Non-traditional heart attack riskier than thought

Patients less likely to be given preventive medications, U of A study finds

EDMONTON A little-studied type of heart attack that occurs in patients with no blocked arteries is more common, more dangerous and requires more caution from doctors than previously believed, new University of Alberta research has found.

The study, which followed more than 36,000 Alberta heart patients over a 12-year period, is considered the world’s first long-term effort to track the unheralded cardiac condition Minoca.

“It really confirmed to us that this is not a benign condition and we need to pay more attention to it,” said lead author Dr. Kevin Bainey, an interventional cardiologist at the Mazankowski Alberta Heart Institute.

“We need to be vigilant in terms of trying to investigate the ultimate cause of that heart attack, because that obviously has implications on the medications or therapies we would advise for these patients.”

Minoca, an acronym for myocardial infarction with non-obstructive coronary arteries, is an umbrella term used to describe a variety of different heart attacks not caused by blocked arteries.

Examples could include attacks linked to a tear in the heart artery, a stressful event or inflammation of the heart muscle, Bainey said.

Such Minoca events have been historically treated with less concern than traditional heart attacks involving obstructions to the arteries.

“Previously these patients were reassured about their prognosis and were really not given any reason or cause for their heart attack, so it left patients somewhat confused,” Bainey said.

Bainey decided to get a better handle on whether Minoca presented a serious risk or not.

The authors found that among the population of heart attack victims in Alberta from 2002 to 2014, the incidence of Minoca was about six per cent.

A year after suffering an attack, Minoca patients had a five per cent chance of dying or suffering another heart attack, compared with a nine per cent risk faced by those who experienced a traditional heart attack.

After five years, Minoca patients had an 11 per cent chance of dying, whereas the death rate among traditional cardiac patients was 16 per cent.

The results clearly show the dangers posed by Minoca are not as insignificant as formerly believed, which will hopefully convince the medical community to expend more effort nailing down the causes of each patient’s attack, Bainey said.

He noted the study found Minoca patients were far less likely than other cardiac patients to be prescribed preventive medications such as cholesterol-busting drugs — even though such therapies have proven to be beneficial.

As well, while 25 per cent of traditional-style heart attacks caused by plugged arteries involve women, researchers found women accounted for a little over half of the Minoca population. Bainey said it’s still unclear why. The research is published in the International Journal of Cardiology.