients at high risk of prolonged AF after SAVR. Their report appears in The Journal of Thoracic and Cardiovascular Surgery.

Study Participants and Design

The retrospective study was performed on 720 adults who underwent an isolated SAVR at Mass General between July 2011 and June 2017. Unlike previous investigations of AF after SAVR, the researchers avoided potential bias by excluding patients who had a preoperative history of AF.

Patients had routine electrocardiography examinations following surgery. The primary outcome of the study was the development of AF within 30 days after surgery:

• Transient AF — resolved within the first 30 days postoperatively
• Prolonged AF — persisted for at least one month beyond postoperative day 30

The median follow-up time for all patients was 1.4 years and 25% had more than 3.5 years of follow-up.

Incidence of AF

• 46% of patients developed AF at any time postoperatively
• 22% of patients developed transient AF. These patients are unlikely to require long-term antiarrhythmic therapy or anticoagulation, and their contribution to the risks associated with AF is unclear
• 24% of patients developed prolonged AF, with a median duration of 1.6 years (range, 33 days to 5.5 years). This is the population at greatest risk and most likely to benefit from prophylactic interventions

Independent Predictors of AF

In multivariable analyses, predictors of any AF (transient + prolonged) were age >65 and preoperative use of beta-blocker. Additionally, predictors of prolonged AF were age >65 (OR, 1.05; 95% CI, 1.02–1.07; P < .01) and moderate to severe left atrial enlargement (OR, 1.66; 95% CI, 1.01–2.74; P = .04). Of patients who had both risk factors, 40% developed prolonged AF.

Interestingly, current smoking reduced the risk of prolonged atrial fibrillation by 43%. They speculated that, since previous studies have shown that smokers are adapted to a greater baseline adrenergic state due to nicotine-induced catecholamine release, this tolerance protects against postoperative inflammation and the need for inotropic drugs, which contribute to the development of postoperative AF.

Applying the Results to Practice

The researchers emphasize that they included only preoperative variables in their multivariate analyses. Therefore, surgeons can use the results to make preoperative decisions about whether to offer a prophylactic procedure at the time of surgery.

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Learn more about Cardiac Surgery at Mass General

Refer a patient to the Corrigan Minehan Heart Center