Cardiac adaptation to high altitudes after short‐ and long‐term exposure among Chinese Han lowlanders

Abstract Background Short‐term, high altitude (HA) exposure raises pulmonary artery systolic pressure (PASP) and decreases left ventricular volumes. However, relatively little is known of the long‐term cardiac consequences of prolonged exposure in Chinese Han lowlanders, a highly adapted HA population. Aims We studied cardiac structure and function by echocardiography to investigate short‐term adaptation and potential long‐term cardiac remodeling. Methods This study included 301 healthy subjects of short‐term exposure (STE), acclimatized Chinese Han lowlanders (AL) at HA, native Tibetans (NT), and sea level residents (SLR) with 75, 77, 69, and 80 participants, respectively. All groups underwent standard echocardiography. Results Compared with SLR, systolic blood pressure (SBP) and heart rate of STE and AL did not significantly increase following HA exposure, but SBP in STE was lower than AL. In lowlanders, HA exposure enlarged right heart and pulmonary artery (PA), reduced left ventricular (LV) diastolic function. This decrease in LV diastolic function increased with exposure time. Compared with SLR, ejection fraction did not change significantly in STE, but decreased in AL. Interventricular septal end‐diastolic thickness (IVSd) increased both in STE and AL compared with SLR. Compared with NT, AL population had higher SBP and the greater diameter of PA. Conclusions In Chinese Han lowlanders, exposure to HA enlarged right ventricle and decreased the diastolic function of LV. LV systolic function was preserved after short‐term HA exposure but decreased after long‐term HA exposure. It was possible to speculate that ethnicity contributed to the observed difference in heart.