| Acquired |
| Metabolic disorders |
| Hypokalemia |
| Hypomagnesemia |
| Hypocalcemia |
| Starvation |
| Anorexia nervosa |
| Liquid protein diets |
| Hypothyroidism |
| Bradyarrhythmias |
| Sinus node dysfunction |
| AV block - second or third degree |
| Antiarrhythmic drugs |
| Quinidine |
| Procainamide or N-acetylprocainamide |
| Disopyramide |
| Amiodarone |
| Sotalol |
| Dofetilide, ibutilide, azimilide, sematilide |
| Antimicrobial drugs |
| Erythromycin, clarithromycin, telithromycin, azithromycin (minor) |
| Pentamidine |
| Some fluoroquinolones (eg, sparfloxacin, gatifloxacin, levofloxacin, moxifloxacin) |
| Other - Spiramycin, chloroquine, halofantrine mefloquine |
| Antihistamines |
| Terfenadine |
| Astemizole |
| Psychotropic drugs |
| Thioridazine |
| Phenothiazines |
| Tricyclic or tetracyclic antidepressants |
| Haloperidol and other batyrophenones |
| Selective serotonin reuptake inhibitors |
| Risperidone |
| Methadone |
| Other drugs |
| Vasodilators - Prenylamine, bepridil, mibefradil |
| Diuretics - Via electrolyte changes (hypokalemia, hypomagnesemia) |
| Serotonin antagonist - Ketanserin |
| Motility drugs - Cisapride, domperidone |
| Droperidol - may be safe at the low doses used by anesthesiologists (0.625 to 1.25 mg) |
| Ranolazine |
| HIV protease inhibitors |
| Miscellaneous - Organophosphate insecticides, probucol, cocaine, terodiline, papaverine, certain Chinese herbs, chloral hydrate, arsenic trioxide, cesium chloride, levomethadyl |
| Other |
| Myocardial ischemia or infarction |
| Intracranial disease |
| HIV infection |
| Hypothermia |
| Connective tissue diseases with anti-Ro/SSA antibodies |
| Congenital |
| Jervell and Lange-Nielsen syndrome |
| Romano-Ward syndrome |
| Idiopathic |
