PHILADELPHIA – The last 4 miles of a marathon can be a killer, in more ways than one.
Among U.S. marathon participants, the incidence of sudden cardiac arrests (SCA) peaked starting at mile 23 and continuing till the finish at 26.2 miles, based on data collected from more than 1.7 million runners who participated in U.S. marathons during 1976-2009.
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Marathoners are most likely to suffer a sudden cardiac arrest near the end of the lengthy race.
Among the 30 SCA experienced by 1,710,052 marathon runners, 16 (53%) occurred at mile 23 or beyond, Kevin M. DuPrey, D.O., and his associates reported in a poster at the annual congress of delegates of the American Academy of Family Physicians. Six of the other 14 SCA occurred during miles 15-22, so that 73% of all SCA occurred during the final 43% of the race. Five of the SCA occurred during miles 6-14, and three happened in the races’ first five miles.
The findings, derived from web-based survey responses by 88 marathon medical directors, also highlighted the life-saving impact of treating cardiac arrests with an automated external defibrillator (AED). Among the 20 cases known to have received AED treatment, 17 runners survived (85%). In contrast, among eight runners known to have not received AED treatment, two survived (25%). In two cases, definitive information about AED use was not available, and one of these patients died. Ten of the 30 runners who had an in-race SCA died. Statistical analysis showed that AED use was significantly linked with survival.
Given the life-saving potential of AED use and the link between SCA and distance into the race, marathon organizers should focus AED placement in the final miles of a race, the researchers concluded. "Results from a recent study showed that proximity of AED to a collapsed runner was a major determinant of survival," wrote Dr. DuPrey, a researcher at Crozier-Keystone Health System in Springfield, Pa., and his associates.
Another previously reported study they cited documented a sharp reduction in fatality among marathon runners who had an SCA starting in 1995, the period when AEDs became more routinely available at marathons (J. Amer. Coll. Cardiol. 2005;46:1373-4). In two large U.S. marathons, the fatality rate fell from one in 55,000 in 1976-1994 to one in 220,000 during 1995-2004.
Autopsies of 9 of the 10 fatalities in the current survey revealed coronary artery disease in seven, an anomalous coronary artery in one, and no clear pathology in one. Twenty-eight of the 30 SCA (93%) occurred in men, and the cases averaged 50 years old, ranging from 19 to 82 years old.
Dr. DuPrey and his associates had no disclosures.