2 September 2013
NEW DELHI: The risk of getting a heart attack is highest in winter and lowest in summer, according to latest research based on analysis of more than 100,000 patients in seven European countries.
The researchers found that levels of several cardiovascular risk factors (such as blood pressure, waist circumference and total cholesterol) were higher in winter (January to February) and lower in summer (June to August) compared to the annual average.
The findings were presented at the congress of the European Society of Cardiology currently meeting at Amsterdam by Dr Pedro Marques-Vidal from Switzerland. The study used cross-sectional data from 10 population based studies in 7 countries. Information was obtained on cardiovascular risk factors in 107,090 subjects aged 35 to 80 years. The country breakdown was as follows: 21,128 subjects in Belgium, 15,664 in Denmark, 1,626 in France, 18,370 in Italy, 25,532 in Norway, 9,359 in Russia and 15,411 in Switzerland.
Levels of blood pressure, lipids, glucose, body mass index (BMI, kg/m2) and waist circumference were compared according to season. All data were adjusted for age, gender and smoking. Data on blood pressure, lipids and glucose were adjusted for BMI and whether or not the patient was taking medication.
'The study suggests that particular care with CVD prevention should be taken over the winter months,' said principal investigator Pedro Marques-Vidal. 'It is important that emergency resources are strengthened in winter.'
Systolic blood pressure levels were on average 3.5 mmHg lower in summer than in winter. One explanation for the lower blood pressure levels seen in the summer, he speculated, is that higher ambient temperatures lead to vasodilation (broadening of blood vessels) and perspiration. It is also possible that higher levels of physical activity and a different dietary intake in summer may reduce obesity.
Waist circumference was on average 1 cm smaller in summer than in winter, while total cholesterol was, on average, 0.24 mmol/L lower in summer than in winter. Dr Marques-Vidal said: ""We observed a seasonal variation in waist circumference but BMI did not change throughout the year. We have no clear explanation for this finding. Total cholesterol may increase during the winter because of changes in eating habits. There was no seasonal variation in glucose, probably because several cohorts did not collect blood samples in the fasting state. We have begun a study on seasonality of food intake which may help explain these findings.""
"Our large scale study shows that some cardiovascular risk factors take holidays over the summer. This may explain why deaths from cardiovascular disease are higher in winter than summer. People need to make an extra effort to exercise and eat healthily in the winter to protect their health," Dr Marques-Vidal added.
""Our team is currently conducting another study to find out if the seasonal pattern in cardiovascular risk factors reverses in the southern hemisphere, where seasons are inverted relative to the northern hemisphere. Based on preliminary data, it does seem to be the case. The overall study is expected to collect information on almost 200,000 subjects from over 12 countries," he said.
Published by: The Times Of India