Low physical activity level may confer risk for instant, short-term MI death
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Moderate to high physical activity levels were associated with lower risk for instant and 28-day death related to MI, according to results published in the European Journal of Preventive Cardiology.
“Less myocardial stunning, less ischemia-induced arrhythmias, improved left ventricular function and improved survival after a cardiac arrest have been documented in patients hospitalized with MI who experience pre-infarction angina; an equivalent of ischemic preconditioning,” Kim Wadt Hansen, MD, PhD, postdoctoral research fellow in the department of cardiology at Bispebjerg Frederiksberg University Hospital in Copenhagen, Denmark, and colleagues wrote. “Despite this strong biological basis for a cardioprotective effect of physical activity, prospective studies on the relation between physical activity and risk for death during the acute phase of a MI are scarce.”
For a collaborative pooled analysis of 10 European cohort studies, researchers assessed 28,140 patients with an incident MI, a baseline physical activity assessment, conventional CV risk factors and available data on MI and death. The participants were stratified by weekly physical activity level: sedentary (< 7 metabolic equivalents of task [MET] hours), low (7-16 MET hours), moderate (16.1-32 MET hours) or high (> 32 MET hours) based on an individual’s calculated net weekly energy expenditure.
The primary outcome was instant and 28-day fatality related to MI.
Of the 4,976 participants who died within 28 days, 3,101 (62.3%) were classified as instant fatal MI. Participants with low (OR = 0.79; 95% CI, 0.6-1.04), moderate (OR = 0.67; 95% CI, 0.51-0.89) or high (OR = 0.55; 95% CI, 0.4-0.76) levels of physical activity demonstrated lower adjusted odds for instant fatal MI compared with patients with sedentary physical activity levels. The results suggest individuals with moderate and high physical activity levels had a 33% and 45% lower risk for instant MI fatality, the researchers wrote.
Researchers observed similar results for 28-day fatal MI among patients with low (OR = 0.85; 95% CI, 0.71-1.03), moderate (OR = 0.64; 95% CI, 0.51-0.8) or high (OR = 0.72; 95% CI, 0.51-1) levels of physical activity compared with sedentary patients. In the analysis of instant fatal MI, researchers found a low to moderate degree of heterogeneity (I2 = 47.3%) but not in analysis of 28-day fatal MI (I2 = 0%).
According to a press release from the European Society of Cardiology, based on these findings, even a low amount of leisure-time physical activity may be beneficial against fatal MI, but statistical uncertainty prevents the researchers from providing definitive conclusions.
“Our pooled analysis provides strong support for the recommendations on weekly physical activity in healthy adults stated in the 2016 European Guidelines on CVD prevention in clinical practices, especially as we used cutoff values for physical activity comparable to those use in the guidelines,” the researchers wrote. “We believe that our findings may be helpful to all health providers in their consultancy of healthy adults.”
Perspective
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Michael S. Emery, MD, MS, FACC
This is an interesting study as it looks specifically at the risk of dying from a MI in relation to baseline physical activity rather than just the risk for having an MI. While the study is not a randomized clinical trial, which is difficult to design and carry out when attempting to answer the type of question being investigated, the authors compiled a large population of observational cohorts resulting in 28,140 patients with an incident MI, with 17.7% dying within 28 days and 62.3% of those dying instantly. As might be expected, the risk for dying from an MI (both immediate death and 28-day death) in those groups of patients with moderate to high level of baseline physical activity was significantly lower. Exercise and, perhaps more specifically, “fitness” continue to be a significant factor in CV morbidity and mortality, which is an important message in our current environment of rising obesity and sedentarism.
While determining the biological mechanisms for the reduction in this outcome was not part of the study, it is likely multifactorial related to improvement in traditional risk factors that often naturally accompany improved fitness as well as underlying biological principles of the vasculature and myocardium with exercise. It should be noted that exercise does not make anyone immune to CVD or death from an MI. Caregivers need to continue to encourage their patients to improve their health via exercise and nutrition and connect them to community resources that can support their goals toward health. Fitness is a hedge against sickness and, specifically based on this study, a hedge against dying from a MI.
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