QT-Prolonging Drugs Often Given To At-Risk Inpatients

NEW ORLEANS — Nearly 40% of a large series of patients with a known preexisting long QT interval received an order for a QT-prolonging medication while hospitalized, thereby increasing their risk for sudden cardiac death.

Further, at-risk patients rarely underwent monitoring for further widening of the QT interval. Indeed, 8% had an ECG within 48 hours after starting the new QT-prolonging medication, Dr. Ravi K. Mareedu reported at the annual scientific sessions of the American Heart Association.

This is a situation fraught with potential for iatrogenic injury, according to Dr. Mareedu of the Medical College of Wisconsin, Milwaukee. A possible solution: adoption of automated hospital prescribing interventions that trigger formal surveillance protocols when QT-prolonging drugs are used in patients with a known long QT interval.

Dr. Mareedu reported on 1,586 inpatients with 2,616 ECGs showing a prolonged QT that was specifically noted in the ECG report. During 3,258 hospital admissions, 599 of these patients (38%) received an order for any of 34 known QT-prolonging medications generally considered contraindicated in the setting of a long QT interval. Two-thirds of these patients were in critical care units at the time.

Antiarrhythmic agents accounted for more than half of all prescriptions for QT-prolonging medications, with amiodarone leading the way. Another 30% were for haloperidol. There were 115 orders for erythromycin and other QT-prolonging antimicrobials, 82 for methadone, and 97 orders for chlorpromazine and other antinausea drugs.