Myocardial enterovirus infection with left ventricular dysfunction: benign disease compared with idiopathic dilated cardiomyopathy

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-alph 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 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 mean follow-up period of 25.8 ± 13.7 months, 1 patient in the enteroviruspositive 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 decrease in mean left ventricular end-diastolic diameter from 66 to 61 mm (p < 0.05) and 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 6-month course of subcutaneous interferon-alph (3 × 106 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 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-alph treatment. These observations indicate that myocardial enteroviral infection with associated left ventricular dysfunction is distinct disease entity with benign course.