Clinical characteristics of acute myocardial infarction in migrant bird population and impact of migration-induced temperature changes on AMI subtypes

Background　Multiple studies have indicated a close relationship between temperature and the occurrence of acute myocardial infarction (AMI). However, there is limited reporting on the impact of temperature variation due to short-term migration across different climate zones on AMI, as well as the clinical characteristics of the affected population. Objective　To investigate the clinical features of AMI in the seasonal migrants and explore the role of temperature variation in the onset of AMI among this cohort. Methods　This case-control study consecutively enrolled AMI patients who were hospitalized and underwent coronary angiography at Hainan Hospital of PLA General Hospital during the winter months from 2012 to 2022. Based on travel history, patients were divided into the seasonal migrant cohort and the local resident cohort. Baseline characteristics, coronary angiography findings, interventional treatment strategies, and in-hospital outcomes were compared between the two cohorts. Subsequently, propensity score matching (PSM) was employed to balance the baseline characteristics between the two groups before comparison. A further comparison was made of the clinical characteristics of the two types of AMI within the seasonal migrants. A piecewise regression model was employed to examine the nonlinear relationship between the arrival-to-onset interval and acute ST-segment elevation myocardial infarction (STEMI) in seasonal migrants with AMI. Additionally, a multivariable Logistic regression model was used to evaluate the association between the temperature difference and STEMI in seasonal migrants with AMI. Results　A total of 514 patients were included, comprising 350 (68.09%) seasonal migrants with AMI and 164 (31.91%) local residents with AMI. Compared to local residents, the seasonal migrants were older (63.1 ± 11.6 years vs 59.6 ± 11.6 years, P=0.001), had a higher proportion of female patients (22.00% vs 10.98%, P=0.004), more pre-existing risk factors, and a higher incidence of inhospital cardiogenic shock (18.00% vs 10.98%, P=0.042). Moreover, after PSM, their risk of in-hospital cardiogenic shock remained significantly higher than that of the local residents (21.31% vs 9.84%, P=0.013). Segmented regression model revealed a threshold effect in the relationship between the arrival-to-onset interval and different AMI subtypes among seasonal migrant patients. When the arrival-to-onset interval was≤31 d, it demonstrated a significant inverse association with the probability of STEMI (OR=0.928, 95% CI: 0.880 - 0.979, P=0.006). Furthermore, multivariable Logistic regression analysis indicated a significant positive correlation between the temperature difference and STEMI in seasonal migrants with AMI (OR=1.079, 95% CI: 1.035 - 1.125, P＜0.001). For every 1° C increase in temperature difference, the probability of STEMI increased significantly by 7.9%. Conclusion　Seasonal migrants with AMI are at a higher risk of in-hospital cardiogenic shock; a threshold effect exists in the relationship between the arrival-to-onset interval and STEMI in this population, and the temperature difference is an independent risk factor for STEMI in seasonal migrants with AMI.