Systemic Amyloidosis and Cardiac Autonomic Neuropathy Associated with Waldenstrom's Macroglobulinemia

A 73-year-old male with long-standing Waldenstrom's macroglobulinemia complicated with systemic amyloidosis presented with a witnessed syncopal episode. He had complaints of orthostatic dizziness and palpitations for few months. Orthostatic hypotension and peripheral neuropathy were demonstrated on physical examination. EKG, 24-hour Holter monitoring, and 2D echocardiogram were unremarkable. MRI of the brain ruled out stroke. Patients with amyloidosis can develop cardiovascular disease through amyloid cardiomyopathy, small vessel disease, conduction defects, pericardial effusion, or autonomic denervation. After ruling out other life-threatening causes, Ewing's battery of tests was done to rule out cardiac autonomic neuropathy. Two heart rate tests and one blood pressure test were abnormal which indicated severe cardiac autonomic neuropathy. Cardiac autonomic neuropathy can mask symptoms of acute coronary syndrome and hence early diagnosis using the simple bedside maneuver is beneficial. The test is also important for prognostication. Absence of augmentation of cardiac output from inadequate autonomic stimulation will lead to postural hypotension, exercise intolerance, and tachycardia. There may be no change in heart rate with Valsalva or deep breathing both of which increase parasympathetic tone. As the condition progresses, it may result in cardiac denervation which can result in silent myocardial infarction, syncope, and sudden death.