An Experimental Model for Dilated Cardiomyopathy after Rabbit Coronavirus Infection

A rabbit model for coronavirus-induced dilated cardiomyopathy is described. Acute rabbit coronavirus infection results in virus-induced myocarditis and congestive heart failure. Of the survivors of rabbit coronavirus infection, 41% had increased heart weight and heart weight-tobody weight ratios, biventricular dilation, myocyte hypertrophy, myocardial fibrosis, and myocarditis consistent with the development of dilated cardiomyopathy. These changes were also seen in the remaining 59% of the survivors, except that the degree of myocyte hypertrophy was reduced and only right ventricular dilation was present. In most survivors, myocarditis was usually mild (1-5 foci/transverse section), but in some cases it was severe (>20 foci/transverse section). Interstitial and replacement fibrosis was more pronounced in the papillary muscles. These data suggest that rabbit coronavirus infection may progress to dilated cardiomyopathy. Dilated cardiomyopathy (DCM) is a debilitating chronic illness with an incidence of --0.73-7.5 casesflOO,OOO population/year in developed countries 1. In developing countries, this number is probably significantly higher 1. DCM is characterized by a grossly enlarged heart, ventricular dilation, and low ejection fractions that can frequently result in the formation of ventricular thrombi. Histologic examination reveals myocyte hypertrophy, fibrosis, and occasionally myocarditis The 2-to 3-year survival rate of a patient with DCM is --50% 4, with death frequently occurring from chronic congestive heart failure (CHF) and to a lesser extent from ventricular arrhythmias or pulmonary or peripheral emboli