BACKGROUND: The stratification of risk for sudden death in hypertrophic 
cardiomyopathy (HCM) continues to be a true challenge due to the great 
heterogeneity of this disease's presentation, as most individuals remain 
asymptomatic during their entire lives and others present sudden death as first 
symptom. Recent studies have suggested that myocardial fibrosis may represent an 
important substrate for the malignant ventricular arrhythmias, that are 
responsible for the cases of sudden death related to this disease.
OBJECTIVE: To assess the prevalence and quantification of myocardial fibrosis 
(MF) in hypertrophic cardiomyopathy (HCM) patients with implantablecardioverter 
- defibrillator (ICD) indicated due to their high risk or recovered from cardiac 
sudden death.
METHODS: Twenty-eight HCM patients with ICD were submitted to multidetector 
computed tomography to assess myocardial fibrosis by delayed enhancement 
technique.
RESULTS: Myocardial fibrosis was present in 96% of these HCM patients with 
(20.38 +/- 15.55 g) comprising 15.96 +/- 10.20% of the total myocardial mass. MF 
was observed in a significantly higher prevalence as compared to other classical 
risk factors for sudden death.
CONCLUSION: It is possible to conclude that there is a high prevalence of 
myocardial fibrosis in hypertrophic cardiomyopathy patients with high-risk or 
recovered from cardiac sudden death, like those with clinical indication to 
implantable cardioverter -defibrillator. The higher prevalence of myocardial 
fibrosis in comparison to classical risk factors of worse prognosis raise the 
hypothesis that the myocardial fibrosis may be an important substrate in the 
genesis of lifethreatening arrhythmias in these high risk HCM population.