Abstract
Background Although numerous studies have been published evaluating the positive or negative effects of altitude on cardiovascular disease, many of them are conflicting. Methods and Results Data come from 2 cross-sectional surveys using a similar method in China; and a total of 34 215 residents, aged ≥35 years, were eligible and recruited in the study. Left ventricular diastolic dysfunction (LVDD), according to the 2009 American Society of Echocardiography guidelines, was defined and evaluated. Altitude was divided into low (<1500 m), middle (1500-3500 m), and high (≥3500 m) level groups. Among the 34 215 participants (aged 55.87 years; men, 45.92%; altitude ranging from 3.1 ~ 4507 m), 15 099 (crude prevalence, 44.13%), 517 (crude prevalence, 1.51%), and 272 (crude prevalence, 0.79%) were diagnosed as having grades I, II, and LVDD, respectively. Compared with low-level group, the odds ratios (ORs) (95% CIs) of LVDD for middle- and high-level groups were 1.65 (1.49-1.82) and 1.89 (1.63-2.19), respectively (P(trend)<0.001). The ORs (95% CI) were 1.43 (1.31-1.56) and 2.03 (1.67-2.47) per 500-m increment for middle- and high-level groups. There was a nonlinear relationship (upward-sloping "W" shape) between altitude and the risk of LVDD, assessed by the restricted cubic spline. For each LVDD grade, ORs (95% CIs) of grade I LVDD for middle- and high-level groups were 1.75 (1.59-1.92) and 1.95 (1.69-2.25), respectively; for grade II, ORs (95% CIs) for middle- and high-level groups were 6.19 (3.67-10.42) and 5.27 (2.18-12.74), respectively. The stratified analyses indicated that LVDD was much more remarkably influenced by elevated altitude in men (P(interaction)=0.0019). Conclusions Higher altitude is associated with increased risk of LVDD among people living over 1500 m, especially for men.