A resting heart rate greater than 100 beats per minute indicates tachycardia, or rapid heartbeat, notes Mayo Clinic. The normal resting heart rate for healthy adults is 60 to 100 beats per minute. Tachycardia normally results from abnormalities in the electrical signals in the heart.
Tachycardia may cause an uncomfortable racing feeling in the chest, chest pain, lightheadedness and shortness of breath, notes Mayo Clinic. Dizziness and fainting may also occur during episodes of tachycardia. Although some instances of tachycardia are benign, causing no complications or symptoms, the condition can cause serious disruptions in heart function, heightening the risk of stroke or even causing sudden cardiac arrest.