Hemodynamic Effects and Clinical Determinants of Defibrillation Threshold for Transvenous Atrial Defibrillation Using Biatrial Biphasic Shocks in Patients with Chronic Atrial Fibrillation

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Abstract
We assessed the relationship between the hemodynamic changes and shock intensity in transvenous atrial defibrillation for chronic AF. The correlation between the clinical profile and atrial DFT and the factors predicting maintenance of SR after successful defibrillation were also investigated. Atrial defibrillation using entirely transvenoas leads has been investigated as an alternative means of managing patients with AF. However, the hemodynamic consequence of this technique and the clinical factors predicting defibrillation efficacy have not been evaluated. Thirty‐seven patients with chronic AF (4 weeks to 60 months) underwent transvenoas atrial defibrillation. Defibrillation was performed by delivering R wave synchronized, biphasic (3/3 ms) shocks with step‐up voltages (20–400 V) between defibrillation catheters in the anterolateral right atrium and the distal coronary sinus. Clinical profile of the patients, the DFT, arterial blood pressure, and RH interval during defibrillation and the 6‐month recurrence rate were determined. SR was restored in 33 (89%) of 37 patients and the DFT was 3.7 ± 1.4 J (317 ± 58 V). Transvenous atrial defibrillation resulted in a mild reduction in blood pressure (6 ± 10 mmHg), but substantial prolongation of longest postshock RR intervals (507 ± 546 ms), which were significantly related to the shock intensity (r = 0.5, P < 0.001). There was no ventricular proarrhythmia. The patients'age, body weight, duration of AF, left atrial diameter, and ejection fraction were not related to the success of defibrillation, not the 6‐month maintenance rate of SR (39%). However, the patients'age was related to DFT. Apart from transient reduction in blood pressure and shock related pauses that may require backup pacing, transvenous biatrial defibrillation was a highly effective and well‐tolerated technique. The absence of clinical determinant for successful defibrillation suggests that restoring SR by transvenous atrial defibrillation could be attempted in most patients with chronic AF.

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