After relevant screening, appropriately prescribed exercise is indicated for most people with a clinically stable heart condition. In most instances, light-to-moderate intensity exercise offers a very high benefit-to-risk ratio and is much safer than a prolonged sedentary lifestyle. Risk stratification ensures that the benefits from regular exercise clearly outweigh any risk of adverse events during exercise. The risk of an exercise-related cardiac is commonly divided into low, moderate, and high-risk categories by respected authorities, including the American College of Sports Medicine.

Risk stratification should:

• Be reviewed at each supervised exercise session as clinical risk may change quickly due to disease progression or clinical deterioration  
• Place patients in the higher risk category when risk classification is not clear cut. When in doubt, always seek medical advice.
• Always default to treating apparently low-risk patients as high risk when all necessary information for a comprehensive risk stratification is unavailable. In cases already known to be high risk, delay exercise prescription until the required further information is obtained.
• Identify high-risk patients who should ideally commence exercise in a hospital-based program, if available. However, many patients may be unable or unwilling to do this, in which case a conservative exercise program in a community environment may be appropriate.

TIP:  Never assume risk is static as risk may increase due to disease progression or clinical deterioration. When in doubt, seek medical advice. 

Screening for conditions where exercise is contraindicated, or should be undertaken with caution, should be completed as part of the safety and risk stratification process. Contraindications for exercise are detailed in the table below. Some cardiovascular conditions require stabilisation and further medical intervention before exercise can safely be performed. Guidance from the patient’s medical practitioners may be necessary.

Table 1: Conditions where exercise is contraindicated

A Clinical Guide for Assessment and Prescription of Exercise and Physical Activity in Cardiac Rehabilitation. A CSANZ Position Statement [#a-clinical-guide-for-assessment-and-prescription-of-exercise-and-physical-a].

Low risk (all must be present in order to consider low risk):

• Resting ejection fraction ≥50%
• Uncomplicated MI or revascularisation procedure
• Absence of complicated ventricular arrhythmias at rest or during exercise
• Absence of signs or symptoms of post-event/procedural ischaemia
• No untreated coronary lesion >50% on angiography
• Normal haemodynamics during exercise testing and recovery (i.e., appropriate increases and decreases in HR and systolic BP with increasing workloads and recovery)
• Absence of angina or other significant symptoms (eg dyspnoea, light-headedness or dizziness) during or after ex

Moderate risk (any of these findings places patient as at least moderate risk):

• Ejection fraction 30-50%
• Ejection fraction <30% with an implantable cardioverter defibrillator (ICD) in situ
• Angina or other significant symptoms (eg dyspnoea, light headedness or dizziness) at moderate levels of exercise or in recovery
• Untreated coronary lesion of 50-70% on angiography

High risk (any of these findings places patient at high risk):

• Ejection fraction < 30% without an ICD
• Untreated coronary lesion > 70% on angiography
• History of cardiac arrest
• Complex arrhythmias including ventricular tachycardia, frequent (>6/min) multiform PVCs at rest or with exertion
• Complicated MI or revascularisation procedure
• NYHA classification functional class III-IV symptoms
• Abnormal haemodynamics during exercise, especially flat or decreasing systolic BP or chronotropic incompetence with increasing workload
• Angina or other significant symptoms (eg dyspnoea, light-headedness or dizziness) at low levels of exercise (<5 METS) or in recovery
• Congestive HF requiring hospitalisation in the past 2 months
• Non-cardiac vascular events in the past 2 months
• Complex congenital heart disease associated with oxygen desaturation at rest or during exercise
• Silent ischaemia (ECG changes during exercise testing in the absence of symptoms)
• Advanced renal failure

Adapted from the American Association of Cardiovascular and Pulmonary Rehabilitation Guidelines for Cardiac Rehabilitation and Secondary Prevention Programs.[#american-association-of-cardiovascular-and-pulmonary-rehabilitation.-2013] 

Note: Risk categories are a guide only and should always be combined with a clinical judgement of exercise tolerance.

Exercise and medication titration:

Prescribed cardiac medications may impact on exercise response and medication titration commonly affects exercise tolerance.  While angiotensin-converting enzyme (ACE) inhibitors, beta-blockers, digoxin and nitrates tend to improve functional capacity in the longer term, dose increases often cause a transient decrease in exercise tolerance.  Prior to exercise, check for recent medication adjustments with the patient or titrating clinician.  

Symptoms such as dizziness, increased dyspnoea and fatigue may necessitate a temporary reduction in exercise intensity and duration until the patient adapts and symptoms resolve. Persistent symptoms following up-titration of medication may warrant returning to the previous dose at the discretion of the supervising doctor.

Temperature regulation considerations in heart failure:

A reduced cardiac reserve results in impaired thermoregulation in people with HF, which can decrease exercise tolerance in hot or humid conditions. Common medications, such as beta-blockers and diuretics, may exacerbate this problem. Therefore, exercise prescription should be modulated in these conditions.  

Patients should wear appropriate clothing to facilitate heat loss and to aid evaporative cooling through sweating. Patients may be required to relax their fluid restriction slightly and should discuss this with their medical practitioners. Exercise and manual activities outdoors should be avoided on hot days.

Heart failure decompensation precautions:

Heart failure is characterised by fluctuations in clinical status, with periods of decompensation, which may require hospitalisation, and occur more frequently as the condition progresses. Decreases in exercise tolerance may be quite profound and in some instances, exercise may need to be substantially reduced or avoided completely. It is essential to review risk regularly for these patients. After medical clearance, exercise can be gradually re-introduced, and the patient encouraged to progress toward optimal levels as tolerated.

Viral and infection precautions:

If unwell, patients should refrain from exercising until their symptoms resolve. A rule of thumb is to spend the same length of time gradually building back up to pre-ailment levels of exercise as the period of the ailment. For patients recovering from COVID-19, refer to relevant guidelines. [#hughes-dc-orchard-jw-partridge-em-et-al.-return-to-exercise-post-covid-19-i]

Patients with HF are particularly susceptible to common infections, which can lead to rapid and substantial deterioration in their exercise capacity. Accordingly, these patients should be encouraged to remain up to date with vaccinations.  

Exercising with oxygen:

Some cardiac patients with advanced disease or co-existing respiratory diseases, may benefit from supplemental oxygen during exercise. Recording oxygen saturation at rest and on exertion will help determine this need. Patients on long-term oxygen therapy should always train with supplemental oxygen as prescribed by a qualified medical practitioner.

Aquatic exercise precautions in heart failure:

Aquatic exercise performed in thermo-neutral water (32-34°C) to the level of the xiphisternum is safe in appropriately selected heart failure patients. Exercise in this environment has been shown to improve exercise capacity, muscle strength and quality of life, and may provide an effective alternative for those unable to participate in traditional land-based programs.

Current evidence suggests avoiding aquatic exercise for those with biventricular HF and/ or pulmonary hypertension. Decompensated HF remains an absolute contraindication.

There is currently limited data pertaining to swimming and HF due to the lack of specific research in this area. Clinicians should therefore use clinical judgement when advising patients about swimming. Supervision may be recommended for certain individuals. 

Co-morbidity considerations:

Exercise prescription for patients with cardiac disease should consider common co-morbidities including:

• Other cardiac conditions such as Ischaemic heart disease and a arrhythmias
• Diabetes
• Chronic respiratory disease (see The Australian Lung Foundation Pulmonary Rehabilitation Toolkit)
• Peripheral vascular disease
• Musculoskeletal disorders

See also co-morbidities and exercise for specific conditions