Physical activity with coronary heart disease: 150 minutes a week linked to 38% lower death risk

People who have had a heart attack, or been told that the arteries around their heart are narrowed, tend to get two messages at once: take care, and keep moving. The second is standard advice. How much movement goes with living longer in this group is less well charted, because most of the big studies of exercise and survival were done in people whose hearts were healthy to begin with.

Researchers at the University of Edinburgh have now pooled the studies of patients themselves. Zhiwei Tao, Tessa Strain and colleagues, writing in the European Journal of Preventive Cardiology in September, combined 17 long-term studies of people with coronary heart disease, the condition in which the vessels feeding the heart muscle are narrowed or blocked. Earlier work had shown that active patients die at lower rates, but in the authors’ words the dose-response relationship remains uncertain: nobody had a reliable curve of how survival changes as weekly activity rises from nothing. Theirs falls steeply at first and then flattens, and the largest gap sits at about the amount health agencies already recommend for everyone.

How much physical activity went with lower death rates?

The curve rests on a great many people. Seventeen studies included 176,862 patients, and across the studies that reported it, 31,783 of them died during follow-up. Each study had asked participants about activity outside work, such as walking, cycling, sport and housework, and then tracked who was still alive years later.

Studies record activity in different ways, so the team converted everything into one unit: the energy a person spends on activity above what the body burns at rest. A useful landmark on that scale comes from an earlier analysis of the general population, which used the same unit and described one point on it as equivalent to the recommended 150 min/week of moderate-to-vigorous aerobic physical activity. Moderate means a brisk walk or its equal.

At that landmark, survival was plainly better. Relative to doing none, estimated mortality risk was 38% lower at the 150-minute level.

Does more exercise keep helping with coronary heart disease?

Not by much, on these figures. At twice the amount, the equivalent of 300 minutes a week, the death rate was 39% lower than with no activity, which is one percentage point better than at 150. The team reports that the curve showed a non-linear inverse association, meaning a line that bends: steep between nothing and the guideline minimum, close to level after it. The authors summarize that the link was seen particularly at low-to-moderate levels.

An independent study of heart patients found the same bend. In a trial population of 15,486 patients from 39 countries with stable coronary disease, Ralph Stewart of Auckland City Hospital and colleagues saw death rates fall as exercise rose, in a pattern that was steeper at lower compared with higher exercise levels. Their conclusion was that the largest benefits occurred between sedentary patient groups, that is, in the step from doing nothing to doing a little.

Very high amounts are where the picture blurs. At roughly three and a half times the guideline minimum, the Edinburgh estimate became too vague to use: it was compatible with anything from half the death rate to two-thirds higher. The reason is thin data. Only 8 of 17 studies had data extending that far, and when the team changed its assumptions for converting activity into a common unit, the calculation produced a different high-dose shape.

That uncertainty matters because one earlier study raised a flag. Ute Mons and colleagues at the German Cancer Research Center followed 1038 subjects with stable CHD, the abbreviation for coronary heart disease, for ten years. The least active did worst by far. But the group that reported strenuous activity every day also fared worse than the moderately active, with the most frequently active patients also having increased hazards of cardiovascular death. The authors called it a finding which warrants further investigation. The new analysis neither confirms nor dismisses it.

What do exercise trials in heart disease show?

All of the above comes from watching what patients chose to do. The stronger test is a randomized trial, in which some patients are assigned to exercise and others are not, and for coronary heart disease there are many. They mostly test cardiac rehabilitation, a supervised program of exercise, often with education, offered after a heart attack or a procedure to open or bypass an artery.

A Cochrane review led by Grace Dibben at the University of Glasgow gathered 85 such trials covering 23,430 people with CHD. Its results are more modest than the cohort curve. Over one to three years, the reviewers found there may be little to no difference in all-cause mortality between those assigned to exercise and those who were not. Deaths from heart and circulatory causes told a better story: a large reduction in cardiovascular mortality was found, along with fewer heart attacks over the longer term. Summing up, the review credits exercise programs with a likely small reduction in all-cause mortality.

A small reduction in trials and 38% in cohorts cannot both be the effect of exercise. The trial figure is the safer guide to what activity itself does. The cohort figure also includes whatever else separates patients who exercise from patients who do not.

Are active heart disease patients simply the healthier ones?

Partly, yes. A heart that pumps poorly, breathlessness and other illnesses all make activity harder and all shorten life, so in any survey the least active group includes many of the sickest. Statistical adjustment narrows that problem without removing it.

A review of nine cohorts from the University of Bern shows both the promise and the difficulty. A total of 9 prospective cohorts included 33,576 patients whose activity was recorded more than once. Compared with those who stayed inactive, the death rate was 45% lower in those who were inactive but became active, which is the result that most resembles a real-life change. Yet those who stopped being active lost most of the advantage, and the authors warn that this pattern may be confounded by disease progression: people often stop because they are getting worse.

Two further cautions apply to the Edinburgh result. Activity was reported by patients themselves, and people tend to overstate it. And the 17 studies disagreed with each other considerably about the size of the effect, which makes the pooled 38% an average of quite different answers.

A Korean study offers some encouragement all the same. In a cohort that included 131,558 people with cardiovascular disease and 310,240 without, activity was tied to lower death rates in both, and the benefit in the secondary prevention group was shown to be greater than that in the primary prevention group. Secondary prevention is the term for people who already have the disease.

Where the 150-minute figure sits in heart disease guidance

The Edinburgh team notes that the amounts linked to lower mortality were consistent with the range recommended in current ESC guidelines, ESC being the European Society of Cardiology. The World Health Organization’s 2020 guidelines set the same weekly range for adults in general and extend their recommendations to people living with chronic conditions or disability, with the summary that some physical activity is better than none.

The evidence under that advice has long been thinner for patients than for the public. Stewart’s group opened its 2017 paper by observing that recommendations for physical activity in patients with stable coronary heart disease (CHD) are based on modest evidence. The new curve fills in part of that gap. What it supports most firmly is the low end of the range. How much activity, and what kind, suits someone with heart disease depends on their condition and treatment, which their cardiologist or rehabilitation team assesses.

For people with coronary heart disease, the step that counted most in these studies was the first one, from no activity to some.