Epidemiological survey of ECG changes in early repolarization among healthy naval afloat personnel

Objective To investigate the incidence, distribution features and clinical significance of early repolarization among healthy naval afloat personnel, so as to provide evidence for medical evaluation. Methods 12-lead synchronous ECGs at rest and related medical evaluation data of 434 healthy afloat personnel were investigated. The subjects were divided into 2 groups in accordance with or without detection of early repolarization. Then, the data obtained were compared between the 2 groups. Results (1) Early repolarization was detected in 127 naval afloat personnel, with the incidence of early repolarization being 29.3% (127/434). Early repolarization waves were most commonly seen in inferior wall leads (Ⅱ, Ⅲ, aVF), accounting for 48.8% (62/127), which were followed by the inferolateral leads (Ⅱ, Ⅲ, aVF) and the left chest leads (V4-V6), accounting for 19.7% (25/127). Other kinds of lead combination were rarely seen. (2) The incidence of early repolarization was not closely related to either different age stages, or different types of vessels(P>0.05), but was more or less related to heart rates (χ2=5.17, P<0.05). The slower the heart rate, the higher the incidence of early repolarization. (3)With regard to the Heng typing of early repolarization, there were 6 cases in type 1 (4.7%), 25 cases in type 2 (19.7%), 3 cases in type 3 (2.4%), 58 cases in type 4 (45.7%), 6 cases type 5 (4.7%) and 29 cases in the mixed type (22.8%). (4) There were 126 cases of early repolarization with acclivitous ST-segment elevation (99.2%), and 1 case of horizontal ST-segment elevation (0.8%), with the amplitude of ST segment elevation being ≤0.20 mV. Conclusions Early repolarization was commonly seen among naval afloat personnel, with the abortive wave of low amplitude and narrow time limit as the most prevailing wave. In the Hengtyping, type 4 was the most prevailing, which was actually a common change in early repolarization of ECG, which would not result in malignant arrhythmia and cardiac sudden death clinically. But for those with obvious J wave (Heng type 1) or those with horizontal ST-segment, efforts should be made in close medical follow-ups and monitoring, so that malignant cardiac events could be prevented. Key words: Early repolarization; Morphological features; Hengtyping; Naval afloat personnel