If too-fast, too-slow, or skipped heartbeats resolve within a short period of time, they are unlikely to be serious. However, if you’ve noticed changes recently, or if your heartbeat frequently seems abnormal, see your healthcare provider. “Frequently” means having several unusual heartbeats in the space of a minute, or several that occur in groups of three or more. If an unusual heartbeat is accompanied by severe dizziness or loss of consciousness, it is a medical emergency: Call 911 immediately.