Results of endomyocardial biopsy in patients with spontaneous ventricular tachycardia but without apparent structural heart disease.

To evaluate possible occult myocardial disease in 18 patients whose only major manifestation of heart disease was spontaneous ventricular tachycardia or fibrillation, right ventricular endomyocardial biopsies were performed. None of the patients had symptoms of ischemic or congestive heart disease, and at catheterization none had significant lesions of the coronary arteries or regional wall motion abnormalities of the left ventricle. The mean left ventricular ejection fraction (65 +/- 7%), mean right ventricular ejection fraction (55 +/- 9%), mean cardiac index (3.0 +/- 0.5 1/min/m2), mean right atrial pressure, mean pulmonary capillary wedge pressure, and mean pulmonary artery systolic pressure were normal. However, right ventricular endomyocardial biopsy specimens were abnormal in 16 of 18 (89%) patients: nine (50%) had changes of a significant, although nonspecific, cardiomyopathy with myocellular hypertrophy, interstitial and perivascular fibrosis, and vascular sclerosis; three (17%) had subacute inflammatory myocarditis; two (11%) had diffuse abnormalities of the intramyocardial arteries; and two (11%) had pathologic changes consistent with arrhythmogenic right ventricular dysplasia. In the two (11%) patients with normal biopsy specimens, one had Wolff-Parkinson-White syndrome and the other had mitral valve prolapse. Although histologic abnormalities were found in 89% of these patients, performance of right ventricular endomyocardial biopsies in this group of patients should be considered a research procedure. We conclude that the majority of patients who have serious ventricular arrhythmias but no apparent structural cardiac abnormalities have abnormal right ventricular biopsy specimens and that the arrhythmias may be the first manifestation of a variety of primary myocardial abnormalities.