Temporal repolarization abnormality and ventricular arrhythmic risk in takotsubo syndrome

Abstract Background Abnormalities in the repolarization process are known to be associated with the development of ventricular arrhythmias (VAs). In takotsubo syndrome (TTS), repolarization abnormalities, such as prolongation of the QT interval, prolongation of the T-wave peak point–T-wave end point (Tpe) interval, and giant negative T waves, are observed in electrocardiograms performed during the acute phase. However, the temporal changes in these findings during long-term follow-up and their relationship to prognosis have not been fully evaluated. Purpose The aim of this study was to demonstrate the temporal changes in repolarization parameters and to evaluate the relationship between abnormal repolarization parameters and prognosis in TTS. Methods One hundred and thirty-six consecutive patients with TTS were retrospectively included in this study. A total of 1237 twelve-lead electrocardiograms, performed from the date of diagnosis (day 0) within one year, were analyzed. QT intervals and Tpe intervals were measured manually. The corrected QT (QTc) interval and corrected Tpe (cTpe) interval were calculated using Bazett’s formula. The maximum voltage of T-wave inversion in any lead (max TWI) was also measured for each electrocardiogram. The mean QTc, cTpe, and max TWI were calculated by day from day 0 to 15, and by defined periods after day 16 (as shown in the figure). In addition, the longest QTc intervals, longest cTpe intervals, and deepest max TWI during follow-up were compared between patients with and without VAs. Results Of the 136 patients, 95 (70%) were female, and their age was 71 ± 13 years. The left ventricular ejection fraction was 40 ± 12% at diagnosis. Double-peaked trajectories of the QTc interval, cTpe interval, and max TWI were clearly observed during the clinical course of TTS (Figure 1). The first peak of the QTc and cTpe intervals occurred on day 2. After the QTc and cTpe intervals shortened, they prolonged again and reached the second peak on day 14. After the second peak, the QTc and cTpe intervals gradually normalized during the 1-year follow-up (Figure 1A and 1B). The max TWI had the first peak on day 2 and the second peak on day 15 (Figure 1C). Six patients experienced VAs during follow-up; five patients had VAs at day 0, and one patient at day 2. The longest QTc interval tended to be higher (591 ± 65 vs. 543 ± 64, P = 0.075), and the longest cTpe interval was significantly higher (188 ± 36 vs. 147 ± 40, P = 0.013) in patients with VAs compared to patients without VAs, while there was no significant difference in the deepest max TWI between patients with and without VAs (-0.76 ± 0.35 vs. -0.93 ± 0.55, P = 0.455). Conclusions While double-peaked trajectories of the repolarization parameters were clearly observed during the clinical course of TTS, VAs occurred during in acute phase in all cases, suggesting that repolarization abnormalities around the first peak may be associated with the occurrence of VAs.Figure 1