Primary Care Corner with Geoffrey Modest MD: Sudden Cardiac Death in Young Athletes in the U.S.

By Dr. Geoffrey Modest

A recent article looked at the demographics and epidemiology of sudden death in young athletes from the United States National Registry from 1982-2011 (see Maron BJ. Am J Med (2016) 129, 1170).

Details:

• 2406 athlete deaths were reported to the registry, of whom 842 had confirmed cardiovascular causes associated with exercise, and with autopsy examination.

Results:

• Mean age 18, 89% male, 46% white/43% African-American or other minority. 25% of deaths were during competition, 39% during practice, 17% during recreational activity, 18% unassociated with physical activity. 66% were junior high or high school, 19% in college. 35% playing basketball, 30% football.
• Mortality rate in males exceeded females by 6.5-fold (1:121,691 and 1:787,392 athlete-years, respectively; p <0.001)
• Cause of sudden death:
  • Hypertrophic cardiomyopathy (HCM): 302 athletes (292 males, 10 females), 36% of cases. 152 in African-American/138 in white
  • Congenital coronary anomalies: 158 athletes (127 males, 31 females), 19% of cases. 77 in African-American/72 in white
  • Indeterminate cause with left ventricular hypertrophy/possible HCM (autopsy finding abnormal hearts with increased heart weight and mild left ventricular thickening): 77 athletes (73 males, 4 females), 9% of cases. 31 in African-American/40 in white
  • Myocarditis: 57 athletes (46 male, 11 female), 7% of cases. 24 in African-American/30 and white
  • Arrhythmogenic right ventricular cardiomyopathy: 43 cases (31 male, 12 female). 8 in African-American and 35 in white

Commentary:

• The US National Registry of Sudden Death in Athletes prospectively assembles data on the deaths of young athletes in competitive athletics, for those engaged in organized team or individual sports requiring regular training and competition, and have had sudden death. [not sure how inclusive this registry is for those just doing recreational sports — those in noncompetitive athletics may be significantly underreported]
• This study confirms that hypertrophic cardiomyopathy was by far the single most common cause of sudden death in athletes in the US and was far more common in males and females. Coronary artery anomalies, arrhythmogenic right ventricular cardiomyopathy, and prolonged QT syndrome (though the latter only occurred in 18 individuals, 2.1% overall) were more frequent percentagewise in females.
• Overall hypertrophic cardiomyopathy was more common in African-Americans than in whites and least common in white females.
• The significant increase in cardiac deaths in males over females (greater than 6-fold) was also found in the French national registry (30-fold difference, though for marathon running it was 6-fold).
• Structurally normal hearts were found in less than 5% of the athletes.
• For a review of the American Heart Association and the American College of cardiology guidelines, see https://stg-blogs.bmj.com/bmjebmspotlight/2015/01/21/primary-care-corner-with-geoffrey-modest-md-ekg-screening-in-young-peopleathletes/ .
• Given the relatively high percentage of athletes dying from hypertrophic cardiomyopathy (and especially if you include those with LVH but considered to be indeterminate in terms of the specific HCM criteria), these data reinforce the American Heart Association recommendations for pre-participation screening (see or Maron BJ. JACC. 2014; 64: 1479). A brief review of the criteria:
  • The 14-element recommended screen for preparticipation in competitive athletes includes 7 items on personal history (chest discomfort on exertion, unexplained syncope or near syncope, excessive dyspnea or palpitations on exertion, heart murmur, elevated blood pressure, prior restriction from participating in sports, and prior testing of the heart by a physician), 3 on family history (sudden death before age 50 in at least one relative, disability from heart disease in a close relative prior to the age of 50, known history of specific cardiac diseases including hypertrophic cardiomyopathy, long QT syndrome, ion channelopathies, Marfan syndrome, clinically significant arrhythmias), and 4 items on physical exam including heart murmur likely to be organic, femoral pulses to exclude aortic coarctation, physical stigmata of Marfan’s, hypertension)
  • However, it is noted that personal/family history is often insensitive in identifying cardiac abnormalities, physical exam is often unremarkable (with some abnormalities only detectable by EKG, such as WPW or channel ionopathies), and even HCM is only detected by a murmur at rest in 25%, with an additional 50% on by Valsalva or cardiac exam while standing.
  • The EKG is sensitive but not so specific, given the number of false positives in young athletes
    • 5% of elite athletes have EKGs indistinguishable from HCM
    • The EKG is abnormal in more than 90% of people with HCM but the EKG changes are typically nonspecific (the specificity is about 50 to 60%, as per doi.org/10.1161/01.CIR.96.1.214)
    • The sensitivity and specificity for HCM is also largely determined by the cutpoints of voltages used in defining HCM. As noted, false-negative results occur in more than 10% of patients with documented HCM as well as more than 90% with congenital coronary anomalies. (Though 40% of sudden deaths in athletes in the Minnesota study were from diseases that could reliably be picked up by EKG)
    • The guidelines are more circumspect about using screening EKGs. Prior guidelines I’ve seen have been more strongly against using EKG. This one suggests that there are real concerns about the availability of trained people to read EKGs in younger people, there are lots of false positives leading to lots of echocardiograms (and potentially scaring/medicalizing the kids and families), and the cost to the system is quite high, given the large number of EKGs that would be done. And the issue in the US is different, for example, from the Italian data showing potential benefit from EKG screening, since that area of Italy (Veneto) had a very large % of sudden death from arrhythmogenic right ventricular cardiomyopathy which can be found on EKG more easily
  • The recommendations: use the 14 point screening guideline as above. Screening with 12 lead EKG’s may be considered in young healthy people age 12 to 25, not necessarily limited to athletes, mandatory and universal mass screening with EKG is not recommended for anyone.

So, sudden cardiac death, not surprisingly, is a pretty devastating though infrequent outcome for young and basically healthy kids.  My concerns are that sudden death clearly happens to those who are not super-competitive athletes (66% happened in junior high or high school; overall only 25% during competition and 39% during practice – and I’m not sure how complete the above database is, especially in those not in competitive athletics), and that these deaths are potentially preventable, to the extent that the questionnaire is reliable. I would not be surprised, for example, if the mortality in a kid with HCM were as great in an unfit 7^th grader working hard on the basketball court for 15 minutes vs the remarkably fit varsity player…. It seems to me, given this, that we really should be screening all young kids with the questionnaire, perhaps on entry to junior high school, which really means also interviewing parents/guardians since kids are likely quite unreliable in knowing the specifics of the family history.