(004) Creation of a Mobile-based Application to Assess Risk of Psychiatric Medications in the Setting of Prolonged QTc Interval.

Abstract:

Background:

Consultation-Liaison (CL) psychiatrists frequently provide consultation for patients prescribed psychotropic medications who have complex cardiopulmonary disease, including prolonged QTc interval and risk for fatal ventricular arrhythmias, like torsades de pointes (TdP). CL Psychiatrists routinely utilize QTc measurements, along other risk factors, to inform risk-benefit analysis when recommending psychotropic medications known to prolong QTc. In order to assess the risk of certain psychotropic medications, the literature suggests relying on EKG parameters not routinely available on automated EKG interpretations. For example, in conditions where a ventricular conduction delay results in a widening of the QRS interval, different methods of correcting the QT interval are required. However, the methods most supported by the literature require complex calculations, limiting their clinical utility especially during behavioral emergencies, as there were no application based or online calculators that offer these formulas. (Funk et al, 2021)

Method:

Using the Calconic online interactive calculator platform, we created an online calculator that provides the CL psychiatrist with a point-of-care assessment of the QTc interval. This calculator includes the Hodges formula for correcting QTc; Hodges is thought to provide more accurate rate correction than the more commonly available Bazett formula which can overestimate QTc in tachycardic patients. (Beach et al, 2018). In addition, the calculator identifies prolonged QRS intervals and offers four methods for correction: the Bogossian formula with Hodges correction for QTc, the Rautaharju formula for QTc, corrected JT interval (JTc) and the JT prolongation index (JTi). The calculator is optimized for mobile devices, but can be accessed by any web browser (tinyurl.com/QTcCal). We present three cases derived from our clinical experiences to demonstrate the utility of the calculator.

Cases:

#1: Patient taking methadone and QTc -Bazett prolongation in setting of elevated heart rate. The online calculator recalculates the QTc interval using the Hodges correction supports a recommendation to continue methadone.

#2: Patient on aripiprazole and QTc-Bazett prolongation in setting of widened QRS interval. The online calculator corrects for heart rate and widened QRS interval with multiple formulas, the results which support a recommendation to continue aripiprazole.

#3: Acute agitation and QTc-Bazett prolongation in an elderly patient. The online calculator corrects for heart rate and widened QRS; however, with these corrections, the risk of TdP remained elevated and the clinician recommends using intravenous valproate for agitation instead of antipsychotics.

Conclusion:

The interactive online calculator is an effective, point-of-care tool to assist CL psychiatrists in assessing the arrhythmia risk of QTc prolonging medication, including antipsychotics in medically ill patients.

References:

Beach SR, Celano CM, Sugrue AM, et al. QT Prolongation, Torsades de Pointes, and Psychotropic Medications: A 5-Year Update. Psychosomatics. 2018;59 (2):105-122.

Funk MC, Beach SR, Bostwick JR, et al. QTc Prolongation and Psychotropic Medications. Am J Psychiatry. 2020;177(3):273-274.