Clinical, electrocardiographic, and laboratory findings in children with amitriptyline intoxication

Abstract

Background: Amitriptyline is one of the major tricyclic antidepressants, and the data on amitriptyline poisoning in children are limited. Objectives: To present our experiences with amitriptyline poisoning in children, particularly with regard to its effects on electrocardiogram (ECG) and relation with clinical status.

Methods: Clinical, laboratory, and electrocardiographic findings in 52 children admitted with amitriptyline poisoning were reviewed. Patients were divided into 2 groups according to age, as 6 years or younger (group A) and older than 6 years (group B).

Results: Mean age was 4.6 +/- 3.0 years. Thirty-one patients were male, and 41 were 6 years or younger. Ingested amitriptyline dose was known in 23 patients (range, 2.3 mg/kg-27 mg/kg). The most frequent findings were lethargy (76.9%), sinus tachycardia (57.7%), and coma (48.1%). Four patients had a history of convulsion. The most common laboratory abnormalities were hyponatremia (26.9%) and leukocytosis (25%). Elevated transaminase levels were observed in 4 patients. In ECG, 11 (22.4%) patients had QTc prolongation and in 4 (8.2%) of them, it was significant. In 4 patients (8.2%), the QRS duration was 100 ms or longer and in 15 patients, the R wave in aVR was 3 mm or longer. The frequencies of clinical, laboratory, and electrocardiographic findings were similar between the 2 age groups (P > 0.05). No clinically apparent arrhythmias were observed. The positive predictive value of a widened QRS was 100% in terms of coma. None of the patients with an R wave in aVR of less than 3 mm developed convulsion; thus, the negative predictive value of an R wave in aVR of 3 mm or longer was 100% in terms of convulsion.

Conclusions: Amitriptyline poisoning may result in severe toxicity. Frequencies of clinical, laboratory, and ECG findings were similar in the 2 age groups. Amitriptyline overdose results in some ECG changes that can possibly help to predict the results of poisoning. Absence of an R wave in aVR of 3 mm or longer predicts seizures with a high negative predictive value, and a QRS duration of 100 or longer ms predicts coma with a high positive predictive value.