Understanding Sudden Cardiac Arrest in Athletes

Dr Richard Bowry MB BS FRCA FRCPC

We have all heard stories of runners who have collapsed during races. While these traumatic events are uncommon, they’re inevitably interpreted as evidence for the danger of being active. As an MD who runs, I thought it would be worth sharing the highlights from a recent review article in the Canadian Medical Association Journal.¹ It summarises the current research regarding sudden cardiac arrest, what we can all do both to prevent it and how to be prepared should one of our running companions collapse.

Before giving up running, it is important to understand the context. If you were to follow 100,000 runners for a whole year, less than one runner (0.75) would experience cardiac arrest.^2,3 By comparison, if you were to track 100, 000 participants on a specific day, the expected number of deaths for skiing and snowboarding is 0.25, whereas with scuba diving that would go up to 3, mountain hiking would be 6, parachuting 18, and mountaineering 600.⁴

When we think of sudden cardiac arrest in athletes, for those under the age of 35, the most common causes are an abnormal heart rhythm, thickened heart muscle (hypertrophy), abnormal coronary arteries or an inflamed heart from an infection. For those older than 35, coronary artery disease is added to the list and becomes the most common problem.^5-10

What is surprising is that nearly 30 percent of athletes who suffer sudden cardiac arrest had warning signs that they ignored. So before embarking on an aggressive exercise plan you should ask yourself.^11,12

• Have I ever felt severely dizzy or faint, unexpectedly short of breath, or had chest pain during or immediately after exercise?
• Do I have any first-degree relatives who died suddenly or had severe cardiac disease under 60-years-old?

If the answer to either of these questions is “Yes,” then it is worthwhile undergoing a more thorough evaluation by a cardiologist with specific expertise in sports medicine.

If the answer to both is “No,” then there is very little value in routine screening. In one study looking at elite soccer players, 6 out of 8 sudden cardiac deaths occurred in individuals who were considered healthy using history, examination, 12-lead ECG and echocardiography.¹³

The take home message is that for the majority of athletes there is very little that can be done to prevent the rare occurrence of sudden cardiac death. On the bright side, survival rates for athletes who experience sudden cardiac death and have prompt resuscitation, is very high.  Some studies have shown that where prompt resuscitation is available the survival rate is between 89 and 100 percent.¹⁴ Where resuscitation is delayed, the survival is still better than the general population, but falls to around 44 percent.²

So, what is the one thing can you do that is both cheap and effective?

Learn how to perform CPR and use an Automated External Defibrillator

The ability of our club runners being able to perform these skills can make the difference between survival and death. 

References

1. Fanous, Y., & Dorian, P. (2019). The prevention and management of sudden cardiac arrest in athletes. CMAJ, 191(28), E787-E791.
2. Landry CH, Allan KS, Connelly KA, et al.; Rescu Investigators. Sudden cardiac arrest during participation in competitive sports. N Engl J Med 2017;377:1943-53.
3. Mohananey D, Masri A, Desai RM, et al. Global incidence of sports ­related sud­den cardiac death. J Am Coll Cardiol 2017;69:2672-3.
4. Windsor JS, Firth PG, Grocott MP, et al. Mountain mortality: a review of deaths that occur during recreational activities in the mountains. Postgrad Med J 2009;85: 316-­21.
5. Marijon E, Tafflet M, Celermajer DS, et al. Sports ­related sudden death in the general population. Circulation 2011;124:672­-81.
6. Bohm P, Scharhag J, Meyer T. Data from a nationwide registry on sports­ related sudden cardiac deaths in Germany. Eur J Prev Cardiol 2016;23:649­-56.
7. Bagnall RD, Weintraub RG, Ingles J, et al. A prospective study of sudden car­diac death among children and young adults. N Engl J Med 2016;374:2441­-52.
8. Sweeting J, Semsarian C. Sudden cardiac death in athletes. Heart Lung Circ 2018;27:107-2­7.
9. D’Silva A, Papadakis M. Sudden cardiac death in athletes. Eur Cardiol 2015;10: 48-­53.
10. Risgaard B, Winkel BG, Jabbari R, et al. Sports­ related sudden cardiac death in a competitive and a noncompetitive athlete population aged 12 to 49 years: data from an unselected nationwide study in Denmark. Heart Rhythm 2014;11:1673-­81. 
11. Finocchiaro G, Papadakis M, Robertus JL, et al. Etiology of sudden death in sports insights from a United Kingdom regional registry. J Am Coll Cardiol 2016;67:2108-­15.
12. Maron BJ, Thompson PD, Ackerman MJ, et al.; American Heart Association Council on Nutrition, Physical Activity, and Metabolism. Recommendations and consider­ations related to preparticipation screening for cardiovascular abnormalities in competitive athletes: 2007 update: a scientific statement from the American Heart Association Council on Nutrition, Physical Activity, and Metabolism: endorsed by the American College of Cardiology Foundation. Circulation 2007;115:1643­-55.
13. Drezner JA, Sharma S, Baggish A, et al. International criteria for electrocardio­graphic interpretation in athletes: consensus statement. Br J Sports Med 2017;51: 704-­31.
14. Drezner JA, Toresdahl BG, Rao AL, et al. Outcomes from sudden cardiac arrest in US high schools: a 2­year prospective study from the National Registry for AED Use in Sports. Br J Sports Med 2013;47:1179-­83.