Diagnostic yield of updated indications for endomyocardial biopsy and its clinical predictors in a Chinese cohort.

Introduction: The challenging and restrictive settings have been proposed in the updated indications for endomyocardial biopsy (EMB), but no data shows its performance. This study aimed to evaluate the diagnostic yield and find its clinical predictors.

Methods: All EMB performed between 2018 and 2022 were reviewed. Their clinical scenario and diagnostic yield were categorized retrospectively. Repeated and inadequate biopsies were excluded. Multivariate analysis was used to find the predictors.

Results: A total of 681 cases were collected (median age 44.0 years, 65.5% male) and 230 cases (33.8%) yielded specific diagnosis. The higher yield (52.8%) was found in clinically suspected myocarditis while no significant difference between cases with and without acute unstable hemodynamics (66.7% vs 47.1%; P=0.130). There was a much higher yield in unexplained restrictive or hypertrophic cardiomyopathy (RCM/HCM) with suspected infiltrative or storage disorder compared to those without (86.2% vs 10.3%; P<0.001). Dilated cardiomyopathy showed a lower yield, with or without recent-onset moderate-to-severe cardiac dysfunction (13.6% vs 16.3%; P=1.000). The same was true for unexplained atrioventricular block and ventricular arrhythmias (AVB/VA), with or without obvious structural abnormalities (8.2% vs 10.3%; P=0.675). On multivariate analysis, diffuse late gadolinium enhancement (odds ratio [OR] 4.14, 95% confidence interval [CI] 1.86-9.25; P=0.001), time course of disease ≤12 months (OR 3.31, 95% CI 1.75-5.57; P<0.001), elevated（≥1250 pg/ml）NT-proBNP (OR 2.91, 95% CI 1.67-5.06; P<0.001), and elevated (>0.068 ng/ml) hs-cTnI (OR 2.37, 95% CI 1.33-4.22; P=0.004) were independently associated with diagnostic yield.

Conclusion: Our results partially support the restrictive settings. EMB can achieve higher yield for unexplained RCM/HCM with suspected infiltrative or storage disorder, as well as strictly defined clinically suspected myocarditis, even in hemodynamically stable patients. However, the restrictive settings of unexplained AVB/VA and dilated cardiomyopathy did not show a clear advantage in diagnostic yield. The predictors this study found may help clinicians in selecting adequate candidates.