Ventricular arrhythmia burden and implantable cardioverter-defibrillator outcomes in transthyretin cardiac amyloidosis

Background: As targeted treatments for amyloid transthyretin cardiomyopathy (ATTR-CM) are becoming available, we aim to characterize the rates of ventricular arrhythmias (VAs), implantable cardioverter-defibrillator (ICD) utilization, and their impact on survival.

Methods: This is a retrospective cohort study of 130 patients with ATTR-CM diagnosed at Emory University's Cardiac Amyloidosis Center between April 2012 and September 2020. VAs were defined as nonsustained or sustained ventricular tachycardia and ventricular fibrillation.

Results: Of 130 patients, 42 had wild-type disease (wtATTR) and 88 had hereditary variants (hATTR), most commonly Val122Ile (89%). At ATTR-CM diagnosis, 80 (62%) patients had EF ≤ 40% consistent with systolic heart failure. Of the 69 (53%) patients with documented VAs significantly higher rates occurred among those with EF ≤ 40% compared with EF > 40% (67% vs. 28%, p = .001). Thirty-two patients (25 hATTR, 7 wtATTR) had primary prevention ICDs implanted. Eight (25%) of these patients received appropriate ICD therapy while two (6%) experienced inappropriate therapy. Comparing patients with EF ≤ 35% with and without ICDs did not reveal any survival difference (3.3 ± 0.5 vs. 2.8 ± 0.4 years, p = .699).

Conclusions: High rates of VAs and appropriate ICD therapy were found among a unique cohort of largely hereditary ATTR-CM patients with a high rate of systolic heart failure.