[Stress factors in acute myocardial infarct: the role of physical exertion and unusual life events].
OBJECTIVE
It is controversial whether the onset of myocardial infarction is a "random" event or whether there are triggering factors of the disease. Previous reports on possible triggers were based on case studies or inadequately controlled studies. The TRIMM study (Triggers and Mechanisms of Myocardial Infarction) was designed to determine the influence of physical activity and other external factors on the acute risk of myocardial infarction.


METHODS
At Klinikum Steglitz, Berlin, all consecutive patients with myocardial infarction were included. In the Augsburg area, all patients with myocardial infarction in a prospectively defined cohort (n = 330,000) were registered by monitoring 26 hospitals. Information on the circumstances and possible triggers of the disease was obtained by standardized interviews. The control group was matched for age, sex, precinct, and time of a control event. The statistical analysis included a case-control comparison of patients with control subjects and a case-crossover comparison comparing the average exposure to a possible trigger with the time of the last exposure prior to the onset of disease.


RESULTS
From January 1989 to December 1991, 1194 patients (74% men, 61 +/- 9 years) were enrolled 13 +/- 6 days after myocardial infarction. During the initial three hours after awakening, the occurrence of myocardial infarction was almost threefold compared to other times of day. A multivariate analysis yielded a twofold risk of myocardial infarction during physical exertion, statistically independently of time of day. 7.1% of patients had engaged in exertional physical activity at onset of the event, as opposed to 3.9% of control subjects. The case-crossover analysis demonstrated a relative risk of 2.1 (1.6-3.1) of exertional physical activity within 1 hour prior to myocardial infarction. Patients whose average frequency of physical exertion was < 4 versus > or = to 4 times per week had relative risks of 6.9 versus 1.3 (p < 0.01). Unusual life events within 24 hours and 24 hours to 4 weeks prior to the event occurred with similar frequencies and control subjects.


CONCLUSIONS
Physical exertion appears to increase the acute risk of myocardial infarction in patients with coronary heart disease, particularly in untrained individuals. Unusual life events, however, are of less importance for the acute risk of disease. These findings are important for further investigation of triggering mechanisms of myocardial infarction and for improving preventive strategies.
Willich
S N
SN
Kardiopulmologische Abteilung, Klinikum Steglitz, Freie Universität Berlin.
Lewis
M
M
Arntz
H R
HR
Löwel
H
H
Schubert
F
F
Stern
R
R
Schröder
R
R
D000328:Adult; D000368:Aged; D005260:Female; D015438:Health Behavior; D006801:Humans; D008016:Life Change Events; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000209:etiology*; D005082:Physical Exertion; D011446:Prospective Studies; D012307:Risk Factors; D013312:Stress, Physiological / Q000150:complications*
Belastungssituation beim akuten Myokardinfarkt: Die Rolle von körperlicher Anstrengung und ungewöhnlichen Lebensereignissen.