Background: A comparative retrospective study was performed to compare the distribution of risk factors and complications in patients with acute coronary syndrome (ACS) at high-altitude vs low-altitude areas in Yemen.
Methods: The records of 768 patients from Sana'a (high altitude) and Aden (low altitude) were reviewed. Risk factors assessed were age, hypertension, diabetes mellitus, hyperlipidemia, cigarette smoking, and reported history and family history of coronary artery disease (CAD). Complications of ACS of interest were heart failure, arrhythmias, cerebrovascular accident (CVA), and death.
Results: The mean age of ACS patients at high altitude was significantly lower than those at low altitude (55.3 years [SD = 8.2] vs 56.8 years [SD = 7.1]; P = .007). History of hyperlipidemia was significantly higher in high-altitude patients than in low-altitude patients (49.2% vs 38.3%; odds ratio [OR] = 1.563; P = .002). Reported history of CAD was also significantly higher at higher altitudes (16.7% vs 9.4%; OR = 1.933; P = .003). Previous history of diabetes mellitus and tobacco smoking was slightly higher with borderline significance. Hypertension and reported family history of CAD were comparable among high- and low-altitude patients. In terms of in-hospital complications, CVAs were significantly higher in high-altitude patients than in low-altitude patients (7.8% vs 4.4%; P = .0001). Heart failure, arrhythmias, and death rates were comparable in both groups of patients. Wall motion abnormalities were comparable, whereas the ejection fraction was lower in the high-altitude patients (49.8% [SD = 16.08] vs 54.8% [SD = 16.23]; P = .0001).
Conclusions: ACS occurs at a younger age at high altitudes. Patients who live in high-altitude regions are also more likely to have hyperlipidemia and a previous history of CAD. Stroke and reduced left ventricular ejection fraction (LVEF) occur more commonly in high-altitude ACS patients. High altitude may generally be a risk factor for ACS.