Delayed contrast enhancement of MRI in hypertrophic cardiomyopathy

Abstract

Fibrotic lesions in the myocardium exhibit delayed contrast enhancement (DCE) on MR images. On the other hand, plexiform fibrosis is observed in hypertrophic cardiomyopathy (HCM), indicating an association of this condition with the pathogenesis of heart failure and arrhythmia. To examine the occurrence and extent of DCE and its relation to cardiac function and arrhythmia in HCM, we studied 59 patients with HCM who had undergone MRI. The relationship of DCE to cardiac function and arrhythmia was further investigated. DCE occurred in 45 (76.3%) of the 59 patients with HCM, with a high frequency of localization in regions, where the right ventricle is attached. As for the relationship of DCE to cardiac function, a significant decrease (P = 0.007) in cardiac function was observed in the group in which 4 or more segments exhibited DCE, compared with the group in which DCE was observed in 3 or less segments. Regarding the relationship of DCE to arrhythmia, both the occurrence of DCE and the extent of DCE were significantly larger (p < 0.05, p = 0.026, respectively) in the group with VT. These results indicate that DCE may save to identify severe cases of HCM on the basis of cardiac function, arrhythmia, and pathophysiological aspects.

Introduction

Idiopathic hypertrophic cardiomyopathy is by definition characterized by marked hypertrophy of the left ventricular wall due to no apparent causes. Its association with sarcomere-related gene abnormalities has been reported [1], [2], [3], [4]. It is one of the major causes of sudden death in young individuals [5], and the pathological profile includes diastolic dysfunction [6], [7] and lethal arrhythmia [8]. Histopathological studies have shown that hypertrophy and disarray of myocardial cells, small fibrotic lesions known as plexiform fibrosis, are observed in the hypertrophic left ventricular walls in association with microvascular lesions in the myocardium [9], [10]. Furthermore, these fibroses may be associated with the development of lethal arrhythmia [11], diastolic dysfunction [12], or what is called diastolic-phased hypertrophic cardiomyopathy [13], [14], [15], [16]. Fibrotic lesions in the myocardium have been clearly detected at autopsy, but their diagnosis in living patients has been difficult.

On the other hand, in recent years, experimental and clinical studies have clearly demonstrated that the fibrotic lesions in the myocardium of the infarcted heart show a delayed contrast enhancement (DCE) pattern on gadolinium-contrast MR imaging [17], [18], [19], [20], [21]. Therefore, the purpose of this study is to determine whether DCE is observed on MR images of patients with hypertrophic cardiomyopathy and to determine their localization and their relationship to global left ventricular function, arrhythmia, and neurohormonal factors.