LAUSR

OBJECTIVE In patients with ST-segment elevation myocardial infarction (STEMI), disturbed cardiac repolarization before percutaneous coronary intervention (PCI) is a risk factor for malignant ventricular arrhythmia. We tested the hypothesis that sleep-disordered breathing (SDB) in patients with STEMI is associated with disturbed cardiac repolarization. METHODS Thirty-three patients with STEMI who underwent PCI were prospectively enrolled. To assess cardiac repolarization, the heart-rate corrected interval from the peak of the T wave to the end of the T wave (TpTec) and QTc intervals were assessed with 12-lead electrocardiography before PCI, within 24 h after PCI, and 12 weeks after PCI. SDB defined as an apnea-hypopnea index (AHI) ≥15 per hour was diagnosed by polysomnography. RESULTS Before PCI, patients with SDB had a significantly prolonged TpTec interval compared to patients without SDB (133 vs 104 ms, p = 0.035). Within 24 h after PCI, the TpTec interval was 107 vs 92 ms (p = 0.178). QTc intervals showed a similar pattern (pre-PCI: 443 vs 423 ms, p = 0.199; post-PCI: 458 vs 432 ms, p = 0.115). In multiple linear regression analyses, AHI was significantly associated with prolonged TpTec intervals (pre-PCI: B-coefficient = 1.11, 95% confidence interval (CI) 0.48-1.74, p = 0.001; post-PCI: B = 0.97, 95% CI 0.29-1.65, p = 0.007), prolonged QTc intervals (pre-PCI: B = 1.05, 95% CI 0.20-1.91, p = 0.018; post-PCI: B = 1.37, 95% CI 0.51-2.24, p = 0.003), and higher TpTe/QT-ratios (pre-PCI: B = 0.16, 95% CI 0.05-0.27, p = 0.007; post-PCI: B = 0.13, 95% CI < 0.01-0.25, p = 0.036), independent of known risk factors for cardiac arrhythmia. CONCLUSION In patients with STEMI, SDB was significantly associated with disturbed cardiac repolarization before and after PCI, independent of known risk factors. These findings suggest that SDB may contribute to the risk of developing malignant ventricular arrhythmia.