Abstract
BACKGROUND
Sudden cardiac arrest (SCA) is the leading cause of death among young competitive athletes during sports and exercise. A detailed analysis of survival outcomes should inform prevention strategies.
OBJECTIVES
The purpose of this study was to determine survival outcomes and trends following SCA among young competitive athletes in the United States and to explore outcomes based on race and exertional status.
METHODS
This observational study identified cases of SCA among young competitive athletes through longitudinal surveillance by the National Center for Catastrophic Sports Injury Research from July 1, 2014, to June 30, 2023. Young athletes ≥11 years of age competing in middle school, high school, club, college, or semiprofessional/professional sports, and former athletes (within 1 year of participation) with SCA during exercise, rest, or sleep were included. The primary outcome was survival from SCA. Multivariable log binomial regression estimated survival proportion ratios by race and exertional status.
RESULTS
A total of 641 athletes with SCA were identified during the 9-year study period (mean age 17 ± 3 years; 85% male). Overall survival was 49% (315 of 641). Survival from SCA occurring during exercise was 57% (275 of 481). The majority of cases were in high school athletes (61%), followed by college (15%) and middle school (12%) athletes. Overall survival (range 30%−66% per academic year; P = 0.007) and survival from exertional SCA (range 38%−72% per academic year; P = 0.03) both increased throughout the study period. Among exertional SCA events, survival was higher among athletes who experienced SCA during a game/competition vs practice/training (70% vs 53%; P = 0.001). Black race (RR: 0.63; 95% CI: 0.53–0.76), Other race (RR: 0.69; 95% CI: 0.50–0.94), and nonexertional SCA (RR: 0.43; 95% CI: 0.32–0.59) were associated with lower survival from SCA after adjusting for sex and level of competition.
CONCLUSIONS
Although survival from SCA among young competitive athletes in the United States has improved in the last decade, important racial disparities in outcomes were observed warranting additional research and prevention strategies.
Keywords: screening, sudden cardiac arrest, sudden cardiac death, young competitive athletes
Sudden cardiac arrest (SCA) is the leading medical cause of death among young competitive athletes.1–3 Although previous studies have documented the incidence and causes of SCA in athletes, limited evidence has characterized survival outcomes and trends in this population.4,5 Substantial efforts have been undertaken to lower the risk of sudden cardiac death (SCD), including improved emergency preparedness, increased access to automated external defibrillators (AEDs), and more intensive preparticipation cardiovascular screening to identify conditions at increased risk of SCA/SCD.6–10
Survival after SCA is highly dependent on early recognition and a rapid response, including prompt cardiopulmonary resuscitation (CPR) and access to an AED.8,9 Sport practices and competitions offer a unique opportunity to respond quickly to the sudden collapse of an athlete as most exercise-related SCA events are witnessed. Indeed, consensus recommendations universally support the development and implementation of emergency action plans for SCA in schools, at sporting facilities, and for other organizations hosting athletic events for competitive athletes.6,8,9,11,12
Recently a 20-year evaluation of SCD cases in National Collegiate Athletics Association (NCAA) athletes demonstrated a decline in SCD incidence over time, although no data on SCA cases with survival were reported.1 Whether the likelihood of survival following SCA has changed over time and what associated factors, such as sex, race, level of competition, and exertional status, may influence outcomes in a large population of young competitive athletes remains uncertain. The purpose of this study was to determine survival outcomes and trends following SCA among young competitive athletes in the United States and to explore outcomes based on race and exertional status.
METHODS
This study was conducted in collaboration with the National Center for Catastrophic Sports Injury Research (NCCSIR) and the University of Washington (UW) Medicine Center for Sports Cardiology. The study was approved by the Institutional Review Board at the University of North Carolina at Chapel Hill.
CASE IDENTIFICATION.
Prospective longitudinal surveillance by the NCCSIR identified cases of SCA with and without survival among young competitive athletes from July 1, 2014, to June 30, 2023. Detailed methods for case identification have been previously reported.2 Each individual year of the study was defined as July 1 through June 30 of the following calendar year to reflect academic years. Athletes were identified through multiple independent search strategies including: 1) surveillance of traditional and social media sources; 2) the Parent Heart Watch database; 3) the NCAA Resolutions list; and 4) direct reporting to the NCCSIR, UW Medicine Center for Sports Cardiology, or National Federation of State High School Associations. Duplicate cases were excluded.
INCLUSION CRITERIA.
All competitive athletes ≥11 years of age participating in middle school, high school, club, college, or semiprofessional/professional sports, and former athletes (within 1 year of participation in competitive sports) who experienced an SCA or SCD event during the study period were included in this analysis. SCA was defined as an unexpected, abrupt collapse in which the individual received CPR and/or defibrillation and survived. SCD was defined as a sudden unexpected death resulting from a cardiac cause based on review of autopsy, coroner, and medical records, or a sudden death in a structurally normal heart with no other explanation for death and a history consistent with a cardiac-related death. Cases occurring during exercise in which autopsy, coroner, or medical records could not be obtained were included as cardiac in nature if the event details supported an abrupt collapse requiring cardiac resuscitation. Cases with limited information but in which the athlete received placement of an implantable cardioverter-defibrillator were also included as cardiac in nature. Commotio cordis was considered a cardiac etiology for SCA/SCD.
Cases of possible SCA/SCD were excluded if participation as a competitive athlete could not be confirmed; there were no autopsy, coroner, or medical records available for a nonexertional death to determine the presence or absence of a cardiac cause; a cardiac etiology could not be determined based on review of autopsy, coroner, or medical records (including autopsy-negative cases) for cases occurring during rest or sleep in which an alternative cause could not be excluded; or a noncardiac diagnosis was identified. Exertional collapse associated with sickle cell trait was considered a noncardiac diagnosis, and drowning without a clearly identifiable cardiac etiology was also excluded.
All cases of confirmed SCA/SCD in a competitive athlete were included in the analysis regardless of the activity at the time of the event, including those occurring during exercise, within 1 hour of exercise, at rest, or during sleep. Exertional SCA/SCD was defined as occurring during exercise, whereas nonexertional SCA/SCD occurred shortly following exercise (<1 hour), at rest, or during sleep.
DATA COLLECTION AND PANEL ADJUDICATION.
The data collected for all cases included demographic information, home and school addresses, sports participation, details of the SCA/SCD event, media reports, and when available interviews with the family or school staff, medical history, hospital records, cardiovascular findings, and medical examiner and autopsy reports. All sources of information were used to classify race/ethnicity. If medical or postmortem records were not available or did not define race/ethnicity, then media reports and athlete photos were used to determine race/ethnicity. If the race/ethnicity could not be determined, it was classified as unknown.
Adjudicated etiologies of SCA/SCD were determined by integrative review of all available records using previously published definitions (Supplemental Table 1).2 Cases were reviewed by a multidisciplinary panel of physicians with experience in sports cardiology, sports medicine, and cardiovascular pathology. Any differences of opinion were resolved by panel discussion and unanimous consensus. When there was more than 1 possible etiology of SCA/SCD upon review of records, the most likely etiology of SCA/SCD was reported as the primary cause of death. If there were multiple possible causes with no clear primary cause of SCA/SCD, the etiology was defined as “other” and further detailed. If the adjudicated etiology differed from the cause of SCA/SCD presented on the medical or postmortem records, the adjudicated cause of SCA/SCD was reported in the current analysis.
STATISTICAL ANALYSIS.
Standard descriptive statistics were used to describe the demographic and event information. Categorical variables were described with frequencies (n) and percentages (%), and continuous variables were described with mean ± SD. A chi-square test was utilized as a post hoc analysis to assess differences in the proportion of total survival from exertional SCA by race. The Cochran Armitage test for trend was used to assess for a trend in the percent survival from SCA by academic year over the 9-year period. A 2-proportion chi-square test was utilized to compare for differences in the proportion of total SCA/SCD events for exertional SCA with survival between events occurring during game/competition vs practice/training. A log binomial regression model assessed the association with survival from SCA for athlete race and exertional status at time of SCA controlling for sex and level of competition. Based on clinical and theoretical rationale, sex and level of competition were adjusted for as potential confounders in the multivariable log binomial regression. For level of competition, we included middle school, high school, club, and a combined group for college/semiprofessional/professional because of small numbers in the semiprofessional/professional category. Former athletes (within 1 year of participation in competitive sports) were reallocated to their last known level of competition. A total of 60 athletes with missing data for race (n = 25) and exertional status (n = 35) were excluded from the multivariable regression analysis. For modeling purposes, other race included Hispanic/Latino, Asian, and other race given few non-White, non-Black athletes in the study. Analyses assessed for differences in survival for exertional SCA events, because events occurring during exertion would be more likely to be witnessed and receive prompt resuscitation. Statistical analyses were performed using R version 4.4.2, A Language and Environment for Statistical Computing (R Core Team) and SAS version 9.4. Data are presented according to the STROBE reporting guidelines for observational studies (Supplemental Table 2).
RESULTS
A total of 796 potential SCA/SCD events were captured and reviewed over the 9-year study period, and 641 SCA/SCD events among young competitive athletes (age range 11–29 years) met inclusion criteria (Figure 1). Among these, 481 (75%) SCA/SCD events occurred during exertion, 22 (3%) occurred within 1 hour following exertion, 103 (16%) occurred during relative rest or sleep, and exertional status was unknown in 35 (5%) cases. The majority of SCA/SCD cases were identified in male compared with female athletes (85% vs 15%) and among high school athletes (61%), followed by college (15%) and middle school (12%) athletes. Characteristics for the total cohort and among athletes with an exertional SCA/SCD event stratified by survival are presented in Table 1. There was a significant difference in survival from exertional SCA by underlying race (White 68%, Black 43%, other 46%; P < 0.001).
FIGURE 1. Flow Diagram for Study Inclusion.
SCA = sudden cardiac arrest; SCD = sudden cardiac death.
TABLE 1.
Demographics of Young Competitive Athletes With Sudden Cardiac Arrest and Death
| Total (N = 641) |
Exertional Only (n = 481) |
|||||
|---|---|---|---|---|---|---|
| SCA (n = 315) |
SCD (n = 326) |
% Survival | SCA (n = 275) |
SCD (n = 206) |
% Survival | |
| Age, ya | 16 ± 3 | 17 ± 3 | 16 ± 3 | 16 ± 3 | ||
| Sex | ||||||
| Male | 271 (86) | 276 (85) | 50 | 236 (86) | 175 (85) | 57 |
| Female | 44 (14) | 50 (15) | 47 | 39 (14) | 31 (15) | 56 |
| Race and ethnicity | ||||||
| White | 182 (58) | 141 (43) | 56 | 156 (57) | 72 (35) | 68 |
| Black | 88 (28) | 146 (45) | 38 | 78 (28) | 105 (51) | 43 |
| Hispanic/Latino | 16 (5) | 25 (8) | 39 | 15 (5) | 17 (8) | 47 |
| Asian | 6 (2) | 8 (2) | 43 | 6 (2) | 6 (3) | 50 |
| Other | 1 (0.3) | 3 (0.9) | 25 | 1 (0.4) | 3 (1) | 25 |
| Unknown | 22 (7) | 3 (0.9) | 88 | 19 (7) | 3 (1) | 86 |
| Athletic level | ||||||
| Middle school | 36 (11) | 44 (13) | 45 | 35 (13) | 34 (17) | 51 |
| High school | 206 (65) | 182 (56) | 53 | 175 (64) | 124 (60) | 59 |
| Club sports | 22 (7) | 15 (5) | 59 | 21 (8) | 10 (5) | 68 |
| College | 39 (12) | 54 (17) | 42 | 33 (12) | 22 (11) | 60 |
| Semipro/pro | 9 (3) | 9 (3) | 50 | 9 (3) | 4 (2) | 69 |
| Former athlete | 3 (1) | 22 (7) | 12 | 2 (0.7) | 12 (6) | 14 |
| Primary sporting disciplines | ||||||
| Football | 70 (22) | 111 (34) | 39 | 59 (22) | 67 (33) | 47 |
| Basketball | 97 (31) | 84 (26) | 54 | 88 (32) | 64 (31) | 58 |
| Track/XC | 29 (9) | 31 (9) | 48 | 27 (10) | 22 (11) | 55 |
| Soccer | 32 (10) | 26 (8) | 55 | 27 (10) | 18 (9) | 60 |
| Baseball | 27 (9) | 16 (5) | 63 | 22 (8) | 3 (2) | 88 |
| Swimming | 7 (2) | 10 (3) | 41 | 6 (2) | 7 (3) | 46 |
| Wrestling | 9 (3) | 6 (2) | 60 | 7 (3) | 3 (2) | 70 |
| Lacrosse | 11 (3) | 4 (1) | 73 | 9 (3) | 3 (2) | 75 |
| Volleyball | 5 (2) | 7 (2) | 42 | 5 (2) | 4 (2) | 56 |
| Ice hockey | 7 (2) | 5 (2) | 58 | 6 (2) | 3 (2) | 67 |
| Other | 8 (3) | 4 (1) | 67 | 7 (3) | 2 (1) | 78 |
| Softball | 4 (1) | 5 (2) | 44 | 4 (2) | 2 (1) | 67 |
| Tennis | 2 (0.6) | 6 (2) | 25 | 1 (0.4) | 3 (2) | 25 |
| Cheerleading | 4 (1) | 3 (0.9) | 57 | 4 (2) | 0 (0) | 100 |
| Dance | 1 (0.3) | 4 (1.2) | 20 | 1 (0.4) | 3 (2) | 25 |
| Golf | 1 (0.3) | 2 (0.6) | 33 | 1 (0.4) | 1 (0.5) | 50 |
| Rowing/crew | 1 (0.3) | 0 (0) | 100 | 1 (0.4) | 0 (0) | 100 |
| Boxing | 0 (0) | 1 (0.3) | 0 | 0 (0) | 0 (0) | Not applicable |
| XC skiing | 0 (0) | 1 (0.3) | 0 | 0 (0) | 1 (0.5) | 0 |
Values are mean ± SD or n (%), unless otherwise indicated.
Age was unknown in 39 athletes with SCA and in 5 athletes with SCD.
Pro = professional; SCA = sudden cardiac arrest; SCD = sudden cardiac death; XC = cross country.
Etiologies for SCA/SCD among cases with enough information for adjudication (367 of 641; 57%) are presented in Figure 2. Data sources used for case adjudication stratified by the etiology of SCA/SCD are presented in Supplemental Table 3. The most common etiologies among those with SCA/SCD included hypertrophic cardiomyopathy (HCM 20%), congenital coronary artery abnormalities 13%), and idiopathic left ventricular hypertrophy/possible cardiomyopathy (11%). Etiologies of SCA/SCD stratified by competition level are presented in Table 2. Among SCA cases with enough information for adjudication (128 of 315, 41%), the most common etiologies included HCM (23%), long QT syndrome (14%), and congenital coronary artery abnormalities (12%). Among SCD cases with enough information for adjudication (239 of 326, 73%), the most common etiologies included HCM (18%), idiopathic left ventricular hypertrophy/possible cardiomyopathy (17%), and autopsy-negative sudden unexplained death (AN-SUD) (15%). There was enough information for case adjudication among 105 of 275 (38%) athletes with exertional SCA and 142 of 206 (69%) athletes with exertional SCD. Etiologies associated with exertional SCA and SCD are presented in Table 3.
FIGURE 2. Etiology of Sudden Cardiac Arrest and Death Among Athletes With Enough Information for Adjudication (n = 367).
Other includes 4 multiple cardiac abnormalities, 3 myocardial fibrosis/ischemia of unknown cause, 2 restrictive cardiomyopathy (CM), 2 left ventricular noncompaction CM, 2 hypertensive heart disease, 1 VF with history of atrioventricular block with pacemaker, 1 vasculitis of the left main coronary artery, 1 hypokalemia from Gitelman’s syndrome, 1 cardiac mass, 1 exertional sudden cardiac arrest with known congenital liver disease, 1 cardiac tamponade. AC = arrhythmogenic cardiomyopathy; AN-SUD = autopsy negative sudden unexplained death; CAD = coronary artery disease; CPVT = catecholaminergic polymorphic ventricular tachycardia; DCM = dilated cardiomyopathy; HCM = hypertrophic cardiomyopathy; LVH = left ventricular hypertrophy; NOS = not otherwise specified; SCD = sudden cardiac death; USCA = unexplained sudden cardiac arrest; WPW = Wolff-Parkinson-White syndrome.
TABLE 2.
Adjudicated Etiologies of SCA and SCD Among Young Competitive Athletes Stratified by Competition Level
| Cardiovascular Etiology | Total | Middle School | High School | Club | College | Semiprofessional/Professional | Former Athletes | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| SCA (N = 128) |
SCD (N = 239) |
SCA (n = 15) |
SCD (n = 35) |
SCA (n = 84) |
SCD (n = 137) |
SCA (n = 10) |
SCD (n = 5) |
SCA (n = 14) |
SCD (n = 40) |
SCA (n = 3) |
SCD (n = 6) |
SCA (n = 2) |
SCD (n = 16) |
|||
| Aortic dissection | 0 | 10 (4) | 0 | 1 (3) | 0 | 6 (4) | 0 | 0 | 0 | 3 (8) | 0 | 0 | 0 | 0 | ||
| ACM | 10 (8) | 9 (4) | 0 | 0 | 8 (10) | 2 (1) | 1 (10) | 0 | 1 (7) | 3 (8) | 0 | 2 (33) | 0 | 2 (13) | ||
| AN-SUDa | Not applicable | 35 (15) | Not applicable | 7 (20) | Not applicable | 21 (15) | Not applicable | 0 | Not applicable | 6 (15) | Not applicable | 1 (17) | Not applicable | 0 | ||
| Brugada | 2 (2) | 3 (1) | 0 | 1 (3) | 2 (2) | 1 (1) | 0 | 0 | 0 | 1 (3) | 0 | 0 | 0 | 0 | ||
| CM NOSa | Not applicable | 4 (2) | Not applicable | 1 (3) | Not applicable | 3 (2) | Not applicable | 0 | Not applicable | 0 | Not applicable | 0 | Not applicable | 0 | ||
| CPVT | 7 (6) | 1 (0.4) | 3 (20) | 1 (3) | 4 (5) | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | ||
| Commotio | 12 (9) | 1 (0.4) | 2 (13) | 0 | 7 (8) | 0 | 0 | 0 | 1 (7) | 0 | 2 (67) | 1 (17) | 0 | 0 | ||
| Congenital | 4 (3) | 5 (2) | 1 (7) | 2 (6) | 2 (2) | 3 (2) | 1 (10) | 0 | 0 | 0 | 0 | 0 | 0 | 0 | ||
| CCAA | 15 (12) | 33 (14) | 2 (13) | 9 (26) | 8 (10) | 20 (15) | 4 (40) | 2 (40) | 1 (7) | 1 (3) | 0 | 1 (17) | 0 | 0 | ||
| CAD | 3 (2) | 5 (2) | 0 | 0 | 2 (2) | 2 (1) | 0 | 0 | 0 | 2 (5) | 0 | 0 | 1 (50) | 1 (6) | ||
| DCM | 2 (2) | 5 (2) | 0 | 1 (3) | 1 (1) | 1 (1) | 0 | 0 | 1 (7) | 2 (5) | 0 | 0 | 0 | 1 (6) | ||
| Hypertensive heart | 0 | 2 (1) | 0 | 0 | 0 | 1 (1) | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 (6) | ||
| HCM | 30 (23) | 43 (18) | 2 (13) | 8 (23) | 20 (24) | 25 (18) | 1 (10) | 0 | 7 (50) | 7 (18) | 0 | 1 (17) | 0 | 2 (13) | ||
| Idiopathic LVHa | Not applicable | 41 (17) | Not applicable | 3 (9) | Not applicable | 22 (16) | Not applicable | 0 | Not applicable | 11 (28) | Not applicable | 0 | Not applicable | 5 (31) | ||
| Unexplained SCAb | 4 (3) | Not applicable | 0 | Not applicable | 3 (4) | Not applicable | 1 (10) | Not applicable | 0 | Not applicable | 0 | Not applicable | 0 | Not applicable | ||
| LVNC | 1 (1) | 1 (0.4) | 0 | 0 | 1 (1) | 1 (1) | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | ||
| Long QT | 18 (14) | 5 (2) | 0 | 0 | 15 (18) | 2 (1) | 1 (10) | 0 | 1 (7) | 1 (3) | 1 (33) | 0 | 0 | 2 (13) | ||
| Myocarditis | 3 (2) | 15 (6) | 1 (7) | 1 (3) | 1 (1) | 11 (8) | 0 | 0 | 0 | 1 (3) | 0 | 0 | 1 (50) | 2 (13) | ||
| Other | 1 (1) | 12 (5) | 0 | 0 | 1 (1) | 9 (7) | 0 | 1 (20) | 0 | 2 (5) | 0 | 0 | 0 | 0 | ||
| Restrictivea | 2 (2) | Not applicable | 1 (7) | Not applicable | 0 | Not applicable | 1 (10) | Not applicable | 0 | Not applicable | 0 | Not applicable | 0 | Not applicable | ||
| Valve | 4 (3) | 4 (2) | 2 (13) | 0 | 1 (1) | 4 (3) | 0 | 0 | 1 (7) | 0 | 0 | 0 | 0 | 0 | ||
| WPW | 10 (8) | 5 (2) | 1 (7) | 0 | 8 (10) | 3 (2) | 0 | 2 (40) | 1 (7) | 0 | 0 | 0 | 0 | 0 | ||
Values are n (%).
Definition only included in SCD cases.
Definition only included in SCA cases.
ACM = arrhythmogenic cardiomyopathy; AN-SUD = autopsy negative sudden unexplained death; CAD = coronary artery disease; CCAA = congenital coronary artery abnormality; CM = cardiomyopathy; CPVT = catecholaminergic polymorphic ventricular tachycardia; DCM = dilated cardiomyopathy; HCM = hypertrophic cardiomyopathy; LVH = left ventricular hypertrophy; LVNC = left ventricular noncompaction; NOS = not otherwise specified; WPW = Wolff-Parkinson-White syndrome; other abbreviations as in Table 1.
TABLE 3.
Adjudicated Etiologies of Exertional SCA and SCD Among Young Competitive Athletes
| Cardiovascular Diagnosis | Exertional SCA (n = 105) |
Exertional SCD (n = 142) |
Survival% |
|---|---|---|---|
| Aortic dissection | 0 | 5 (3) | 0 |
| ACM | 7 (7) | 8 (6) | 47 |
| AN-SUDa | Not applicable | 23 (16) | Not applicable |
| Brugada | 2 (2) | 1 (1) | 67 |
| CM NOSa | Not applicable | 1 (1) | Not applicable |
| CPVT | 5 (5) | 0 | 100 |
| Commotio | 12 (11) | 1 (1) | 92 |
| Congenital | 4 (4) | 4 (3) | 50 |
| CCAA | 13 (12) | 25 (18) | 34 |
| CAD | 2 (2) | 3 (2) | 40 |
| DCM | 2 (2) | 2 (1) | 50 |
| Hypertensive heart | 0 | 1 (1) | 0 |
| HCM | 27 (26) | 24 (17) | 53 |
| Idiopathic LVHa | Not applicable | 22 (15) | Not applicable |
| Unexplained SCAb | 2 (2) | Not applicable | Not applicable |
| LVNC | 0 | 1 (1) | 0 |
| Long QT | 15 (14) | 2 (1) | 88 |
| Myocarditis | 2 (2) | 7 (5) | 22 |
| Other | 0 | 6 (4) | 0 |
| Restrictive CMb | 2 (2) | Not applicable | Not applicable |
| Valve | 4 (4) | 3 (2) | 57 |
| WPW | 6 (6) | 3 (2) | 67 |
SURVIVAL OUTCOMES AND TRENDS.
The overall survival proportion was 49% (range 30%−66% per academic year) (Figure 3) with a significant increase identified over the 9-year period (2-sided z-statistic 2.70; P = 0.007). For exertional SCA, the overall survival proportion was 57% (range 38%−72% per academic year) with a significant increase over the 9-year period (2-sided z-statistic 2.21; P = 0.03). The highest survival rate (72%) for exertional SCA occurred in the last academic year of the study (2022–2023). Among exertional SCA events, survival was higher among athletes who experienced SCA during a game/competition vs during practice/training (70% vs 53%; P = 0.001). For nonexertional SCA, the overall survival proportion was 27% (range 8%−50% per academic year) with no statistically significant change in survival trend throughout the study period (2-sided z-statistic 1.56; P = 0.12).
FIGURE 3. Percent Survival From SCA in Young Competitive Athletes in the United States.
Blue bars = sudden cardiac death, n = total cases per academic year. Green bars = sudden cardiac arrest with survival, n = total cases per academic year. Connected dots = percent of sudden cardiac arrest with survival (2-sided z-statistic 2.70; P = 0.007 trend toward survival). Abbreviations as in Figure 1.
PREDICTORS OF SURVIVAL FROM SCA.
Results of the multivariable log binomial regression analysis to assess for the association of race and exertional status with survival from SCA are presented in Table 4. Black race (RR: 0.63; 95% CI: 0.53–0.76) and other race (RR: 0.69; 95% CI: 0.50–0.94) compared with White race, and nonexertional SCA (RR: 0.43; 95% CI: 0.32–0.59) were independently associated with a relative reduction in survival from SCA adjusting for sex and level of competition.
TABLE 4.
Univariable and Multivariable Log Binomial Regression Analysis for Factors Associated With Survival From Sudden Cardiac Arrest
| RR | 95% CI LB | 95% CI UB | P Value | |
|---|---|---|---|---|
| Univariable Log Binomial Regression Model (n = 641)a,b | ||||
| Male | 1.06 | 0.84 | 1.33 | 0.63 |
| Level of competition | 0.02 | |||
| Middle school | 0.90 | 0.70 | 1.17 | 0.44 |
| High school | 1.21 | 1.02 | 1.43 | 0.03 |
| Club sports | 1.23 | 0.93 | 1.62 | 0.15 |
| College/semipro/pro | 1.00 | |||
| Racea | <0.0001 | |||
| Black | 0.70 | 0.58 | 0.85 | 0.0002 |
| Other | 0.80 | 0.58 | 1.12 | 0.20 |
| White | 1.00 | |||
| Exertional statusb | ||||
| Nonexertional | 0.48 | 0.35 | 0.64 | <0.0001 |
| Exertional | 1.00 | |||
| Multivariable Log Binomial Regression Model (n = 581)c,d | ||||
| Race | <0.0001 | |||
| Black | 0.63 | 0.53 | 0.76 | <0.0001 |
| Other | 0.69 | 0.50 | 0.94 | 0.02 |
| White | 1.00 | |||
| Exertional status | ||||
| Nonexertional | 0.43 | 0.32 | 0.59 | <0.0001 |
| Exertional | 1.00 | |||
Model excluded athletes with missing race (n = 25).
Model excluded athletes with missing exertional status (n = 35).
Model excluded athletes with missing values for race (n = 25), exertional status (n = 35).
Multivariable model adjusted for level of competition (P = 0.10) and sex (P = 0.25). Binary categorical variables included exertional SCA as a reference vs nonexertional SCA. Multilevel categorical variables included college/semipro/pro as a reference vs middle school vs high school vs club sports, and White race as a reference vs Black race vs other race (which included Hispanic/Latino, Asian, and other race).
SURVIVAL BASED ON SPORTING DISCIPLINE AND SCA ETIOLOGY.
Among sporting disciplines with ≥10 exertional SCA/SCD events, athletes participating in baseball had the highest percentage of survival (88% survival, 22 SCA vs 3 SCD cases) and athletes participating in football (47% survival, 59 SCA vs 67 SCD cases) and swimming (46% survival, 6 SCA vs 7 SCD cases) had the lowest survival percentage (Table 1).
Table 3 presents the outcome for 247 athletes with SCA during exertion based on adjudicated underlying SCA/SCD etiology. Among etiologies with ≥10 SCA/SCD events, athletes with commotio cordis (92% survival, 12 SCA vs 1 SCD) and long QT syndrome (88% survival, 15 SCA vs 2 SCD) had the highest survival percentage.
The Central Illustration depicts the major results and findings from this study.
CENTRAL ILLUSTRATION. Survival Outcomes After Sudden Cardiac Arrest in Young Competitive Athletes From the United States.
The major findings and results from the current study are depicted.
DISCUSSION
We report survival outcomes and trends among young competitive U.S. athletes following SCA. This is the largest study to date reporting survival outcomes in young competitive U.S. athletes, and the first to analyze the association between athlete race and exertion with survival using a log binomial regression model.
The study has several key findings that warrant highlighting. First, the proportion of athletes who survived a SCA event increased throughout the study period, with the highest survival (72%) from exertional SCA occurring in the last year of the period (2022–2023). Second, survival was higher for athletes who sustained an exertional SCA event during a game/competition compared with an exertional SCA event during practice/training. Finally, Black and other race and nonexertional SCA were associated with a higher likelihood of death when controlling for sex and level of competition.
Previous studies have demonstrated that survival from exercise-related SCA has improved through prompt recognition of SCA, bystander CPR, and rapid access to an AED.13,14 Although this study did not investigate resuscitation variables, it is reasonable to presume that the increased survival is related at least in part to improved emergency preparedness for SCA at sporting events. The NCAA requires member institutions to have an emergency action plan (EAP) that is reviewed and rehearsed annually,15 and EAPs with access to AEDs at sporting facilities is widely supported by the National Federation of State High School Associations and the National Athletic Trainers’ Association.12 However, other sporting leagues with less resources, such as club and academy sports, may not have similar mandates or resources. In a previous study among Amateur Athletic Union (AAU) youth club basketball teams, there were markedly low rates of required CPR training for coaches (35%), AED availability at games (35%), and EAPs that were rehearsed annually (6%).16 Likewise, a study comparing survival rates among male adolescent basketball players with SCA at an AAU-sponsored vs school-sponsored event found more frequent bystander CPR (91.2% vs 53.9%; P = 0.004), more common AED use (79.4% vs 30.8%; P = 0.002), and higher survival (70.6% vs 38.5%; P = 0.043) at school-sponsored events.17 While survival trends from this study are encouraging, more work needs to be done at all levels of competition to improve survival rates in young competitive athletes with SCA.
Survival from exertional SCA was also more likely during games/competitions vs practice/training. The underlying reason for this finding is unknown but may relate to an increased likelihood of bystander CPR (from athletic medical staff or fans) or improved AED availability at games/competitions. In a recent study assessing survival from exertional SCA among high school athletes, the survival rate was 83% if there was an athletic trainer present and 85% if an onsite AED was used.5 The lower survival rate for nonexertional SCA is expected, because nonexertional SCA events are less likely to be witnessed (eg, during sleep) or may occur in locations with lower access to AEDs or training medical staff. The data in this study support that further work is needed to improve outcomes for exertional SCA events that occur during practice/training. Our results provide a compelling rationale to ensure that proper emergency preparedness for SCA and access to AEDs are established at all sporting facilities used for practice/training and not just venues for games/competitions. In addition, sporting disciplines with lower overall survival percentages (eg, football and swimming) suggest that enhanced emergency training and preparations are needed for sports that provide a potential barrier to rapid resuscitation procedures, such as the presence of chest pads/equipment or activity in a pool. These findings collectively support ongoing recommendations to have the following: 1) AEDs accessible within minutes at all sporting venues; 2) universal education in CPR and the recognition of SCA in athletes for coaches; 3) athletic trainers present at practice, training, and game events; and 4) the development and implementation of EAPs for SCA that are rehearsed at least annually.4,18,19
The most common etiology for SCA/SCD in this study was HCM, similar to prior studies accounting for both SCA and SCD events in competitive athletes in the United States.2,20 Our study also found that AN-SUD was among the most common postmortem findings following SCD, which is consistent with studies including only SCD in young competitive athletes from the United States and the United Kingdom1,3,21 However, the percentage of SCA/SCD cases related to arrhythmogenic cardiomyopathy in our study (5.2%) is lower than previous studies from Europe21,22 but consistent with prior studies from the United States.1–3,20 The lower rate of arrhythmogenic cardiomyopathy as a cause of SCA/SCD in the United States could be related to different postmortem examinations, different disease prevalence/penetrance, or perhaps different disease awareness and cardiovascular screening practices.
Despite improved survival rates, Black and other race were associated with death following SCA in young competitive athletes after adjustment for sex, level of competition, and exertional status. These data are concerning because Black athletes have also been found to have a greater incidence of SCA/SCD compared with White athletes.1–3 The reasons underpinning the lower survival rate are unknown but could be related to social determinants of health and/or school resources for emergency preparedness. Arthur et al23 examined the association of race and area deprivation and found that Black athletes with SCA come from neighborhoods with greater socioeconomic deprivation than White athletes or other-race athletes with SCA. Similarly, Rim et al24 found that the area deprivation index, a combined metric for numerous social determinants of health, was significantly higher among Black than White American-style football athletes and associated with early cardiovascular risk markers such as higher diastolic blood pressure and arterial stiffening. Schattenkerk et al5 also reported that minority high school student-athletes with exercise-related SCA had a lower survival rate compared with White non-Hispanic student-athletes with SCA (51.1% vs 75.9%; RR: 0.67; 95% CI: 0.49–0.92). There was also a nonsignificant monotonic increase in survival found with increasing median household or family income and with decreasing percent minority students or the proportion of students on free/reduced-cost lunch. Taken together, these studies suggest that social determinants of health and community resources, via structural racism that frequently correlates with self-reported race, may be related to worse outcomes among Black athletes with SCA. We believe these findings do not reflect intrinsic biologic differences across different self-reported racial groups and are more likely to be related to social determinants of health.25 There is also recent data from the general population demonstrating that Black and Hispanic individuals are less likely to receive bystander CPR.26 Overall, the underlying cause for worse outcomes among Black and other-race athletes following SCA remains unknown and represents an important area of future work. Research is needed to further understand and address these disparities, including studies assessing how area socioeconomic deprivation and other social determinants of health may affect outcomes and emergency preparedness for SCA during sport.
STUDY LIMITATIONS.
First, there is no mandatory reporting system for young athlete SCA or SCD events in the United States, so cases of SCA/SCD may have been missed and the total number of events underestimated. Nonexertional SCA/SCD events may be significantly under-reported compared with exertional SCA/SCD events that may attract more media attention. Second, cases of SCA could have been excluded if an athlete had a SCA event at rest or during sleep but without information for case adjudication supporting a cardiac collapse or confirming a cardiac etiology. Examples of noncardiac causes of sudden death events at rest or during sleep include death by suicide and overdose; thus, a cardiac etiology was not presumed. Conversely, cases of a sudden exertional collapse requiring cardiac resuscitation but without confirmation of a precise cardiac etiology may have theoretically been related to a noncardiac cause, but this would be very rare and unlikely to affect the results. Third, robust data on bystander CPR and AED use, emergency response and resuscitation timing, and other resuscitation-related information were not available. Therefore, definitive conclusions cannot be drawn for differences when comparing survival rates among groups, and additional research is needed to elucidate the underlying reason for race-related differences in survival from SCA among athletes. Fourth, because race is a social construct,25 it is possible that athletes could have identified with a different race than reported in this study. Athletes in the study were also classified using a single race category by the data collection team, so athletes who self-identify as multiple races may not have been accurately characterized. Race was also unknown among 25 of 641 (3.9%) athletes, which may have affected results. Fifth, the precise cardiovascular etiology of SCA/SCD could not be determined in 27% of the SCD group and 59% of the SCA group because of limited available information, which may have affected the results. Some etiologies such as unexplained SCA may be underestimated because of the limited availability of medical records. Undiagnosed primary electrical disease such as long QT syndrome or catecholaminergic polymorphic ventricular tachycardia in cases of AN-SUD death also may have influenced a more precise account of survival outcomes based on disease etiologies. Finally, there were missing data for exertional status (n = 35) and race (n = 25), leaving 581 of 641 (91%) included in the multivariable log binomial regression model, which could have affected the results.
CONCLUSIONS
In this large prospective cohort of young competitive athletes with SCA, survival outcomes improved throughout the study period. Although these data may be encouraging, further education, research, and policy changes are needed to improve outcomes following SCA among young athletes. Specifically, universal emergency preparedness to sports-related SCA, especially in the practice setting, is needed and should include broader education on the recognition of SCA in athletes, CPR training for potential rescuers, and access to AEDs. Black and other-race athletes demonstrated an increased risk of death following SCA compared with White athletes. The underlying cause of this finding is unknown, and future investigations are needed to understand and address racial disparities in survival from SCA in athletes.
Supplementary Material
ACKNOWLEDGMENT
The authors thank the Parent Heart Watch and National Collegiate Athletic Association for their assistance in data collection.
FUNDING SUPPORT AND AUTHOR DISCLOSURES
This research is supported, in part, by the National Center for Catastrophic Sports Injury Research (NCCSIR) at the University of North Carolina at Chapel Hill. NCCSIR is supported by the National Collegiate Athletic Association, the National Federation of State High School Associations, the National Athletic Trainers’ Association, the National Operating Committee on Standards for Athletic Equipment, and the American Medical Society for Sports Medicine. Conclusions drawn from or recommendations based on the data provided by the NCCSIR are those of the author(s) and do not necessarily represent the official views of the NCCSIR or any of the supporters. Dr Churchill has received funding from the National Institutes of Health/National Heart, Lung, and Blood Institute to study cardiovascular outcomes among athletes and receives compensation for his role as team cardiologist for the Boston Bruins. Dr Baggish has received funding from the National Institute of Health/National Heart, Lung, and Blood Institute, the National Football Players Association, the American Heart Association, and the American Medical Society for Sports Medicine to study cardiovascular outcomes among elite athletes and receives compensation for his role as team cardiologist from the U.S. Olympic Committee/U.S. Olympic Training Centers, U.S. Soccer, and U.S. Rowing. Dr Kucera is supported by funds from the NCCSIR, which is funded by National Collegiate Athletic Association, the National Federation of State High School Associations, the National Athletic Trainers’ Association, the National Operating Committee on Standards for Athletic Equipment, and the American Medical Society for Sports Medicine. Dr Harmon has received funding from the American Medical Society for Sports Medicine, Football Research, Inc, the Pac-12, and the American Heart Association. Dr Drezner has received funding from the American Medical Society for Sports Medicine, the American Heart Association and the NCCSIR. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
ABBREVIATIONS AND ACRONYMS
- AED
automated external defibrillator
- AN-SUD
autopsy negative sudden unexplained death
- CPR
cardiopulmonary resuscitation
- EAP
emergency action plan
- HCM
hypertrophic cardiomyopathy
- NCAA
National Collegiate Athletic Association
- SCA
sudden cardiac arrest
- SCD
sudden cardiac death
Footnotes
The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the Author Center.
APPENDIX For supplemental tables, please see the online version of this paper.
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