Maybe it's the eggnog. Or maybe the Christmas feast. Or perhaps it's all that snow shovelling. Whatever the reason, the holidays tend to be a time when heart attacks spike. So experts at the University of Ottawa Heart Institute are warning Canadians to be on the lookout for the classic signs.

A number of U.S.-based studies have noted an increase in "heart events" over the holidays – dubbing it "holiday heart syndrome" or a "Merry Christmas coronary."

Emergency room physicians and cardiologists have long noted that deadly heart attacks increase during the winter. A few studies have even found distinct spikes around Christmas and New Year's Day.

One study published in Circulation in 2004, looked at 53 million U.S. death certificates from 1973 to 2001. They found an overall increase of 5 per cent more heart-related deaths during the holiday season.

When researchers looked at individual years, they found varying increases in cardiac deaths for every holiday period they studied except two.

According to the Circulation study, "The number of cardiac deaths is higher on Dec. 25 than on any other day of the year, second highest on Dec. 26, and third highest on Jan. 1."

Part of the problem might be the cold weather, which can cause blood vessels to constrict, thereby raising blood pressure. Frigid temperatures also increase stress on the heart. Throw in some show shovelling or other forms of physical exertion and you could have the recipe for a heart attack.

That might explain why there are more heart attacks in the winter in cold parts of the U.S., but it doesn't explain the sudden spike on Christmas Day, nor does it explain why heart events rise as a whole in December in places such as California, where many parts of the state enjoy pretty balmy winters.

Dr. Andrew Pipe, chief of the division of Prevention and Rehabilitation at the University of Ottawa Heart Institute says a number of factors may contribute:

  • overeating
  • drinking too much alcohol
  • reduced exercise
  • emotional stress

Pipe notes that too much alcohol has been linked with atrial fibrillation – a common disturbance of heart rhythm, which can increase the risk of stroke, heart attack, and heart failure.

It's also possible that holiday revelers simply don't feel comfortable calling for an ambulance on Christmas or New Year's Day and may delay getting treatment so as not to make a fuss. Butanyone who suspects they're having a heart attack should get help right away.

Signs of a heart attack include:

  • uncomfortable chest pressure, squeezing, fullness or pain, burning or heaviness
  • discomfort in other areas of the upper body, such as the neck, jaw, shoulder, arms, back
  • shortness of breath
  • sudden sweating
  • nausea
  • light-headedness

If you are suddenly experience any of these signs, you should:

  • Call 9-1-1 or your local emergency number immediately, or have someone call for you
  • Stop all activity and sit or lie down and wait for emergency medical personnel to arrive
  • If you take nitroglycerin, take your normal dosage
  • If you are experiencing chest pain, chew and swallow one adult 325 mg tablet or two 80 mg tablets of ASA (acetylsalicylic acid, commonly referred to as Aspirin). Other pain medicines such as acetaminophen or ibuprofen do not work the same way as ASA and therefore will not help

While a large proportion of patients who experience holiday heart attacks have a known condition that predisposes them to this risk, many who are afflicted may not have been aware that they were at risk. So the Heart Institute offers the following tips:

Keep moving, but don't over-exert yourself: Take time to exercise. A daily walk can be both relaxing and health enhancing. But avoid over-exerting yourself physically through activities such as heavy snow shovelling if you have known risk factors (e.g. smoking, high blood pressure, elevated cholesterol levels) or a family history of heart disease.

Watch what you eat and drink: Enjoy the season's pleasures, but in moderation. Avoid excess salt, fatty foods and too much alcohol.

Get the flu shot: The flu vaccine is always a heart-healthy choice, says the Heart Institute, especially if you are over 65 or have known heart disease.

Be merry: The holidays can be stressful. Schedule some ‘down time' and take a daily walk.

Be generous: Helping those less fortunate is good for the heart

When in doubt – find out: If you feel chest pain or other symptoms, don't delay in calling 911 for emergency help. Don't postpone investigation of unusual symptoms because you don't want to spoil the holiday celebrations.

The Heart Institute also recommends using the New Year to make some heart-healthy lifestyle changes, such as eating more sensibly, exercising more regularly, and most important of all: stopping smoking.