Heritability of left atrial size in the Tecumseh population

Background: Little is known about the determinants of atrial size, and no study has analyzed whether genetic factors are involved in the pathogenesis of LA enlargement. Materials and methods: We studied the heritability of echocardiographic left atrial size in 290 parents from the Tecumseh Blood Pressure Study and 251 children from the Tecumseh Offspring Study. All data from the parents and children were obtained at the same field office in Tecumseh, USA. Left atrial dimension was determined echocardiographically in accordance with American Society of Echocardiography guidelines with the use of leading-edge-to-leading-edge measurements of the maximal distance between the posterior aortic root wall and the posterior left atrial wall at end systole. Results: For correlation between the left atrial dimensions of the parents and their offspring, several models were generated to adjust the atrial dimensions in both groups for an increasing number of clinical variables. After removing the effect of age, gender, height, weight, skinfold thickness, and systolic blood pressure, parent-child correlation for left atrial size was 0.19 (P = 0.007). Further adjustment for left ventricular mass and for measuring left ventricular diastolic function increased the correlation to 0.25 (P = 0.001). Conclusions: The present data indicate that heredity can explain a small but definite proportion of the variance in left atrial dimension.