Diagnostic and prognostic utility of right-sided catheterization and endomyocardial biopsy in idiopathic dilated cardiomyopathy.

To determine the value of cardiac catheterization and endomyocardial biopsy in patients with heart failure and dilated cardiomyopathy, the records of 61 patients (36 men, 25 women, ages 13 to 65 years) with this disorder were reviewed. Myocardial lymphocytic infiltration was present in 8 (13%). Three had myocyte degeneration and necrosis ("definite" myocarditis), whereas the other 5 had no degeneration or necrosis ("equivocal" myocarditis). Compared with the 53 without lymphocytic infiltration, these 8 patients more often had symptoms of a preceding viral illness (88 vs 30%, p = 0.002) and had a shorter duration of cardiac symptoms (18 +/- 18 vs 109 +/- 132 days [mean +/- standard deviation], p less than 0.001). Histologic features of the biopsy did not relate to survival, but right- and left-sided intracardiac pressures were higher (p less than 0.05) in nonsurvivors. Thus, (1) endomyocardial biopsy is most likely to show lymphocytic infiltration in patients with symptoms of a preceding viral illness and a short duration of cardiac symptoms, and (2) right- and left-sided hemodynamic variables at the time of biopsy may offer insight into prognosis.