Red flags Certain findings suggest a more serious etiology: Light-headedness or syncope (particularly if injury occurs from syncope) Chest pain Dyspnea New onset of irregularly irregular heart rhythm Heart rate > 120 beats / minute or < 45 beats / minute while at rest Significant underlying heart disease Family history of recurrent syncope or sudden death Exercise-induced palpitations or, particularly, syncope Interpretation of findings History (see table Suggestive Historical Findings in Patients With Palpitations) and, to a lesser extent, physical examination provide clues to the diagnosis.