Common Triggers of Acute Myocardial Infarction
By Harold L. Karpman, MD, FACC, FACP
Clinical Professor of Medicine, David Geffen School of Medicine at UCLA
Dr. Karpman reports no financial relationships relevant to this field of study.
SYNOPSIS: Physical exertion and anger or emotional upset are common one hour before the onset of symptoms of acute myocardial infarction (AMI). Although either exposure may act alone as the external trigger for AMI, the greatest magnitude of association was seen in those subjects who experienced both physical exertion and anger or emotional upset one hour before the onset of symptoms of AMI.
SOURCE: Smyth A, et al. Physical activity and anger or emotional upset as triggers of acute myocardial infarction. Circulation 2016;134:1059-1067.
Cardiovascular disease is the leading cause of death worldwide.1 More than 90% of the risk of developing an acute myocardial infarction (AMI) has been attributed to long-term exposure to multiple risk factors such as hyperlipidemia, exogenous obesity, and lack of exercise.2 Published studies have identified potential external triggers for AMI, including anger, emotional upset, and physical exertion.3,4 The prevalence of potential triggers of AMI also may vary by geographical region in that triggers that have been found to be important in one region or ethnic group may be absent or different in others. The INTERHEART study20 was a case-control study of first AMIs conducted in 262 centers across 52 countries.2,5 Highly trained staff performed a standardized physical exam on participants and then administered a carefully structured questionnaire. Participants who had suffered an AMI were questioned carefully about physical activities and episodes of anger or emotional upset in the one hour before the onset of symptoms and during the same hour on the previous day. All collected data were transferred to the Population Health Research Institute at the McMaster University and Hamilton Health Sciences in Hamilton, Ontario, Canada. The authors concluded that physical exertion and anger or emotional upset were common events in the one hour before the onset of symptoms of AMI and that either exposure could act as an external trigger for AMI. The greatest magnitude of association was seen in those with both physical exertion and anger or emotional upset in the one hour before the onset of AMI symptoms. The authors reported no differences in numbers of events related to geographical area, in whether the subjects did or did not present with a history of previous cardiovascular disease, in subjects who had a history of taking cardiovascular prevention medications, or who possessed a significant number of cardiovascular risk factors.
The results reported by the INTERHEART investigators certainly confirm previous findings that physical exertion and anger or emotional upset may act as external triggers for AMI.6-10 Physical exertion and emotional upset both contributed an additive effect, and they have been reported to cause sympathetic activation,6 catecholamine secretion,11 and modification of myocardial oxygen demand because of systemic vasoconstriction, increased heart rate, and increased blood pressure.12-14 In addition, these events actually may precipitate the rupture of an already vulnerable atherosclerotic coronary artery plaque.15 These findings previously have led to recommendations that the impact of link between triggering events and their pathophysiological consequences may be reduced through the use of aspirin, beta-blockers, statins, or angiotensin-converting enzyme inhibitors.16 However, the authors of the INTERHEART study found no beneficial modification produced by cardiovascular prevention medication on the prevention of AMI associated with physical exertion or anger or emotional upset. Although regular physical activity is known to play a role in the long-term prevention of cardiovascular disease,17 vigorous physical exertion definitely may act as a trigger of AMI. Therefore, clinicians should continue recommending regular physical activity while noting that short-term, intense physical activity may carry a risk of triggering AMI. The authors reported that emotional upset and the negative effects of acute emotional disturbance,9 acute depression,18 and work-related stress19 were reported as significant triggers for AMI. Numerous limitations were noted in the design of this study. First, the study was performed only on patients who were hospitalized for their first AMI and did not include non-hospitalized patients with AMI. Next, since many of the conclusions were based on patient recall of intensity of exposure to any triggering events, it must be recognized that a patient’s ability to recall timing and intensity of stimuli varies greatly and is open to question.
Since the patients in the INTERHEART study were all hospitalized with their first AMI, the conclusions cannot be applied to the effect of triggering events in a secondary prevention population or in those patients with atypical AMI. Despite the limitations of the study, the results are valuable, and clinicians should consider counseling their patients to avoid any of the triggers outlined above, which could result in an acute AMI.
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- Yusuf S, et al. Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): Case-control study. Lancet 2004;364:937-952.
- Culic V, et al. Meta-analysis of possible external triggers of acute myocardial infarction. Int J Cardiol 2005;99:1-8.
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- Ounpuu S, et al. INTER-HEART: A global study of risk factors for acute myocardial infarction. Am Heart J 2001;141:711-721.
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- Thompson PD, et al. Exercise and physical activity in the prevention and treatment of atherosclerotic cardiovascular disease: A statement from the Council on Clinical Cardiology (Subcommittee on Exercise, Rehabilitation, and Prevention) and the Council on Nutrition, Physical Activity, and Metabolism (Subcommittee on Physical Activity). Circulation 2003;107:3109-3116.
- Steptoe A, et al. Acute depressed mood as a trigger of acute coronary syndromes. Biol Psychiatry 2006;60:837-842.
- Möller J, et al. Work related stressful life events and the risk of myocardial infarction: Case-control and case-crossover analyses within the Stockholm Heart Epidemiology Programme (SHEEP). J Epidemiol Community Health 2005;59:23-30.
- Smyth A, et al. Physical activity and anger or emotional upset as triggers of acute myocardial infarction. Circulation 2016;134:1059-1067.
Physical exertion and anger or emotional upset are common one hour before the onset of symptoms of acute myocardial infarction.
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