P160 WHEN IMPEDANCE TRENDS LIE, REMOTE MONITORING HELPS FOR DIAGNOSIS

Abstract

Abstract An 82–years old female patient with history of hypertension, diagnosis of dilatative cardiomyopathy with normal coronary arteries and permanent atrial fibrillation (AF) was implanted with a dual chamber implantable cardioverter defibrillator (ICD), Guidant Ventak Prizm DR (Boston Scientific,Marlborough,USA) as a secondary prevention of sudden cardiac death in 2002. The ICD was electively replaced in 2005 and in 2010 with a Guidant, Vitality 2 DR (Boston Scientific,Marlborough,USA). In 2016, despite an optimized medical therapy, the patient experienced an episode of palpitation due to an AF with high ventricular response. Considering the difficulties of the heart rate management with the pharmacological therapy the patient underwent to an ablation of AV node. In 2017 we performed a third replacement of the ICD downgrading the system to a single chamber ICD, Fortify Assura VR (Abbott,Sylmar,USA) and providing the patient with a bedside–transmitter Merlin@home (Abbott,Sylmar,USA) The patient, followed for 4 years remotely, did not experience ventricular arrhythmias and the ventricular lead electrical parameters, including pacing and shock impedances, were stable and in the normal range. In March 2021 an alert of the Merlin system triggered an unscheduled transmission that showed several episodes of ventricular oversensing. The episodes revealed that an electrical interference inhibited the ventricular pacing causing episodes of asystole with a maximum duration of three seconds (Fig.1). Unexpectedly electrical parameters such as the pacing and shock impedances showed a stable and normal measurements (Fig .2), while the chest X–rays showed that the ventricular lead was kinked at 90–degrees below the clavicle evidencing a lead fracture (Fig.3). The patient was therefore implanted with a new ventricular lead avoiding inappropriate shocks and further episodes of asystole. The occurrence of a lead failure represents an insidious and potentially harmful event for the device implanted population, especially for ICD or pacemaker–dependent patients. The diagnosis of a lead failure is not easily predictable, and it is usually driven after a clinical event of inappropriate shock or unexplained syncope. Our case highlighted how Remote Monitoring is extremely helpful even more in this case of apparently correct functioning based on electric measurements.