| Life threatening cardiac conditions |
| Arrhythmia (eg, Wolff-Parkinson-White syndrome, prolonged QT syndrome, cardiac structural abnormalities [congenital heart disease, intracardiac tumors]) |
| Hypertrophic cardiomyopathy (HCM) |
| Myocarditis |
| Sick sinus syndrome |
| Pacemaker malfunction |
| Life threatening non-cardiac conditions |
| Hypoglycemia |
| Toxic exposure |
| Pheochromocytoma |
| Common conditions |
| Premature atrial contractions |
| Premature ventricular contractions |
| Fever |
| Anemia |
| Exercise |
| Emotional arousal |
| Anxiety, panic attack |
| Hyperventilation syndrome |
| Drug-induced (caffeine, herbal medications, dietary supplements, albuterol, isotretinoin) |
| Postural orthostatic tachycardia syndrome (POTS) |
| Other conditions |
| Acute rheumatic fever with valvular disease |
| Hyperthyroidism |
| Mitral valve prolapse |
