Magnetic resonance imaging of myocardial fibrosis in hypertrophic cardiomyopathy.

Myocardial fibrosis can occur in patients who have hypertrophic cardiomyopathy in the absence of epicardial coronary disease. In such patients, myocardial fibrosis has been linked to a poorer prognosis than in those without fibrosis. Gadolinium-DTPA delayed-enhancement magnetic resonance imaging (de-MRI) accurately identifies regions of myocardial fibrosis. We used de-MRI to screen for myocardial fibrosis in 8 patients with nonobstructive hypertrophic cardiomyopathy that had been diagnosed by 2-dimensional echocardiography. After localization of the heart and acquisition of electrocardiographically gated cine images, gadolinium-DTPA (0.2 mmol/kg) was administered to the patient. Fifteen minutes later, de-MRI images were obtained using a T1-weighted, inversion-recovery fast, low-angle shot sequence. Images were gated to end-diastole and obtained during a single breath-hold. The inversion time was modified iteratively to obtain maximal nulling of the signal from the ventricular myocardium. Regions of myocardium with abnormally high signals (>300% of remote normal myocardium) were designated as fibrotic. Eight patients with hypertrophic cardiomyopathy underwent de-MRI. The mean age was 52 years, the mean left ventricular mass was 201 grams, and the mean ejection fraction was 0.68. In the 6 patients with recent clinical deterioration, de-MRI showed clearly delineated areas of myocardial fibrosis; no such areas were seen in the 2 asymptomatic patients. We conclude that patients with symptomatic hypertrophic cardiomyopathy display regions of abnormal signal intensity on de-MRI that likely represent fibrosis. This technique may provide useful information in the evaluation of such patients and warrants further study.