Prevalence of ventricular arrhythmias and role of implantable cardioverter-defibrillator in cardiac amyloidosis.

Cardiac amyloidosis is an underdiagnosed disease that is caused by myocardial deposition of misfolded light chain (AL) or transthyretin (ATTR) amyloid fibrils, leading to restrictive cardiomyopathy and eventually death if untreated. Ventricular arrhythmias are common in cardiac amyloidosis, and the prevalence is higher in AL than ATTR. There are multiple suspected pathogenic mechanisms for ventricular arrhythmia including activation of inflammatory cascade from direct amyloid deposition, and electro-mechanical as well as autonomic dysfunction due to systemic amyloid deposition. Cardiac amyloidosis is associated with an increased risk of sudden cardiac death, and the risk is higher in AL than ATTR. Finally, the role of implantable cardioverter-defibrillators in cardiac amyloidosis is controversial, and while successful termination of life-threatening ventricular arrhythmias has been reported in few studies, there has been no evidence of improvement in outcomes when used for primary prevention in patients with cardiac amyloidosis.