All rights reserved. AbstractTricyclic antidepressant (TCA) drugs are well known medications for depression, nocturnal enuresis and chronic pain. The severe morbidity and mortality associated with these drugs is well documented due to their cardiovascular and neurological toxicity. The aim of this study is to predict the morbidity and mortality factors in patients with acute TCA toxicity in relation to outcome toxicity measures (coma grade, ECG findings and duration of hospitalization) and to detect early evidence of cardiotoxicity using quantitative analysis of Troponin I. The present study was conducted on 100 patients presented to the PCC of Ain Shams University hospitals during the period from October 2009 to March 2011 with acute TCA toxicity of both sex and different ages. Patients were divided into 3 groups according to poisoning severity score (PSS) into group I (mild toxicity), group II (moderate toxicity) and group III (severe toxicity). All subjects were examined for: I) sociodemographic data; II) medical evaluation; III) investigations including arterial blood gases, serum electrolytes (Na and K), random blood sugar, serum troponin I level and electrocardiography (ECG) monitoring; IV) outcome including coma grade, ECG findings and duration of hospitalization. Risk factors (sex, coingestion, time delay and previous attempts) had no effect on difference between groups, while age and mode of toxicity were significantly different (p-value <0.05) between groups. Type of TCA ingested had significant effect (p-value <0.05) on both coma grade and endotracheal intubation. The dose of TCA had a highly significant effect (p-value <0.0001) on severity of toxicity, coma grade and ECG findings. ADORA criteria (QRS interval >100 msec, cardiac dysrhythmias, altered mental status, seizures, respiratory depression and hypotension) had a high significant effect (p-value <0.0001) on ECG findings, coma grade and type of TCA ingested. The risk factors for intubation in the present study were evident in patients with dothiepin or amitriptyline ingestion, old age, abnormal ECG, deep coma, seizure and two or more ADORA criteria. ECG changes had no relation (P-value >0.05) with all risk factors except for the age and the mode of poisoning. Duration of hospitalization (DOH) had a highly significant (p-value < 0.001) relation with the severity of toxicity in the studied groups, ECG findings and coma grade. Grade of coma had no relation (P-value >0.05) with all risk factors except for the dose of TCA. Level of troponin I was non evident in predicting cardiotoxicity. Conclusion:Reed's coma scale is an indicator either for evaluation of poisoning severity in individual TCAs or for assessment of relative toxicity between different types of TCAs. ECG findings especially QRS duration is an easy, cheap and available diagnostic tool in Emergency Room (ER) to help not only in diagnosing TCA poisoning but also in predicting its severity and occurrence of other complications.