Background

Atrial fibrillation is common among patients with heart failure and ICDs. For rhythm-control electrical cardioversion is necessary. Besides a standard external cardioversion an internal cardioversion through the ICD is equally used in clinical practice. Efficacy and risk of lead and device malfunction need to be considered. It is unclear whether internal or external cardioversion should be preferred in these patients.

Methods

50 patients have to be included. Patients with an ICD undergoing elective cardioversion for atrial fibrillation were randomized half and half to either internal or external cardioversion. Internal Cardioversion was performed with maximum output and external cardioversion was done with up to 360 J. We hypothesized that internal cardioversion is noninferior to external cardioversion. The primary end point was conversion rate of atrial fibrillation to sinus rhythm. The secondary endpoint was lead and device integrity as composite of electrical lead and device measurements.

Results

N=42 patients were randomized. 85% were male, age was 72 +/- 8 years, BMI was 28 +/- 4 kg/m², 64% of the patients had an ischemic heart disease, mean LV-EF was 29,5% and the majority of patients had received the ICD for primary prevention (59,5%). We included 1/2/3 chamber ICDs of four manufacturer and all devices were implanted on the left side. Cardioversion was successful in the external cardioversion group in 94,4% and 28,6% in the internal cardioversion group (P<0.01). There were no clinically significant differences found pre and post cardioversion in both groups for sensing, capture threshold, impedance or battery voltage. Adverse events caused by external or internal cardioversion were not observed.

Conclusion

Our preliminary results could not show a noninferiority. In fact the results show that external cardioversion was superior compared to internal cardioversion for the restoration of sinus rhythm in patients with atrial fibrillation. Potential and feared damage to the leads or device through application of direct biphasic current through external cardioversion patches was not observed.