Influence Of Weather On Hospital Admissions For Eldly Acute Myocardial Infarction

Object i ve:The purpose of this study was to determine whether a time variation could be observed in the admission of acute myocardial infarction (AMI) in patients older than65in nearly three years. We investigated the association between meteoro-logical parameters(eg.air temperature,atmospheric pressure,relative humidity, precip-itation, wind speed) and hospital admissions for AMI.Methods:A retrospective analysis of patients diagnosed with AMI between March1,2009and February29,2012in the department of Cardiology of The Second Hospital of Tianjin Medical University was carried out. Detailed records of patient’s general clinical data,such as admission time,gender,age,complications and so on. We calculated the number of AMI cases day by day,grouping on the general clinical data. we analysis that whether a seasonal or monthly or weekly variation could be observed in the admission of AMI in the elderly.The meteorological parameters, including air temperature,atmospheric pressure,relative humidity,rainfall,wind speed,were provid-ed by the database of the Tianjin Meteorological Administration.Meteorological factor-s can be divided into four groups by percentile, respectively.Then analysis whether differences among the groups in AMI admissions can be tested.Results:There were908patients totally in the1095-day study.Our results show that①The admission of AMI distribution was regular in seasons and months. A peak period of the admission of AMI was recorded during winter, while minimum number of events were found during summer(P<0.01). And the monthly occurrence of AMI was highest in January and lowest in June (P<0.05). But the variation was only found in the patients which had coronary heart disease history or ST segment elevated in ECG or had poor heart function (P<0.05).(2)When the daily average temperature is lower than2.8℃, the risk of AMI admission increased compared to when the daily average temperature is higher than15.9℃(P<0.01). When the daily maximum temperature is lower than7.6℃, the risk of AMI admission increased compared to when the daily maximum temperature is higher than20.6℃(P<0.01). And when the daily minimun temperature is lower than-0.3℃, the risk of AMI admission increased compared to when the daily minimun temperature is higher than11.7℃(P<0.01).There were no difference in the groups of diurnal range and24hour temperature variation.People who is aged between75-89or male or CHD patient or is with high blood pressure is suspective to lower temperature(P<0.05).There were sig-nificant differences among the groups of cardiac function(P<0.05).③Compared to the condition of atmospheric pressure below1016hPa,the risk of admission reased when atmospheric pressure above1025hPa(P<0.05).When atmospheric pressure between994.1hPa and1008.0hPa,the risk of admission is the smallest to the person who is aged between75-89or female or CHD patient or is with high blood pressure (P<0.05).The patients whose cardic function is Killip’sⅢ were easier to admission when atmospheric pressure above1025hPa(P<0.01).④There were no difference among the groups of relative humidity.But in the subgroups, when relative humidity between37%and52%,the people who is younger old people and whose cardic function is poor and the patients of CHD mergerd hypertension is less suspective to AMI(P<0.05).⑤There were no difference among the groups of rainfall.But to men and NSTEMI,the risk of admission is lower when the rainfall of24hour is less than10mm or the snowfall of24hour is less than2.4mm(P<0.05).Compared to the condition of the rainfall of24hour is less than10mm or the snowfall of24hour is less than2.4mm and no precipitation,the patients who merged CHD and hypertention is less dangerous when the rainfall of24hour isbetweenlOmm and25mm(P<0.05).⑥There were no difference among the groups of wind speed totally.But to the patient who merged CHD and hypertention or had the history of OMI or was NSTEMI is the most dangerous under the condition of the wind speed below0.9m/s(P<0.05).Conelus i on:Results of our study reveal that the admission of AMI shows a characteristic rhythm with respect to seasons and months.Meteorological parameters have a significant influence on the occurrence of AMI. We should formulate corresponding preventive measures combined with the elderly own characteristics,in order to reduce the occurance of AMI.