Trial design: congestive heart failure
Endomyocardial biopsy plays a role in diagnosing patients with unexplained cardiomyopathy

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Abstract

Background

The etiology of cardiomyopathy is usually inferred from clinical information and preliminary laboratory 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 secondary to doxorubicin toxicity (0%). EMBx was more sensitive than clinical diagnosis in detecting myocarditis and amyloidosis, and proved to be very specific in detecting ischemic cardiomyopathy, myocarditis, amyloidosis, and hemochromatosis.

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.

Section snippets

Selection of patients

The study group consisted of 1230 patients who underwent EMBx for evaluation of unexplained cardiomyopathy at The Johns Hopkins Hospital between December 1982 and December 1997. Most of these patients were referred for biopsy after initial evaluation in a physician's office or in another hospital. Therefore, some common causes of heart failure that are more easily identifiable (ie, ischemic heart disease, hypertension, etc) are underrepresented in this patient group. Since we currently do not

Role of EMBx in diagnosing patients with unexplained cardiomyopathy

A specific final diagnosis was identified in 316 (37%) of 845 patients with initially unexplained cardiomyopathy. Myocarditis was the most common final diagnosis in this population, followed by ischemic heart disease and infiltrative disorders. The remaining 529 (63%) patients who did not have a clear explanation for their cardiomyopathy were classified as having idiopathic cardiomyopathy (Table I, second column).

In 264 (31%) of the 845 patients, the final diagnosis differed from the initial

Discussion

Assessment of the cause of cardiomyopathy can usually be made based on the clinical presentation, history, physical examination, and selected laboratory studies. However, there are certain patients whose diagnoses remain unclear despite extensive initial evaluations. These patients may be referred to a tertiary care center to undergo EMBx. Since its introduction into clinical practice in 1963,9 EMBx has gradually become an accepted diagnostic intervention. It is mainly utilized for monitoring

References (13)

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