THE ARRHYTHMOGENIC RIGHT VENTRICLE - DYSPLASIA VERSUS CARDIOMYOPATHY

Twenty-four patients presenting with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ventricular tachycardia of right ventricular origin associated with structural abnormalities of the right ventricl e) were divided into two groups with left ventricular ejection fractio n (LVEF) above or below 45%. The distribution of LVEF in the group wit h LVEF below 45% was comparable with the distribution in 6 patients wi th idiopathic dilated cardiomyopathy who had ventricular tachycardia o riginating in the left ventricle (P = 0.2). They also had the same unf avorable long-term prognosis. Therefore, it is suggested that the term , arrhythmogenic right ventricular cardiomyopathy (ARVC), be restricte d to patients with a LVEF below 45%. Histological data obtained in the ARVC group showed signs of acute or chronic myocarditis (in the right and left ventricles). It can be hypothesized that patients with arrhy thmogenic right ventricular dysplasia (ARVD) may be prone to develop i nfectious myocarditis. In patients in whom an abnormal host immune res ponse had been seen, progressive deterioration of right and left ventr icular function could be observed. This pattern may be superimposed on the genetically determined background of ARVD. This could explain the wide spectrum of clinical presentation observed in patients with tach ycardia originating in an abnormal right ventricle.