Regular exercise of moderate intensity is widely encouraged to reduce one’s long term risk of heart disease. The incidence of sudden cardiac death of an athlete is a rare tragedy that is related to the increased risk associated with strenuous exercise in the presence of a quiescent cardiac abnormality.
Pre-exercise cardiac screening for individuals participating in high intensity or competitive sports is recommended by the major international sports organizations. The objective of screening is to identify these “silent” but high risk structural and electrical problems that predispose to fatality during high intensity exercise.
In younger athletes (<35 year old), the usual causes of sudden cardiac death are due to structural abnormalities – both inherited and acquired – affecting the heart muscle, the heart valves or anomalous origin of the coronary arteries, which supply the heart muscle. Another major subset of conditions that confer a higher risk are electrical cardiac abnormalities. The mechanism of sudden death is thought to be secondary to a malignant arrhythmia.
In older people, the most common cause of sudden cardiac death is due to coronary artery plaque rupture leading to a heart attack. High blood pressure, smoking, high LDL cholesterol, diabetes and a strong family history of premature coronary disease accelerate this risk.
The vast majority of individuals who have suffered a fatal cardiac event are well, with no prior symptoms. However, worrying clinical features include:
The pre-exercise cardiac screen comprises taking a medical history, physical examination, an ECG and echocardiogram. All the tests are safe, non-invasive and can be done in a clinic setting and take no longer than 1 hour to perform. At present, genetic testing for common genetic cardiac conditions is not routinely used for screening purposes.
Another pre-exercise screen test one can consider is cardiopulmonary exercise testing (CPET), which is a non-invasive simultaneous measurement of the cardiovascular and respiratory system during exercise to assess an individual’s exercise capacity. Whilst CPET has numerous applications for evaluating a wide range of cardiac problems, the peak VO2 max achieved is a measure of someone’s maximal physiological uptake of oxygen and a surrogate marker of cardiovascular fitness. The peak VO2 max can be used to guide exercise training programs.
Pre exercise screening has the potential to identify a high risk subgroup of individuals who can be counselled accordingly, whilst encouraging the vast majority to exercise without restriction and enjoy the health benefits. If judged to be of significantly high risk, those individuals may be candidates for primary prevention of sudden cardiac death by implantation of an automated cardio-defibrillator.
Dr Rohit Khurana
Senior Consultant Cardiologist
The Harley Street Clinic Heart and Vascular Centre