부산대학교 도서관

Variations in the dispersion of ventricular repolarization can be quantified by T-wave time-warping based index, $d_w$. However, the early phase of the T-wave can be affected by ST-segment changes during ischemia. We hypothesized that restricting $d_{w}$ to the T-wave peak-to-end ($T_{pe}$) would circumvent this limitation while still quantifying variations in repolarization dispersion. A total of 101 ECG recordings from patients undergoing coronary occlusion, together with their control recordings, were analyzed. A series of $d_{w}$ values was calculated by quantifying the $T_{pe}$ morphological variations between the T-waves at different occlusion stages and a baseline T-wave. We introduced a normalized version of $d_w$, $\mathcal {R}_d$, reflecting variations of $d_w$ during occlusion relative to control recordings ($\mathcal{R}_d = 1$ corresponds to the same level of variation). The $d_w$ series followed a gradually increasing trend with occlusion time, reaching median [range] $\mathcal {R}_d$ values of 9.44 [1.01, 80.74] at the occlusion end. $\mathcal {R}_d$ at occlusion end was significantly higher than threshold values of 1, 2, 5, and 10 in 94.1%, 85.11%, 64.4% and 48.5% of patients, respectively. The spatial lead-wise analysis of $d_w$ showed distinct distributions depending on the occluded artery, suggesting a relation with the ischemia location. The relative variation $\mathcal {R}$ with ischemia of index $d_w$ (9.4) is greater than that of the T-wave amplitude (7.7), $T_{pe}$ interval (2.7) and T-wave width (3.0). In conclusion, $d_w$ tracks ischemic-induced variations in repolarization dispersion in a more robust manner than classical indexes, avoiding the impact of ST segment elevation/depression or early T-wave distortions, thus warranting further clinical studies.