Emotional distress after myocardial infarction: Importance of cardiorespiratory fitness

There is considerable evidence that psychosocial stress and emotional distress play significant parts in the pathogenesis and progression of major cardiovascular disease (CVD).1 Many clinicians may be unfamiliar with this burgeoning literature and, as a consequence, these associations have been under-recognized and under-appreciated by physicians involved in the diagnosis and treatment of patients with CVD.1 The link between psychosocial stress/emotional distress and CVD is now widely established. Although there have been thousands of publications on this topic in the past two decades, some of the most important epidemiological data on the crucial role of psychosocial stress/emotional distress in coronary heart disease (CHD) comes from the INTERHEART study,2 which evaluated major risk factors for CHD and psychosocial stress in a group of 11,119 patients with myocardial infarction and 13,648 age- and sex-matched controls from 262 centers and 52 countries. Of the nine major modifiable CHD risk factors, psychosocial stress was third in importance, behind only lipids and slightly behind smoking, and psychosocial stress accounted for close to a third of the population attributable risk of acute myocardial infarction. Many other studies support the link between psychosocial stress/emotional distress and major CVD and CVD prognosis.1 In this issue, Norlund et al.3 assess the factors associated with emotional distress in patients with myocardial infarction from the SWEDEHEART registry. They assessed 27,267 consecutive patients with their first myocardial infarction, who were followed up at 2 and 12 months post-myocardial infarction. They showed not only that symptoms of emotional distress were prevalent in 38 and 33% of patients at 2 and 12 months, respectively, after myocardial infarction, but also that previous emotional distress (especially depression and anxiety), female sex, young age, smoking, being from outside the Nordic countries, neither employed nor retired, and having re-admissions for major CVD events were all strongly related with emotional distress post-myocardial infarction. They concluded that these factors could be targeted for potential rehabilitation following major CHD events. Although we applaud these investigators for their large and well-performed analysis of factors predicting the prevalence of emotional distress among a large cohort of patients with myocardial infarction, they appear to have missed the opportunity to examine the role of cardiac rehabilitation, physical activity/exercise training or levels of cardiorespiratory fitness (CRF) in their analysis, which may be crucial in evaluating patients with, or at risk of, psychosocial stress/emotional distress and for predicting prognosis.1 We previously demonstrated that levels of physical activity and CRF predict the prevalence of psychosocial stress/emotional distress, especially depression, in large cohorts of patients.4–7 Depression has been identified as a risk factor in patients with CHD and this deserves appropriate screening and intervention by practicing physicians.8 Exercise training is the cornerstone of cardiac rehabilitation and has been shown to reduce the risk for all-cause mortality.1 Decreases in CRF during late middle age also strongly predict the development of depression as reported to physicians.9 A positive emotional outlook on life has also predicted increases in physical activity among initially inactive men, potentially increasing their ability to increase CRF and lower their CVD risk.10 An additive effect was noted in which people with low levels of negative emotional distress and high levels of CRF were associated with a 63% lower risk of premature mortality compared with people with higher levels of emotional distress and low levels of CRF.11 It has also been reported that higher CRF is associated with a lower risk of mortality independent of other mortality predictors in a cohort of 5240 men with emotional distress.12 Considering that the current study was performed in patients after myocardial infarction, we are particularly interested in the impact of cardiac rehabilitation and exercise training (CRET) on psychosocial stress and increased mortality risk related to psychosocial stress.1 Emotional distress/psychosocial stress, including anxiety, hostility and, especially, depression, play major parts in the development of CHD and also affect prognosis in patients with CHD, including those with emotional distress/psychosocial stress after myocardial infarction.1 As a result of the evidence that emotional distress/psychosocial stress, especially depression, is a risk factor for CHD, there is considerable support for the value of interventions designed to reduce emotional distress (Figure 1).1,8,13,14 It has been shown that CRET programs result in reductions in psychosocial stress, including anxiety, stress, hostility and depression.1 It also has been shown that persistently low levels of physical activity after acute myocardial infarction are associated with the development of depression during follow-up15 and that depression is associated with a significantly increased risk of mortality in patients with CHD and in patients with CHD and concomitant heart failure.1,16–18 In patients taking part in CRET programs, improvements in CRF after a formal program were associated with marked reductions in depression and a reduction in the depression-related increased mortality rate. Although CRET is generally associated with improvements in emotional distress/psychosocial stress and prognosis,1,16–18 a randomized trial of cardiac rehabilitation patients showed the additional benefits of stress management training (SMT) combined with a traditional CRET program.1,19–21 A group of 151 patients with CHD were randomized to a standard CRET or SMT-enhanced CRET program; a matched group of patients with CHD who did not engage in a CRET program formed a non-random control group. During a mean follow-up period of 5.3 years, patients randomized to the CRET program had far fewer major outcomes than the matched CRET-eligible patients who did not attend a CRET program. In addition, those who engaged in a CRET program along with SMT had greater reductions in composite psychosocial stress levels than those undergoing a CRET program alone and they also experienced fewer cardiac events, suggesting an additional benefit of SMT when combined with CRET.21 In another study, it was shown that patients with persistent depression after CRET had higher mortality rates22 and that although other comorbid psychosocial stress conditions, including anxiety and hostility, added to this risk, almost all of the high mortality risk was explained by depression. Several reasons for the interest by medical practices in the evaluation and treatment of psychosocial stress. Reproduced with permission from Rozanski et al.13 We congratulate Norlund et al.3 for their study showing the high prevalence of emotional distress in a large cohort of patients from Sweden post-myocardial infarction. However, substantial data indicate that the value of physical activity, exercise training and CRF should not be overlooked23 and strategies to improve physical activity and reduce emotional distress should be a priority for the primary and secondary prevention of emotional distress and for reducing major adverse clinical outcomes.24 As the leading method to do this is with formal CRET programs in the secondary prevention of CHD, efforts are needed to increase referrals to these programs and to increase participation and improve engagement with this effective treatment. We also need to increase compliance and reduce the drop-out rate. We need to include new innovative modalities, including the use of pedometers and accelerometers, smart phones and telemedicine to make this treatment more cost-effective and available to a higher percentage of patients.25–27 The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. The author(s) received no financial support for the research, authorship, and/or publication of this article.