'Heart in the mouth' moments during a big football match may literally put fans' lives at risk, research shows.
German fans followed their team passionately
Researchers studied the effects on German fans of watching their home team compete in the 2006 World Cup finals.
For men the risk of having a heart attack or another cardiovascular problem was three times higher on days when the German team was in action.
Munich's Ludwig-Maximilians University found that female fans had an 82% increased risk.
The researchers found that cardiac emergencies usually occurred within two hours of the start of a match.
They looked at 4,279 medical reports from the seven days the German team played, the 24 days when matches involved teams from other countries, and 242 other days in 2003, 2005 and 2006.
Six of the seven games in which the German team participated were associated with an increase in the number of cardiac emergencies.
The largest number occurred during a June 30 quarter-final in which Germany defeated Argentina in a dramatic penalty shoot-out.
The next game, Germany's semi-final loss to Italy, produced almost as many heart attacks.
In contrast, Germany's match against Portugal for third place, produced no spike in heart-related problems. Germany defeated Portugal 3-1.
Writing in the New England Journal of Medicine, the researcher said: "Apparently, of prime importance for triggering a stress-induced event is not the outcome of a game - a win or a loss - but rather the intense strain and excitement experienced during the viewing of a dramatic match, such as one with a penalty shoot-out."
The researchers said previous research had shown that stress could induce abnormal heart rhythms.
However, the impact of stress on severe heart problems is less clear. They suggest that the release of stress hormones may directly influence the functioning of heart and immune system cells.
The researchers suggested that doctors might want to consider upping the dose for at-risk patients already on medication before a big game.
Alternatively, they say behaviour therapy to manage stress may be an option.
Cathy Ross, a cardiac nurse for the British Heart Foundation, said: "Intense changes in emotions, whatever the cause, can lead to chest pain or even a heart attack in people with diagnosed coronary heart disease - people whose arteries have narrowed over many years."
But she added: "Factors such as sleep deprivation, poor diet, smoking and binge drinking, which are all associated with such big occasions, may also have acted as a cardiac event trigger - rather than just the excitement of the match."