BY ANTHONY SHAW, BSc

SUDDEN CARDIAC DEATH SCD is defined as a non-traumatic, non-violent, unexpected event resulting from sudden cardiac arrest within six hours of a previously witnessed normal heart (1). It has long been established that physical activity significantly improves cardiac health, reducing the risk of atherosclerosis and subsequent SCD in young individuals (2), however, a small but significant number of athletes still die suddenly. These tragic events are often highly

publicised, particularly when they involve high profile sports people. Over the last few years, events such as the deaths of professional footballers Marc Vivian Foe, Miklos Feher and more recently, the young Sevilla player Antonio Puerto and the Motherwell captain, Phil O’Donnell, in conjunction with the cardiac arrest and subsequent resuscitation of Clive Clarke in England, have highlighted the problem. In addition, there have also been a number of exercise related SCDs in high profile events in the UK including the London Marathon and the Great North Run.

THE FACTS Estimates on the number of people who die of SCD are varied. Research from the USA suggests a figure of between 1 in 200,000 and 1 in 300,000 (3). The true figure however is likely to be higher as there is no systemic national registry for sudden cardiac deaths in sport, and experts in cardiac pathology are rarely responsible for performing post mortem examinations. Furthermore deaths from electrical rather than structural disorders cannot be identified during a post-mortem examination (4). It is thought that approximately 2% of all SCDs fall into this category following testing performed on the first degree relatives of SCD victims (5). The major cause of SCD in athletes can be divided into two groups depending on the athletes’ age. The majority of deaths in athletes over 35 years are due to coronary artery disease, whereas SCD in younger athletes is usually due to inherited or congenital disorders of the heart (5). The majority of these SCDs occur either during or immediately after exercise, suggesting that whilst exercise is not directly responsible for causing SCD, it can act as a trigger

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CARDIAC SCREENING AS A RESULT OF SUDDEN CARDIAC DEATH IN ATHLETES

Sudden cardiac death (SCD) is an uncommon occurrence but when it happens the consequences are far reaching. The death of young, apparently healthy individuals who are considered to be at the pinnacle of fitness, impacts upon sport, their peers, family and friends and the community as a whole. More often than not, these events occur with little or no prior warning. This article looks at the background of SCD, the principle causes and the number of people it affects as well as examining the principles of cardiac pre-participation screening of athletes as a means of limiting the number of SCDs.

(1). Of 157 young athletes in the United States who suffered SCD between 1986-1995, 90% died during or immediately after a training session (6). The vast majority of SCDs occur in the male population, with a ratio of approximately 10:1. This may be related to the higher participation rates of males in competitive sports and more intensive training loads (7). However it has also been suggested that there may be a greater prevalence and/or phenotypic expression in young males of cardiac disease at risk of arrhythmic cardiac arrest, such as the cardiomyopathies (8-9).

There are a number of conditions that can be attributed to SCD, some of which are summarised in Table 1. Most SCDs are due to inherited

structural and functional cardiovascular abnormalities. Hypertrophic cardiomyopathy (HCM), an unexplained or abnormal thickening of the left and/ or right ventricle accounts for 40-50% of all such deaths (1).

CARDIAC SCREENING Cardiac screening is becoming more common and a number of sporting organisations in the United Kingdom currently perform cardiac screening. However there is divided opinion

sportEX medicine 2008:36(Apr):6-8