Acute Myocardial Infarction Hospitalizations between Cold and Hot Seasons in an Island across Tropical and Subtropical Climate Zones-A Population-Based Study.

Min-Liang Chu,Chih-Wei Lee,Han-Lin Chen,Jen-Che Hsieh,Tsung-Cheng Hsieh,Chiao-Yu Shih

doi:10.3390/ijerph16152769

Abstract

We investigated the effects of cold and hot seasons on hospital admissions for acute myocardial infarction (AMI) at the junction of tropical and subtropical climate zones. The hospitalization data of 6897 AMI patients from January 1997 to December 2011 were obtained from the database of the National Health Insurance, including date of admission, gender, age, and comorbidities of hypertension, diabetes mellitus (DM), and dyslipidemia. A comparison of AMI prevalence between seasons and the association of season-related AMI occurrences with individual variables were assessed. AMI hospitalizations in the cold season (cold-season-AMIs) were significantly greater than those in the hot season (OR 1.15; 95% CI 1.10–1.21). In the subtropical region, cold-season-AMIs were strongly and significantly associated with the ≥65 years group (OR1.28; 95% CI 1.11 to 1.48). In the tropical region, cold-season-AMIs, in association with dyslipidemia relative to non-dyslipidemia, were significantly strong in the non-DM group (OR 1.45; 95% CI 1.01 to 2.09) but weak in the DM group (OR 0.74; 95% CI 0.55 to 0.99). The cold season shows increased risks for AMI, markedly among the ≥65 years cohort in the subtropical region, and among the patients diagnosed with either DM or dyslipidemia but not both in the tropical region. Age and comorbidity of metabolic dysfunction influence the season-related incidences of AMI in different climatic regions.

Highlights

Acute myocardial infarctions (AMI) are severe cardiovascular events that are caused by a sudden and critical reduction in blood flow to the coronary arteries
The main findings of this study suggest that the cold season incidence of AMI increased significantly compared to the hot season on the island of Taiwan, regardless of the subtropical and tropical regions
The present study showed that diabetes mellitus (DM) patients without dyslipidemia and non-DM patients with dyslipidemia appeared to be more susceptible to AMI during the cold season, but DM patients with dyslipidemia and non-DM patients without dyslipidemia were susceptible, regardless of the season, and more markedly in the tropical region

Summary

Introduction

Acute myocardial infarctions (AMI) are severe cardiovascular events that are caused by a sudden and critical reduction in blood flow to the coronary arteries. Evidence has indicated that coronary artery occlusion may be influenced by long-term chronic physiological risk factors and by short-term exposure to physical, psychosocial, and environmental temperature triggers [1]. Mortality risks have been reported to be attributable to non-optimum cold and hot temperatures, mostly the contribution of cold, from several cities across multiple climate zones [2]. The health consequences of adverse hot temperatures will become more serious after the impacts of climate change, especially for vulnerable populations [3]. The frequency of AMI occurrences is highly related to seasonal changes in temperature [4]. In the studies from cold and temperate climate zones worldwide, hospital

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