Dr Bikash Rai Das, Senior Consultant Heart Surgeon, Health City Hospital, Guwahati, firstname.lastname@example.org
Many people are not aware that heart attack can occur not only because of the physical exertion in winter but also because of the cold temperatures. Winter is the most common season for heart attacks. Cold weather may increase the risk of a heart attack, according to new research in the UK.
Each 1.8 degree Fahrenheit reduction in temperature on a single day was linked to about 200 additional heart attacks. Research also shows there are up to 53 per cent more chances of heart attacks in winter than in summer, and twice as many chances of heart attacks a day in January compared to July.
Cold weather leads to more heart attacks, according to research presented at the European Society of Cardiology Congress in 2013. This research showed that only temperature was significantly correlated with heart attack, which increased by 7 per cent for each 10°C decrease in minimum temperature. The greatest risk came within two weeks of cold-weather exposure, and those with coronary heart disease were most vulnerable to temperature changes. Studies have shown that heart attacks and complications related to heart disease occur more frequently in the morning hours.
Why does cold weather increase heart attack risk?
There are most likely several factors involved. For starters, cold temperatures can cause a rise in your blood pressure along with increasing levels of proteins that raise your risk of blood clots.
Cold temperatures cause arteries to tighten, restricting blood flow and reducing the oxygen supply to the heart, all of which can set the stage for a heart attack. In cold weather, there is more oxygen demand by the heart because it is working harder to do the work and maintain body heat. A potential mechanism to explain the increased risk of heart attacks associated with decreasing temperature is the stimulation of cold receptors in the skin and therefore, the sympathetic nervous system, leading to a rise in hormone levels. Moreover, increased platelet aggregation and blood viscosity during cold exposure promote clot formation.
When the weather is cold, the heart must also work harder to maintain body heat and the arteries are tightened because of cold, which restricts blood flow and reduces the oxygen supply to your heart. When combined, all of these factors could trigger a heart attack, especially in the elderly or those with existing heart disease.
There is also the issue of hypothermia, which occurs when the body temperature falls below normal. Heart failure is the leading cause of death in hypothermia cases, which is why it's very important to dress appropriately for the weather if someone plans to be outdoors in the cold. There is another factor, too, that may help explain why heart attacks occur more often during the winter, and this one has nothing to do with temperatures. Still, it may very well be more influential than all of these others combined – a lack of sunlight. Sunlight can help our skin produce vitamin D which is required for heart health. Because sunlight is scarce during the winter months, it can be very difficult to maintain high enough vitamin D levels. If someone’s vitamin D levels are not optimised, the person may be very likely putting his heart at risk. Low temperature is by far the most important environmental trigger for heart attack. People at risk of heart attack (for example elderly patients with diabetes and hypertension) can minimise their risk by avoiding big changes in temperature. This means wearing suitable clothes when going from the warm indoors to the colder outdoors, even beyond winter time.