EXERCISE POST-MI 4Reduced arrhythmias

Frequent ventricular ectopics (a beat produced from the heart ventrical and not the usual sinoatrial node) are one of the risk factors for sudden death after a heart attack.

Exercise training increases the threshold for ventricular ectopic activity and controlled trials have shown that ectopic beats occur less often in trained than untrained post-infarct patients. This may be because exercise helps increase heart rate variability which has been associated with decreased mortality after infarct.

5 Improved lipid profiles

Controlled trials of exercise rehabilitation have shown that total cholesterol can be lowered and HDL cholesterol elevated, but the level of activity must be high. This benefit of exercise is enhanced if the patient can lose weight. A combination of diet and exercise has been shown to result in regression of atheroma.

6 Lowered blood pressure

Exercise reduces blood pressure in hypertensive subjects and in mild hypertension may remove the need for drug treatment. In the rehabilitation course the patient can be taught the importance of other actions such as reduced salt intake, moderate alcohol consumption and weight loss.

7 Improved Exercise-based ECG test fibrinolysis

Exercise reduces the tendency of the blood to clot. A high level of the clotting

factor, plasma fibrinogen, and low fibrin breakdown activity are powerful risk factors for coronary disease and cigarette smoking probably exerts much of its atherogenic effect by this route. Fibrinolytic activity is increased by exercise and the more vigorous the exercise the greater the fibrin breakdown.

8 Psychological benefit

The great majority of patients who suffer the physical injury of a heart attack also suffer psychological damage. Fear and anxiety are the initial reactions, shortly followed by depression and loss of confidence.

After discharge from hospital anxiety levels are likely to be high. Although most patients make a reasonable recovery in their psychological state, a minority are left with a variety of mental problems. One study found that 50% of patients not back at work six months after an infarct were suffering from cardiac neurosis rather than from cardiac damage.

Potential complications of exercise training for

cardiac patients Exercise is extremely safe and serious complications are rare. A meta-analysis of 40 trials in the USA involving exercise training in patients with heart conditions found the mortality rate during exercise to be one death per 784,000 patient hours. None of the studies showed an increase in adverse effects compared to control groups. However it is strongly advised that all cardiac patients, particularly high risk groups, undergo a full health assessment and exercise-based ECG prior to commencing an activity programme.

Hypotensive episodes

Falls in blood pressure are most commonly seen in hot weather in patients with severe left ventricular dysfunction and those on hypotensive medication, particularly combinations such as nitrates with beta-blockers. Loss of fluid is a common contributor. They may feel faint, dizzy, sweat profusely and become confused. The patient should lie flat with legs elevated. Fluid replacement is also important. If symptoms persist an ambulance should be called.

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Arrhythmias

Irregular electrical heart activity such as atrial fibrillation, supraventricular tachycardia and frequent ectopic beats are commonly induced by exercise but are usually self-limiting. Signs of arrythmias may include dizziness, shortness of breath, nausea or palpatations. If any of these occur the patient should stop exercising until the symptoms are relieved. If they continue the patient should see a doctor immediately. Ventricular tachycardia is rare but dangerous and usually occurs with no symptoms.

Ventricular fibrillation

Occasions when the heart stops beating completely are rare and occur approximately once per 100,000 patient hours of exercise. Immediate defibrillation is almost always successful. Defibrillation equipment and a trained member of staff are essential when working with high risk patients.

Acute myocardial infarction

This is rarer still and occurs about once per 300,000 patient hours of exercise.