Few athletes survive sudden cardiac arrest (SCA)
Jun 20, 2006 - 9:32:37 PM
Cardiopulmonary resuscitation (CPR) and automated external defibrillators (AED's) had surprisingly little effect on the survival rates for young athletes who experience sudden cardiac arrest (SCA), according to a new study published in the July 2006 edition of Heart Rhythm. Of the nine intercollegiate athletes the study examined between 1999 and 2005, eight did not survive.
The study is the first of its kind to look at the timing and details of resuscitating young competitive athletes who experienced SCA, a sudden and lethal arrhythmia causing an abrupt loss of heart function.
"The findings of this small cohort raise concerns regarding the effectiveness of early defibrillation in young athletes," said Jonathan A. Drezner, MD, Associate Director of the Sports Medicine Fellowship in the Department of Family Medicine at the University of Washington in Seattle and lead author of the study. "The survival rates in these young athletes are significantly lower than expected, despite appropriate and timely response."
In all cases, the athletes suffered a witnessed collapse, meaning there were bystanders who were able to respond immediately to the athlete, and they all received CPR. AED's were applied to all the athletes by athletic trainers or by responding emergency medical services (EMS) and in seven cases, a shock was deployed. Nevertheless, only one out of nine athletes in the study survived, a striking finding considering the young age, otherwise good health and physical conditioning of the athletes, and early defibrillation.
The authors stated that several factors could explain the low survival rate. Most importantly, the underlying cause of SCA in the athletes might have influenced their lack of response to resuscitation and defibrillation. While there has been convincing evidence of successful SCA survival rates due to public access to AED's, the benefit of these programs has been shown in an older population that was more likely to have experienced SCA due to atherosclerosis, or narrowing of the coronary arteries.
In comparison, the underlying cause of SCA in the majority of athletes in this study was attributed to structural heart disease, namely hypertrophic cardiomyopathy, a condition in which the muscle of the heart is abnormally enlarged. "These results suggest that SCA caused by structural heart disease may be more resistant to defibrillation," Dr. Drezner remarked.
Delayed recognition of cardiac arrest by first responders, duration and intensity of exercise prior to arrest, metabolic and physiologic adaptations during exercise and vascular changes are other potential factors that may have affected survival.
Dr. Drezner emphasized that improved emergency planning with training in CPR and access to AED's is critical to saving lives. "It's possible that in this young athletic population our response time needs to be even shorter, and our CPR even better. Immediate recognition of a cardiac arrest, early CPR, and prompt access to defibrillators are still needed in the hope of preventing these catastrophic events."
The authors concluded that the study findings reinforce a need for future research on SCA in young athletes and the effect of early defibrillation on young patients with structural heart disease. "Clearly, we need to understand this better," noted Dr. Drezner.
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