Due to the limited efficacy of
drug therapy in
atrial fibrillation and the high rate of recurrence, strong efforts were made to find non-pharmacological strategies. For three years now, the implantable atrial
defibrillator Metrix from InControl has been available as an alternative
therapy. From October 1995 to the present the atrial
defibrillator was implanted in 179 patients worldwide. The sensitivity of the system and its algorithms to detect
atrial fibrillation is 90%; the specificity to detect sinus rhythm is 100%. In 121 of 179 patients, 748 episodes of spontaneous
atrial fibrillation were treated with 2.4 shocks per episode. No proarrhythmic event or
stroke was seen. A
cardioversion to sinus rhythm could be achieved in 95% of patients; the overall clinical success rate was 88%. In 7% of all patients, early recurrence of
atrial fibrillation (ERAF) occurred that could not be converted into stable sinus rhythm after further
cardioversions and antiarrhythmic
therapy. In 4.1% there were lead-related complications, in 4 patients the device had to be explanted because of ineffective
therapy, and in 3 patients the device had to be changed because of loss of telemetry or early depletion of battery. In 8 patients, postoperative complications were seen (
infections,
pneumothorax and
thrombosis of the subclavian vein). Overall, the implantable atrial
defibrillator Metrix is an effective and safe alternative in treating
atrial fibrillation.