Review of electrocardiogram ordering in the context of prescribing combinations of known QT prolonging medicines

Type of funding sources: None.

The risk of medication-induced QT prolongation can be mitigated by reviewing electrocardiograms (ECG) in a hospital inpatient setting. Currently, within the Electronic Medical Record (EMR), decision support tools do not exist to conduct ECG monitoring when prescribing multiple QT prolonging medications. This retrospective review of prescribing data from 2021 looked to assess if we are appropriately ordering ECGs. The results could potentially guide developing decision support tools within the EMR to influence the prescribing of QT-prolonging medications and reduce the risk of QT-prolongation in hospitalised patients.

To ascertain the prevalence of baseline and follow-up ECGs when three or more known QT prolonging medications were concurrently administered.

QT prolonging medications were defined using Crediblemeds [1], an online resource aimed to support the safe prescribing of QT prolonging medications. Known QT prolonging medications were defined as medications which prolong the QT interval and are associated with Torsades de Pointes. A retrospective review of inpatient prescribing in 2021 was conducted by extracting data from the EMR. Patients who received three or more of these medications on the same calendar day were included. Information reported included patient demographics, details of QT prolonging medication and whether ECGs were performed. Certain intra-operative medications were excluded from review due to the short patient exposure time to the medication. ECGs were reviewed independently by two pharmacists and the QTc interval was calculated using the Bazett formula.

A total of 70 patients received three or more QT prolonging medications. In total, 30 (43%) patients had a baseline ECG performed within seven days of medication commencement and 6 (9%) patients received both a baseline and follow-up ECG within 24 hours of medication administration. One patient had a prolonged QTc (>500msec) on their baseline ECG. Baseline ECGs were not performed in 29 (41%) of patients whereas Eleven patients (16%) had an ECG on record, but it was older than seven days prior to medication administration. Three patients without a baseline ECG had a follow-up ECG within 24 hours after medication administration. Overall, 28 different medications were identified with Ondansetron, Ciprofloxacin and Escitalopram appearing most commonly.

This audit indicates that clinicians are not consistently ordering ECGs at baseline or utilising follow up ECGs when prescribing concurrent QT prolonging medications which may increase the risk of preventable patient harm. Though QT prolongation was not detected on follow-up ECGs, this may be impacted by the low prevalence of follow-up ECGs. The utilisation of decision support tools within the EMR may improve ECG monitoring in patients at risk of QT prolongation.