Response by Smyth et al to Letters Regarding Article, “Physical Activity and Anger or Emotional Upset as Triggers of Acute Myocardial Infarction: The INTERHEART Study”
We thank Culic for his comments on our recent publication,1 but we wish to make 2 comments. First, we would like to clarify the assessment methods of physical exertion. Participants were asked about physical exertion in 2 ways: as a potential triggering event in the hour before acute myocardial infarction (AMI) and in the same hour on the previous day, and the usual level of physical activity. Therefore, we must clarify that we do not know whether mild to mderate physicial activity preceded AMI; instead we know that 24.6% of the overall cohort had a mild exercise pattern of usual physical activity. That said, we agree that it would be interesting to explore a different definition of physical activity, such as those used in other studies,2 in addition to anger or emotional upset as a potential triggering event.
Second, although we acknowledge that the effect of triggers may differ between those with and without biologically active vulnerable plaques, we believe it is important to clarify that it is unlikely that engaging in heavy physical exertion or becoming angry or emotionally upset, in the absence of other cardiovascular risk, would lead to AMI. We agree that patients with high levels of comborbidity, cardiovascular risk, or previous cardiovascular disease are most likely to alter their physical activity, either consciously or through limitations induced by their health status. However, because the INTERHEART study (Effect of Potentially Modifiable Risk Factors Associated with Myocardial Infarction in 52 Countries) included only participants with first AMI, with a relatively small number of participants with previous cardiovascular disease (5% reported a history of stroke and 17% reported a history of angina), it is unlikely that this influences our results. Instead, we believe that the absence of significant difference on analyses stratified by the baseline level of physical activity is more likely to be explained by the participant’s interpretation and response to the question on heavy physical exertion before AMI.
We also thank Templin et al for their comments on our article.1 The prevalence of physical activity and anger or emotional upset in our study was higher than many previous studies, which we believe occurred because participants were asked about potential trigger events without explicit definitions or examples of heavy physical exertion, anger, or emotional upset. Similarly, AMI was defined based on clinical symptoms plus electrocardiographic findings or elevations in troponin, consistent with clinical practice. We acknowledge that this approach would not identify Takotsubo syndrome. However, we believe that our findings are robust and apply to the vast majority of presentations of AMI because Takotsubo syndrome is responsible for a low proportion of presentations with acute coronary syndrome, as outlined by Templin et al.
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- © 2017 American Heart Association, Inc.