EXERCISE TO TREAT CORONARY DISEASE

Exercise for treating Coronary Heart Disease (CHD):

Angina
Angina pectoris is the tight central chest pain, sometimes radiating to the left arm, brought on by exercise. The pain brings the sufferer to a halt and settles within a few minutes.
Angina was first described in the 18th century by Dr Heberden. He reported on one of his patients who “was cured by sawing wood for half an hour a day”. Exercise is an effective treatment for angina because it improves cardio-respiratory fitness. The fitter you are the more efficient are your heart and muscles so that any given effort makes a smaller demand on the heart. This allows an increase in effort before the threshold for angina is reached. Additional long term benefit comes from the effect of exercise on bringing in “collateral” vessels to bypass the responsible narrowed artery. Exercise also helps to reduce all the risk factors which have caused the angina in the first place.

Heart attacks
These became a serious and increasing problem early in the 20^th century. When a heart attack was diagnosed, prolonged bed rest was thought to be essential if the patient’s life were to be saved. Exertion too soon after the attack was thought to risk rupture of the damaged heart. Doctors and nurses went to absurd lengths to keep the patient at complete “rest” for several weeks. This included spoon feeding them and insisting on the use of that most exercise-intensive utensil, the bed pan. When the patient was eventually released from hospital, the advice was for exercise to be restricted in favour of a peaceful, sedentary life.

Rehabilitation
In the 1940s and 50s some of the undesirable consequences of bed-rest were being appreciated – deconditioning, boredom, depression, venous thrombosis and chest infection to mention just a few. The idea of early mobilisation was gaining credibility. In Cleveland, Ohio, a far-seeing cardiologist called Herman Hellerstein and his colleagues developed a comprehensive rehabilitation programme with graduated exercise training as the centre-piece. The idea was to “…add life to years and perhaps years to life” for “habitually sedentary, lazy, hypokinetic, sloppy, endomesomorphic overweight males” by a programme of enhanced physical activity. (He appears to have held his coronary patients in high regard!). It was shown that patients who had recovered from a heart attack could have their physical fitness improved, exercise ECG changes reduced and psychological status raised by a course of exercise. Patients were also educated in appropriate diet, counselled to give up smoking and encouraged to continue gainful employment and normal social life. This whole package is known as cardiac rehabilitation and it is now offered to most patients recovering from heart attacks, heart surgery or stenting of narrowed coronary arteries.

The outcomes of cardiac rehabilitation
Over the past 50 years there have been numerous controlled trials of exercise based cardiac rehabilitation in patients recovering from such events as heart attacks and heart surgery.  Meta-analyses of the results have indicated a roughly 25% fall in the mortality rate in treated groups over the subsequent three years. Interestingly when exercise-only programmes have been compared with more comprehensive programmes, the exercise only treatments fare as well as those offering in addition counselling, education and risk factor advice. Maybe the exercise is the most effective element.

Management in the longer term
The long-term outlook of the survivors of heart disease is greatly benefited by exercise and increased physical fitness. Exercise capacity is a powerful predictor of prognosis. For every 1 metabolic equivalent or MET¹ reduction in VO₂ max² there is an increased risk of death of 13%.  The ten year mortality in CHD patients with a VO₂ max of less than 15 is more than double that of those with a VO₂ max of more than 22.  Physical fitness in CHD patients is a better predictor of future life expectancy than any other measure. This effect is partly because low fitness reflects greater heart damage – even so, increasing fitness with exercise training reduces mortality risk to the level of untrained subjects with an equivalent fitness level.

Heart failure
One important result of the cardiac damage from coronary disease can be heart failure. In this condition the ability of the heart to pump out enough blood for daily living is impaired with resulting tiredness and breathlessness and restriction of activities. Exercise training has been shown to bring a number of benefits to heart failure patients. These include improved exercise capacity and improved health-related quality of life. Length of life and risk of hospitalisation are not greatly affected.

1. See glossary and Blog “Measuring exercise dose”, 01.02.2020
2. For those who may have missed it, VO₂ max is the best measure of physical fitness and is explained in Blog “Exercise and oxygen” 25.01.2020.

PS
Golf is good for you.
A recent article in the British Medical Journal³ reports on the exercise habits of 480,000 US adults. The study finds that, over a follow up period of 8.75 years, the risk of death was reduced by 11% for those engaging in adequate muscle activity, by 29% in those performing adequate aerobic activity and by 40% for those doing both. A comment in the same Journal⁴  recommends golf as the perfect exercise to attain that 40% reduction in the chance of dying prematurely – provided that you either carry your clubs or pull them on a trolley. The effective exercise dose of using a powered trolley is about half that of pulling or carrying the clubs so may not be enough to make golf such a health enhancing experience.
As the commentator says “Doctors frequently impart unpalatable information regarding lifestyle. This message is different. Play golf regularly and carry or pull the bag, if you can, to enhance wellbeing. A round a day keeps the doctor away”.

     3. BMJ 2020;370:m2031 http://dx.doi.org/10.1136/bmj.m2031 
     4. BMJ 2020;370:m3167 http://dx.doi.org/10.1136/bmj.m3167