Doctors have called for heart shock machines to be installed in football stadia in Portugal ahead of next year's European Championships.
Watching football can put a strain on some people's hearts
It follows a Swiss study which showed that deaths from heart attacks increased there by 60% during last summer's World Cup finals.
Doctors believe the risks may be higher for fans who attend live matches.
They say the noise and collective anxiety inside a stadium can put strain on some people's hearts.
Doctors in Switzerland compared death rates from heart attacks in 2002 with those from the previous year.
They found that deaths from heart attacks outside hospital were 60% higher during the World Cup compared to the same period in 2001.
Although the researchers cannot prove that the rise was a result of people watching the football matches, they believe that there may well be a link.
Previous studies have also found evidence to suggest that more people have heart attacks when major football tournaments are on.
Research published in the British Medical Journal last year found that heart attacks increased by 25% when England lost to Argentina in a penalty shoot-out during the 1998 World Cup.
The Swiss researchers told the European Cardiology Congress in Vienna that the stress and anxiety associated with watching a football match can put a strain on some people's hearts.
However, they added that many football fans may increase their risk by doing less physical exercise, and smoking and drinking more during a tournament.
They suggested that GPs should advise patients of the risk and that extra doctors and ambulance crews should be on call during tournaments.
The findings have been seized upon by senior doctors in Portugal, which will host the European Football Championships next June.
Dr Manuel Carregeta, president of the Portuguese Federation of Cardiology, said football stadia should be fitted out with vital life-saving equipment to treat any fans who suffer a heart attack while attending matches.
He said all 10 stadia which will host the championship's 31 matches should be required to store defibrillators, which can be used to shock a fluttering heart to its normal rhythm.
"The risk of suffering a heart attack is greater when you watch a game live because of the noise and collective anxiety," he said.
"We need to avoid the rise in deaths due to heart problems which happen every time there is a big football event, " he told the daily newspaper Correio de Manha.
Dr Carregeta said football fans could reduce their risk of having a heart attack before a match by eating a light meal, and avoiding coffee and alcohol.