Congestive Heart Failure Endomyocardial biopsy plays a role in diagnosing patients with unexplained cardiomyopathy Hossein Ardehali, MD, PhD, a Atif Qasim, MD, b Thomas Cappola, MD, f David Howard, c Ralph Hruban, MD, d Joshua M. Hare, MD, a Kenneth L. Baughman, MD, FACC, a,e and Edward K. Kasper, MD, FACC a Baltimore, Md, Boston, Mass, and Philadelphia, Pa Background The etiology of cardiomyopathy is usually inferred from clinical information and preliminary labora- tory studies. Patients with unexplained cardiomyopathy may be referred for endomyocardial biopsy (EMBx). It is unknown whether pathological information obtained from EMBx is beneficial or alters the diagnosis established clinically. This study was undertaken to evaluate the utility of EMBx in confirming or excluding a clinically suspected diagnosis. Methods We evaluated 845 patients with initially unexplained cardiomyopathy who underwent EMBx between 1982 and 1997 at The Johns Hopkins Hospital. For each patient, an initial clinical diagnosis, an EMBx diagnosis, and a final diagnosis prior to discharge based on all available data were established. Results The final diagnosis differed from the initial clinical diagnosis in 264 (31%) of these patients; EMBx made the diagnosis in 196 (75%) of these cases. Initial diagnoses most frequently altered were myocarditis (34%) and idiopathic cardiomyopathy (25%). Initial diagnoses least likely to be altered were those in which biopsy was used to confirm or grade a previously documented illness, such as hemochromatosis (11%), amyloidosis (18%), or cardiomyopathy second- ary to doxorubicin toxicity (0%). EMBx was more sensitive than clinical diagnosis in detecting myocarditis and amyloi- dosis, and proved to be very specific in detecting ischemic cardiomyopathy, myocarditis, amyloidosis, and hemochroma- tosis. Conclusions In patients with unexplained cardiomyopathy after a standard evaluation, the clinical assessment of the etiology is inaccurate in 31% of patients. EMBx establishes the final diagnosis in 75% of these patients with a high degree of specificity. (Am Heart J 2004;147:919 –23.) See related Editorial on page 759. Cardiomyopathy is a common disorder resulting from a variety of causes that lead to impaired cardiac performance and often results in congestive heart fail- ure. Despite recent advances, congestive heart failure remains a major cause of morbidity, hospitalizations and mortality, 1 and accounts for a large proportion of health care expenditures in developed countries. 2 In the developed world, the most common cause of cardiomyopathy is coronary artery disease; however, many other causes have been characterized. It is im- portant to identify the cause of cardiomyopathy in or- der to devise an appropriate treatment strategy. The current guidelines recommend that patients with car- diomyopathy undergo a 12-lead EKG, a chest radio- graph, blood chemistry including thyroid and liver function test, urine analysis, and cardiac imaging, usu- ally a transthoracic echocardiography. 3 Patients with risk factors for atherosclerosis may be subjected to coronary angiography. These studies may help to con- firm the clinical diagnosis and evaluate selected causes for the cardiomyopathy. Despite evaluation, there remains a group of patients in whom the cause of the cardiomyopathy cannot be explained. These patients may be referred to a tertiary care center for endomyocardial biopsy (EMBx). 4 Al- though this procedure has become a common diagnos- From the a Division of Cardiology, Department of Medicine, The Johns Hopkins Hospi- tal, b Johns Hopkins University School of Medicine, c Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, d Department of Pathology, The Johns Hopkins Hospital, Baltimore, Md, e Division of Cardiology, Department of Medicine, Brigham and Women’s Hospital, Boston, Mass, and f Division of Cardiovascular Medi- cine, Department of Medicine, Hospital of the University of Pennsylvania, Philadelphia, Pa. Submitted May 23, 2003; accepted September 9, 2003. Reprint requests: Hossein Ardehali, MD, PhD, Johns Hopkins University, 844 Ross Building, 720 Rutland Ave, Baltimore, MD 21205. E-mail: hardehal@jhmi.edu 0002-8703/$ - see front matter © 2004, Elsevier Inc. All rights reserved. doi:10.1016/j.ahj.2003.09.020