The prognostic value of altitude in patients with heart failure with reduced ejection fraction

Objective: It is well known that the altitude may affect the cardiovascular system. However, there were a few data related to the effect of altitude on the adverse outcome in patients with heart failure with reduced ejection fraction (HFREF). The aim of the present study was to investigate the role of intermediate high altitude on the major adverse cardiovascular outcome in patients with HFREF. Methods: Patients with HFREF admitted to the outpatient clinics at the first center at sea level and the second center at 1890 m were prospectively enrolled in the study. HFREF was defined as symptoms/signs of heart failure and left ventricular ejection fraction <40%. The major adverse cardiac outcome (MACE) was defined as all-cause death, stroke, and re-hospitalization due to heart failure. The median follow-up period of the study population was 27 months. Results: The study included 320 (58.55% male, mean age 65.7±11.2 years) patients. The incidence of all-cause death was 8.5%, stroke 6.1%, re-hospitalization due to decompensated heart failure 34.3%, and MACE 48.9%. In Kaplan-Meier analysis, patients with HFREF living at high altitude had more MACE (71.1% vs. 25.3%, log rank p=0.005) and presented with more stroke (11.3% vs. 2.1%, log rank p=0.001) and re-hospitalization due to heart failure (65.1% vs. 20.1%, log rank p<0.001) rates than those at low altitude in the follow-up; however, the rate of all-cause death was similar (9.4% vs. 8.1%, log rank p=0.245). Conclusion: In the present study, we demonstrated that the intermediate high altitude is the independent predictor of MACE in patients with HFREF. High altitude may be considered as a risk factor in decompensating heart failure.