Left atrial size and left ventricular hypertrophy correlate with myocardial fi brosis in patients with hypertrophic cardiomyopathy

INTRODUCTION: In hypertrophic cardiomyopathy (HCM) risk assessment with respect to sudden cardiac death (SCD) is currently based on the presence or absence of different risk markers (RM). Recently, myocardial fibrosis as detected by gadolinium-enhanced magnetic resonance imaging (GE-MRI) has been suggested as additional RM. We evaluated the prevalence of myocardial fibrosis and examined correlations with other risk markers in patients considered to be at increased risk. METHODS: We included 50 patients with HCM with > 1 (2-4) RM who underwent GE-MRI to check for myocardial fibrosis. Late enhancement was assessed semi-quantitatively using a 17-segment model of the LV (from 0 = absent, 1 = point-shaped, 2 = limited to 1 LV segment, 3 = involving > or = 2 segments). Outflow obstruction was present in 25 patients, the other 25 (1 after septal ablation and after myectomy) were non-obstructive. RESULTS: Patients (33 men; mean age 44 +/- 13 years; NYHA class: 2.0 +/- 0.9) had a number of RM of 1.7 +/- 0.8. Evidence of myocardial fibrosis > or = 2 was found in 39 patients (mean score: 2.3 +/- 0.9). Correlations were found between left atrial diameter (eta = 0.5), septum thickness (eta = 0.6), and severity of fibrosis. Patients with fibrosis 2 had larger left atria (50 +/- 7 vs 43 +/- 7 mm, P = 0.007) and a thicker septum both on echocardiography (25 +/- 6 vs 17 +/- 5 mm, P < 0.001) and on GE-MRI (28 +/- 5 vs 20 +/- 4 mm, P = 0.01). No correlations were found between fibrosis score and other RM, global LV mass on GE-MRI, or other clinical variables. CONCLUSIONS: Left ventricular hypertrophy and left atrial size, as two markers for global disease severity, correlate with the severity of fibrosis on GE-MRI.