Atrial fibrillation carries a risk of clot forming in the chamber of the heart because the blood flows 'more slowly' with the irregularity. Bits of the clot can fly off to the lungs so we normally anticoagulate these patients. Ectopics are not thought to have this risk - primarily because for most of the time the heart beat (or heat beat!!!) is 'normal' and the ectopic is just an 'extra' beat.
Recently there has been a suggestion than some people with loads of ectopics may in fact have paroxysmal atrial fibrillation, but for the present the risk is small or zilch - two quite different conditions