Scientific letter Use of POCUS in cardiovascular screening of young athletes: diagnostic value in the era of international electrocardiographic criteria

To the Editor,

The use of electrocardiographic (ECG) assessment in preparticipation cardiological screening is currently supported by the clinical guidelines due to its ability to detect heart disease, a common cause of sudden cardiac death in athletes younger than 35 years.¹ The 2017 publication of the international criteria for ECG interpretation in athletes² defines normal, borderline, and pathological findings, which substantially improved the sensitivity and specificity compared with previous criteria.³ Despite this, the assessment continues to generate false positives that cause worry in athletes and their relatives and temporarily limit their sporting activity.

Point-of-care ultrasound (POCUS) could improve the diagnostic yield of these electrocardiographic criteria through the use of focused protocols. Their usefulness in detecting structural findings with prognostic value has been demonstrated in several studies.⁴

Our study was designed with the main objective of evaluating the applicability of POCUS in cardiovascular screening programs and its role in determining eligibility for competitive sports if there are pathological ECG findings according to international criteria. To do so, we included a total of 978 athletes from different types of sport, with a mean age of 16.7 ± 3.7 years, mostly soccer players (65%), and mostly male (81%) (table 1). All the athletes were registered with an association, training 3 to 5 days per week and competing at the weekend. Cardiologists specialized in the care of athletes performed the assessment, which included a history, physical examination, resting ECG, and POCUS focusing on the diagnosis of structural heart disease. The POCUS protocol involved measurement in M mode of septal thickness and posterior wall thickness; measurement of the aortic diameter, left atrial diameter, and left ventricular end-diastolic diameter on the parasternal long axis view; measurement of the right ventricular outflow tract diameter and checking the aortic valve and the coronary ostia on the parasternal short axis view, and study of the mitral and aortic valves with Doppler (including mitral filling pattern, septal tissue Doppler, aortic flow continuous Doppler, and color Doppler of both valves), as well as a general cardiac or 4-chamber view. The athletes were classified based on the interpretation of their ECG in line with international criteria. The study was approved by the Hospital IMED Valencia ethics committee, and all the athletes gave signed informed consent.

Table 1.

General characteristics of the study population: demographic, electrocardiographic, and echocardiographic variables

Total sample: 978 athletes
Demographic parameters
Age, y	16.7 ± 3.7
Male	782 (81)
Race/ethnicity
White/Caucasian	889 (91)
Black/African-American	64 (6)
Asian	25 (3)
Sport
Soccer	636 (65)
Tennis	111 (11)
Indoor soccer	99 (10)
Basketball	42 (4)
Other	90 (9)

Investigations
Electrocardiogram		Echocardiogram
Heart rate, bpm	61.2 ± 13.6	Septal thickness, mm	9.4 ± 1.5
Axis,°	74.2 ± 24.0	LV end-diastolic diameter, mm	48.4 ± 4.2
QRS width, ms	91.1 ± 9.7	LV end-systolic diameter, mm	25.3 ± 3.4
Corrected QT interval, ms	399.2 ± 21.9	Posterior wall thickness, mm	9.7 ± 1.6
Right bundle branch block	364 (27)	LVEF, %	66.6 ± 4.2
Sokolow-Lyon index, mm	36.1 ± 9.3	Indexed LV mass, g/m^2	96.2 ± 20.8

LV, left ventricle; LVEF, left ventricular ejection fraction.

Pathological ECG criteria were found in 35 athletes (3.6% of the total): 27 due to negative T waves or ST-segment depression, 6 due to the presence of 2 or more ectopics on ECG, 1 due to prolonged QT interval, and 1 due to pre-excitation syndrome (table 2). POCUS during the screening visit, estimated to take < 5 minutes, showed an excellent diagnostic yield in the assessment of repolarization abnormalities classified as pathological according to the international criteria. This allowed significant structural heart disease to be ruled out in 25 of the 27 athletes with negative T waves (in this context, a reduction in the rate of ECG false positives of up to 92.5%). In the 2 remaining athletes, a suspected diagnosis of hypertrophic cardiomyopathy was reached. In the first case, this was on the basis of septal hypertrophy with a maximum midapical thickness of 15 mm in the presence of negative T waves on ECG in the inferior leads and V₅-V₆. In the second case, it was on the basis of negative T waves with ST-segment depression in III and V₄-V₆, a lateral hypertrabeculation pattern with spongiform appearance on POCUS, and cardiac magnetic resonance showing a nonobstructive hypertrophic cardiomyopathy pattern.

Table 2.

Pathological ECG parameters according to international criteria

ECG parameter	Athletes (% of the total)	POCUS ruled out structural heart disease (%)	Comments
All pathological criteria	35 (3.6)	25 (71)
Inverted T waves/ST depression	27 (2.8)	25 (93)	2 athletes with a diagnosis of hypertrophic cardiomyopathy (cardiac magnetic resonance, genetic study)
Ventricular ectopics (2/+)	6 (0.6)	0	Cardiological follow-up (Holter ECG)
Prolonged QT interval	1 (0.1)	0	Outpatient follow-up
Ventricular preexcitation	1 (0.1)	0	Electrophysiology study and successful ablation

ECG, electrocardiogram; POCUS, point-of-care ultrasound.

In the patients with the other pathological findings described (long QT, ventricular ectopics and pre-excitation syndrome), POCUS did not lead to changes in the impression from the electrocardiographic assessment, and therefore eligibility was delayed due to the need for other diagnostic tests.

Therefore, POCUS was especially useful in patients with repolarization abnormalities on ECG, present in 3% of the sample and in line with previous studies.⁵ In addition, and although it was not the aim of this study, it was able to detect other structural abnormalities not detected on ECG, such as coronary anomalies (we were able to confirm the normal position of the ostia in more than 90% of the athletes) or common valvulopathies such as bicuspid aortic valve or mitral valve prolapse. Although these conditions rarely affect prognosis in athletes, their early detection enables regular cardiological follow-up and treatment if required.

The limitations of this study include the sample size, the high percentage of male soccer players, and the analysis of results from a single medical center.

Despite these limitations, we can conclude that POCUS as part of the cardiovascular screening of young athletes is a fast and simple technique that allows exclusion of the presence of significant structural heart disease in individuals with repolarization abnormalities that are classified as pathological according to international ECG interpretation criteria.

Its incorporation into cardiovascular screening programs could significantly reduce the false positive rate from ECG and accelerate eligibility for sports in cases of certain pathological ECG findings with suspected cardiomyopathy.

FUNDING

No funding.

AUTHORS’ CONTRIBUTIONS

All authors contributed substantially to the conception and design of the study and the data collection, analysis, and interpretation. They also all participated in the writing and critical review of the manuscript for its final approval.

CONFLICTS OF INTEREST

None.