Objectives: Endomyocardial biopsy samples from patients with idiopathic dilated cardiomyopathy were screened for the presence of enterovirus genome. Patients with enterovirus-positive samples were further studied with regard to disease course, histologic variables and response to interferon-alpha treatment.
Background: Studies of patients with idiopathic dilated cardiomyopathy have reported widely divergent clinical outcomes, suggesting that there is no unique underlying pathogenetic mechanism.
Methods: Five left ventricular endomyocardial biopsy samples were screened for the presence of the enterovirus genome by an established in situ hybridization technique in combination with a histologic, histomorphometric and immunohistologic workup. The course of the disease was then prospectively followed for up to 50 months. Virus-positive patients whose condition deteriorated were treated with interferon-alpha.
Results: Of 77 patients, 20 (26%) had enterovirus-positive and 57 (74%) enterovirus-negative biopsy samples. During a mean follow-up period of 25.8 +/- 13.7 months, 1 patient in the enterovirus-positive group and 11 in the enterovirus-negative group died. Four patients in the enterovirus-negative group underwent heart transplantation (p < 0.05). The surviving 19 enterovirus-positive patients had a decrease in mean left ventricular end-diastolic diameter from 66 to 61 mm (p < 0.05) and a mean increase in left ventricular ejection fraction from 0.35 to 0.43 (p < 0.05). In contrast, enterovirus-negative patients had no significant change in end-diastolic diameter or left ventricular ejection fraction. Four patients in the enterovirus-positive group whose condition deteriorated were treated with a 6-month course of subcutaneous interferon-alpha (3 x 10(6) U every second day). This treatment induced hemodynamic improvement in all four patients and eliminated the persistent enteroviral infection in two.
Conclusions: Enterovirus-positive patients have a better heart transplantation-free survival rate and hemodynamic course, with fewer histologic changes, than do enterovirus-negative patients. In addition, enterovirus-positive patients respond favorably to interferon-alpha treatment. These observations indicate that myocardial enteroviral infection with associated left ventricular dysfunction is a distinct disease entity with a benign course.