Electrocardiographic Findings in Female Professional Basketball Athletes

Key Points

Question

What is the spectrum of electrocardiographic (ECG) findings in female professional basketball athletes?

Findings

In this cross-sectional study of 173 Women’s National Basketball Association athletes, 136 athletes (78.6%) had training-related ECG findings while just 8 athletes (4.6%) had an abnormal ECG finding according to the International Recommendations for Electrocardiographic Interpretation in Athletes. Left ventricular adaptations associated with athletic remodeling were present in 64 athletes (47.1%), demonstrating training-related ECG findings.

Meaning

In this cross-sectional study, training-related ECG patterns were commonly observed and the rate of abnormal ECG classification was low in this athlete group.

This cross-sectional study describes reference ranges for electrocardiography findings among female professional basketball athletes.

Abstract

Importance

Previous studies of professional basketball athletes have characterized manifestations of athletic remodeling by echocardiography and electrocardiography (ECG) in males and echocardiography in females. There is a paucity of female, basketball-specific ECG data.

Objective

To generate reference range ECG data for female professional basketball athletes.

Design, Setting, and Participants

This is a cross-sectional study of ECGs performed on female professional basketball athletes. The Women’s National Basketball Association mandates annual preseason ECGs and echocardiograms for each athlete and has partnered with Columbia University Irving Medical Center to annually review these studies. Data for this study were collected during preseason ECG and echocardiography cardiac screening between April and May 2022. Data analysis was performed between February and July 2023.

Exposure

Athlete ECGs and echocardiograms were sent to Columbia University Irving Medical Center for core lab analysis.

Main Outcomes and Measures

Quantitative ECG variables were measured. ECG data were qualitatively analyzed for training-related and abnormal findings using the International Recommendations for Electrocardiographic Interpretation in Athletes. Findings from ECGs were compared with corresponding echocardiographic data.

Results

There were a total of 173 athletes (mean [SD] age 26.5 [4.1] years; mean [SD] height, 183.4 [9.1] cm; mean [SD] body surface area, 2.0 [0.2] m²), including 129 Black athletes (74.5%) and 40 White athletes (23.1%). By international criteria, 136 athletes (78.6%) had training-related ECG changes and 8 athletes (4.6%) had abnormal ECG findings. Among athletes with at least 1 training-related ECG finding, left ventricular structural adaptations associated with athletic remodeling were present in 64 athletes (47.1%). Increased relative wall thickness, reflecting concentric left ventricular geometry, was more prevalent in athletes with the repolarization variant demonstrating convex ST elevation combined with T-wave inversions in leads V1 to V4 (6 of 12 athletes [50.0%]) than in athletes with early repolarization (5 of 42 athletes [11.9%]) (odds ratio, 7.40; 95% CI, 1.71-32.09; P = .01). Abnormal ECG findings included T-wave inversions (3 athletes [1.7%]), Q waves (2 athletes [1.2%]), prolonged QTc interval (2 athletes [1.2%]), and frequent premature ventricular contractions (1 athlete [0.6%]).

Conclusions and Relevance

This cross-sectional study provides reference ECG data for elite female basketball athletes. International criteria–defined training-related findings were common, whereas abnormal ECG findings were rare in this athlete group. These reference data may assist basketball programs and health care professionals using ECGs in screening for female athletes and may be used as a stimulus for future female-specific ECG inquiries.

Introduction

Exercise-induced cardiac remodeling is dependent on several factors, including type and intensity of sport activity, sex, and age.¹ To appropriately classify morphologic and electrocardiographic (ECG) findings in athletes as either training-related or potentially abnormal, detailed reference datasets are needed. With few exceptions, most published cardiac athlete data comprise mixed-sport athletes and exclusively, or predominantly, male athletes.² The International Recommendations for ECG Interpretation in Athletes³ provide guidance to help distinguish training-related ECG changes from separate findings that require further investigation; however, the criteria’s limitations include not being sex- or sport-specific.

Despite available echocardiographic reference data for National Basketball Association (NBA) and Women’s National Basketball Association (WNBA) athletes^4,5 and ECG reference data for NBA athletes,⁶ the spectrum of ECG findings in professional female basketball athletes has not been described. As such, characterizing the ECG profiles of professional female basketball athletes is important, given their propensity to develop significant cardiac remodeling and the growing use of ECGs in large-scale screening programs for female athletes.

Methods

This cross-sectional study was approved by the WNBA, the Women’s National Basketball Players Association, and the institutional review board (IRB) of Columbia University Irving Medical Center (CUIMC). Pursuant to the institutional review board approval at CUIMC, informed consent was not required for this study because ECGs and echocardiograms were obtained as part of the routine evaluation of all athletes, anonymized, and analyzed retrospectively. This study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline for cross-sectional studies.

Study Population

WNBA policy mandates an ECG and echocardiogram (stress echocardiogram for league entrance) for each athlete annually as part of the preseason medical evaluation. For this study, the results of ECGs and echocardiograms performed by WNBA team-affiliated physicians during the 2022 preseason (April to May) were sent to the investigators for core laboratory analysis via a league-wide electronic medical records system.

ECG Analysis

Quantitative ECG data were obtained through manual measurements by the investigators. The qualitative characteristics of each ECG were analyzed using the international criteria³ to identify training-related and abnormal ECG findings per criteria definitions. Each ECG was reviewed by at least 2 cardiologists with expertise in sports cardiology and electrophysiology (B.S.L., E.Y.D., J.A.H., and S.T.), using a uniform protocol and worksheet containing all definitions of training-related and abnormal ECG findings under the international criteria.³ All abnormal ECGs were subsequently rereviewed by 2 additional investigators (M.S.B. and D.J.E.) for final adjudication.

Echocardiograms

Two-dimensional transthoracic echocardiograms were performed using the commercially available systems at each WNBA training site. Of 173 athletes included in the ECG analysis, 169 athletes had corresponding echocardiograms available for review; 4 athletes were not required to complete an echocardiogram due to removal from team rosters during the preseason period. Left ventricular (LV) dimensions, including the interventricular septum, posterior wall thickness, and LV end-diastolic diameter (LVEDD), were measured per American Society of Echocardiography recommendations.⁷ We calculated LV mass with a validated method and indexed it by body surface area (BSA). Left atrial volume was calculated using the biplane area-length method. Relative wall thickness was calculated as (2 × posterior wall thickness) / LVEDD.

Statistical Analysis

Continuous variables are presented as means with SDs. Racially and ethnically stratified sample sizes were insufficient to draw statistically relevant conclusions regarding differences in these parameters with respect to race and ethnicity. The Fisher exact test was used in the comparison of ECG repolarization patterns with echocardiographic variables. For all statistical analyses, a 2-tailed P < .05 was considered significant. Statistical analysis was performed using OpenEpi version 3.01.⁸ Data analysis was performed between February and July 2023.

Results

WNBA Athlete Characteristics and ECG Findings

There were a total of 173 athletes (mean [SD] age 26.5 [4.1] years; mean [SD] height, 183.4 [9.1] cm; mean [SD] BSA, 2.0 [0.2] m²), including 129 Black athletes (74.6%) and 40 White athletes (23.1%). ECG findings, including conventional measurements and the prevalence of training-related findings, are shown in Table 1.

Table 1. Baseline Characteristics, Conventional ECG Measurements, and Training-Related ECG Findings.

Characteristic	Athletes, No. (%) (N = 173)
Age, mean (SD), y	26.5 (4.1)
Height, mean (SD), cm	183.4 (9.1)
Weight, mean (SD), kg	78.2 (11.0)
Body surface area, mean (SD), m2a	2.0 (0.2)
Race and ethnicity, No. (%)
Black	129 (74.6)
White	40 (23.1)
Otherb	4 (2.3)
Conventional ECG measurements, mean (SD)
Heart rate, bpm	56.9 (10.1)
PR interval, ms	168 (28)
QRS duration, ms	90 (9)
QTc interval, ms	415 (31)
Max voltage, limb leads, mm
R	12.9 (4.2)
V1-V3 S	11.8 (5.2)
V5-V6 R	15.5 (4.8)
Training-related ECG findings
Sinus bradycardiac	106 (61.3)
PR interval ≥200 ms	18 (10.3)
Mobitz type 1 s-degree atrioventricular nodal block (Wenckebach)	2 (1.2)
Junctional rhythm	3 (1.7)
Ectopic atrial rhythm	3 (1.7)
Premature atrial contractions	2 (1.2)
Isolated premature ventricular contractions	2 (1.2)
Incomplete right bundle branch block	17 (9.8)
Early repolarization	42 (24.3)
Convex ST elevation followed by T-wave inversiond	12 (6.9)
Right ventricular hypertrophye	2 (1.2)
Left ventricular hypertrophy (Sokolow-Lyon)f	18 (10.4)
Left ventricular hypertrophy (Cornell)g	4 (2.3)
Any training-related ECG finding	136 (78.6)

Abbreviations: bpm, beats per minute; ECG, electrocardiographic.

^a Body surface area is measured by the equation √([height(cm) × weight (kg)] / 3600).

^b Includes Asian and Hispanic athletes.

^c Sinus bradycardia is defined as heart rate less than 60 bpm.

^d As measured via leads V1 through V4.

^e Right ventricular hypertrophy defined as R in V1 +S in V5 or V6 > 10.5 mm.

^f Left ventricular hypertrophy (Sokolow-Lyon) is defined as S in V1 + R in lead V5 or V6 35 mm or greater.

^g Left ventricular hypertrophy (Cornell) S in V3 + R in aVL 28 mm or greater.

By international criteria, 136 athletes (78.6%) had at least 1 training-related ECG feature. Common training-related findings included sinus bradycardia (106 athletes [61.3%]), early repolarization (42 athletes [24.3%]), LV hypertrophy (LVH) (18 athletes [10.4%]), and a PR interval 200 milliseconds or greater in (18 athletes [10.3%]). Convex ST elevations combined with T-wave inversions (TWI) in leads V1 to V4 (convex STE), an ECG pattern classified as training-related in Black athletes,^3,9,10 was present in 12 athletes (6.9%), all of whom were Black. Of the borderline ECG findings, 17 athletes (9.8%) had left atrial enlargement (LAE) and 4 athletes (2.3%) had right atrial enlargement. No athletes had QRS axis deviation or a complete right bundle branch block.

We compared training-related ECG findings with corresponding echocardiographic measurements in these athletes. In 17 athletes meeting ECG criteria for LVH and LAE, there were low positive predictive values for LVH (3 athletes [17.6%]) and LAE (10 athletes [58.8%]) as determined by echocardiography. In 136 athletes with at least 1 training-related ECG finding, 64 athletes (47.1%) demonstrated by echocardiography 1 or more findings of increased LVEDD, increased LV mass index, or increased relative wall thickness, per American Society of Echocardiography definitions,⁷ but we did not find an association between the presence of training-related ECG findings and these indices of athletic remodeling when analyzed individually. We compared echocardiographic findings in athletes with early repolarization and athletes having the convex STE ECG early repolarization variant, also classified as a training-related pattern in Black athletes per international criteria. We observed that increased relative wall thickness, reflecting concentric LV geometry, was more prevalent in athletes with convex STE (6 of 12 athletes [50.0%]) than in athletes with early repolarization (5 of 42 athletes [11.9%]) (odds ratio, 7.40; 95% CI, 1.71-32.09; P = .01). Additionally, athletes with convex STE had lower mean (SD) LVEDD compared with athletes with early repolarization (48.0 [2.7] mm vs 50.3 [3.2] mm; P = .03).

There were 8 athletes (4.6%) with an abnormal ECG finding as defined by international criteria. Abnormal parameters included TWI (3 athletes [1.7%]), Q waves (2 athletes [1.2%]), prolonged QTc interval (2 athletes [1.2%]), and frequent premature ventricular contractions (1 athlete [0.6%]) (Table 2). In 3 athletes with TWI, 2 had anterior TWI (V1-V4) and 1 had inferior TWI (II, III, avF). No athletes had lateral or inferolateral TWI. In 8 athletes with ECG findings classified as abnormal, no underlying cardiac anomalies have thus far been identified by additional investigations, including resting and stress echocardiograms and medical staff clinical evaluation and assessment.

Table 2. Abnormal ECG Findings.

Finding	Total athletes, No. (%) (N = 173)
Abnormal ECG classification per international recommendations
Overall	8 (4.6)
Long QT interval (QTc >480 ms)	2 (1.2)
Left bundle branch block	0
Intraventricular conduction delaya	0
Q wavesb	2 (1.2)
ST segment depressionc	0
Abnormal T-wave inversiond	3 (1.7)
Ventricular preexcitation (WPW)e	0
Frequent premature ventricular contractionsf	1 (0.6)
≥2 Borderline findings	0
Borderline ECG findingsg
Left atrial enlargement	17 (9.8)
Right atrial enlargement	4 (2.3)
QRS axis deviation	0
Right bundle branch block	0

Abbreviations: ECG, electrocardiographic; WPW, Wolf Parkinson White.

^a Intraventricular conduction delay is defined as any QRS duration 140 ms or greater.

^b Q/R ratio 0.25 ms or greater or 40 ms or greater in duration in 2 or more leads (excluding III, aVR).

^c ST-segment depression is defined as at least 0.5 mm below PR in 2 or more leads.

^d Abnormal T-wave inversion is defined as 1 mm or greater in 2 or more leads (excluding III, aVR, V1, and T-wave inversion in V1-V4 in Black athletes when preceded by J point and/or ST elevation).

^e Ventricular preexcitation is defined as PR less than 120 ms with delta wave and wide QRS (≥120 ms).

^f Frequent premature ventricular contractions is defined as at least 2 on a 10-second tracing.

^g Borderline ECG findings, when present in isolation, are considered unlikely to represent cardiac pathology in athletes, but 2 or more borderline findings are classified as abnormal.³

Discussion

In this cross-sectional study, we observed that training-related ECG findings were common in female professional basketball athletes (78.6%) while international criteria–defined abnormal ECG findings were rare (4.6%). We found that 47% of athletes with at least 1 training-related ECG finding per international criteria had corresponding findings of underlying LV structural adaptations that are components of athletic remodeling. Additionally, we found that the early repolarization variant of convex STE more frequently reflected the presence of underlying concentric LV geometry compared with standard early repolarization. The implications, if any, for the longitudinal significance of this difference are unknown at this time.

Compared with other studied female athlete groups, abnormal ECG classification in female professional basketball athletes was similar to that observed in elite female rowers (3.0%)¹¹ (using Seattle Criteria¹²) but lower than in female professional soccer players (11.5%) (using international criteria).¹³ Abnormal ECG findings were additionally less prevalent in female professional basketball athletes compared with previous data obtained in male professional basketball athletes.⁶ This finding differs from those in professional soccer athletes, where the prevalence of abnormal ECG findings was higher in females than males.¹³ The most common ECG abnormality in female professional basketball athletes, similar to what has been reported in other female athlete groups, was TWI.^13,14 However, our data differ in that TWI were less common in females than males; TWI were present less frequently in female professional basketball athletes than reported in male professional basketball athletes,⁶ whereas in US national soccer athletes and Italian Olympic mixed-sport athletes, females had more TWI than males.^13,14

These data help to demonstrate that ECG patterns, including TWI and the prevalence of abnormal ECG classification, vary both between sex and sport. In elite female basketball players, the international criteria perform well, and there are fewer ECGs classified as abnormal than observed in female professional soccer players. These data help to confirm the utility of the international criteria for this athlete group. Generation of additional female- and sport-specific datasets will further refine cardiac screening and care for athletes across all sporting disciplines.

Limitations

There are several limitations to this study. Due to the small number of abnormal findings, subgroup analysis is limited. Longitudinal follow-up data for those with abnormal ECGs are lacking. While these data are directly applicable to elite female basketball athletes, the degree to which it may be extrapolated to female youth basketball athletes or elite female athletes of other sporting disciplines is unknown. Moreover, it is unknown how ECG findings would compare with nonathletic females with similar body habitus.

Conclusions

This cross-sectional study provides reference ECG data for elite female basketball athletes and has direct applicability to female basketball programs that use or are considering using ECGs as part of a screening protocol, and to health care professionals caring for female basketball athletes. These data may be used as reference and stimulus for future female-specific and sport-specific ECG inquiries.

Supplement.

Data Sharing Statement