VA AND SCD RELATED TO SPECIFIC POPULATIONS In athletes, VAs range from isolated PVCs, cou- plets, and NSVT, to sustained VT and SCA leading to Infrequent PVCs and short runs of repetitive NSVT, especially in the absence of structural heart dis- ease, are more common in nonathletes, but they are generally benign, requiring only a limited workup and rarely lead to disqualification for sports.S10.1-2,S10.1-3 In contrast, longer runs of NSVT, especially when exer- cise-induced, and sustained VT and SCA/SCD are in- frequent, but they have a higher incidence in athletes than that reported for the general population in the corresponding age groups. Reported estimates of SCD range from 1 per 53703 athlete-years in the National Collegiate Athletic Association databaseS10.1-4 per 200000 in Minnesota high school students.S10.1-5 Among those studies judged to have better epidemio- logical protocols, estimates were in the range of 1 per These figures compare with a general population risk of 1.0 to 1.9/100000 in adolescents and young adults.S10.1-7,S10.1-8 Moreover, there appears to be both sport and sex differences in the magnitude of risk, with males being at higher risk than females in most sports,S10.1-7,S10.1-9 blacks at higher risk than whites, and male basketball players being the single highest risk group in the United States, 1 A study that included both competitive and rec- reational athletes showed that both groups are at a higher risk for SCD than the general population, with recreational athletes having greater cumulative SCD occurring at an older age, and a different distribution of diseases. Postmortem data on SCD in athletes reveal that 25% to 40% are autopsy- negative, suggesting a role for genetic molecular dis- orders in these victims S10.1-4,S10.1-10,S10.1-11 and for family Another limitation of SCD data analysis in ath- letes centers on noncardiac causes, some of which mimic cardiac events. 