Prolonged QTc Interval and Polymorphic Ventricular Tachycardia in a Patient with Multiple Myeloma- associated Cardiac Amyloidosis

Systemic amyloid light chain (AL) amyloidosis (previously known as primary amyloidosis) is a multisystem disease characterized by the extracellular deposition of fibrils composed of immunoglobulin light chains within various organs. AL amyloidosis is associated with different types of monoclonal plasma cell dyscrasias, including multiple myeloma and other monoclonal gammopathies.1 Cardiac involvement is clinically reported in approximately one-half of all cases, but the heart is affected pathologically in up to 90% AL amyloidosis patients.2,3 Patients with cardiac amyloidosis can present a wide spectrum of clinical manifestations, but usually have symptoms of congestive heart failure and echocardiographic evidence of restrictive cardiomyopathy. The present report describes an unusual case of multiple myeloma-associated cardiac amyloidosis in a patient who presented a long QT interval (QTc) and polymorphic ventricular tachycardia (VT).