Outcomes of pacing in patients with cardiac amyloidosis - a single center experience

Abstract

BACKGROUND: Cardiac amyloidosis (CA) is associated with sinus node dysfunction (SND) and conduction system disease (CSD) yet data on pacing indications and outcomes is scarce. METHODS: Retrospective review of patients (pts) with CA who had device implantation due to pacing indication at our institution. RESULTS: At total of 51 (mean age 67.2±9.2 years, 90.2% male) pts with immunoglobulin light chain (n=27, 52.9%), hereditary transthyretin (n=7, 13.7%) and wild-type transthyretin (n=17, 33.3%) CA were included. Indication for pacing was exercise intolerance (n=16, 31.4%), syncope (n=16, 31.4%), congestive heart failure (n=5, 9.8%) and palpitation (n=2, 3.9%) with SND (n=23, 45.1%), CSD (17=33.3%) and uncontrolled atrial fibrillation (n=11, 21.6%). 16 (31.4%) pts received defibrillators (ICD) for primary prevention, of whom 8 (15.7%) had left ventricular ejection fraction (LVEF) ≤35%. Atrial (P wave: 1.7±1.2mV, threshold: 1.1±0.5mV/0.5±0.2ms) and right ventricular (RV) (R wave: 7.9±3.8mV, threshold: 0.8±0.4mV/0.4±0.1ms) lead parameters were satisfactory at implantation. During follow-up (mean 36.6±33.6 months), 26 (51%) pts reported symptomatic improvement (SI). Syncope was the only predictor of SI (OR 16.4, 95%CI 1.8-145.2, p=0.01) while exercise intolerance was not (OR 0.09, 95%CI 0.02-0.44, p=0.003). First-time life-threatening ventricular arrhythmias (VA) occurred in 6 (11.8%) pts, 3 (5.9%) had ICD implanted for LVEF ≤35%, 3 (5.9%) without ICD and LVEF ≥35%. Syncope was not predictive of first-time VA. RV lead noise led to inappropriate ICD shocks in 1 patient. Atrial lead sensing failure occurred in 6 (11.8%) and loss of capture in 5 (9.8%). CONCLUSION: Device implantation in patients with cardiac amyloidosis is safe but atrial lead failure is common. Syncope usually improves with pacing whereas other factors should be considered in those presented with exercise intolerance. Selection of pts who need pacing for prophylactic ICD implantation is challenging as neither left ventricular ejection fraction nor syncope are predictive of arrhythmic events.