MYOCARDIAL ENTEROVIRUS INFECTION WITH LEFT-VENTRICULAR DYSFUNCTION - A BENIGN DISEASE COMPARED WITH IDIOPATHIC DILATED CARDIOMYOPATHY

Objectives. Endomyocardial biopsy samples from patients with idiopathic dilated cardiomyopathy mere 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 trans plantation (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 myo cardial enteroviral infection with associated left ventricular dysfunction is a distinct disease entity with a benign course.