Why ‘healthy’ folks have heart attacks

Hearing that a close friend or family member has had a heart attack is always shocking and upsetting, but never more so than when that person has been perceived as being “healthy”.

The disbelief is tangible — “but he is so slim, he is so active, he eats well”. And from the cardiologist: “you are not my typical patient” or “his cholesterol is in range”. This leaves patients and their family and friends feeling baffled and helpless.

In Canada in 2012 (the most recent published figures) the leading cause of death was all cancers at just over 74 000 people succumbing to the disease, with heart disease being the second cause of death at nearly 49 000.

This order is reversed in the USA with the figures from 2015 showing 614 000 deaths from heart disease and 592 000 deaths from all cancers.

Risk factors for heart disease include the following:

• Smoking — which increases blood pressure and contributes to blocked arteries • Lack of exercise • Not eating enough fruit and vegetables

• Eating trans fats and saturated fats, and high sodium intake • Being overweight or obese • Having high cholesterol, in particular, the bad cholesterol LDL

• Having diabetes, especially when blood sugars are poorly controlled • Prolonged stress Staggeringly, 9 in 10 Canadians over the age of 20 have at least one risk factor for heart disease.

Even worse, 4 out of every 10 Canadians have 3 or more risk factors! In 2012, 1.6 million Canadians were known to have heart disease!

The coronary arteries are the blood vessels that supply oxygen-rich blood to the heart muscle. Narrowing of these arteries compromises this supply.

One of the main components of heart disease is plaque formation. Plaque is a greasy layer of proteins, fats (including cholesterol) and inflammatory cells which accumulates inside the coronary arteries, thus narrowing the lumen, making it difficult for the blood to flow as freely as it should.

In most cases, this accumulation is a slow process allowing the body to adjust , sometimes by forming tiny new blood vessels allowing ongoing blood flow to the heart muscle.

This is why people can have up to 90 per cent blockage of a coronary artery before they get any symptoms such as chest pain, or angina, weakness and shortness of breath.

This plaque accumulation is not the main cause of heart attacks however.

It is the smaller plaques, that are blocking less than half of the artery that are often the main culprit.

These undergo acute disruption which leads to unstable angina or acute myocardial infarction (MI) — that is, a heart attack.

Plaques that have a higher lipid (fat) content and a thin cap are more likely to rupture.

This sets off a reaction in the body whereby our own defences leap in with platelets and inflammatory cells rushing to the site forming a larger clot over the ruptured plaque which can block the artery.

This causes sudden loss of blood and oxygen to the heart muscle, which if prolonged, leads to death of the muscle, hence the MI.

Next week: More about heart disease and what you can do to prevent it.

Dr. Wendy Ross is the lead physician at the Penticton cancer clinic and The Herald’s new health columnist.