Background International recommendations for interpreting the athlete’s ECG define a short PR interval as <120ms. Despite the recommendation that asymptomatic athletes do not require further investigation unless an accessory pathway is suspected, athletes are not infrequently referred for further evaluation. The prevalence of a short PR in athletes has not previously been reported.
Purpose To investigate the prevalence of short PR in young athletes and its association with age, gender and ethnicity.
Methods Between 2011–2014, 15,572 athletes aged 14–35 underwent cardiac screening including an ECG. An athlete was defined as an individual participating in sport ≥6hrs/wk. ECGs were analysed by 2 independent experts. Athletes in whom the PR interval was not fixed were excluded. A short PR was defined as <120ms.
Results Amongst 15,572 athletes (mean age 18.6 years, 92% white, 80% male), the mean PR interval was 151msec and shorter in females vs. males, white vs. non-white and adolescent (≤16 years) vs. older (17–35 years) athletes (table 1).
An isolated short PR was present in 765 (4.9%) athletes and was more common in females vs. males (6.2% vs. 4.2%; p<0.0001) (figure 1). The prevalence of short PR in athletes reduced significantly with advancing age, present in 9% of 14 year olds but only 3.2% of 17–35 year olds (p<0.0001). The prevalence of short PR was similar between ethnic groups (4.7% white vs 4.2% non-white; p=0.55). The overall prevalence of the Wolff-Parkinson-White pattern was 0.08%.
Conclusions A short PR interval is a fairly frequent finding in this cohort with a predilection for younger and female athletes. Possible explanations for shorter conduction time include anatomically smaller hearts, higher sympathetic tone or enhanced resting AV node conduction. The high frequency of short PR in young athletes suggests that in the absence of an accessory pathway or symptoms its presence should not prompt further investigation. Long-term follow-up studies are required in order to draw definitive conclusions.
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