NEW ICD-TECHNOLOGIES - FIRST CLINICAL-EXPERIENCE WITH DUAL-CHAMBER SENSING FOR DIFFERENTIATION OF SUPRAVENTRICULAR TACHYARRHYTHMIAS

Inappropriate ICD therapy for supraventricular arrhythmias remains an unsolved problem and may lead to serious clinical situations. Current algorithms for differentiation of supraventricular and ventricular arr hythmias are based on ventricular sensing solely and, therefore, lack sensitivity and specificity. This preliminary analysis from a multicen ter trial comprises data from the first 26 patients who received a Res -Q(TM) Micron active-can ICD (Sulzer Intermedics) with a ventricular d efibrillation lead and an additional bipolar lead for atrial sensing. Digitized atrial and ventricular waveform storage as well as interval charts from 102 induced and 30 spontaneous arrhythmia episodes were pr ospectively collected and analyzed with regard to appropriateness of I CD therapy. From all 132 arrhythmia episodes, high-quality stored dual -chamber intracardiac electrograms (IEGM) could be retrieved for furth er analysis: in 40 (30%) episodes, atrial fibrillation (AF with rapid ventricular response 22, AF with VT 9, AF with VF 9) was identified as the underlying intrinsic rhythm, and inappropriate ICD therapy was de livered in 4/22 (18%) episodes of AF with rapid ventricular response. In the remaining 92 (70%) episodes, sinus rhythm was the underlying at rial rhythm (SR with VT 13, SR with VF 79), and no inappropriate thera py was observed. Three of 22 (15%) high-energy shocks delivered for ve ntricular arrhythmias (VT 9, VF 9, rapid AF 4) terminated AF at the sa me time. In total, there were 3 complications (2 atrial lead dislodgme nts, 1 revision for bleeding). Both atrial lead dislodgments occurred in the 2 patients with passive-fixation leads compared to none in the 24 patients with active-fixation leads (p = 0.003). In conclusion, dua l-chamber sensing and waveform storage of the new Res-Q(TM) Micron off er very helpful diagnostic tools for the detection of inappropriate IC D-therapy. Placement of an additional atrial lead is safe and does not interfere with proper ICD function. However, for avoidance of atrial lead dislodgment, active fixation lends are recommended. With the test ed active-can lead configuration, the efficacy of successful atrial ca rdioversion by high-energy shocks delivered for ventricular arrhythmia s seems to be low.