BACKGROUND: Hypertrophic cardiomyopathy (HCM) is reported to show patchy midwall 
myocardial hyperenhancement on delayed-enhancement magnetic resonance imaging 
(DE-MRI). The intramural distribution of myocardial hyperenhancement and its 
correlation with clinical symptoms, ventricular arrhythmias, and cardiac 
function have not been described forsymptomatic apical HCM.
PURPOSE: To evaluate the features and significance of myocardial 
hyperenhancement on DE-MRI insymptomatic apical HCM.
MATERIAL AND METHODS: Thirteen patients with symptomatic apical HCM and their 65 
apical segments were investigated. Myocardial hyperenhancement and regional and 
global functional parameters were determined with MRI. We investigated the 
intramural distribution and frequencies of this myocardial hyperenhancement and 
compared them with the patients' clinical symptoms, the presence of ventricular 
arrhythmias, and cine MRI.
RESULTS: Eight (61.5%) patients with symptomatic apical HCM displayed apical 
myocardial hyperenhancement, and 22 (33.8%) of the 65 apical segments examined 
showed myocardial hyperenhancement. Of the myocardial hyperenhancement observed, 
81.8% showed a subendocardial pattern.The hyperenhanced apical myocardium had a 
lower percentage of systolic myocardial thickening, and was associated with 
serious symptoms (e.g. syncope) and ventricular arrhythmias.
CONCLUSION: Patients with symptomatic apical HCMshowed myocardial 
hyperenhancement involving the subendocardial layer, which might be related to 
regional systolic dysfunction, serious clinical symptoms, and ventricular 
arrhythmias.