A-fib—Whether New or Preexisting—Raises Mortality in Patients Undergoing TAVR

Up to a third of patients undergoing transcatheter aortic valve replacement (TAVR) also have atrial fibrillation (A-fib), which increases their risk of all-cause and cardiac mortality more than twofold, according to registry data published online February 5, 2013, ahead of print in Circulation: Cardiovascular Interventions.

Researchers led by Stephan Windecker, MD, of Bern University Hospital (Bern, Switzerland), looked at 389 high-risk elderly patients with symptomatic severe aortic stenosis who underwent TAVR and were enrolled in a prospective registry between August 2007 and October 2011. Patients received either the CoreValve (58%; Medtronic, Minneapolis, MN) or Sapien (42%; Edwards Lifesciences, Irvine, CA) heart valves.

Higher Mortality Not Driven by Stroke

One-third of patients had A-fib: 26.7% preexisting and 6.9% new-onset. The mean CHA₂DS₂-VASC score was 4.5 ± 1.2, with the majority (96%) having a score greater than 3.

Procedural results were the same in patients with and without A-fib, but on regression analysis, all-cause mortality at 1 year was more than twice as high among patients with the condition, mainly driven by a higher rate of cardiac mortality. Stroke, meanwhile, was similar between the 2 groups (table 1).

Table 1. Clinical Outcomes at 1 Year After TAVR

Patients with preexisting A-fib had greater mortality risk (HR 2.50; 95% CI 1.48-4.23; P = 0.00061) than those with new-onset A-fib (HR 1.91; 95% CI 0.78-4.68; P = 0.16). All-cause mortality was increased for any type of A-fib (table 2).

Table 2. Mortality Risk at 1 Year by A-fib Type

The increased mortality risk in patients with A-fib was consistent across multiple subgroups defined by age, diabetes, renal function, CAD, and LVEF. Among patients with A-fib, mortality risk at 1 year correlated with CHA₂DS₂-VASC score and was highest in patients with scores greater than 6 (HR 4.12; 95% CI 2.07-8.20; P = 0.00039).

Antithrombotic regimen after TAVR differed in patients with vs. without A-fib. In patients with the condition, 31% received dual antiplatelet therapy at discharge, whereas 53% received a vitamin K antagonist alone or in combination with clopidogrel or aspirin. In patients without A-fib, these rates were 84% and 11%, respectively.

The authors speculated as to how A-fib could increase mortality risk, especially when stroke rates were similar.

“In most cases, the development of [A-fib] is an expression of advanced heart disease with structural remodeling and myocardial fibrosis, which by accelerating the process of cardiac senescence may increase cardiovascular mortality,” they write. “Moreover, the loss of atrioventricular synchrony and the variation in ventricular cycle length lead to impaired ventricular filling, reduced cardiac output, and increased afterload, which are hemodynamic factors known to adversely affect clinical outcomes among heart failure patients.”

According to Ted Feldman, MD, of Evanston Hospital (Evanston, IL), the rate of A-fib in the current study is similar to that found in other valve repair populations, including those undergoing mitral procedures.

“It’s a little bit of a surprise regarding the magnitude of the added risk, given that the aortic stenosis population is already so sick,” he told TCTMD in a telephone interview, adding that the mean CHA₂DS₂ score in the study of over 4 is “remarkable,” especially compared with a study like PROTECT-AF in which two-thirds of patients had a score of 2 or lower in the trial of the Watchman device (Atritech, Plymouth, MN).

Bad Company

In addition to the high CHA₂DS₂ scores, Dr. Feldman described the similar stroke rates as “striking.”

“So the CHADS score and the A-fib seem to capture something unique rather than simply saying these patients are going to have more strokes and therefore more mortality,” he said. “A specific reason is not apparent. It’s hard to say it’s the A-fib, because stroke isn’t the answer, so it’s the company [A-fib] keeps and that would require a huge population and a lot of work to sort out.”

The presence of A-fib shouldn’t deter from performing a TAVR procedure, Dr. Feldman continued, but it should affect clinician-patient discussions. “The A-fib adds a lot to the discussion about their risks of mortality after the procedure, and this paper puts a sharper point on that,” he said. “The only important procedural implications of A-fib are anticoagulation management before and after the procedure because many of these patients are on [warfarin], and that adds a significant challenge to their periprocedural management.”

He noted that of the 2 factors, A-fib was a larger predictor of mortality than CHA₂DS₂ score. “Most of the patients were in this 1 to 6 CHADS range, and they all did about the same on Kaplan Meier,” Dr. Feldman said.

Study Details

Rates of permanent, persistent, and paroxysmal A-fib in the study were 67.3%, 7.7%, and 25.0%, respectively.

 

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Source:
Stortecky S, Buellesfeld L, Wenaweser P, et al. Atrial fibrillation and aortic stenosis: Impact on clinical outcomes among patients undergoing transcatheter aortic valve implantation. Circ Cardiovasc Interv. 2013;Epub ahead of print.

 

 

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