The Association Between Temperature Variability and Acute Coronary Syndrome Admissions: A Retrospective Study

Introduction Meteorological factors have been suggested to influence acute coronary events, but the role of temperature variability remains incompletely understood. This study aimed to evaluate the association between meteorological parameters, particularly temperature variability, and hospital admissions for acute coronary syndrome (ACS). Methods This retrospective observational ecological time-series study included 1,376 patients who were hospitalized in two cardiology centers between January 2009 and December 2010. ACS was defined as the combination of ST-elevation myocardial infarction (STEMI), non-ST-elevation myocardial infarction (NSTEMI), and unstable angina pectoris (USAP). Meteorological data, including temperature and humidity parameters, were obtained from official records. Seasonal differences were analyzed, and the relationship between meteorological variables and ACS admissions was evaluated using correlation and linear regression analyses. Results A total of 981 patients were classified as having ACS. The highest number of ACS admissions was observed in May (n = 122), while the lowest occurred in September (n = 35). Total ACS admissions were similar during the cold season compared to the warm season (83.2 ± 21.3 vs. 80.3 ± 33.2, p = 0.86). In regression analysis, maximum humidity change (β = 0.122, p = 0.048), mean temperature (β = 0.813, p = 0.027), mean temperature change (β = -0.171, p = 0.025), minimum temperature change (β = 0.154, p = 0.016), and minimum humidity (β = -0.465, p = 0.014) were significantly associated with ACS admissions. Additionally, maximum temperature change (β = 0.886, p = 0.015) and daily temperature variation (β = -1.151, p = 0.004) showed significant associations with daily ACS admissions. Conclusions Although ACS admissions were numerically higher during colder periods, this difference did not reach statistical significance. Several temperature variability parameters were significantly associated with daily ACS admissions. These findings suggest that short-term fluctuations in temperature may be associated with ACS admissions, but causal relationships cannot be established because of the retrospective observational study design.