Posted on 08/03/2012

Minneapolis, MN--Researchers say they have definitively confirmed that there is a link between the sickle cell trait and sudden cardiac death in African-American athletes.

While previous research has shown some evidence for the association, Kevin Harris, Tammy Haas, and Barry Maron (Minneapolis Heart Institute Foundation) and E. Randy Eichner (University of Oklahoma) say that their study comprises "the first sizeable patient series" to confirm the link.

They found that of 2,642 athlete deaths in the U.S. Sudden Deaths in Athletes Registry, 23 (0.9%) occurred in athletes with the sickle cell trait. This group was aged 12-22 years and 21 (91%) were male. All were African American.

All athletes with the trait experienced noninstantaneous collapse with gradual but rapid deterioration, i.e., dyspnea, fatigue, weakness, and muscle cramping. Each event occurred during vigorous or exhaustive maximal physical exertion usually during training and most often occurred during football conditional drills (n=22) early in the season.

The authors note that deaths among athletes with the sickle cell trait were also most common in the summer and early autumn months of June to October (74%). Twenty (87%) deaths occurred in Southern or border states, most commonly Florida, Texas, Mississippi, North Carolina, and Ohio.

Moreover, they say that potential triggers for collapse in athletes with the sickle cell trait included high environmental temperatures (≥80°F in 87% cases).

Notably, sickle cell trait deaths occurred predominantly in football players (83%), constituting 2.6% of all 723 deaths occurring in the sport and 7.0% of deaths in the 271 African-American football players (i.e., one in 14).

Commenting in a press statement, Maron said the findings show "convincing evidence of a causal relationship between the sickle cell trait and the deaths of young, Black competitive athletes, especially football players."

Writing in the American Journal of Cardiology, his team says that although the pathophysiology and determinants of sickle cell trait events are not fully understood, it is likely that cardiovascular collapse occurs under conditions that increase risk for exertional sickling of red blood cells, including heat stress, dehydration, illness, and altitude.

The researchers conclude that understanding the risks, mechanisms, and event triggers of the sickle cell trait "may allow lifesaving alterations in training methods to be implemented."

They remark: "To not acknowledge this link between sickle cell trait and sudden death creates the possibility of a failure to fully protect the athlete community."

SOURCE: Medical Research News, American Journal of Cardiology