Sustained ventricular arrhythmia and sinus node dysfunction revealing a cardiac amyloidosis: A case report

Amyloidosis is an infiltrative multisystem disease due to extracellular deposition of fibrils in tissues and organs. Cardiac involvement can result in progressive heart failure, conduction abnormalities and arrhythmias and is associated with a poor prognosis. Atrial arrhythmias and non-sustained ventricular arrhythmias are the most common arrhythmias in cardiac amyloidosis. However, the association of sinus node dysfunction and sustained ventricular arrhythmia is quite exceptional.

A 59-year-old male patient was admitted with a gradually worsening dyspnea with a lipothymic discomfort. Upon emergency department, an initial electrocardiogram revealed a severe bradycardia related to a sinus node dysfunction. A transthoracic echocardiography and cardiac magnetic resonance imaging showed features suspicious for cardiac amyloidosis. The diagnosis of AL cardiac amyloidosis with multiple myeloma was confirmed based on histological evidence. During hospitalization, the patient presented a sustained unstable ventricular tachycardia which has been converted by electrical cardioversion. He was treated with an implantable cardioverter-defibrillator (ICD) for secondary prevention with one episode of appropriate therapy. Unfortunately, the patient died few weeks later.

The AL subtype of cardiac amyloidosis is associated with higher rates of arrhythmias, especially VT. The management of arrhythmias in cardiac amyloidosis is complex and remains challenging given the lack of evidence. ICD was not associated with longer survival; these findings underscore the importance of careful patient selection for ICD.

As prognosis improves with the advances made in the medical treatment of cardiac amyloidosis, further studies are required to guide the management of all types of arrhythmias in cardiac amyloidosis.