Clinical significance of abnormal electrocardiographic patterns in trainedathletes

Background-The prevalence, clinical significance, and determinants of abnor mal ECC patterns in trained athletes remain largely unresolved. Methods and Results-We compared ECG patterns with cardiac morphology (as as sessed by echocardiography) in 1005 consecutive athletes (aged 24 +/- 6 yea rs; 75% male) who were participating in 38 sporting disciplines. ECG patter ns were distinctly abnormal in 145 athletes (14%), mildly abnormal in 257 ( 26%), and normal or with minor alterations in 603 (60%). Structural cardiov ascular abnormalities were identified in only 53 athletes (5%). Larger card iac dimensions were associated with abnormal ECG patterns: left ventricular end-diastolic cavity dimensions were 56.0 +/- 5.6, 55.4 +/- 5.7, and 53.7 +/- 5.7 mm (P < 0.001) and maximum wall thicknesses were 10.1 +/- 1.4, 9.8 +/- 1.3, and 9.3 +/- 1.4 mm (P < 0.001) in distinctly abnormal, mildly abno rmal, and normal ECGs, respectively. Abnormal ECGs were also most associate d with male sex, younger age (<20 years), and endurance sports (cycling, ro wing/canoeing, and cross-country skiing). A subset of athletes (5% of the 1 005) showed particularly abnormal or bizarre ECG patterns, but no evidence of structural cardiovascular abnormalities or an increase in cardiac dimens ions. Conclusions-Most athletes (60%) in this large cohort had ECGs that were com pletely normal or showed only minor alterations. A variety of abnormal ECG patterns occurred in 40%; this was usually indicative of physiological card iac remodeling. A small but important subgroup of athletes without cardiac morphological changes showed striking ECG abnormalities that suggested card iovascular disease; however, these changes were likely an innocent conseque nce of long-term, intense athletic training and, therefore, another compone nt of athlete heart syndrome. Such false-positive ECGs represent a potentia l limitation to routine ECG testing as part of preparticipation screening.