Experiences in cardiovascular screening of professional athletes using echocardiography and electrocardiography at Jakaya Kikwete Cardiac Institute in Tanzania- a cross-sectional observational study

Abstract

Background

Sudden cardiac deaths (SCD) in professional athletes have resulted in a need for cardiovascular screening. There is a general paucity of data regarding screening for SCD risks in African professional athletes, including those in Tanzania.

Aim

To determine professional athletes’ electrocardiographic and echocardiographic characteristics.

Methodology

A cross-sectional study at Jakaya Kikwete Cardiac Institute in Dar Es Salaam, Tanzania, involved professional athletes from 2021 to 2023 Data on anthropometrics, physical examination, and family history were entered into a standardized questionnaire. All patients underwent 12-lead electrocardiograph (ECG) and two-dimensional echocardiography. Continuous variables were tested for normality using the Kolmogorov-Smirnov test. ECG and echocardiography findings of men and women athletes were compared by using the unpaired Student’s t-test for continuous variables. The chi-square test was used to evaluate the differences in proportions for categorical ECG and echocardiographic findings of men and women athletes. The p-value of < 0.05 was statistically significant.

Results

Eighty-six professional athletes were included, most of whom were men (62%). There was a statistically significant mean difference in men(M) vs. women(W) in heart rate (53 M vs. 60 W p <.001), PR interval (176 M vs. 164 W p <.043) and left ventricular internal diameter in diastole (46 M vs. 41 W p <.001). The most prevalent normal ECG finding in men athletes was early repolarization, and sinus arrhythmia in women athletes.

Conclusion

Most of our athletes had normal physiological changes. We recommend a 1–2 years cardiovascular screening for competitive athletes.

Supplementary Information

The online version contains supplementary material available at https://doi.org/10.1186/s12872-026-06286-7.

Lay summary

Sudden cardiac death is not uncommon, especially in professional athletes. This study investigated screening of the heart using echocardiography and electrocardiography to identify the presence of heart problems that may lead to sudden cardiac death.

Key findings

• Most athletes had what are considered normal heart changes seen in people who engage in intense training.

• A few athletes had problems in their hearts, which shows the importance of screening.

Background

Sudden cardiac deaths (SCD) in professional athletes have resulted in a need for cardiovascular screening using electrocardiography and echocardiography. The incidence of SCD worldwide is controversial due to a lack of heterogeneous criteria; however, a study in the US has reported the highest incidence of SCD among division I male basketball players (1:8188 [White, 1:5848; Black, 1:7696 athlete-years]). Male sex, Black race, and basketball are associated with a higher incidence of SCD [1].

The incidence of sudden cardiac death is high in African Americans [1].

Inherited cardiac conditions are the most common cause of SCD in young athletes under 35 years. A systematic review done by D’Ascenzi et al. reports that causes of SCD differ in the USA compared to Europe; whereas in the US, most athletes had hypertrophic cardiomyopathy and anomalous origin of coronary arteries, while ACM and channelopathies were more frequent in Europe [2].

There is generally limited data regarding SCD screening in African athletes. Hallak et al. conducted a systematic review on cardiac screening of athletes in the Middle East and Africa, which involved four studies; no women athletes were included in these studies. The review reports commonly known underlying triggers of SCD in athletes in all four studies, including Wolff-Parkinson-White syndrome (WPW), arrhythmogenic right ventricular cardiomyopathy (ARVC), and hypertrophic cardiomyopathy (HCM), whose prevalence ranged between 0.47% and 0.49% [3].

Detecting disease early in asymptomatic athletes through screening is paramount in reducing the risks of sudden cardiac death [4].

However, there is a paucity of published data regarding cardiovascular screening of professional athletes in Tanzania.

Screening using 12-lead electrocardiograph (ECG) can detect dangerous arrhythmia and can also be used to differentiate physiological changes related to sports training from features suggestive of an underlying pathological state [5] it is crucial for clinicians to comprehend the mechanisms underlying sudden cardiac death while interpreting electrocardiograms [6].

Echocardiography plays a vital role in risk assessment for SCD. Two-dimensional echocardiography can elucidate the presence of structural abnormalities such as hypertrophic cardiomyopathy, where ventricular maximal wall thickness left is one of the most important factors [7].

Meanwhile, strain echocardiography may show abnormal myocardial deformation, which indirectly reflects myocardial fibrosis, and may be present clinically as cardiac arrhythmia [8].

This study aims to establish Tanzanian professional athletes’ ECG and echocardiographic characteristics.

Methodology

We conducted a cross-sectional observational study at Jakaya Kikwete Cardiac Institute (JKCI) in Dar Es Salaam, Tanzania, involving Tanzanian professional athletes who were footballers preparing for local and international tournaments from 2021 to 2023. We used a continuous sampling method.

The Jakaya Kikwete Cardiac Institute is a public national specialized cardiovascular teaching and research hospital in Dar es Salaam, Tanzania. It caters to both pediatric and adult populations with patients referred from across the country. Services offered include diagnostics and imaging, as well as interventional cardiology procedures and cardiothoracic surgery.

Study objectives

1. We determined the cardiovascular risks assessment for sudden cardiac death in Tanzanian professional athletes.

2. We identified gender-specific physiological electrocardiographic and structural adaptation to exercise to accurately detect potential pathology.

• Hypothesis: Sudden cardiac death is not uncommon, especially in professional athletes. This study investigated screening of the heart using echocardiography and electrocardiography to identify the presence of heart problems that may lead to sudden cardiac death.

• Study population: Tanzanian professional athletes preparing for local and international tournaments

• Sampling technique: continuous sampling method

• Study type: Cross sectional observational study

Definition of a professional athlete

A professional athlete is an individual who competes in sports for compensation, participating in official events that can attract varying audience sizes. These athletes may be self-employed or affiliated with sports organizations, and they dedicate significant time to physical training, strategic preparation, and competition [9] (Figs. 1 and 2).

Fig. 1.

Box and whiskers plot showing the mean Heart rates between male and female with the outliers

Fig. 2.

ECG of a 17-year-old male athlete with a borderline QTc, and T wave inversion in leads V3 and V4 (anterior leads). The QTc interval is 465 ms which is just borderline and NOT prolonged in a range compatible with diagnosis of Long QT syndrome. In the legend please mention the T wave inversion in anterior leads

Cardiovascular screening

Height, weight, blood pressure, and HR were measured, and a standardized questionnaire was completed [10], which cleared the athlete’s personal and family history. A physical examination was also performed (general examination, cardiovascular system, musculoskeletal and neurological examinations were done).

Resting 12-lead electrocardiography

12-lead ECG was done using GE MAC 2000, the players were positioned supine, and after 5 min of rest, ECG was recorded at a standard speed of 25 mm /s. ECGs were analyzed and interpreted independently by experienced cardiologists using international criteria for electrocardiographic interpretation in athletes [11–14].

2D-Transthoracic echocardiography

A 2-dimensional echocardiography was done using GE Vivid IQ T-9, Siemens Accuson X-300 and Siemens Juniper; standard views were obtained using the American Society of Echocardiography protocol [15]. The images were reviewed and interpreted by experienced cardiologists.

Statistical analysis

The data were analysed using SPSS software (Chicago, IL; version 20. Continuous variables were tested for normality using the Kolmogorov-Smirnov test. Electrocardiography and echocardiography findings of men and women athletes were compared to evaluate differences between means using the unpaired Student t-test for continuous variables. The X² test was used to evaluate the differences in proportions for categorical ECG and echo findings of men and women athletes. The p-value of < 0.05 is statistically significant.

Permission to conduct the study was formally sought from the IRB unit of JKCI, and patients’ consent to participate in the study was also requested and granted.

Results

Demographic characteristics

Our study cohort comprised 53(62%) men and 33(38%) women Tanzanian professional athletes who were all footballers. The men athletes ranged from 18 to 36 years, and the women athletes ranged from 15 to 29 years. There was a statistically significant mean difference in age (25 M vs. 21 W p <.001), Height (173 M vs. 162 W p <.001), weight (73 M vs. 58 W p <.001), heart rate (53 M vs. 60 W p <.001), PR interval (176 M vs. 164 W p <.043), LVIDd (46 M vs. 41 W p <.001) as shown in Table 1.

Table 1.

Demographic, ECG and echo characteristics of athletes

	Male	Female	P-value
Age in Yrs (mean)	25	21	< 0.001*
Height in CM	173	162	< 0.001*
Weight in Kg	73	58	< 0.001*
Heart Rate beats/min	53	60	< 0.001*
PR interval	176	164	< 0.043*
LVEF in %	62	62	< 0.914
LVIDd in CM	46	41	< 0.001*
LA in CM	31	31	< 0.769
E/A ratio	1.52	1.47	< 0.699
TAPSE	19	19	< 0.792

LVEF Left ventricular ejection fraction, LVIDd Left ventricular internal diameter diastole, LA Left atrium

P value of < 0.05 is statistically significant

The athletes showed normal physiological changes in ECG as shown in Table 2.

Table 2.

ECG findings according to the international recommendation criteria

	Male (n = 53)	Female (n = 33)
normal ECG	53	33
Prolonged PR interval	9	3
Early Repolarization	32	9
Sinus Arrhythmia	11	19
Short PR interval		1
Incomplete RBBB		1

Discussion

This study explores echocardiographic and electrocardiographic findings of 86 professional athletes (footballers) who attended the Jakaya Kikwete cardiac Institute in Tanzania. Most of these athletes were men at 53(62%). The men athletes’ ages ranged from 18 to 36 years, and the women athletes’ ages ranged from 15 to 29 years.

ECG findings

Most of the athletes in this study had normal ECG. There normal ECG findings were in keeping with Ngabea MA et al. [16]. a study done in Nigeria whereby, they had ECG characteristics consistent with normal physiological changes.

Women had more sinus arrhythmia compared to men, which was in keeping with other studies, such as that of OM Corici et al. [17].

Sinus bradycardia was found more in men than in women athletes with statistical significance (p < .001*) as reported by Bram Bessem et al. [18]. This may be because these athletes had a prolonged time of exercise, as low heart rate is related to an elevated vagal tone secondary to exercise [19].

In sports, a prolonged PR interval is frequent and harmless. Our study found a prolonged PR interval more in men than women, with a significant statistical difference (P <.043*). A study by Sharma et al. revealed a type I atrioventricular block phenomenon in athletes [20] We also had one woman with a short PR interval, which is common in women than men, in keeping with a study by G-Parry Williams et al. [21].

Early repolarization is observed in 25–40% of highly trained sportspersons, more common among men [22], which is the finding we got in our study that three-quarters of our male athletes had early repolarization compared to women.

The study’s ECG findings align closely with established physiological adaptations in athlete’s heart, where regular endurance training induces benign electrical remodeling such as sinus bradycardia, prolonged PR intervals, and early repolarization due to enhanced vagal tone and structural changes like left ventricular hypertrophy. Sinus bradycardia predominated in male footballers (p < .001), reflecting heightened parasympathetic activity from prolonged aerobic exercise, a pattern more pronounced in endurance athletes compared to strength-trained individuals. Early repolarization in 75% of males mirrors the 25–40% prevalence in highly trained athletes, particularly males, driven by myocardial electrophysiological modulation rather than pathology.

Gender-specific differences observed—sinus arrhythmia and short PR more common in females—conform to broader patterns where women exhibit distinct autonomic and repolarization responses, including relatively higher resting heart rates and less QRS voltage elevation than men. Prolonged PR intervals in males (p < .043) represent harmless first-degree AV block from vagal predominance, while the rare, prolonged QT cases warrant scrutiny to exclude pathology amid these adaptations. These align with international criteria distinguishing training effects from sudden cardiac death risks.

All studies revealed normal physiological ECG changes such as that of Christian Shmeid et al. [23] concerning with our study.

Echocardiographic findings

Cardiac dimensions- women athletes have lower absolute cardiac dimensions than men athletes [24]. Furthermore, in a study by Sangare et al. [19] they found that women athletes had higher indexed left ventricular diameter; however, in our study, we found that men had higher left ventricular internal diameter in diastole compared to women athletes, and this difference was statistically significant with the P value < 0.001* conforming with Flanagan et al study [24].

Our study showed no difference in left ventricular ejection fraction, right ventricular systolic function and left ventricular diastolic function between men and women athletes. And most of the indices were within normal range.

Male athletes’ larger absolute left ventricular internal diameters in diastole (p < .001) reflect sex-dimorphic remodeling, with men showing greater cavity enlargement from volume overload in sports like football, though indexed values may vary. Female athletes typically exhibit smaller absolute dimensions but relatively larger indexed cavities, preserving normal geometry without exceeding dilated cardiomyopathy thresholds (e.g., LVEDD up to 66 mm in elite females). Preserved ejection fraction, right ventricular function, and diastolic parameters across sexes underscore functional adaptation without systolic or diastolic impairment, consistent with adolescent-to-adult progression were males remodel more extensively post-puberty.

Conclusion

Most athletes exhibited normal ECG and echocardiogram findings consistent with physiological adaptations.

These observations reinforce established guidelines on pre-participation cardiovascular evaluation in athletes, emphasizing early detection of at-risk individuals. Future studies should explore gender-specific screening thresholds and longitudinal outcomes in diverse athletic cohorts to refine protocols.

We recommend a 1–2 year ‘s cardiovascular screening for competitive athletes.

Study limitation

Because all the data are collected at a single point in time, it is difficult to determine whether all the physiological changes or ecg abnormality preceded the exercise.

Abbreviations

SCD

Sudden cardiac death

ECG

Electrocardiography

WPW

Wolff-Parkinson-White syndrome

ARVC

Arrhythmogenic right ventricular cardiomyopathy

HCM

Hypertrophic cardiomyopathy

Authors’ contributions

HM, FS, EK, AN, DM collected data, analyzed data, and drafted the manuscript- JK, GM, PK, PP, PK reviewed the manuscript- HM-Corresponding Author.

Funding

This study did not receive any funding.

Data availability

The data are available upon request.

Declarations

Ethics approval and consent

The study was conducted according to the Helsinki declaration, Ethical approval from JKCI institutional research review board was given. All participants consented to participate

Consent for publication

All participants consented for publication.

Competing interests

The authors declare no competing interests.