Background. Low energy endocavitary cardioversion is a new alternative to transthoracic shock in patients with chronic AF. Nevertheless, patient discomfort and possible induction of ventricular arrhythmias should be further evaluated.
Methods. Sixteen patients with chronic AF were included in the study. Two 6F custom-made catheters (Electro-Catheter, Inc.) were used for shock delivery and one tetrapolar lead for ventricular synchronization. Without sedation and in a random order, patients underwent two sequences of shocks to determine the ADT at rest and during exercise. Exercise was performed isometrically by the superior limbs. Atrial fibrillation was reinduced by atrial pacing. After each shock, the patients were requested to grade their discomfort with a score from 1 to 5. The power of the study was >90 % in detecting a 25 % difference in the ADT between groups.
Results. Patients were classified into two groups: Nine patients (group A) underwent the first cardioversion during exercise; seven patients (group B) underwent the first cardioversion at rest. In total, the mean (±SD) ADT was 6.70 ± 1.54 J during exercise and 7.02 ± 1.82 J at rest (p = 0.59). A significantly lower ADT was observed in the second shock sequence than the first one (6.32 ± 2.09 J vs. 7.40 ± 0.87 J, p < 0.05). The discomfort score was 3.25 ± 0.86 at rest and 2.94 ± 0.77 during exercise (p = 0.09). No complications occurred.
Conclusions. Low energy endocavitary cardioversion is a safe and effective procedure in patients with chronic AF. Discomfort is not generally severe enough to result in procedure termination. The ADT is not influenced by exercise and is higher in chronic than in reinduced AF.
(J Am Coll Cardiol 1997;29:576–81)