Aims:
Premature ventricular contractions (PVCs) are thought to be innocent in children with normal hearts, especially if they disappear during exercise. The aim of our study was to study the natural history of PVCs in childhood and whether there is a difference between PVCs originating from the right [premature ventricular contraction with left bundle branch block (PVC-LBBB)] or the left ventricle [premature ventricular contraction with right bundle branch block (PVC-RBBB)].

Methods and Results:
We evaluated children with frequent PVCs and anatomically normal hearts (n=59; 35M/24F) by 12-lead ECG, echocardiography, Holter recording, and an exercise test. Age at the first visit was 7.1±4.3 years (mean±SD), and follow-up was 3.1±3.1 years. We could evaluate each child for 2.5±1.5 times. Premature ventricular contraction with left bundle branch block was seen in 41% of the children; PVC-RBBB in 36%; and undetermined in 23%. Mean percentage PVCs in the Holter recording decreased (14.3±13.7% in the age group 1–3 years to 4.8±7.2% in the age group ≥16 years; P=0.08). Mean percentage PVC-LBBB did not change (12.3±21.4 vs. 11.7±5.5%), whereas PVC-RBBB decreased (16.3±4.2 to 0.6±1.4%; P<0.02).

Conclusion:
We conclude that there is a difference in the natural history between PVC-LBBB and PVC-RBBB in children with an anatomically normal heart. Premature ventricular contraction with right bundle branch block disappears during childhood. Follow-up of these children seems not necessary. Premature ventricular contraction with left bundle branch block does not disappear and, therefore, it may be necessary to follow these children even during adulthood.