BACKGROUND:

The diagnosis of unexplained heart failure is challenging. Endomyocardial biopsies (EMBs) remain the gold standard for definitive diagnosis of unexplained heart muscle diseases. However, EMB is rarely used, although EMB analysis is a prerequisite for establishing an aetiology-based diagnosis to identify those patients in whom specific therapy would be appropriate.

METHODS:

We enrolled n=7415 consecutive patients with unexplained heart failure (mean age 52.6 ± 15.1 years), who underwent EMB. Analysis included histology, immunohistochemistry, molecular virology, and gene-expression profiling.

RESULTS:

EMB diagnostics revealed an incidence of 4.4% (n=324) of acute myocarditis including active myocarditis according the Dallas criteria (n=80), sarcoidosis (n=93) and eosinophilic myocarditis (n=18), and histologically confirmed giant cell myocarditis (n=30).

A large proportion of analysed EMBs were virus-positive (67.5%), of which the majority revealed parvovirus B19 DNA (n=3798) and other single- or co-infections including human herpes virus 6 (n=692), Epstein-Barr virus (n=125), Coxsackievirus B3 (n=50) and Adenovirus (n=6).

Other forms of cardiomyopathies (dilated cardiomyopathy, hypertrophic cardiomyopathy, arrhythmogenic right ventricular dysplasia) were diagnosed in 23.2% (n=1720) of the patients.

7.5% (n=553) of the patients were diagnosed for storage disorders including AL amyloidosis (n=168) and ATTR amyloidosis (n=375), Morbus Fabry (n=3), lipomatosis (n=4), and heamochromatosis (n=3).

CONCLUSIONS:

Based on EMB-results, in 67.4% of this large cohort of patients an aetiology-driven, therapeutically relevant heart muscle disease could be diagnosed. Our data clearly demonstrate the need for advanced EMB-based diagnosis, which has a direct clinical consequence in terms of specific therapeutic option in a remarkably high percentage of patients with unexplained heart failure.