First degree AV block in asymptomatic young individuals is a benign condition that does not warrant detailed invasive investigation or restriction on fitness to fly.
First degree A-V block, defined as prolongation of the PR interval on the surface electrocardiogram, is a not uncommon finding on electrocardiographic screening of asymptomatic young individuals. Prevalences of from 0.65% to 1.1% have been reported. In the majority of cases the PR prolongation may be rendered normal by autonomic intervention. Long-term follow-up studies have indicated that although the risk of subsequent coronary artery disease may be slightly increased, the risk of sudden death, syncope or advanced A-V block is not. Apart from the exclusion of organic heart disease, detailed invasive investigation is not warranted. It is a benign condition and as such no restriction on fitness to fly need be made on these individuals, but there may be a case for increased electrocardiographic scrutiny.
Bexton et al. (Mon,) studied this question.