Are the existing athlete’s ECG interpretation criteria also valid when screening master athletes?

Sudden cardiac death (SCD) is the leading cause of death in athletes and its incidence is higher in males, Black athletes and certain sports. ¹ Sudden cardiac arrest (SCA)/SCD incidence also increases with age due to the higher prevalence of coronary artery disease (CAD), which accounts for more than 80% of SCD cases in athletes older than 35 years.^2,3

Screening with resting electrocardiogram (ECG) for early detection of cardiac disease associated with higher risk of SCA/SCD in young athletes (≤35 years) allows for therapy intervention and lifestyle/physical activity modification. In the last 15 years, athlete’s ECG interpretation criteria have significantly improved their specificity, allowing a reduction in the false positive rate and unnecessary investigations, while maintaining a high sensitivity to detect cardiac diseases associated with a high risk of SCA/SCD in athletes ≤35 years, mainly cardiomyopathies, ion channelopathies and congenital accessory pathways. ECG interpretation standards have been modified several times, leading to the most recently published International Criteria, ⁴ but all the consensus standards recognize the low sensitivity of resting ECG to detect CAD,^4–7 which is the cause of most SCA/SCD cases in athletes older than 35 years. Existing consensus standards include criteria which consider as either borderline or abnormal, ECG patterns (T wave inversion, pathological Q waves, ST segment depression, left or right bundle branch block, abnormal R wave progression, left anterior hemiblock, and atrial fibrillation) that may suggest underlying CAD, but are mainly recommended for screening young athletes in whom CAD is rare.^4–7

Ventricular arrhythmias may also be a sign of underlying cardiac disease, more frequently related to cardiomyopathies or primary electrical abnormalities, and in middle-aged athletes also with CAD. According to most recent consensus standards, ≥2 premature ventricular contractions (PVCs) in a 10 s resting ECG tracing should be considered as an abnormal finding and lead to further investigations (echocardiography, 24 h ECG monitoring and maximal exercise testing).^4,6,7 PVCs originating from the right or left ventricular outflow tract (infundibular) or distal left fascicle are considered more benign, if associated with a normal ECG. ⁴ By contrast, PVCs with a left bundle branch block and superior or intermediate axis seem to be more frequently associated with structural heart disease, at least in young athletes, and it has been suggested that should lead to extensive further evaluation, even in the presence of just one PVC in the resting ECG. Although Zorzi and colleagues found no difference in the prevalence and morphology of ventricular arrhythmias in the 12-lead 24 h ECGs of 134 healthy middle-aged athletes and 134 age-matched sedentary controls, the truth is that the prognostic significance of the different PVCs’ morphologies in middle-aged and older athletes is still not well known. ⁸

As no specific ECG interpretation criteria exist for master athletes, Panhuyzen-Goedkoop et al. ⁹ aimed to test the effectiveness of three sets of existing ECG standards (ESC-2005, ⁵ Seattle ⁶ and International criteria ⁴ ) to detect high-risk cardiac conditions (HRCCs) in a large sample of athletes (N = 2578) of >35 years screened from 2006 to 2010. The results of this cross-sectional study, published in the current issue, showed that 494 of the 2578 athletes (mean age 47.9 years) required further specialized cardiovascular evaluation (cardiac imaging, exercise testing, ECG Holter monitoring, etc.) due to initial screening (personal history, physical exam and 12-lead resting ECG) abnormalities.

While atrial enlargement (4.1%) and left ventricular hypertrophy (3.8%) were the most common ECG abnormalities when using the ESC-2005 or Seattle criteria, ST-segment deviation (2.6%) and T-wave inversion (2.2%) were most frequent when using the International criteria. At initial screening, ESC-2005 criteria were used to decide for further cardiovascular evaluation, and when compared with the other two standards, ESC-2005 showed the highest sensitivity, enabling to detect more HRCC (46, 1.8%) compared with Seattle (33, 1.4%) and International criteria (24, 1.3%). As expected in this age group of athletes, CAD (24, 0.9%) was the most frequently detected HRCC.

This is a novel and interesting study as there are no specific ECG interpretation criteria for the growing group of active individuals >35 years old, with higher prevalence of CAD and therefore higher cardiovascular risk. Moreover, until specific ECG standards for master athletes are developed, proving that the existing criteria developed using studies performed with athletes ≤35 years old may be used when screening athletes older than 35 years will surely be of help for clinicians assessing this growing group of middle-aged active individuals.

The main limitations of the study are related to being retrospective and to where just one of the three ECG interpretation criteria sets (ESC-2005) was used to select those individuals that needed further cardiovascular evaluation at the initial screening. This aspect certainly questions the validity of the calculated specificity of the Seattle and International criteria in this study with master athletes.

As mentioned by the authors in the discussion, prospective multicentric studies including a mid- to long-term follow-up of large groups of middle-aged athletes are needed, for a more precise assessment of the predictive value of ECG findings in this age group of athletes. For instance, some of the conditions considered as borderline or even normal findings in young athletes, such as left ventricular hypertrophy, J point elevation, right and left atrial enlargement, and complete right bundle branch block, may be more frequently associated with cardiac disease in master athletes. The presence of symptoms, a positive family history, abnormalities in the physical exam and/or a high risk SCORE, will help in assessing the predictive value of these ECG findings. ¹⁰

Further studies with a prospective design would also benefit from including more female master athletes, as well as master athletes of other ethnicities, with a higher prevalence of HRCC and higher incidence of SCA/SCD.