Unexpected overdose with diltiazem: value of toxicological screening

We describe a 59-year-old woman who was admitted in deep coma with bradycardia, hypotension and fixed pupils. The cause of her severe condition was unclear. Cerebral and myocardial infarction was excluded. Temporary transcutaneous pacing was not successful, nor was atropine or norepinephrine (noradrenaline), but the patient responded well to isoprenaline infusion. Since she was known to have a psychiatric history, toxicological screening was performed which showed a severe diltiazem overdose. Later we discovered that she took diltiazem for angina pectoris. The patient survived and was discharged without neurological or cardiological deficits after two days of treatment. This case report emphasises the importance of toxicological screening in unconscious patients with no apparent cause. We review the clinical features and treatment options of diltiazem overdose and discuss the value of toxicological screening.