Prolonged ventricular repolarization → increased risk of ventricular arrhythmias
Males >440-450 ms
Females >500 ms
Rule of thumb: Normal<unk>  interval is less than half of preceding RR interval<unk>  interval is from the beginning of the Q wave to the end of the T wave
Rate dependent and should become proportionately shorter with increasing heart rate
Males >440-450 ms
Females >500 ms
Rule of thumb: Normal<unk>  interval is less than half of preceding RR interval
Rate dependent and should become proportionately shorter with increasing heart rate
Antiarrhythmics
Amiodarone, disopyramide, dofetilide, flecainide, ibutilide, mexiletine, procainamide, quinidine, sotalol
Antibiotics
Macrolide
Azithromycin, erythromycin, clarithromycin
Fluoroquinolone
Ciprofloxacin, gatifloxacin (most common), gemifloxacin, levofloxacin, moxifloxacin, ofloxacin
Other
Pentamidine, telithromycin, trimethoprim-sulfamethoxazole
Antidepressants
Amitriptyline, citalopram, doxepin, fluoxetine, nortriptyline, paroxetine, sertraline, venlafaxine
Antiemetics
Dolasetron, droperidol, granisetron, ondansetron
Antifungals
Fluconazole, itraconazole, ketoconazole, voriconazole
Antihypertensives
Nicardipine
Antineoplastics
Lapatinib, nilotinib, sunitinib, tamoxifen
Antimalarials
Chloroquine, halofantrine
Antipsychotics
Chlorpromazine, clozapine, galantamine, haloperidol, lithium, paliperidone, pimozide, quetiapine, risperidone, thioridazine, ziprasidone
Antivirals
Amantadine, atazanavir, foscarnet
Diuretics
Indapamide
Immune suppressants
Tacrolimus
Opiates
Methadone
Phosphodiesterase inhibitors
Sildenafil, Vardenafil
Skeletal muscle relaxants
Tizanidine
Urinary antispasmodics
Solifenacin
Amiodarone, disopyramide, dofetilide, flecainide, ibutilide, mexiletine, procainamide, quinidine, sotalol
Macrolide
Azithromycin, erythromycin, clarithromycin
Fluoroquinolone
Ciprofloxacin, gatifloxacin (most common), gemifloxacin, levofloxacin, moxifloxacin, ofloxacin
Other
Pentamidine, telithromycin, trimethoprim-sulfamethoxazole
Azithromycin, erythromycin, clarithromycin
Ciprofloxacin, gatifloxacin (most common), gemifloxacin, levofloxacin, moxifloxacin, ofloxacin
Pentamidine, telithromycin, trimethoprim-sulfamethoxazole
Amitriptyline, citalopram, doxepin, fluoxetine, nortriptyline, paroxetine, sertraline, venlafaxine
Dolasetron, droperidol, granisetron, ondansetron
Fluconazole, itraconazole, ketoconazole, voriconazole
Nicardipine
Lapatinib, nilotinib, sunitinib, tamoxifen
Chloroquine, halofantrine
Chlorpromazine, clozapine, galantamine, haloperidol, lithium, paliperidone, pimozide, quetiapine, risperidone, thioridazine, ziprasidone
Amantadine, atazanavir, foscarnet
Indapamide
Tacrolimus
Methadone
Sildenafil, Vardenafil
Tizanidine
Solifenacin
QT prolongation
Cardiovascular-mediated syncope
T wave changes
Dysrhythmias:
ST segment elevation
WPW 
ST segment depression
Long QT Syndrome/QT prolongation