Use of Implantable Electronic Devices in Patients With Cardiac Amyloidosis

Arrhythmias are a major cause of morbidity and mortality in the course of cardiac amyloidosis (CA). Less commonly, they may be the initial manifestation that lead to the diagnosis. With improved therapeutic interventions for amyloidosis, it is no longer considered to be a terminal untreatable condition, and there is increasing recognition of the role of implantable electronic devices in CA. The frequency and nature of arrhythmias are largely determined by the type of amyloidosis. Bradyarrhythmias are more common in the transthyretin form of amyloidosis, and risk for ventricular arrhythmias is higher in the light-chain form. Pacemaker implantation is often required and effective for alleviation of symptoms. The role of implantable cardioverter-defibrillators (ICDs) remains controversial, especially for primary prevention of sudden death. Traditional risk stratification tools for sudden death do not appear to be applicable to CA, because decline of left ventricular (LV) systolic dysfunction to the point of the usual indication for an ICD implant in other cardiomyopathies, ie, LV ejection fraction ≤ 35%, usually marks end-stage disease in CA when pump failure becomes the predominant cause of death. The challenge remains the identification of markers for sudden death in early stages of the disease. Included in this review is a general overview of available data on the nature of bradycardia and ventricular arrhythmias, including the role of implantable electronic devices for the treatment of these conditions. Published series of ICD use in CA are summarized and the role of newer pacing techniques, including biventricular pacing, is discussed.