Adverse cardiac events in ICU patients with presumptive antidepressant overdose

BACKGROUND: Antidepressants account for most poison-related admissions to intensive care units. In selected patients with confirmed cyclic antidepressant intoxication a QRS interval <0.1 s in the ECG limb leads during the first six hours excludes adverse cardiac events. However, the incidence of cardiac events and the value of ECG criteria have never been assessed prospectively on patients with presumed antidepressant overdose. AIM: To assess ingested drugs, adverse cardiac events, and ECG findings in ICU patients with a presumptive diagnosis of antidepressant overdose. METHODS: 103 consecutive patients with a presumptive diagnosis of antidepressant overdose were enrolled and prospectively followed. Outcome criteria were arrhythmias, mortality, and duration of the ICU stay. RESULTS: Mixed intoxication was identified in 66 (64%) patients. Tricyclic antidepressants were found in 88 (85%), and serotonin-reuptake inhibitors in 25 (24%) patients. Mean APACHE II score was 9.5 (SD +/- 6.0). Arrhythmias affected 15 (15%) and cardiopulmonary resuscitation was performed on 4 (4%) patients. Three patients (3%) died in the ICU. Median duration of the ICU stay was 1 day (12 hours to 6 days). Adverse cardiac events affected patients with normal and prolonged QRS interval at study entry. CONCLUSIONS: Mixed intoxication is present in most ICU patients with suspected antidepressant overdose. There is a considerable risk for adverse cardiac events, even in the presence of normal ECG recordings within the first six hours after hospital admission.