Outcome and incidence of appropriate implantable cardioverter-defibrillator therapy in patients with cardiac amyloidosis

Background: Cardiac amyloidosis (CA) is associated with a poor prognosis with the proposed mechanism of sudden cardiac death in the majority of patients being pulseless electrical activity. However, the incidence of ventricular arrhythmias (VA) and implantable cardioverter-defibrillator (ICD) indications in CA patients are unclear. We performed a detailed evaluation of our CA population undergoing ICD implantation and assessed appropriate ICD therapy and survival predictors.

Methods: We included consecutive patients from June 2008 to November 2014 in five centers. ICDs were systematically interrogated and clinical data recorded during follow-up.

Results: Forty-five patients (35 males, mean age 66±12years) with CA who underwent ICD implantation (84.4% primary prevention) were included. CA types were hereditary transthyretin in 27 patients (60%), light chain (AL) in 12 (27%) and senile in 6 (13%). After a mean follow-up of 17±14months, 12 patients (27%) had at least 1 appropriate ICD therapy occurring after 4.7±6.6months. Patients with or without ICD therapy had no significant differences in baseline characteristics, amyloidosis type, LVEF, and type of prevention although there was a trend towards a better 2D global longitudinal strain in patients with ICD therapy (P=0.08). Over the follow-up, 12 patients died (27%) and 6 underwent cardiac transplantation (13%). From multivariate analysis a worse prognosis was associated with higher NT-proBNP level (>6800pg/mL, HR=5.5[1.7-17.8]) and AL type (HR=4.9[1.5-16.3]).

Conclusions: Appropriate ICD therapies are common (27%) in CA patients. No specific strong VA predictor could be identified. However, patients with advanced heart disease, especially with AL-CA, display a poorer outcome.