Clinical Reasoning: A 33-year-old man with cardiomyopathy and myopathy

An 18-year-old Hmong man sought medical care because of worsening performance on military training exercises. He had a previous syncopal episode with prompt recovery. His medical and developmental history were otherwise unremarkable. A chest radiograph revealed cardiomegaly and, after further cardiac tests, he was diagnosed with postinfectious or idiopathic cardiomyopathy. His cardiac function deteriorated and heart transplantation was pursued. During preoperative evaluation, his serum creatine kinase (CK) was noted to be persistently elevated in the 4,000s, prompting further investigation, but since he was not weak or otherwise symptomatic, definitive diagnosis and treatment were not pursued. When 19 years old, he underwent orthotropic heart transplantation. In the following years, he had multiple stents placed for coronary artery disease and developed type 1 diabetes mellitus, but he worked as an information specialist and cared for himself. The authors thank H. Brent Clark, MD, PhD, Department of Laboratory Medicine and Pathology, University of Minnesota, for his assistance preparing the figure.