Electrocardiographic criteria for tricyclic antidepressant cardiotoxicity

Am J Cardiol. 1986 May 1;57(13):1154-9. doi: 10.1016/0002-9149(86)90691-0.


To determine if electrocardiographic findings characterize tricyclic antidepressant (TCA) overdose and cardiotoxicity, 25 patients suspected of taking an overdose of TCA were studied. Toxicologic assays for a TCA were positive in 11 patients (+TCA, n = 11). Toxicologic study results for a TCA were negative in 14 patients (-TCA, control subjects). Patients with positive TCA results (+TCA) had a significantly greater heart rate (117 +/- 23 vs 100 +/- 22 beats/min, p less than 0.05), QRS duration (103 +/- 15 vs 87 +/- 10 ms, p less than 0.005) and corrected QT interval (449 +/- 38 vs 418 +/- 36 ms, p less than 0.05) than control patients (-TCA) on admission. Patients with positive TCA results also had a more rightward terminal 40-ms frontal plane QRS vector (195 +/- 51 degrees vs 54 +/- 64 degrees, p less than 0.001) than control patients. This observation has not been previously reported. A terminal QRS vector of 130 degrees to 270 degrees accurately discriminated between -TCA and +TCA patients (positive and negative predictive value = 1.00). Counterclockwise rotation (normalization) of the terminal frontal plane QRS vector was noted in +TCA patients during hospitalization. All +TCA patients had a sinus tachycardia, a corrected QT interval 418 ms or longer, and a terminal QRS vector between 130 degrees and 270 degrees. Using these values as selection criteria, a computer-aided search of 15,064 electrocardiograms (ECGs) recorded in our emergency department was performed. The likelihood of encountering such an electrocardiographic pattern in this population was 1.0%.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Antidepressive Agents, Tricyclic / poisoning*
  • Computers
  • Diagnosis, Differential
  • Diagnostic Errors
  • Electrocardiography / methods*
  • Heart / drug effects*
  • Heart / physiopathology
  • Humans


  • Antidepressive Agents, Tricyclic