Table 1. The 2007 AHA/ACCF/ESC Guidelines for Endomyocardial Biopsy (Modified From the AHA/ACCF/ESC “Role of Endomyocardial Biopsy in the Management of Cardiovascular Disease” [1]).

Class I: clinical scenarios where EMB “should be performed”
1	New-onset heart failure (HF) with onset < 2 weeks duration, in addition to: 1) normal or dilated left ventricle (LV); 2) hemodynamic compromise
2	New onset HF with duration 2 weeks to 3 months, in addition to either dilated LV and new ventricular arrhythmias or second/third degree heart block, or failure to respond to usual care within 1 to 2 weeks
Class IIa: clinical scenarios where EMB “may be considered reasonable”
3	HF of more than 3 months duration, in addition to either dilated LV and new ventricular arrhythmias or second/third degree heart block, or failure to respond to usual care within 1 - 2 weeks
4	HF with dilated cardiomyopathy of any duration with suspected allergic reaction and/or eosinophilia
5	HF with suspected anthracycline cardiomyopathy
6	HF with unexplained restrictive cardiomyopathy
7	Suspected cardiac tumors (exception of typical myxomas)
8	Unexplained cardiomyopathy in the pediatric population
Class IIb: clinical scenarios where EMB “may be considered”
9	HF with duration of 2 weeks to 3 months with a dilated LV, without new arrhythmia/heart block, that does respond to usual care within 1 - 2 weeks
10	Suspicion for iron overload in unexplained HF of > 3 months duration with a dilated LV, without arrhythmias/heart block, that does respond to usual care
11	HF associated with unexplained hypertrophic cardiomyopathy (if an infiltrative or storage disease is suspected)
12	Suspected arrhythmogenic right ventricular cardiomyopathy when other evaluations have been inconclusive
13	Unexplained ventricular arrhythmia