Heritability of central systolic pressure augmentation - A twin study

Less than 50% of the variance in left ventricular mass is explained by conv entional factors such as age, blood pressure, and body size. Genetic influe nces may account for part of the unexplained variance. The central (aortic) pressure augmentation index has been suggested as a noninvasive measure of pulsatile load, which is a Likely determinant of left ventricular mass. We quantified the genetic influence on augmentation index and determined the extent to which this influence is dependent on the effects of age, height, heart rate, and blood pressure. We performed a classical twin study compose d of 225 monozygotic and 594 dizygotic female white twin pairs aged 18 to 7 3 years. Augmentation index and mean arterial pressure were based on the ce ntral pressure wave derived from the radial waveform as measured by applana tion tonometry. Quantitative genetic modeling techniques were used to analy ze the data. The heritability of augmentation index was 37%, whereas herita bilities for blood pressure traits varied between 13% and 25%. Most of the variance in augmentation index could be explained by genetic and environmen tal factors specifically influencing augmentation index. Only a relatively small part of the total variance in augmentation index could be attributed to genes in common with height (3.1%), heart rate (4.6%), and mean arterial pressure (5.6%). Age explained 19% of the total variation in augmentation index. In conclusion, augmentation index has a significant heritable compon ent, which is largely independent of the influence of blood pressure, heart rate, height, and age. Finding genes for the augmentation index could help to unravel pathophysiological mechanisms causing left ventricular hypertro phy and lead to improvements in prevention, diagnosis, and treatment of at- risk populations.