ECG abnormalities as predictors in Tricyclic antidepressant overdose
Date First Published:
July 12, 2005
Last Updated:
April 26, 2007
Report by:
Fawad Azam, Medical student (MRI)
Search checked by:
Tom Bartram, MRI
Three-Part Question:
In [Tricyclic antidepressant overdose] which [ECG abnormalities] are predictive of [seizures and arrythmias]
Clinical Scenario:
You are called to the emergency department following the arrival of a 23 year old male electrician who is suspected of ingesting 25 imipramine tablets. You are shown an ECG that was taken shortly after his arrival. You wonder which ECG abnormalities are predictive of complications.
Search Strategy:
MEDLINE 1966-April 2007 PubMed Interface
Search Details:
(Antidepressant or tricyclic or amitriptyline or dothiepin or nortriptyline or imipramine or desipramine or protriptyline or clomipramine or doxepin) and (overdose or poisoning or self poisoning or toxic) and (ecg or ekg or electrocardiogram)
Outcome:
237 studies were found, 1 recent Meta-Analysis and 1 review paper
Relevant Paper(s):
| Study Title | Patient Group | Study type (level of evidence) | Outcomes | Key results | Study Weaknesses |
|---|---|---|---|---|---|
| A meta-analysis of prognostic indicators to predict seizures, arrhythmias or death after tricyclic antidepressant overdose Bailey B. Buckley NA. Amre DK 2004 | Papers identified from Medline and Cochrane register for studies that investigated criteria for prediciting outcomes in TCA overdose. Papers assessed by 2 investigators. Studies included if possible to construct 2x2 table from TCA concentration or ECG abnormalities against clinical outcomes. The following diagnostic tests were evaluated (1)TCA concentration (2)QRS>0.10 seconds (3)QTc>430 ms (4)R/S ratio >0.7 (5)Right axis deviation of 120-270 degrees in the terminal 40ms frontal plane QRS vector |
Meta analysis | Number of Studies | 941 studies found, 18 studies were included in the review | Some studies excluded due to mixed outcomes |
| Pooled Sensitivity & Specificity to predict Death | QRS=0.81 & 0.62; QTc= 0.50 & 0.68; T40= 0.33 & 0.71 respectively | ||||
| Pooled Sensitivity & Specificity to predict Seizures | QRS=0.69 & 0.69; T40= 0.50 & 0.72 respectively | ||||
| Pooled Sensitivity & Specificity to predict Ventricular Arryhthmias | QRS=0.79 & 0.46; QTc= 0.78 & 0.56;T40= 0.33 & 0.71; R/S ratio= 0.47 & 0.97 respectively | ||||
| Positive & Negative Likelihood ratios for Death | QRS= 2.13 & 0.31; QTc= 1.56 & 0.74; T40= 1.14 & 0.94 respectively | ||||
| Positive & Negative Likelihood ratios for Seizures | QRS= 3.18 & 0.38; T40= 1.79 & 0.69 respectively | ||||
| Positive & Negative Likelihood ratios for Ventricular Arryhthmias | QRS=1.46 and 0.46; QTc= 1.77 & 0.39; T40= 1.14 & 0.94; QTc= 1.77 & 0.39; R/S ratio= 15.7 & 0.55 respectively | ||||
| Tricyclic antidepressant poisoning : cardiovascular toxicity. Thanacoody HK. Thomas SH. 2005 UK | review of known papers and studies regarding ECG changes in tricyclic overdose. including recent meta analysis and case reports. | Review | authors conclusion | QRS prolongation >100ms and Right axis deviation are the most reproducible predictors | Search strategy not included |
Author Commentary:
There are many studies and case reports of the ECG patterns seen in TCA overdose. These changes include prolonged QRS, QTc interval, right axis deviation, R/S ratio in lead aVR, Brugada pattern.The presence of any ECG changes suggests significant TCA overdose which may lead to cardiovascular or neurological sequalae. The studies assessing these changes as predictors of seizures and arrythmias are presented in the comprehensive review by Thanacoody et al. Although no search strategy is included I can find no additional useful papers.
Bottom Line:
The most reliable ECG predictors of seizure and arrhythmia are QRS prolongation >100ms and Right axis deviation.
References:
- Bailey B. Buckley NA. Amre DK. A meta-analysis of prognostic indicators to predict seizures, arrhythmias or death after tricyclic antidepressant overdose
- Thanacoody HK. Thomas SH.. Tricyclic antidepressant poisoning : cardiovascular toxicity.