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Table G-1 QT Interval Interpretation

Risk Factors for TdP: female, structural heart disease, age >70y (or children), electrolyte disturbances (↓ K+, ↓ Mg++, ↓ Ca++), bradycardia, multiple QT-prolonging agents, IV administration or high doses of QT-prolonging drug, increased concentration of QT-prolonging drugs (↓ metabolism 2/2 drug interactions or disease state), baseline QT prolongation (CNS Drugs 2011; 25:473; N Engl J Med 2004;350:1013; N Engl J Med 2003;348:1866)

Table G-2 Psychotropic Medications Effect on QT Interval
Table G-3 Nonpsychotropic QT-Prolonging Agents

  • >450ms ♂; >470ms ♀: correct reversible causes, discontinue offending agents if possible
  • >500ms or prolongation >60ms: correct reversible causes; stop offending agents & refer to cardiologist

ECG Recommendations

(CNS Drugs 2011;25:473; Int Clin Psychopharmacol 2005;20:243; Am J Psychiatry 2001; 158:1774)

  • Consider prior to initiating new psychotropic medication with known cardiac toxicity/QT prolongation; repeat annually
  • Prior to initiating new psychotropic medication with known cardiac toxicity in pts with CV risk factors; consider repeat ECG at steady state
  • Cardiovascular symptoms indicative of QT prolongation or TdP (ex: palpitations, dizziness, syncope)

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