Introduction: Methadone is known to prolong the QT interval, which could induce lethal arrhythmias such as torsades de pointes. To determine the risk of ventricular arrhythmias in cancer patients using methadone, we measured QT dispersion (QTD) and Tpeak-Tend (TpTe) before and after methadone administration and evaluated the correlations between methadone dosage and cardiac repolarization. Methods: We conducted a retrospective observational study with 19 patients undergoing follow-up for cancer pain with methadone. Electrocardiogram (ECG) recordings were obtained from the patients at methadone initiation and 1 week, 1 month, and 2 months later. The QT, corrected QT (QTc), QTD, QTc dispersion (QTcD), TpTe, TpTe/QT, and TpTe/QTc were measured manually via ECG records and analyzed using a repeated measures one-way ANOVA. The correlations between these ECG parameters and each methadone dosage were determined using Spearman's rank correlation coefficient. Results: The QTD, QTcD, TpTe/QT, and TpTe/ QTc remained unchanged, while TpTe was prolonged significantly at 2 months (initiation: 82 ± 17 ms; 2 months: 106 ± 20 ms, p = 0.018). In addition, there was a positive correlation between TpTe and methadone dosage (rs = 0.4, p = 0.041). Conclusions: The findings suggested that small or modest doses of methadone could exert dosedependent effects on cardiac repolarization in cancer patients.

Introduction: Transcatheter aortic valve implantation (TAVI) has been established as an alternative to surgical aortic valve replacement (SAVR) for high-risk patients. To assess the impact of TAVI on cardiac repolarization, we compared QT dispersion (QTD) and the interval from the peak to the end of the T wave (Tpeak-Tend: TpTe) between the patients who underwent TAVI and those who underwent SAVR and TpTe between the patients who underwent TAVI or SAVR. Methods: This retrospective study was approved by the ethics committee of Dokkyo Medical University Hospital. The study included 45 patients who underwent TAVI and 45 patients who underwent SAVR. The QT, corrected QT (QTc), QTD, QTc dispersion (QTcD), Tp-Te, Tp-Te/QT, and Tp-Te/QTc were manually measured in standard 12-lead electrocardiogram (ECG) recordings obtained before surgery, immediately after surgery, 1 month, 3 months, and 6 months after surgery and compared between the two groups. Results: No change was observed in RR, QT, QTc, Tp-Te, Tp-Te/QT, and Tp-Te/QTc in the two groups throughout the study. The QTD and QTcD significant decreased immediately after surgery in the TAVI group as compared to the SAVR group (P \ 0.001). In contrast, QTD and QTcD in the SAVR group gradually, but not significantly declined 6 months after surgery. Conclusions: QTD and QTcD immediately decreased after TAVI as compared to SAVR. Our findings indicate that TAVI more rapidly improved dispersion of spatial repolarization than SAVR.