Comparative evaluation of left and right ventricular endomyocardial biopsy: differences in complication rate and diagnostic performance.

BACKGROUND Endomyocardial biopsy (EMB) represents the gold standard for diagnosing myocarditis and nonischemic cardiomyopathies. This study focuses on the risk of complications and the respective diagnostic performance of left ventricular (LV), right ventricular (RV), or biventricular EMB in patients with suspected myocarditis and/or cardiomyopathy of unknown origin. METHODS AND RESULTS In this 2-center study, 755 patients with clinically suspected myocarditis (n=481) and/or cardiomyopathy of nonischemic origin including those with infiltrative or connective tissue disease (n=274) underwent either selective LV-EMB (n=265; 35.1%), selective RV-EMB (n=133; 17.6%), or biventricular EMB (n=357; 47.3%) after coronary angiography and exclusion of significant coronary artery disease. Cardiovascular magnetic resonance, including late gadolinium enhancement, imaging was performed in 540 patients (71.5%). The major complication rate for LV-EMB was 0.64% and for RV-EMB, 0.82%. Considering postprocedural pericardial effusion that occurred after biventricular EMB, the minor complication rate for LV-EMB varied between 0.64% to 2.89% and for RV-EMB, between 2.24% and 5.10%. Diagnostic EMB results were achieved significantly more often in those patients who underwent biventricular EMBs (79.3%) compared to those who underwent either selective LV-EMB or selective RV-EMB (67.3%; P<0.001). In patients with biventricular EMB, myocarditis was diagnosed in LV-EMB samples in 18.7% and in RV-EMB samples in 7.9% (P=0.002) , and it was diagnosed in both ventricles in 73.4%. There were no differences in the number of positive LV-EMB, RV-EMB, or LV- and RV-EMB findings when related to the site of cardiovascular magnetic resonance-based late gadolinium enhancement. CONCLUSIONS Both LV-EMB and RV-EMB are safe procedures if performed by experienced interventionalists. The diagnostic yield of EMB may be optimized when samples from both ventricles are available. Preferential biopsy in regions showing late gadolinium enhancement on cardiovascular magnetic resonance does not increase the number of positive diagnoses of myocarditis.