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The majority of familial hypertrophic cardiomyopathy (HCM) (70%) is caused by mutations in 2 sarcomere genes, MYH7 and MYBPC3. Prognosis of patients with a MYH7 mutation is worse compared with MYBPC3 patients, but no pathophysiological mechanism causing this outcome has yet been unravelled. We investigated if myocardial regional function differs between pre-hypertrophic MYH7 (MYH7mut) and MYBPC3 (MYBPC3mut) mutation carriers using cardiovascular magnetic resonance.
Magnetic resonance cine imaging was performed in 6 MYH7mut (1 male, 36±12 years) and 18 MYBPC3mut (5 males, 35±13 years) to determine left ventricular mass, ejection fraction and end-diastolic wall thickness (EDWT) according to the 17-segment model of the American Heart Association. Myocardial tissue tagging was used to calculate peak systolic circumferential strain (SCS).
Left ventricular mass index and ejection fraction were comparable between MYH7mut and MYBPC3mut (respectively, 52±6 vs 48±10 g/m2and 61±2 vs 59±5%). Despite slightly larger EDWT in MYH7mut, regional SCS was significantly higher in all segments in MYH7mut compared with MYBPC3mut (Figure 1)
Although MYH7 and MYBPC3 mutations both ultimately result in HCM, peak SCS is higher in MYH7 compared with MYBPC3 carriers before the development of hypertrophy. This apparent different mutation-effect on myocardial function might partly explain the difference in disease onset between HCM caused by the thick filament mutations.
Poster Sessions, Expo North
Sunday, March 10, 2013, 3:45 p.m.-4:30 p.m.
Session Title: Imaging: MRI V – CMR in Hypertrophic and Infiltrative Cardiomyopathies
Abstract Category: 19. Imaging: MRI
Presentation Number: 1272-368
- 2013 American College of Cardiology Foundation