New York, Oct 11 (IANS): Being angry, emotionally upset or engaging in heavy physical exertion may significantly increase risk of a heart attack, warns a large international study.

The researchers found an association (more than twice the risk) between anger or emotional upset and the onset of heart attack symptoms within one hour.

The same was true for heavy physical exertion during the hour before their first heart attack, according to the study published in the American Heart Association's journal Circulation.

However, the association was stronger (more than triple the risk) in those patients who recalled being angry or emotionally upset while also engaging in heavy physical exertion.

"Previous studies have explored these heart attack triggers; however, they had fewer participants or were completed in one country, and data are limited from many parts of the world," said study lead author Andrew Smyth from Population Health Research Institute at McMaster University in Canada.

"This is the first study to represent so many regions of the world, including the majority of the world's major ethnic groups," Smyth said.

For the study, the researchers analysed data from 12,461 patients (average age 58) participating in INTERHEART, a study consisting of patients with first-ever heart attacks across 52 countries.

The researchers said that extreme emotional and physical triggers can raise blood pressure and heart rate, changing the flow of blood through blood vessels and reducing blood supply to the heart.

"This is particularly important in blood vessels already narrowed by plaque, which could block the flow of blood leading to a heart attack," Smyth said.

"Regular physical activity has many health benefits, including the prevention of heart disease, so we want that to continue," he said. 

"However, we would recommend that a person who is angry or upset who wants to exercise to blow off steam not go beyond their normal routine to extremes of activity," Smyth noted.