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.
Objective: 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 for a mean of 23±19 months. Our primary outcome of interest was all-cause mortality.
Results: Baseline characteristics are shown in Figure 1a. Mean EF at the time of ICD implantation was 28±8%. No patients had a history of sustained ventricular arrhythmia at the time of implant. Only a minority of patients were tolerant of neurohormonal blockade due to renal impairment, hypotension or a combination of the two (Figure 1a). Death occurred in 43 (75%) patients without and 16 (84%) patients with primary prevention ICDs (Figure 1b, p=0.26). No deaths were due to arrhythmia. Of the 19 patients with ICDs, 3 had inappropriate shocks delivered for atrial fibrillation and none had therapies for sustained ventricular arrhythmias. On Cox proportional hazards analyses, presence of a primary prevention ICD was not associated with improved survival (HR 0.72, 95% CI 0.4-1.3, p=0.27).
Conclusion: Primary prevention ICDs do not prolong survival in patients with ATTR-CA and an EF < 35%. Our findings are observational and will need to be validated in future prospective studies.