Outbursts of anger may trigger heart attacks, strokes and other cardiovascular problems up to two hours after an outburst, according to a new study.

Researchers from the Harvard School of Public Health examined studies from around the world that spanned a period of 18 years.

Their findings, published in the European Heart Journal, link extreme emotion with a higher risk of cardiovascular events, especially among people who already have cardiovascular problems.

“The risk can accumulate for people with frequent episodes of anger,” said Dr.  Elizabether Mostofsky, a co-author. “This is particularly important for people who have higher risk due to other underlying risk factors or those who already had a heart attack, stroke or diabetes.”

According to the study, people who have an outburst:

  • Have a five-fold increased risk of a heart attack.
  • A more than three-fold risk of a stroke.
  • An increased risk of ventricular arrhythmia.

Researchers say among people who have a low risk of cardiovascular problems and are frequently angry, there would be an extra 158 heart attacks per 10,000 people.

But among high-risk groups, that would translate to an extra 657 heart attacks per 10,000.

The study emphasizes that anger is associated with these health effects but does not necessarily cause them.

The authors say a potential link between anger and heart problems could be that “psychological stress has been shown to increase heart rate and blood pressure, and vascular resistance.” Alterations in blood flow can spark blood clots and result in inflammation, causing health problems.

The researchers suggest doctors ask high-risk patients about their levels of anger and if they find it’s high, they could recommend forms of therapy or counselling to deal with anger or even medications that would minimize the outbursts.