Electrocardiographic abnormalities in medically screened military aircrew

The European Society of Cardiology (ESC) recently published its updated recommendations for electrocardiogram (ECG) interpretation in athletes. It distinguishes ECG changes related to physical training (group 1 abnormalities) from training-unrelated changes (group 2) which may represent underlying electrical and structural heart disorders implicated in exercise related sudden cardiac death. This study sought to prospectively apply the ESC screening criteria to a large cohort of screened military aircrew.

This was a prospective observational study. The 12-lead ECGs of 868 consecutively evaluated healthy aircrew were analyzed for the presence of ESC-defined group 1 and 2 abnormalities.

The average age was 39.6 (11.2) yr (95.4% male). Overall, 402 (46.3%) of ECGs could be classified as entirely normal. However, 466 ECGs (53.7%) were abnormal. Group 1 abnormalities were identified in 400 (46.1%) persons with 66 (7.6%) persons classified as having group 2 abnormalities. The most commonly identified group 1 ECG changes were sinus bradycardia (32.5%), early repolarization (11.8%), and isolated voltage criteria of left ventricular hypertrophy (10.1%). The most commonly noted group 2 abnormalities were left-axis deviation/left anterior hemiblock (2.4%), T-wave inversion (1.6%), and ST-segment depression (1.3%). Prolongation of the QTC > 0.46 s was observed in 0.69% of ECGs.

The vast majority of ECGs performed in military aircrew could be classified as representing likely normal physiological changes. Training unrelated ECG changes, suggestive of possible genuine cardiac pathology, were observed in only a minority of persons who should be considered for further investigation.