Regular exercise reduces cardiovascular disease but acute bouts of exercise can unmask underlying cardiac conditions. What symptoms are suggestive of cardiac causes?
“No pain, no gain” has long been a mantra of the exercise enthusiast. However, exercise can bring on “I just don’t feel right!”. The human body experiences symptoms when the heart isn’t coping with the rigours of exercise (quite distinct from the normal feelings of fatigue).
When the heart isn’t coping with exercise
Angina. Doctors are familiar with classic myocardial ischaemia; a feeling of crushing or tightness in the chest that develops with exercise, becomes more severe as exercise increases and resolves with rest.
However, about 50% of people experience atypical symptoms (particularly women), such as a back-ache, ‘heaviness’ in the shoulders or tingling down the left arm. The feelings don’t have to be painful to be serious. Myocardial ischaemia can occur with little more than mild discomfort… or no uncomfortable sensation whatsoever, just shortness of breath (especially in patients with diabetes).
Heart failure. Breathlessness, muscle fatigue or dizziness are the hallmarks. Patients with heart failure can experience rapid deterioration in exercise capacity with pulmonary or peripheral oedema or the onset of atrial fibrillation or other arrhythmias. They can go from being able to perform routine activities with relative ease, to being unable to get dressed without becoming exhausted, in a matter of days.
Cardiac arrhythmias. These can occur independently of myocardial ischaemia or structural heart defects and may be initiated by exercise. Associated symptoms of palpitations, “a racing heart”, dizziness or feeling unwell can occur. Symptoms of relatively benign supraventricular tachycardias can be difficult to differentiate from life-threatening ventricular arrhythmias, so all exercise-induced arrhythmias should be considered serious until proved otherwise. If associated with syncope or near syncope, they should be treated as a medical emergency.
If symptoms occur during exercise, a resting examination is unlikely to be helpful. If symptoms occur during routine activities, a 24-hour Holter monitor may be indicated. An exercise stress test is a first-line assessment for suspected myocardial ischaemia. Stress echocardiography increases the specificity of exercise testing and is useful for evaluating valvular dysfunction and elevated pulmonary pressures, while radionucleide imaging increases test sensitivity. Exercise stress tests are also indicated for evaluating exercise-induced arrhythmias and hypertension. Cardiopulomonary exercise testing determines peak oxygen consumption (VO2peak). In patients with heart failure, VO2peak < 50% age-predicted is an indicator for advanced therapies such as cardiac transplantation.
Most patients with cardiovascular disease can undertake light to moderate exercise without symptoms. However, when symptoms are apparent during exercise, medical intervention is often warranted. This may involve pharmacological management, percutaneous coronary interventions or surgery, ablation of arrhythmias, or the implantation of a pacemaker or implantable cardioverter defibrillator.
In some instances, the best option may be to educate the patient to exercise below their symptomatic threshold, under the guidance of an exercise professional.
References available on request.
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