Abstract 17716: Myocardial Fibrosis and Segmental Dysfunction in Asymptomatic Hypertrophic Cardiomyopathy Mutation Carriers
Introduction: Familial screening of hypertrophic cardiomyopathy (HCM) patients may identify asymptomatic mutation carriers without HCM phenotype, i.e. apparently normal echocardiogram (no significant left ventricular -LV- hypertrophy) and normal ECG. The aim of the present study was to evaluate whether myocardial structural alterations and subtle myocardial dysfunction could be detected in this group of patients.
Method: A total of 16 HCM families with an identified pathogenic mutation were studied and 41 patients (51±15 yrs, 73% male) with phenotype expression (Mut+/Phen+) and 49 (44±17 yrs, 52% male) patients without phenotype expression (Mut+/Phen-) were observed. In addition, 25 normal control subjects, matched for age and gender with the Mut+/Phen- group were recruited for comparison. All subjects underwent transthoracic echocardiogram, including conventional parameters, myocardial fibrotic content assessment by calibrated integrated backscatter (cIBS) and global and segmental strain measures by speckle tracking analysis.
Results: Majority of patients (70%) had one of the Dutch founder mutations in the Myosin binding protein C gene. All 3 groups had similar LV dimensions and ejection fraction (EF). The anteroseptal cIBS of Mut+/Phen+ and Mut+/Phen- patients were similar (−14.2±4.7 vs. −15.2±3.9 dB, p=0.38) and were both significantly higher compared to controls (−22.7±2.9 dB, p<0.01), suggesting a greater myocardial fibrosis content. Global longitudinal strain was similar between Mut+/Phen- group and controls (−21.0±2.6 vs. −21.3±1.3%, p=ns), while was significantly impaired in Mut+/Phen+ patients (-16.5 ±4.3%, p<0.01). However, segmental strain analysis revealed an impaired anteroseptal strain value both in the Mut+/Phen+ group (−9.2±4.4%) and in the Mut+/Phen- group (−14.2±4.3%) as compared to controls (−19.9±2.9%, p<0.01).
Conclusion: Despite normal LV dimensions and EF and normal wall thickness, patients with HCM+/Phen- exhibit a significantly higher myocardial fibrotic content and impaired segmental strain in the anteroseptal region as compared to controls. These findings may have important implications in the clinical follow-up of these patients.
- © 2010 by American Heart Association, Inc.