The importance of being active after a heart attack

Chest pain is one of the most common reasons for emergency room visits, accounting for about 5% of all admissions. These consultations are entirely appropriate; although the causes of such pain can be quite benign (e.g., somatization, musculoskeletal pain) in some cases, in other cases, the causes are far more serious (e.g., myocardial infarction, pulmonary embolism, aortic dissection) and can lead to sudden death.

Acute coronary syndrome

It is particularly important to seek medical attention in the presence of sensations of tightness, burning, or pressure in the chest, which are classic symptoms of acute coronary syndrome (ACS)—that is, a sudden reduction or blockage of blood supply to the heart caused by obstruction of the coronary arteries. ACS is a medical emergency that must be treated immediately with medications or revascularization procedures (i.e., placement of stents in blocked coronary arteries) to restore blood flow to the myocardium.

Despite their success, these treatments do not correct the underlying causes responsible for arterial blockage. As a result, even though the lives of patients affected by ACS are saved in the short term, they remain at very high risk of complications and sudden mortality thereafter unless they modify their lifestyle habits, particularly with respect to smoking, diet, chronic stress, and  physical activity levels.

Physical inactivity and sedentary behavior

One of the most important lifestyle changes for patients who have experienced a coronary event is an increase in the amount of time devoted to physical activity. In a study that measured physical activity levels in 620 patients after ACS, for example, only 16% adhered to the minimum physical activity recommendations—namely, 30 minutes of moderate activity (such as brisk walking) at least five days per week. This physical inactivity is accompanied by very high levels of sedentary behavior, on the order of 12–13 hours per day spent sitting during the month following hospitalization.

It has long been known that physical inactivity is one of the most important risk factors for cardiovascular disease. In recent years, research has clearly shown that this risk is even more pronounced when inactivity is combined with long periods of sedentary behavior, such as remaining seated for several consecutive hours. In addition to reducing time spent exercising and depriving the body of the cardiovascular and muscular benefits of physical activity, sedentary behavior also appears to be an independent risk factor due to its negative effects on blood vessel function, blood pressure, and glucose metabolism.

In terms of cardiovascular disease prevention, the optimal combination is therefore to reach the minimum threshold of 150 minutes of physical activity per week (and ideally a bit more), while avoiding prolonged periods of sitting as much as possible (Figure 1A). This goal is not always easy to achieve, since a physically active person may also spend long periods sitting and thus be considered “active but sedentary” (Figure 1B). Conversely, some individuals do not engage in structured exercise but nevertheless manage to avoid long periods of prolonged sedentary behavior (Figure 1C). The worst combination is obviously when the absence of exercise is combined with prolonged sedentary behavior—for example, when a person commutes to work by car, sits at a computer for eight hours, then returns home and spends the rest of the day engaging in leisure activities in front of the television or other screens (Figure 1D).

Post–myocardial infarction sedentary behavior

A recent study clearly illustrates the impact of these different activity/sedentary profiles on the risk of cardiovascular mortality in patients who have experienced a coronary event. In this study, researchers recruited 609 individuals (mean age 62 years) who had been admitted to the emergency department with symptoms of acute coronary syndrome and subsequently measured their levels of physical activity and sedentary behavior using an accelerometer. The incidence of cardiac events or cardiovascular mortality during the year following hospitalization was then analyzed according to participants’ activity levels.

As shown in Figure 2, the results are unequivocal: compared with “model” patients who were active and minimally sedentary, physical inactivity combined with high levels of sedentary behavior increased the risk of cardiovascular events by nearly 800%. This increase in risk was less pronounced but remained significant (265%) among individuals who were minimally active but nevertheless limited the duration of their sedentary periods. It should also be noted that even among physically active individuals, long episodes of sedentary behavior appeared to increase the risk of recurrent cardiovascular events (212%). These results underscore the importance of minimizing prolonged periods of sedentary behavior, regardless of one’s level of physical activity.