Sudden Death in Young Adults (JACC 2011, 58:12),  has a wealth of information and will be an article  to reference for a long time.  Finally a large, systematic incidence and etiology study on sudden death in young adults with sound methodology, a defined population (military), mandatory reporting, and post-mortem protocols.

The authors openly question the ascertainment and referral bias of studies with ‘passive surveillance’ methods.  Almost all of the information on the etiology of SCD in young athletes in the U.S. comes from a single registry reporting that hypertrophic cardiomyopathy (HCM) is the leading cause of SCD.  Although competitive athletes may represent a different population, there is potential for ascertainment bias in any study without a systematic and/or mandatory identification of cases.

All other studies find autopsy-negative sudden unexplained death as the leading cause of SCD in young adults, and a proportion of HCM similar to this study (10-15%).  It is striking that sudden unexplained death represented 41% of the cases in this study.

The incidence of SCD in those <20 yo is alarming (3.25/100,000 or 1 in 30,000) and actually higher than we found in NCAA athletes (Circulation, 2011).  This increases to nearly 1 in 25,000 for <35 yo (exactly the incidence found in Italy in the same age range before more rigorous screening).  The authors also found a higher risk in African Americans who represented 15% of the study population but 33% of the SCD cases <35 yo (although the exact risk is not reported).  They include Wolff Parkinson White (WPW)  in the list of possibilities for sudden unexplained death — something I think may represent a higher proportion than we think – in addition to the ion channel disorders.  It is a little surprising to me they report no cases of aortic root dissection.  Also, only 7.5% of deaths due to sudden unexplained death had prodromal symptoms (within a week) of syncope or palpitations, and only 4.3% had chest pain or dyspnea. This provides powerful support of screening with more than just a history questionnaire if the intention is truly to identify those at risk.

Related Publications

Drezner, J, Harmon, K, and Borjesson, M. 2011. Incidence of sudden cardiac death in athletes: where did the science go? BJSM, 45: 947-948.

September 2009 BJSM – deals specifically with cardiac issues and the athlete

Blogs:

• New Guidelines to Improve ECG/EKG Interpretation in Athletes – Guest Blog by Dr Babette Pluim
• Sports Cardiology by Dr Jon Drezner
• Debating Strategies to Reduce Sudden Cardiac Death in Athletes: Dr. Drezner Responds to Sports Cardiology Editorial

Dr. Jonathan Drezner is an Associate Professor of the Department of Family Medicine, Associate Director of the Sports Medicine Fellowship , and Team Physician for the Seattle Seahawks & UW Huskies.