Increased left ventricular (LV) mass is one of the strongest independent predictors of adverse cardiovascular outcomes. [1, 2] The extent of genetic and environmental factors of LV mass has been evaluated predominantly using echocardiography with controversial results. [3-9] However, CT angiography (CTA) provides a more reproducible, 3D volumetric assessment of LV dimensions, including chamber volumes and myocardial mass. [10] Therefore our aim was to estimate the inheritance of the LV mass within same sex twins using CTA.

We measured LV mass of 190 healthy monozygotic (MZ, 58 pair) and dizygotic (DZ, 37 pair) twins who underwent 256-slice CT angiography. We measured LV myocardial mass and end-diastolic volumes (EDV) using a semi-automated software. Epi- and endocardial contours were corrected manually, when necessary (Fig. 1 Fig. 2Fig. 3). We adjusted LV mass for body surface area in further calculations. All continuous variables were expressed as mean ± SD. We carried out structural equation modeling to decompose the inter-twin variance into environmental and genetic effects...

Mean age of MZ and DZ twins was 54.8 ± 9.6 and 58.5 ± 9.5 years (p=0.017), respectively. Mean BMI was 27.8 ± 5.3 kg/m2 for MZ and 27.7 ± 5.3 kg/m2 for DZ twins (p=0.516). The measured mean LV mass and EDV was 84.8 ± 24.7 grams and 122.3 ± 30.3 ml for MZ, 83.1 ± 24.7 grams and 117.7 ± 30.3 ml for DZ twins (p value = 0.841 for LV mass and 0.458 for EDV), respectively. The most parsimonious AE model of...

In this classical twin study we have demonstrated that LV mass and EDV as assessed by coronary CTA are predominantly determined by genetic factors. The unique environmental component provides opportunity for pharmacological modification of LV mass and volume.

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References 1. Kannel, W.B., et al., Electrocardiographic left ventricular hypertrophy and risk of coronary heart disease. The Framingham study. Ann Intern Med, 1970. 72(6): p. 813-22. 2. Barbieri, A., et al., Prognostic impact of left ventricular mass severity according to the classification proposed by the American Society of Echocardiography/European Association of Echocardiography. J Am Soc Echocardiogr, 2011. 24(12): p. 1383-91. 3. Post, W.S., et al., Heritability of left ventricular mass: the Framingham Heart Study. Hypertension, 1997. 30(5): p. 1025-8. 4. Noh, H.M., et al., Genetic...