P1496Usefulness of atrial EGM for atrial and ventricular diagnosis in the DX ICD

Abstract

Introduction and purpose: Automatic implantable defibrillator (ICD) is a first-line therapy in patients at risk of sudden cardiac death. An ICD system using a single lead with floating atrial dipole can provide diagnostic capability of a dual-chamber system (it improves discrimination between SVT/VT and allows monitoring of atrial tachyarrhythmias) without placing an additional atrial lead. We prospectively registered a cohort of patients who received a single-lead ICD system with floating atrial electrodes at our center between March 2014 and November 2016. The baseline characteristics and arrhythmias detected during follow-up were analyzed. Results: Forty-eight recipients of an ICD with a monocoil electrode and an atrial sensor were consecutively enrolled. There was 83.3% male, 58.3% hypertensive, 56.3% diabetics, 81.3% had ischemic heart disease, 77.1% heart failure, and 12.5% had a history of stroke/TIA/thromboembolic event. The mean age was 69±8 years and the mean LVEF was 36±13%. 47.9% of the implants were in secondary prevention. The mean CHA2DS2-VASc at baseline was 4±1.4 points (range 0-7). Eight patients (16.7%) had paroxysmal/persistent atrial fibrillation (AF) at the time of implantation. Upon a median follow-up of 6.4 months (interquartile range 3.5-12.5), AF was identified (not known prior to implantation) in 11 patients (27,5%), being symptomatic in only one case. In this group, the median until diagnosis was 102 days (interquartile range 16.5-307.5 days). The mean duration of the first episode was 8615 h [8 min-34 h], and mean HR was 109 ± 23 bpm [82-135]. The diagnosis of AF with remote monitoring allowed the initiation of oral anticoagulation at an early stage. AF had not been previously diagnosed in none of the 6 patients with history of stroke/TIA, nonetheless in two of them the arrhythmia was detected 12 and 67 days, respectively, after the DX implant. Regarding VT discrimination, the device catalogued 56 episodes as VT (in 12 patients), of which 26 were truly VT. Atrial EGM was crucial in 3 of the 56 episodes to determine VT accurately. Conclusions: A single lead ICD system with floating atrial dipole allows an early diagnosis of AF. In our series, AF episodes were mostly asymptomatic and patients had a high thromboembolic risk, so early detection of AF involves vital implications for our patients.