ECG interpretation using criteria designed specifically for athletes will reduce the number of athletes wrongly suspected of having an underlying cardiac pathology that could put them at risk of sudden cardiac death.

In an editorial published in Heart Lung and Circulation this week Professor Andre La Gerche, head of sports cardiology at the Baker Institute, and colleagues said athletic screening to detect asymptomatic cardiomyopathies that could be triggered by exercise is on the rise – a practice largely driven by health insurers and professional sporting associations fearful of being the ‘outlier sport that has not endorsed screening when one of their athletes dies on the field.’

But concerns about the high false-positive rate when applying standard ECG interpretation criteria to ECGs taken from athletes means the practice could be doing more harm than good.

As many as 30% of athletes are being identified as ‘abnormal’ on existing ECG interpretation criteria, Professor La Gerche and colleagues noted.

That’s because those criteria don’t take into account the normal changes in the healthy hearts of athletes that are common – and usually benign – as a result of their physiological adaption to exercise, the editorial points out.

The emotional and financial toll of an abnormal ECG finding can be significant, they said — especially when it turns out to be wrong.

The tests can set off false alarms that can lead to a cascade of invasive follow-up tests and risky interventions or can force some athletes to quit sports unnecessarily.

According to the editorial about one million athletes with an abnormal ECG will be subjected to additional testing, concern and potential sporting exclusion in the goal of preventing three deaths.

And even then, the awareness of an underlying cardiac pathology may not necessarily prevent a life being lost, the authors added.

New International Criteria that provide athlete-specific guidance on screening for cardiomyopathies reported by the limbic were released earlier this year.

Red, yellow, green

Those criteria have been refined into a “traffic light” approach to interpreting ECGs for athletes – features in the green are normal for an athlete, those in the red should be considered abnormal and signal further evaluation while a ‘‘yellow light” can be normal in isolation or abnormal if there are multiple features present.

The new guidelines provide stricter criteria for most ECG abnormalities.

For example, recognising that T-wave inversion in V1 and V2 is very common among endurance athletes, the new criteria require T-wave inversion to extend to V3 before being considered ‘‘positive” and a trigger for further investigation.

Meanwhile some criteria that were previously considered abnormal have been moved to the yellow category of ‘‘borderline findings” like a right axis deviation coupled with a right bundle branch block, for instance.

 Some pathologies will be overlooked

The authors concede that it ‘stands to reason’ that some pathology will be overlooked as a result of making the criteria for an abnormal ECG in athletes more stringent.

For example, as many as 11% of patients with arrhythmogenic right ventricular cardiomyopathy have T-wave inversion confined to V1 and V2, the authors noted and these patients would be missed with the new criteria.

It’s an acceptable compromise, they argued, given these findings – abnormalities among the general population – are extremely common amongst athlete populations.

It’s important to recognise, too that the ECG will not be able to detect anomalous coronary arteries, premature coronary atherosclerosis, and aortopathies which are important causes of sudden cardiac death in athletes, and may also miss early stages of cardiomyopathies, they added.

Abnormalities pointing to possibly increased sudden-death risk in the new criteria include:

• T wave inversion
• ST segment depression
• Pathologic Q waves
• Complete LBBB
• QRS ≥ 140 ms duration
• Ventricular pre-excitation
• Prolonged QT interval
• Brugada Type 1 pattern
• Profound sinus bradycardia < 30 bpm
• PR interval ≥ 400 ms
• Mobitx Type II 2° AV block
• 3° AV block
• ≥ 2 PVCs
• Atrial tachyarrhythmias
• Ventricular arrhythmias

According to Professor La Gerche and colleagues, the International Criteria represent a current ‘gold standard’ for ECG assessment in athletic populations with proven ability to reduce the number of athletes incorrectly suspected of having an underlying cardiac pathology.

But, the authors also said, while these advances can be expected to minimise the morbidity associated with false positives, speculation will persist as to whether they will also save lives.

“The debate regarding the merits of screening athletes will persist. In many respects, practice is being defined by insurers and bureaucrats as much as it is informed by best evidence … Athletic screening is rapidly becoming a reality and, if screening is to be performed, then it is essential that it is done well.

Screening should be performed using these new International Criteria by cardiologists (or other suitably trained medical practitioners) with expertise in ECG interpretation … only then can screening be performed with minimal potential to cause harm