People should be encouraged to exercise, but caution may be needed with middle-aged weekend warriors, says interventional cardiologist Dr Richard Alcock.
The benefits of regular exercise are well established. It can prevent or improve all the major risk factors that contribute to cardiovascular disease (CVD), including hypertension, diabetes, central adiposity and dyslipidaemia. Exercise also has significant benefits for mental health disorders, which are common but often ignored contributors to CVD.
Atherosclerotic coronary disease is the predominant cause of exercise-related cardiac events in people aged 35 years and over. Although relatively rare, exercise may trigger sudden cardiac arrest and death in individuals with underlying coronary artery disease (either clinically known or not), particularly those who were previously sedentary, or have advanced disease.
For patients with known coronary disease, a cardiac event can occur on average once in every 62,000 hours of exercise. Importantly, the risk of a cardiac event is significantly lower among regular exercisers. Individuals who exercise regularly are much less likely to experience a problem during exercise.
Sudden death
The three major causes of sudden cardiac death during exercise include exercise-induced plaque rupture – more than 50% will not have pre-existing symptoms or a known history of coronary artery disease; myocardial scar-related ventricular arrythmias – silent or known coronary disease with previous MI and associated myocardial fibrosis; and demand ischaemia – an imbalance between coronary blood supply and demand resulting from stable coronary disease with a fixed stenosis.
Ultimately, knowing the coronary plaque burden of the active weekend warrior can help direct investigations to stratify this risk.
Given we are now in the era of coronary artery calcium scores being compared by cyclists at the local coffee shop, should all exercising patients over the age of 45 years be screened for underlying coronary artery disease, and if so, how?
The evidence base for cardiovascular screening in middle-aged athletes is limited. Screening, if performed, needs to target the higher prevalence of coronary artery plaque associated with age.
Evaluating the WW
The 2020 European Guidelines on Sports Cardiology provide a pragmatic approach to the evaluation of the asymptomatic middle-aged athlete. Initial evaluation should always begin with assessment of cardiac risk and consideration of characteristics of the intended exercise program. Characteristics of exercise include the frequency, intensity, time and type of exercise undertaken.
The Australian absolute CVD risk calculator is easily accessible and provides an excellent starting point for assessment. If the CVD risk score is low and the individual is already physically active, then no further investigations are suggested.
However, it is not unreasonable to offer plaque burden assessment in low-risk middle-aged individuals who wish to undertake high or very-high intensity endurance events. A coronary artery calcium score (CAC) can be useful in the over 45 age group for initial plaque burden assessment, with the need for further anatomical or functional imaging dependent on the result.
Intermediate or high-risk CVD scores can be managed depending on the intensity level of intended physical activity. If an individual is undertaking low intensity exercise, then no further investigations are generally required, with the ongoing focus aimed at risk factor surveillance and modification.
At-risk individuals who wish to undertake high or very high intensity activities, should have further assessment, including a measure of plaque burden (CAC or CT coronary angiogram) in addition to a maximal exercise test, preferably with imaging. If there are high risk features identified, then invasive coronary angiography is indicated, and the risk of the coronary lesions assessed and managed.
Exercise is good!
Everyone should be encouraged to exercise. However, particular attention and caution should be given to the previously sedentary middle-aged athlete beginning to exercise, with an increased cardiovascular risk profile, or those middle-aged athletes wanting to exercise at high or very-high levels. Referral to a cardiologist with a special interest in sports cardiology should be considered.
Shared decision-making following diagnosis and risk stratification is essential for exercise prescription in the middle-aged exercising individual.
Physical activity counselling needs to strike a balance between the multiple proven benefits of exercise, the small risk of adverse cardiovascular outcomes, including sudden death, and the patients’ goals for fitness and ongoing participation in relatively strenuous exercise.
ED: Dr Richard Alcock is an interventional cardiologist with the Royal Perth Bentley Group’s Department of Cardiology.