The only reliable means of diagnosing acute cardiac rejection before substantial myocardial damage has occurred is
Echocardiography
ECG
Endomyocardial biopsy
Ultrasound
Of the major complications, allograft rejection is the primary problem requiring surveillance; scheduled endomyocardial biopsy is the only reliable means of diagnosing acute cardiac rejection before substantial myocardial damage has occurred and at a stage that is reversible in the majority of instances. Rejection is characterized by interstitial lymphocytic inflammation that, in its more advanced stages, damages adjacent myocytes; the histology resembles myocarditis. When myocardial injury is not extensive, the “rejection episode” is usually either self-limited or successfully reversed by increased immunosuppressive therapy. Advanced rejection may be irreversible and fatal if it is not promptly treated.