Physical Activity and Mortality in CHD

Study Questions:

What is the association between self-reported exercise and mortality in patients with stable coronary heart disease (CHD)?

Methods:

A total of 15,486 patients from 39 countries with stable CHD who participated in the STABILITY study completed questions at baseline on hours spent each week in leisure time and work activity: mild <3 METs (housework, easy walk, yoga), moderate 3-6 METs (fast walk and other aerobic, gardening), and vigorous >6 METs (running, lifting, strenuous sports or work) exercise. Associations between the volume of habitual exercise in Metabolic Equivalent of Task (MET)-hours/week and adverse outcomes during a median follow-up of 3.7 years were evaluated.

Results:

Mean age was 65 years, and about 20% were female. A graded decrease in mortality occurred with increased habitual exercise, which was steeper at lower compared with higher exercise levels. Doubling exercise volume was associated with lower all-cause mortality (unadjusted hazard ratio [HR], 0.82; 95% confidence interval [CI], 0.79-0.85, adjusting for covariates HR, 0.90; 95% CI, 0.87-0.93). These associations were similar for cardiovascular (CV) mortality (unadjusted HR, 0.83; adjusted HR, 0.92), but myocardial infarction (MI) and stroke were not associated with exercise volume after adjusting for covariates. The association between decrease in mortality and greater physical activity was stronger in the subgroup of patients at higher risk estimated by the ABC-CHD (Age, Biomarkers, Clinical–CHD) risk score (p for interaction = 0.0007).

Conclusions:

In patients with stable CHD, more physical activity was associated with lower mortality. The largest benefits occurred between sedentary patient groups, and between those with the highest mortality risk.

Perspective:

STABILITY (Stabilization of Atherosclerotic Plaque by Initiation of Darapladib Therapy) was a global outcomes trial of a novel inhibitor of Lp-PLA2. It included high risk based upon CV risk factors and post-MI patients defined as >1 month, which would not be considered stable CHD clinically. That more exercise provided greater risk reduction in stable sedentary persons is consistent with other studies, but that the benefit was in the highest risk group is a new finding. Studies showing the benefit of intense exercise are in general population studies with mixed results in post-MI. The failure to decrease MI rate with increasing exercise volume and vigorous exercise might infer the increase in event rates during and for hours after intense exercise.


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