Younger adults commonly experience brief episodes of rapid heart rhythm caused by abnormal electrical circuits present from birth. During ablation, specialists guide small catheters into the heart and remove the tiny area responsible for triggering the abnormal rhythm. As people grow older, atrial fibrillation becomes much more common. Unlike occasional skipped beats, atrial fibrillation can allow blood to collect inside part of the heart, where clots may form. For this reason, many people with atrial fibrillation need blood-thinning medicine even if they undergo successful ablation.