Why winter mornings raise the risk of heart attacks

As temperatures start dipping, most hypertensive people report thickening and clotting of blood and elevated blood pressure, all of which raise the risk of heart attacks. Worldwide, several studies have shown that the risk of having a heart attack during the winter months is twice as high as that of summers.
HOW DOES BLOOD CLOT? HOW DOES BP IMPACT THE HEART?
Blood pressure has an inverse relation to environmental temperature. During winter, the blood pressure increases, making the heart work harder to pump the same amount of blood. To maintain body temperatures, our blood vessels constrict. “This helps your body stay warm decreasing the amount of blood flow to your skin and limbs, which are farthest from the heart, and pulling more blood into your core organs so that you don’t feel the chills. When your blood vessels narrow down, the heart has to use more force to push your blood through smaller passageways, pushing up your blood pressure. When this happens, your blood can be more prone to clotting. A clot that blocks the flow of oxygen and blood to your brain or heart can cause a stroke. Also, winter is the time when we tend to overlook hydration. It’s much easier to become dehydrated in cold weather without feeling thirsty. This makes your blood sticky, which can increase your risk of developing a clot,” says Dr Manish Bansal, Director, Clinical and Preventive Cardiology, Heart Institute, Medanta Hospital, Gurugram. “Additionally, colder temperatures cause the blood’s platelets to stick together more than normal. While platelets typically clump together to form clots that help seal bleeding wounds, cold weather can increase the risk for a dangerous blood clot to form inside the body,” says Dr Kamal Gupta, Principal Consultant Cardiology, Fortis Escorts Hospital, Faridabad.
Dr Sanjeev Jadhav, Chief Cardiac Surgeon at Apollo Hospital, Mumbai, and Director of Heart-Lung Transplant division, said as winter approaches, most cardiologs observed that viscosity of blood (thickness of blood) increases. “That’s why one has to look out for blockages in the arteries caused the sudden formation of blood clots.” Many studies have testified to this. A 2016 study published in the Journal of Stroke and Cerebrovascular Diseases examined nearly 172,000 ischemic stroke hospitalisations in the United States and found they occurred more often in colder average temperatures and when temperatures fluctuated significantly. A German study published the same year in the European Journal of Epidemiology concluded that for every 2.9-degree Celsius drop in temperature over 24 hours, strokes increased 11 per cent, and at  higher rates for those already at risk. In 2019, a study of about 56,000 stroke deaths over a decade in Sao Paulo, Brazil, found that falling temperatures may increase the number of deaths from stroke, particularly among people over 65.
WHY WE SHOULD WATCH OUT FOR PLAQUE RUPTURES?
“People may worry about clots but more than that plaque ruptures are the bigger risk. Additionally, blood pressure tends to go up. This happens because blood vessels tone (the vascular smooth muscle cells in the walls of small arteries and arterioles tend to contract) and become tight. For the same reason, the plaque becomes unstable, gets dislodged and this increases the risk of a heart attack,” says Dr Bansal.

WHY ATTACKS ARE MORE COMMON ON WINTER MORNINGS?

Studies have shown that heart attacks and complications related to heart disease occur more frequently in the morning hours during the winter months. Research suggests that this is usually due to an early-morning rise in blood pressure. Additionally, there is sympathetic hormonal imbalance during the morning hours, upping your risk. It is because of hormonal variations that there is an increase in levels of clotting factors, including fibrinogen. “Blood vessels contract in winter because of increased sympathetic tone. The sympathetic nervous system is the body’s control mechanism which maintains heart rate and blood pressure. The surge in blood pressure may cause the plaques to rupture, resulting in winter morning heart attacks,” adds Dr Bansal.
Dr Manoj Durairaj, noted cardiac transplant surgeon, said that uncontrolled diabetes is among the risk factors of heart attacks. “While there needs to be more studies among the Indian population to understand why silent attacks take place in the wee hours of the morning, it is also due to high blood pressure and arterial stiffness.”

WHO ARE AT RISK?
It is imperative to note that heart attacks will be more likely among those with pre-exing risk factors – smokers, obese people, patients withhigh BP, patients who consume excessive alcohol or those who are already being treated for heart conditions. Therefore, Dr Bansal suggests keeping the following in mind:• Maintain blood pressure through proper medication and regular follow-up• Take all medication to continue as advised• Avoid exposure to extreme cold and wear proper clothing• Avoid excessive consumption of salt• Avoid unhealthy eating practices and binging, which might push up cholesterol levels• Maintain a healthy exercise schedule but do not go overboard. In fact, evaluate your heart and body status before attempting anything extreme. Any unaccustomed exercise can put a strain on the heart, triggering a heart attack.