Skip to main content


Is it true that cold weather triggers heart attacks?


Story continues below advertisement

Canadian winters are often longer, darker and colder than many of us enjoy. The cold temperatures affect more than our daily commute; they have an impact on our health, particularly cardiovascular health.

Studies have shown that when stress tests (which monitor heart activity using an electrocardiogram while the patient walks at various speeds on a treadmill) are conducted in a cold environment, the onset of symptoms, specifically chest pain (angina) and breathlessness, comes much earlier than if the same tests were administered in warmer temperatures.

Cold weather has a two-pronged effect on the cardiovascular system: Arteries that supply the working muscles in the arms and legs with blood constrict or clamp down in an effort to salvage heat, and blood pressure increases. This causes the heart to work harder.

At the same time, the arteries around the heart also constrict, inhibiting the flow of blood and oxygen to the heart muscle. The cold can bring out cardiovascular symptoms by causing the heart to work harder and depriving it of oxygen. Exercise in cold weather, such as shovelling snow, may unmask problems in someone who is predisposed to cardiovascular disease but ordinarily feels fine.

A heart attack occurs when an artery on the surface of the heart is suddenly blocked. Heart attack symptoms include nausea, a heaving feeling in the chest, shortness of breath, perspiration, or pain between the shoulder blades or in the jaw. If symptoms persist longer than 10 to 15 minutes, or are not relieved by rest, phone 911 and get to an emergency room quickly.

One of the biggest problems cardiologists face is patients ignoring their symptoms and arriving at the ER too late. If the heart is deprived of oxygen for longer than 20 minutes, the muscle cells begin to die. The sooner we can get the blocked artery open, the more heart muscle we can save, reducing the risk of death or serious complication.

Shovelling snow is a real-life stressor that can wreak havoc on the heart. If you encounter any of the symptoms listed above, stop shovelling and walk inside.

Story continues below advertisement

Keep these tips in mind:

Don't shovel after a big meal. Digestion requires the heart to work harder than normal, so try to avoid added strain.

Don't shovel after smoking a cigarette. Nicotine increases the level of carbon monoxide in the blood, which forces the heart to pump harder to get oxygen.

Warm up before shovelling to ensure your muscles are ready for exercise.

Don't overdo it. If you feel overwhelmed or extremely cold, stop and go inside. The snow will still be there when you return.

Dr. Eric Horlick is an interventional cardiologist in the Peter Munk Cardiac Centre at the University Health Network in Toronto.

Story continues below advertisement

Report an error

The Globe invites you to share your views. Please stay on topic and be respectful to everyone. For more information on our commenting policies and how our community-based moderation works, please read our Community Guidelines and our Terms and Conditions.

We’ve made some technical updates to our commenting software. If you are experiencing any issues posting comments, simply log out and log back in.

Discussion loading… ✨