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

Iris K Rüssel,Wessel P Brouwer,J Tim Marcus,Tjeerd Germans,Paul Knaapen,Albert C Van Rossum,Jolanda Van Der Velden,Marco Jw Götte

doi:10.1186/1532-429x-13-3

Abstract

BackgroundIncreased left ventricular (LV) torsion has been observed in patients with manifest familial hypertrophic cardiomyopathy (HCM), and is thought to be caused by subendocardial dysfunction. We hypothesize that increased LV torsion is already present in healthy mutation carriers with normal wall thickness.MethodsSeventeen carriers with an LV wall thickness <10 mm, and seventeen age and gender matched controls had cardiovascular magnetic resonance (CMR) cine imaging and tissue tagging. LV volumes and mass were calculated from the cine images. LV torsion, torsion rate, endocardial circumferential strain and torsion-to-endocardial-circumferential-shortening (TECS) ratio, which reflects the transmural distribution in contractile function, were determined using tissue tagging.ResultsLV volumes, mass and circumferential strain were comparable between groups, whereas LV ejection fraction, torsion and TECS-ratio were increased in carriers compared to controls (63 ± 3% vs. 60 ± 3%, p = 0.04, 10.1 ± 2.5° vs. 7.7 ± 1.2°, p = 0.001, and 0.52 ± 0.14°/% vs. 0.42 ± 0.10°/%, p = 0.02, respectively).ConclusionsCarriers with normal wall thickness display increased LV torsion and TECS-ratio with respect to controls, which might be due to subendocardial myocardial dysfunction. As similar abnormalities are observed in patients with manifest HCM, the changes in healthy carriers may be target for clinical intervention to delay or prevent the onset of hypertrophy.

Highlights

Hypertrophic cardiomyopathy (HCM) is characterized by asymmetrical hypertrophy in the absence of increased external load and is caused by mutations in mainly sarcomeric genes that have an autosomal-dominant pattern of inheritance [1,2]
As the genetic defect is present from birth, family members of patients with manifest hypertrophic cardiomyopathy (HCM) are at risk to develop HCM
Since left ventricular (LV) ejection is directly dependent on subendocardial circumferential strain, the constant ratios of torsion to subendocardial circumferential strain (so called torsion-to-shortening ratio (TSR) [9]), detected in humans and animals with structural normal hearts, confirm the interplay between LV ejection and torsion in vivo [9,10]

Summary

Introduction

Hypertrophic cardiomyopathy (HCM) is characterized by asymmetrical (septal) hypertrophy in the absence of increased external load and is caused by mutations in mainly sarcomeric genes that have an autosomal-dominant pattern of inheritance [1,2]. Since LV ejection is directly dependent on subendocardial circumferential strain (area reduction in the short axis directly implies shortening of the circumference), the constant ratios of torsion to subendocardial circumferential strain (so called torsion-to-shortening ratio (TSR) [9]), detected in humans and animals with structural normal hearts, confirm the interplay between LV ejection and torsion in vivo [9,10]. Changes in this ratio indicate transmural differences in fiber shortening. We hypothesize that increased LV torsion is already present in healthy mutation carriers with normal wall thickness

Methods

Results

Conclusion