Active Voice: Sudden Cardiac Arrest and Death in United States Marathons

By David Webner, M.D., and Kevin DuPrey, D.O.

Viewpoints presented in SMB commentaries reflect the opinions of the authors and do not necessarily reflect positions or policies of ACSM.

David Webner, M.D., is a sports medicine physician at the Healthplex Sports Medicine Institute and co-director of the sports medicine fellowship program at the Crozer-Keystone Health System in Philadelphia. His research interests include sports medicine aspects of endurance exercise and sports concussion. He currently is engaged in studies concerning the incidence of sudden cardiac arrest in long-distance running.

Kevin DuPrey, D.O., practices family medicine in the Crozer-Keystone Health System. He graduated from the University of Delaware, earning distinction for his research in vertebrate development. Currently, his research efforts center on improving safety in endurance events. Both Drs. Webner and DuPrey are ACSM members and avid runners who have competed in numerous marathons.

The following commentary reflects Dr. Webner’s and Dr. DuPrey’s views relating to the research article they authored with colleagues and which appears in the October 2012 issues of Medicine and Science in Sports and Exercise® (MSSE), “Sudden Cardiac Arrest and Death in United States Marathons.”

The marathon has long been one of the premier endurance events in distance running. Over the past 20 years, the number of runners competing in marathons worldwide has more than doubled. The majority of marathon deaths are caused by sudden cardiac arrest (SCA) due to underlying coronary artery disease (CAD). Although less common, younger victims of SCA (<30 years old) are more likely to have causes other than CAD, such as hypertrophic cardiomyopathy. Each year, as the marathon becomes even more popular, the total number of high-risk participants also increases. At this time, there is no national reporting system for marathon SCA and death.

While the overall trend of marathon training promotes a healthy lifestyle, SCA and death during the marathon raises important questions: “What is the true extent of the problem?” “Who is at risk for SCA?” “What preventive steps can be taken to improve marathon safety?” Our recent study, reported in MSSE, was conducted to address these questions and to assist with emergency planning at distance events.

A retrospective, Web-based survey was sent to all U.S. marathon medical directors. Our results showed SCA occurs in approximately 1 in 57,000 with a mortality of approximately 1 in 170,000. The majority of these events occurred among men in their fifth decade during the last four miles of the race. Survival was strongly correlated with early use of an automated external defibrillator (AED). In most athletes who died, an etiology consistent with CAD was found at autopsy.

Screening for SCA remains controversial, as risk factors are difficult to assess in a cost-effective manner. Most victims of exercise-related SCA have minimal to no symptoms prior to the event. We recommend an initial medical consultation with a focused history and physical exam for all individuals before participation in the marathon. As recently as 2006, ACSM’s “Guidelines for Graded Exercise Testing and Prescription” (7th Edition) recommended that men age 45 and older and women age 55 and older or those with two or more major cardiac risk factors, those with any signs or symptom of CAD, and those with known cardiac, pulmonary or metabolic disease undergo symptom limited exercise testing prior to beginning any sustained vigorous exercise (>60% VO2 max) program.

The bottom line is that the risk of SCA in the marathon is low, and with no intervention, mortality in these cases is high. A 2005 study by Roberts and Maron showed improved survival following SCA in the marathon, when fixed medical stations at two-to-three-mile intervals and mobile first aid teams on bicycles and golf carts equipped with AEDs were provided. To minimize the risk of death following SCA, we recommend proper training of race medical staff with availability of AEDs throughout the race. If resources are limited, focus should be placed on the last four miles where the majority of SCAs occur.