Diagnostic synergy of non-invasive cardiovascular magnetic resonance and invasive endomyocardial biopsy in troponin-positive patients without coronary artery disease.

Aims: Only few data are available regarding a direct comparison of both non-invasive CMR and invasive EMB with respect to conformity of procedure-derived diagnoses in the same patients. The aim of this study was to elucidate the diagnostic performance of non-invasive cardiovascular magnetic resonance imaging (CMR) and endomyocardial biopsy (EMB) in patients with troponin-I (TnI) positive acute chest pain in the absence of significant coronary artery disease (CAD).

Methods And Results: One thousand one hundred and seventy-four consecutive patients who were admitted with TnI-positive acute chest pain between March 2004 and July 2007 underwent coronary angiography. In 1012 patients (86%), significant CAD (stenosis >50%) was detected as underlying reason for the acute chest pain. In 82 out of the remaining 162 patients without significant CAD, further workup was performed including both CMR and EMB. Cardiovascular magnetic resonance imaging alone enabled a diagnosis in 66/82 (80%) and EMB alone in 72/82 (88%) patients (P = 0.31). Myocarditis was the most frequent diagnosis by both CMR and EMB in this cohort and was detected with a higher frequency by EMB (58 vs. 81%; P < 0.001). With the combined approach comprising CMR and EMB, a final diagnosis could be established applying the 'Believe-The-Positive-Rule' in 78/82 patients (95%). This combined approach turned out to yield more diagnoses than either CMR (P < 0.001) or EMB (P = 0.03) as single techniques, respectively. Comparison of diagnostic CMR procedures with the corresponding diagnostic EMBs demonstrated a substantial match of diagnoses (kappa = 0.70).

Conclusion: Cardiovascular magnetic resonance imaging and EMB have good diagnostic performances as single techniques in patients with TnI-positive acute chest pain in the absence of CAD. The combined application of CMR and EMB yields a considerable diagnostic synergy by overcoming some limitations of CMR and EMB as individually applied techniques.