Our results show a strong and significant increase in the incidence of cardiovascular events (including the acute coronary syndrome and symptomatic cardiac arrhythmia), in a defined sample of the German population, in association with matches involving the German team during the FIFA World Cup held in Germany in 2006. In contrast, the average daily number of cardiac emergencies during soccer matches involving foreign teams was well within the range of values obtained during the control period. Since the incidence ratios were close to 1 for the days around the German matches, it is clear that watching an important soccer match, which can be associated with intense emotional stress, triggers the acute coronary syndrome and symptomatic cardiac arrhythmia.

An association between soccer matches and rates of illness or death from cardiovascular causes has been previously investigated in six retrospective epidemiologic studies.4-9 Four assessed mortality due to myocardial infarction and stroke,4,5,7,8 one assessed hospital admission due to myocardial infarction and stroke,6 and the last involved a combined end point of cardiac and extracardiac diseases.9 Data were collected by central bureaus for statistics. The results are inconsistent: two studies showed an increase in the relative risk of an event on the day of a match,4,5 another showed an increase but did not evaluate it statistically,6 two did not show an increase,7,8 and one showed a decrease.9 In contrast, the conceptual design of the present study was to prospectively evaluate clinical end points (myocardial infarction with ST-segment elevation, myocardial infarction without ST-segment elevation or unstable angina, and symptomatic cardiac arrhythmia) in a predefined population before, during, and after an entire soccer tournament, with assessments by a team of experienced emergency physicians. Using this study design, we found that the risk of an acute cardiovascular event on days on which matches were played by the German team was considerably increased overall, by a factor of 2.7; similar results were also found for all diagnostic subgroups.

Carroll et al.6 found a significant increase in the incidence of acute myocardial infarction after the national team lost a penalty shoot-out, and we have documented an increase in the incidence of cardiac events after the German team won a penalty shoot-out. 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.

Several studies have indicated that triggering is more common in patients with known coronary artery disease than in those without it.1,15,16 Our results are consistent with these findings: cardiovascular events on days of soccer matches with German participation were associated with an increased rate of known coronary heart disease. More specifically, events occurred in all patients more frequently during the 7 days of matches played by the German team than during the control period, and the increase was greater among those with a history of coronary artery disease than among those without such a history (incidence ratio, 4.03 vs. 2.05). We assume that patients with preexisting coronary artery disease had, on average, more extensive underlying disease (more vulnerable plaques), leading to more frequent acute coronary syndromes, than did patients who were considered to be healthy before the event.

The emergency records enabled us to analyze the exact temporal relationship between the emotional trigger (the soccer match) and the onset of symptoms prompting the emergency call. Averaged over all seven games involving Germany, the incidence of events increased during the several hours before the match, the highest incidence was observed during the 2 hours after the start of the match, and the incidence remained increased for several hours after the end of the match. Trigger studies typically assess activities that are regarded as acute trigger mechanisms during the period of 1 or 2 hours before cardiac symptoms occur.15,16 Thus, our findings with respect to the relationship between the timing of the trigger and the cardiovascular event fully concur with those in other trigger studies.

In accordance with other studies,3-6 we found that most of the additional cardiac emergencies occurred in men. This phenomenon may be explained by sex-specific pathophysiological differences17 or by differences in the degree of interest in soccer matches or vulnerability to emotional triggers.18

A trigger can be defined as a stimulus that produces pathophysiological changes leading directly to disease — in this case, cardiovascular diseases.18 Although various mechanisms of stress-induced cardiac arrhythmias have been described,19-21 those underlying the induction of acute coronary syndromes are less clear. As previously reported, stress hormones may directly influence endothelial and monocytic function.22-24 Thus, future evaluations of endothelial and monocytic mediators in patients with stress-induced cardiovascular events might clarify the mechanisms of emotional triggering.

The excess risk of cardiovascular events associated with viewing stressful soccer matches (and probably other sporting events) is considerable, and evaluation of preventive measures is needed, particularly in patients with preexisting coronary artery disease. Interventions that might be considered include the administration or the increase in dose of beta-adrenergic-blocking drugs, antiinflammatory agents such as statins, or antiplatelet drugs such as aspirin, as well as the blockade of stress-mediating receptors. In addition, nonmedical strategies, such as behavioral therapy for coping with stress, should be considered.

Our study has several limitations. The differentiation of myocardial infarction without ST-segment elevation from unstable angina was impossible because of the limited prehospital diagnosis. However, all patients with these diagnoses were found to require hospital admission for further evaluation. In addition, the rate of interhospital transport to specialized medical centers increased equally in all diagnostic subgroups, showing a high rate of serious cardiac events. We therefore believe that the increase in the incidence of myocardial infarction without ST-segment elevation or unstable angina reflected the induction of both conditions by stress, rather than emotionally induced, temporary episodes of angina. To confirm this, we would have to know the troponin levels.

Although the patients' conditions were evaluated by experienced emergency medicine physicians, some misclassifications might have occurred. However, this limitation is unlikely to have affected differently the 7 days of matches played by the German team, the 24 days of matches not involving the German team, and the control period.

Our results do not permit the identification of the exact triggers that provoked the additional cardiovascular events observed. Lack of sleep, overeating, consumption of junk food, heavy alcohol ingestion, smoking, and failure to comply with the medical regimen should all be considered.

In conclusion, we found a significant increase in the incidence of cardiovascular events (consisting of both the acute coronary syndrome and symptomatic cardiac arrhythmia), in a defined sample of the German population, in association with matches involving the German team during the FIFA World Cup, held in Germany in 2006. We hypothesize that these additional emergencies were triggered by emotional stress in relation to soccer matches involving the national team. Future studies are needed to assess stress triggering in association with other sporting events and to analyze the efficacy of medical treatment, nonmedical treatment, or both in reducing this stress-related excess risk of cardiovascular events.