Influence of echocardiographic and radiographic characteristics on atrial sensing amplitude in patients with Linox Smart S DX defibrillation leads.

BACKGROUND Single-lead for implantable cardioverter-defibrillator (ICD) with floating atrial sensing dipole is a new diagnostic tool with the potential advantage in terms of arrhythmia discrimination. We sought to determine whether right heart size and dipole position influence atrial sensing. METHODS Atrial sensing (AS) amplitude was measured during implantation (PP, periprocedural), predischarge (IHFU, in-hospital follow-up) and 3-6 months after the procedure (AFU, ambulatory follow-up). Results were related to atrial dipole position in the right atrium (RA) on the basis of chest X-ray examination as well as right heart dimensions at echocardiography. RESULTS Twenty-four patients were included into final analysis. In 14 (58.3%) patients, sensing dipole was located in regions 1 and 2 of the RA. AS amplitude was greater in regions 1 and 2 when com¬pared to other locations (3.15 vs. 1.2 mV, p = 0.045, 7.53 vs. 3.8 mV, p < 0.001 and 5.63 vs. 2.44 mV, p = 0.017 for PP measurements, IHFU and AFU, respectively). There was a significant negative correlation between AS-PP and short RA dimension (RADs) (r = -0.56, p = 0.02), AS-IHFU and RA area (RAA) (r = -0.45, p < 0.05), AS-AFU and long RA dimension (RADl) (r = -0.46; p = 0.02), AS-AFU and RADs (r = -0,48, p = 0.02), and AS-AFU and RAA (and r = -0.52, p < 0.01). There was no relationship between AS and other right heart dimensions. CONCLUSIONS Larger RA size and low sensing dipole location were associated with lower AS amplitude in single-lead dual chamber ICD.