Increased left ventricular torsion in hypertrophic cardiomyopathy mutation carriers with normal wall thickness

Area of Science:

• Cardiology
• Genetics
• Biomedical Imaging

Background:

• Increased left ventricular (LV) torsion is a known characteristic of manifest familial hypertrophic cardiomyopathy (HCM).
• This torsion is hypothesized to stem from underlying subendocardial dysfunction.
• Early detection of cardiac changes in mutation carriers is crucial for understanding disease progression.

Purpose of the Study:

• To investigate whether increased LV torsion is present in healthy mutation carriers before the development of significant wall thickening.
• To identify potential early markers of myocardial dysfunction in individuals at risk for HCM.

Main Methods:

• Cardiovascular magnetic resonance (CMR) with tissue tagging was used in 17 healthy HCM gene carriers (LV wall thickness <10 mm) and 17 controls.
• LV volumes, mass, torsion, torsion rate, endocardial circumferential strain, and the torsion-to-endocardial-circumferential-shortening (TECS) ratio were quantified.
• The TECS ratio was used to assess transmural distribution of contractile function.

Main Results:

• LV volumes, mass, and endocardial circumferential strain were similar between carriers and controls.
• Carriers exhibited significantly increased LV ejection fraction, torsion, and TECS ratio compared to controls.
• These findings indicate altered LV mechanics in asymptomatic carriers.

Conclusions:

• Healthy HCM gene carriers with normal wall thickness demonstrate elevated LV torsion and TECS ratio.
• These abnormalities suggest subendocardial myocardial dysfunction, mirroring findings in manifest HCM.
• These early changes represent potential targets for therapeutic interventions to delay or prevent HCM development.