Cannabis showed no repolarization change, but fQRS was higher

BACKGROUND: This study aimed to compare the electrocardiographic (ECG) depolarization and repolarization parameters among patients with cannabis use disorder (CUD), methamphetamine use disorder (MUD), and healthy controls (HC). METHODS: This retrospective cross-sectional study included 63 patients with CUD, 63 with MUD, and 63 age-matched male HC's recruited from a substance addiction treatment center. Standard 12-lead ECGs were obtained within the first hour of admission. Parameters assessed included QTc, QT dispersion (QTcd), JTc, JT dispersion (JTcd), Tp-e interval, Tp-e/QTc ratio, P-wave dispersion (PWD), frontal QRS-T angle, frontal QRS axis, heart rate, and fragmented QRS (fQRS). RESULTS: The MUD group demonstrated significantly prolonged QTc, QTcd, and JTcd values compared to both CUD and HC groups (all p < 0.001). ROC analysis identified JTcd as the most discriminative parameter for methamphetamine use disorder (AUC=0.718), outperforming QTc (AUC=0.682) and QTcd (AUC=0.676). Heart rate was significantly elevated in the MUD group compared to CUD (p = 0.008). Cannabis users showed no significant differences in repolarization parameters compared to HCs; however, fQRS prevalence was significantly elevated in both the CUD (14.3%) and MUD (17.5%) groups relative to HCs (1.6%, p = 0.011), suggesting subclinical myocardial structural abnormalities in both groups. DISCUSSION: These findings indicate that methamphetamine use is associated with substantial ventricular repolarization disturbances, with JTcd emerging as the most sensitive ECG marker. Although cannabis did not affect repolarization parameters, elevated fQRS prevalence points to potential subclinical myocardial injury. Routine ECG assessment is warranted in patients with substance use disorders.