JACC: New onset of AF common after TAVI?

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New-onset atrial fibrillation (AF) occurred in one-third of patients undergoing transcatheter arotic valve implantation (TAVI) with no previous history of AF, according to a single center study published Dec. 14 in the Journal of the American College of Cardiology. However, authors of an accompanying editorial wrote that the results should be interpreted with "caution," and that the correlation pinpoints the need for improvement in the identification of patients at risk.

“New-onset atrial fibrillation (NOAF) is a well-known complication of cardiovascular interventions, and its occurrence has been associated with a higher rate of periprocedural cerebrovascular events and cardiac mortality,” Ignacio J. Amat-Santos, MD, of the Quebec Heart & Lung Institute at the Laval University in Quebec City, and colleagues wrote. “However, very few data exist on the occurrence of NOAF following TAVI, and no studies to date have evaluated the predictive factors of this complication during transcatheter valve procedures.”

To bolster these data, Amat-Santos et al performed a single center study at the Laval University, which enrolled 138 patients with no prior history of AF who were undergoing TAVI with a balloon-expandable valve (Sapien, Edwards Lifesciences) between May 2007 and May 2008. The researchers defined NOAF as any episode lasting more than 30 seconds.

Amat-Santos and colleagues noted that cerebrovascular events are the most “worrisome” complications associated with TAVI, which has one of the highest incidence rates reported in interventional cardiology—4 percent. While one-third of these events occur during TAVI procedures, more than 50 percent occur within several days of TAVI, which could suggest that other mechanisms other than those related to the procedure may be involved.

The previously reported PARTNER trial found the incidence of NOAF within 30 days to have occurred in 15 percent of patients, nearly one-half of what was found in the current study. However, Amat-Santos noted that nearly two-thirds of the patients enrolled in PARTNER underwent TAVI via the transfemoral approach. In the current study, 72.5 percent of patients were treated with the transapical approach and 27.5 percent were treated transfemorally.

Results of the PARTNER B trial showed that two-year stroke rate was 13.8 percent in the TAVI group vs. 5.5 percent in the standard therapy group.

Amat-Santos et al reported that 31.9 percent of patients experienced a NOAF at a median time of 48 hours post-TAVI procedure. Eight patients experienced a stroke post-procedure. Nearly 40 percent of the NOAF episodes occurred during or within 24 hours following a procedure. Of these new onsets, 22.7 percent resolved spontaneously and lasted less than 12 hours while 77.3 percent required pharmacological or electrical cardioversion.

For the 44 patients who experienced a NOAF at hospital discharge, 4.5 percent were treated with aspirin, 13.6 percent were treated with aspirin plus clopidogrel (Plavix, Bristol-Myers Squibb/Sanofi-Aventis), 2.3 percent were treated with warfarin alone, 54.5 percent were treated with warfarin plus aspirin and 25 percent were treated with warfarin, aspiring and clopidogrel. Meanwhile 14 patients were treated with amiodarone and 20 patients were administered beta-blockers.

Thirty-day stroke rates were higher in the patients who experienced a NOAF compared with those who did not, 11.4 percent vs. 3.2 percent, respectively. The endpoint of stroke and systemic embolism was also higher for patients who experienced a NOAF, 13.6 percent vs. 3.2 percent, respectively.

Amat-Santos and colleagues found that “a larger atrial size and transapical approach were the predictive factors of NOAF following TAVI.” And while a new onset of AF was linked to higher rates of stroke and systemic embolism, there was no evidence that associated it with higher rates of cardiac mortality.

Amat-Santos and et al concluded that future studies should focus on preventive strategies aimed to reduce a new onset of AF in the TAVI setting.

In the accompanying editorial, Bernard Iung, MD, of Bichat Hospital in Paris, and colleagues wrote that the current study was original yet brought to light the often shushed issue of NOAF. Previously, NOAF has received limited interest because AF is usually a concern in mitral than in aortic valve diseases. Additionally, Iung said that post-op AF is generally considered a common event post-surgery rather than a potential cause of complication.

While Iung et al called the 32 percent of new-onset AF within the 30 days post-surgery “unexpected,” they noted that the current findings “cannot be extrapolated to all cases of TAVI.”

Iung et al said that the impact of AF after TAVI results should be “interpreted with caution, given the small number of embolic events (nine at 30 days) and the number of confounding factors, including anticoagulant therapy.

“Even if the relationship between post-procedural AF and stroke needs to be confirmed by studies comprising a higher number of events, the association raises questions regarding the most appropriate antithrombotic therapy following TAVI,” Iung and colleagues wrote. The fact that Amat-Santos et al found a high number of episodes of AF lasting less than one hour raises concern about recommendations to combine anticoagulant therapy with a single antiplatelet drug as soon as patients experience an episode of AF post-TAVI.

“The potential contribution of post-procedural AF to the occurrence of stroke after TAVI highlights the need to improve the identification of patients at risk, to test pharmacological approaches to reduce the incidence of AF, and to conduct randomized trials to refine antithrombotic therapy in this setting,” Iung and colleagues summed.