The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene is expressed in the heart, but this is not known to cause myocardial dysfunction or abnormalities in the ECG in people with CF. CFTR modulators such as tezacaftor/ivacaftor improve lung function and overall health in people with CF. Minor adverse events have been reported in the early clinical trials, but no consistent changes in the ECGs have been reported. This case highlights an unusual side effect of first degree heart block that occurred after more than 8 months of azithromycin and tezacaftor/ivacaftor in combination. Drug withdrawal and reintroduction confirmed that neither drug alone, but only the combination, caused this change. As tezacaftor/ivacaftor is also present in elexacaftor/tezacaftor/ivacaftor, care may be needed to exclude this delayed interaction with azithromycin.

中文翻译：

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阿奇霉素和 tezacaftor/ivacaftor 与患有囊性纤维化的成人的一级心脏传导阻滞有关

囊性纤维化跨膜电导调节器 (CFTR) 基因在心脏中表达，但目前尚不清楚这会导致 CF 患者的心肌功能障碍或心电图异常。tezacaftor/ivacaftor 等 CFTR 调节剂可改善 CF 患者的肺功能和整体健康。在早期临床试验中报告了轻微的不良事件，但没有报告心电图的一致变化。这个案例突出了在阿奇霉素和 tezacaftor/ivacaftor 联合使用超过 8 个月后发生的一级心脏传导阻滞的不寻常副作用。药物停药和重新引入证实，这两种药物都不是单独的，而是组合引起了这种变化。由于 tezacaftor/ivacaftor 也存在于 elexacaftor/tezacaftor/ivacaftor 中，