Inappropriate detection of supraventricular arrhythmias by implantable dual chamber defibrillators: A comparison of four different algorithms

Inappropriate therapy of supraventricular tachyarrhythmias by an ICD is sti ll a common problem. Dual chamber (DDD) ICDs provide additional atrial sens ing and should result in higher specificity for detection of supraventricul ar tachyarrhythmias. However a direct comparison of different dual chamber algorithms has not been reported. The detection algorithms of four differen t DDD ICDs were tested: Phylax AV, Defender IV; Ventak AV III DR, and Gem D R 7271. Based on arrhythmias recorded from patients undergoing invasive ele ctrophysiological studies and in many cases of catheter ablation at our ins titution, a library consisting of 71 supraventricular and 15 ventricular ta chyarrhythmias was created. The library consists of episodes of atrial fibr illation, atrial flutter with different AV conduction, typical and atypical AV nodal reentrant tachycardia, AV reentrant tachycardia, sinus tachycardi a, and ventricular tachycardia with and without ventriculoartrial conductio n. Atrial fibrillation was appropriately classified by all four algorithms. However, the specificity for detection of other supraventricular tachyarrh ythmias achieved by the Biotronik (12 %) and the Guidant (11 %) devices was significantly lower compared to the specificity of the ELA (28 %) and the Medtronic DDD ICD (20%). This is due to the fact that the Biotronik and the Guidant algorithm classified all supraventricular tachyarrhythmias resulti ng in a stable ventricular rate as ventricular tachycardia, whereas the ELA and Medtronic algorithms performed a more detailed analysis by assessment of PR association, atrial onset, or timing of the atrial event relative to the ventricular event, respectively. Atrial fibrillation, the most common s upraventricular tachyarrhythmia in patients with ICD, was detected by all d evices.