Improving cardiac assessment and monitoring in methadone prescribing at an addiction service

The assessment and monitoring of cardiac risk in patients prescribed methadone is important for patient safety. Although uncommon, QTc interval prolongation is potentially life-threatening. Known risk factors for QTc prolongation include methadone, particularly at doses above 100 milligrams daily. This project aimed to improve the cardiac assessment and monitoring at Barnet Drug and Alcohol Service through raising the awareness of this clinically importance issue as well as through amending the medical assessment guidance to promote the comprehensive assessment of QTc prolongation risk factors and ensure the identification of cardiac risk in patients prescribed methadone. The project also provided guidance on QTc prolongation management and monitoring (including performance of an electrocardiogram) at the service to provide a baseline measurement and arrangement of annual monitoring. Prior to the intervention, a randomised sample of 26 patients that had been prescribed methadone revealed no comprehensive cardiac risk assessments. Analysing 52 medical assessments in the month following the intervention suggested an improvement in assessment and management of QTc interval prolongation risk, with seven comprehensive cardiac risks assessments performed and one patient having QTc interval prolongation identified following an electrocardiogram and appropriately managed. This project was limited by small sample sizes and the relatively low incidence of QTc prolongation. The poor rate of attendance for requested electrocardiograms in this population was noted as a challenge that needed further consideration.