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PHILADELPHIA -- For atrial fibrillation (Afib) patients with obesity, a second set of defibrillation pads for dual direct current cardioversion safely improved the success of the procedure, a randomized trial showed.

Only 2% of obese patients failed their first cardioversion attempt with the dual approach, compared with 14% treated with a standard single direct current cardioversion (DCCV, P=0.002).

After multivariate analysis -- controlling for age, sex, BMI, left ventricular ejection fraction, left atrial volume index, congestive heart failure, obstructive sleep apnea, and antiarrhythmic drug use -- the odds of cardioversion failure were 12.6-fold higher with single DCCV (P=0.03).

No differences emerged between groups in post-procedure chest discomfort or procedure-related complications, reported Joshua D. Aymond, MD, of Ochsner Health in New Orleans, in a presentation at the American Heart Association (AHA) annual meeting.

For his practice in Louisiana, some 10% of cardioversion patients fit the BMI criteria for the trial, and obesity is an increasing issue nationwide, Aymond noted. Cardioversion fails to restore sinus rhythm in some 20-35% of obese patients, compared with less than 10% of those who are not obese, due to increased impedance.

"This study adds credibility and confidence with the use of DCCV, especially in difficult or refractory patients," said late-breaking clinical trial session study discussant Jose A. Joglar, MD, of the University of Texas Southwestern Medical Center and Parkland Health in Dallas. "This can be added to a list of other techniques to optimize cardioversion success, such as manual pressure and higher initial energy."

The multicenter trial included 200 adults undergoing nonemergent cardioversion for Afib from August 2020 to 2023 who had a BMI of 35 or greater and were on adequate anticoagulation. They were randomized 1:1 to single-blind treatment with either usual single DCCV with two pads delivering 200 J of energy total or to dual DCCV with two sets of pads delivering 200 J each from two defibrillator devices, for a total of 400 J.

The groups were well balanced for left ventricular ejection fraction, left atrial volume index, antiarrhythmic drug use, and beta-blocker use.

Of the 14 single DCCV patients who failed initial cardioversion, a second attempt with dual DCCV converted all but two. A third attempt with DCCV was successful in both.

Of the two patients randomized to dual DCCV with an initially unsuccessful attempt, one converted on the second attempt and the other took a third attempt after a period of amiodarone treatment.

Limitations included that only the patient was blinded to treatment assignment, the lack of long-term outcome data, and use of a single pad orientation. "Certainly other orientations of pads could have been tried," such as putting one on the patient's back, Aymond noted.

There are also defibrillators available that have the capacity of delivering 360 J, and applying pressure to the pads with paddles has also proven effective in other studies and may deserve to be more widely used, Joglar noted. "But for now, I think the use of more liberal high energy outputs, especially if you only have 200 J defibrillator, maybe an initial energy of 400 J, certainly have a place in the marketplace and in our general practice."

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