Delayed hyperenhancement in magnetic resonance imaging of left ventricular hypertrophy caused by aortic stenosis and hypertrophic cardiomyopathy: visualisation of focal fibrosis

Objective: To compare the extent and distribution of focal fibrosis by gadolinium contrast-enhanced magnetic resonance imaging (MRI; delayed hyperenhancement) in severe left ventricular (LV) hypertrophy in patients with pressure overload caused by aortic stenosis (AS) and with genetically determined hypertrophic cardiomyopathy (HCM). Methods: 44 patients with symptomatic valvular AS (n = 22) and HCM ( n = 22) were studied. Cine images were acquired with fast imaging with steady-state precession (trueFISP) on a 1.5 T scanner (Sonata, Siemens Medical Solutions). Gadolinium contrast-enhanced MRI was performed with a segmented inversion-recovery sequence. The location, extent and enhancement pattern of hyperenhanced myocardium was analysed in a 12-segment model. Results: Mean LV mass was 238.6 (SD 75.3) g in AS and 205.4 (SD 80.5) g in HCM (p = 0.17). Hyperenhancement was observed in 27% of patients with AS and in 73% of patients with HCM (p < 0.01). In AS, hyperenhancement was observed in 60% of patients with a maximum diastolic wall thickness >= 18 mm, whereas no patient with a maximum diastolic wall thickness, 18 mm had hyperenhancement (p < 0.05). Patients with hyperenhancement had more severe AS than patients without hyperenhancement (aortic valve area 0.80 (0.09) cm(2) v 0.99 (0.3) cm(2), p < 0.05; maximum gradient 98 (22) mm Hg v 74 (24) mm Hg, p, 0.05). In HCM, hyperenhancement was predominant in the anteroseptal regions and patients with hyperenhancement had higher end diastolic (125.4 (36.9) ml v 98.8 (16.9) ml, p, 0.05) and end systolic volumes (38.9 (18.2) ml v 25.2 (1.7) ml, p, 0.05). The volume of hyperenhancement ( percentage of total LV myocardium), where present, was lower in AS than in HCM (4.3 (1.9)% v 8.6 (7.4)%, p < 0.05). Hyperenhancement was observed in 4.5 (3.1) and 4.6 (2.7) segments in AS and HCM, respectively ( p = 0.93), and the enhancement pattern was mostly patchy with multiple foci. Conclusions: Focal scarring can be observed in severe LV hypertrophy caused by AS and HCM, and correlates with the severity of LV remodelling. However, focal scarring is significantly less prevalent in adaptive LV hypertrophy caused by AS than in genetically determined HCM.