Delivered by Ingenta to: Guest User IP: 79.110.19.163 On: Sun, 26 Jun 2016 01:54:31 Copyright: Aerospace Medical Association Aviation, Space, and Environmental Medicine x Vol. 83, No. 11 x November 2012 1055 RESEARCH ARTICLE B OOS CJ, J AMIL Y, P ARK M, M OY W, K HANNA V, T IMPERLEY AC, S HARMA S. Electrocardiographic abnormalities in medically screened military aircrew. Aviat Space Environ Med 2012; 83:1055–9. Background: The European Society of Cardiology (ESC) recently pub- lished its updated recommendations for electrocardiogram (ECG) inter- pretation 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 disor- ders 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. Methods: This was a prospective observa- tional study. The 12-lead ECGs of 868 consecutively evaluated healthy aircrew were analyzed for the presence of ESC-defined group 1 and 2 abnormalities. Results: 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. Conclusions: The vast majority of ECGs performed in military aircrew could be classified as representing likely normal physiological changes. Training unrelated ECG changes, sugges- tive of possible genuine cardiac pathology, were observed in only a minority of persons who should be considered for further investigation. Keywords: screening, ECG, military, sudden cardiac death. C ARDIAC DISEASE IS the leading cause of nontrau- matic sudden death among both civilian and military populations (6,11,17). In those .35-40 yr old these events most commonly relate to underlying atherosclerotic cor- onary artery disease (11). However, in younger persons 35 yr the majority of deaths are nonatherosclerotic and unexplained (with structurally normal hearts on autopsy) in at least a third of cases, or secondary to several well- recognized often inherited cardiac abnormalities, such as hypertrophic and arrhythmogenic right ventricular cardiomyopathy (6,8,17). It is currently unknown whether many of these deaths might have been prevented by the inclusion of a 12-lead electrocardiogram (ECG) as part of the screening process in these populations (5,7). Con- sequently, the issue of ECG screening among sports par- ticipants has been the subject of considerable debate (5,7,10). It is now well recognized that a significant pro- portion of individuals with underlying cardiac disease are asymptomatic, yet exhibit detectable abnormalities on a surface ECG (2,24). Unfortunately, in many circumstances their very first clinical presentation may be with sudden cardiac death (19). The inclusion of a 12-lead ECG has been shown to sig- nificantly improve the detection of cardiac disease over history and examination alone in both civilian and mili- tary populations (1,8,23). The screening of large num- bers of individuals to prevent one rare event is generally deemed financially and administratively prohibitive (5,13). Given the potentially disastrous consequences of failing to identify important silent cardiac disease, cer- tain occupations such as military aircrew mandate the 12-lead ECG as a part of their standard medical evalua- tion and surveillance (12,20,21). Several previous studies have investigated the preva- lence of ECG abnormalities among groups of military personnel, including aircrew (14,15,26). Their findings have, however, been undermined by a lack of consensus in the definitions of an ECG abnormality and its potential significance. Moreover, it can be very difficult to confi- dently distinguish the ECG changes induced by physi- cal training and exercise from genuine pathological ECG changes associated with serious underlying cardiac dis- ease, particularly the inherited cardiomyopathies (8,23). In an attempt to overcome these issues, a Working Group of the European Society of Cardiology (ESC) has recently published their Consensus Recommendations on 12-lead ECG interpretation in athletes (9). This study seeks, for the first time, to prospectively apply the new ESC ECG interpretation guidelines to the routine screening of ap- parently fit UK military aircrew in order to investigate the prevalence of training vs. apparent training-unrelated abnormalities. From the Centre of Postgraduate Medical Research & Education, Bournemouth University, Bournemouth, UK; and the Department of Cardiology, Poole Hospital NHS Foundation Trust, Poole, Dorset, UK; the Aviation Medicine Wing, Centre of Aviation Medicine, Royal Air Force, Henlow, Bedfordshire, UK; and St. George’s Healthcare NHS Trust, London, UK. This manuscript was received for review in December 2011. It was accepted for publication in June 2012. Address correspondence and reprint requests to: Christopher J. Boos, M.D., Consultant Cardiologist, Poole Hospital NHS Founda- tion Trust, Poole, Dorset BH15 2JB, UK; christopherboos@hotmail.com or christopher.boos@poole.nhs.uk. Reprint & Copyright © by the Aerospace Medical Association, Alexandria, VA. DOI: 10.3357/ASEM.3276.2012 Electrocardiographic Abnormalities in Medically Screened Military Aircrew Christopher J. Boos, Yasmin Jamil, Mirae Park, Wayland Moy, Vikram Khanna, Andy C. Timperley, and Sanjay Sharma