The impact of altitude on coronary artery disease severity in non-ST elevation acute coronary syndrome patients: a quasi-experimental study.

Introduction: While the impact of altitude on coronary artery disease (CAD) mortality and acute high-altitude exposure in cardiovascular disease has been studied, no prior research has specifically examined the relationship between CAD severity and long-term residence at higher altitudes. Aim: This study aimed to evaluate the relationship between CAD severity and altitude. Material and methods: A total of 532 de novo non-ST elevation myocardial infarction (non-STEMI) patients admitted to healthcare centers at different altitudes - a low-altitude center (70 m) and a moderate-altitude center (1690 m) - between January 2023 and December 2023 were retrospectively included. Inverse probability weighted propensity score weighting and doubly robust estimation were used to reduce bias and balance covariate distribution. Patients were analyzed based on their living altitude. Results: The median age of the patients was 64 years (IQR: 56-70), and 71.6% were male. SYNTAX scores were significantly higher in the moderate-altitude group, while other demographic and clinical variables were similar between the groups. Living at moderate altitude was an independent predictor of higher SYNTAX scores (estimate: 4.21, 95% CI: [2.34-6.08]; Conclusions: This study demonstrated that living at a higher altitude was associated with higher SYNTAX scores in non-ST elevation myocardial infarction patients, in addition to other well-established risk factors such as hypertension, elevated LDL levels, reduced ejection fraction, and smoking. These findings suggest that altitude-related factors may influence CAD severity and warrant further investigation.