Rapid ventricular response, or RVR, is a serious complication of atrial fibrillation and requires medical treatment, according to Healthline. On its own, atrial fibrillation, sometimes abbreviated afib or AF, may or may not be a serious condition depending on its symptoms and complications.
In AF with RVR, abnormal electrical impulses cause the heart to beat in an abnormal rhythm, resulting in the heart's ventricles, or lower chambers, beating too fast. A patient experiencing atrial fibrillation with RVR typically has the sensation of a fluttering or overly rapid heartbeat, explains Healthline. RVR is dangerous because it causes the ventricles to fail to pump blood out of the heart sufficiently and can lead to a heart attack.