Abstract
Background and Objectives: Aortic arch calcification (AoAC) is associated with a variety of cardiovascular complications. The measurement and grading of AoAC using posteroanterior (PA) chest X-rays are well established. The cardiothoracic ratio (CTR) can be simultaneously measured with PA chest X-rays and used as an index of cardiomegaly. The genetic and environmental contributions to the degree of the AoAC and CTR are not well understood. The purpose of this study was to investigate the effect of genetics and environmental factors on the AoAC and CTR. Materials and Methods: A total of 684 twins from the South Korean twin registry (261 monozygotic, MZ and 81 dizygotic, DZ pairs; mean age 38.6 ± 7.9 years, male/female = 264/420) underwent PA chest X-rays. Cardiovascular risk factors and anthropometric data were also collected. The AoAC and CTR were measured and graded using a standardized method. A structural equation method was used to calculate the proportion of variance explained by genetic and environmental factors behind AoAC and CTR. Results: The within-pair differences were low regarding the grade of AoAC, with only a few twin pairs showing large intra-pair differences. We found that the thoracic width showed high heritability (0.67, 95% CI: 0.59–0.73, p = 1). Moderate heritability was detected regarding cardiac width (0.54, 95% CI: 0.45–0.62, p = 0.572) and CTR (0.54, 95% CI: 0.44–0.62, p = 0.701). Conclusions: The heritable component was significant regarding thoracic width, cardiac width, and the CTR.
Highlights
Cardiovascular disease due to atherosclerosis is the leading cause of mortality worldwide [1]
The present study investigated the genetic and environmental contribution to cardiothoracic ratio and aortic arch calcification phenotypes
Fagard et al investigated the heritability of cardiac size using echocardiography and found that the genetic contributions had a statistically significant impact on the left ventricular mass
Summary
Cardiovascular disease due to atherosclerosis is the leading cause of mortality worldwide [1]. Atherosclerosis is a chronic vascular condition starting with fatty streak line that progresses over time into fibrous plaques These plaques may eventually rupture, leading to thrombosis or stenosis. The cardiothoracic ratio (CTR) has been identified as an effective and accessible method for heart size estimation and cardiomegaly screening [5]. It is obtained by measuring the largest distance between the right and left edges of the heart and thorax on posteroanterior (PA) chest X-rays and dividing the cardiac size by the thoracic size. A structural equation method was used to calculate the proportion of variance explained by genetic and environmental factors behind AoAC and CTR. Conclusions: The heritable component was significant regarding thoracic width, cardiac width, and the CTR
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