Primary prevention implantable cardioverter-defibrillators in transthyretin cardiac amyloidosis

Background: Due to the poor long-term prognosis of patients with transthyretin cardiac amyloidosis (ATTR-CA), the role of primary prevention implantable cardioverter-defibrillators (ICDs) in this patient population remains controversial. We aimed to study the impact of primary prevention ICDs on survival in patients with ATTR-CA.

Methods: Among 382 patients diagnosed with ATTR-CA at our institution between 2004 and 2018, 19 had primary prevention ICDs implanted. This cohort was matched in a 1:3 manner on the basis of age, gender, ejection fraction (EF) and ATTR-CA stage with 57 patients without cardiac devices. Patients were followed up for a mean of 23 ± 19 months. Our primary outcome of interest was all-cause mortality.

Results: Mean EF at the time of ICD implantation was 28 ± 8%. No patients had a history of sustained ventricular arrhythmia (VA) at the time of implant. Only a minority of patients were tolerant of optimal medical therapy due to renal impairment, hypotension, or a combination of the two. Death occurred in 43 (75%) patients without primary prevention ICDs and 16 (84%) patients with primary prevention ICDs, P = .26. Of the 19 patients with ICDs, three had inappropriate shocks delivered for atrial fibrillation, and none had therapies for sustained VAs. On Cox proportional hazards analyses, the presence of a primary prevention ICD was not associated with improved survival (HR 0.72, 95% CI 0.4-1.3, P = .27).

Conclusion: Primary prevention ICDs do not prolong survival in patients with ATTR-CA and a reduced EF. Our findings are observational and will need to be validated in future prospective studies.