About 50 to 80% of patients have at least 1 episode of rejection (average 2 to 3); most patients are asymptomatic, but about 5% develop left ventricle dysfunction or atrial arrhythmias. Incidence of acute rejection peaks at 1 mo, decreases over the next 5 mo, and levels off by 1 yr.

Risk factors for rejection include

Because graft damage can be irreversible and catastrophic, surveillance endomyocardial biopsy is usually done once/yr; degree and distribution of mononuclear cell infiltrate and presence of myocyte injury in specimens are determined. Differential diagnosis includes perioperative ischemia, CMV infection, and idiopathic B-cell infiltration (Quilty lesions).

Mild rejection (grade 1) without detectable clinical sequelae requires no treatment; moderate or severe rejection (grades 2 to 4) or mild rejection with clinical sequelae is treated with corticosteroid pulses (500 mg or 1 g daily for several days) and antithymocyte globulin as needed (see Table: Manifestations of Heart Transplant Rejection by Category*).

The main complication of heart transplantation is cardiac allograft vasculopathy, a form of atherosclerosis that diffusely narrows or obliterates vessel lumina (in 25% of patients). Its cause is probably multifactorial and relates to donor age, cold and reperfusion ischemia, dyslipidemia, immunosuppressants, chronic rejection, and viral infection (adenovirus in children, CMV in adults).

For early detection, surveillance stress testing or coronary angiography with or without intravascular ultrasonography is often done at the time of endomyocardial biopsy.

Treatment is aggressive lipid lowering and diltiazem.