The Electrocardiographic Conundrum in a Patient on Methadone Maintenance Therapy and Cannabis Coingestion: A Case Report of a Heartbreaking Puzzle.

Methadone is considered relatively safe when compared to other opioids. Methadone, however, can cause respiratory depression and QT prolongation. Among patients on methadone maintenance therapy, the rate of cannabis use is high. Multiple hypotheses, including the 'exit hypothesis' or 'the cannabis association with reduced opioid use,' need validation and further research. In this article, we present an interesting case of a 29-year-old female on methadone maintenance therapy for fifteen years who presented with methadone toxicity likely induced by systemic infection and cannabis co-ingestion. The patient had multiple cardiotoxic effects, including prolonged QT interval managed by antiarrhythmic medications, ST-segment elevation, and stress-induced cardiomyopathy managed conservatively. In this case report, the authors want to highlight the possible effects of methadone and cannabis co-injection, methadone toxicity induced by systemic infections, and increased awareness of these potentially catastrophic cardiotoxic effects in patients on high-dose methadone maintenance therapy.