Dynamic changes of QTc interval and prognostic significance in takotsubo (stress) cardiomyopathy

Background Prolonged QT corrected (QTc) intervals are associated with adverse cardiovascular outcomes both in healthy and high‐risk populations. Our objective was to evaluate the QTc intervals during a takotsubo cardiomyopathy (TTC) episodes and their potential prognostic role. Hypothesis Dynamic changes of QTc interval during hospitalization for TTC could be associated with outcome at follow‐up. Methods Fifty‐two consecutive patients hospitalized for TTC were enrolled. Twelve‐lead electrocardiogram (ECG) was performed within 3 h after admission and repeated after 3, 5, and 7 days. Patients were classified in 2 groups: group 1 presented the maximal QTc interval length at admission and group 2 developed maximal QTc interval length after admission. Results Mean admission QTc interval was 493 ± 71 ms and mean QTc peak interval was 550 ± 76 ms ( P  < 0.001). Seventeen (33%) patients were included in group 1 and 35 (67%) patients in group 2. There were no differences for cardiovascular risk factors and in terms of ECG findings such as ST elevation, ST depression, and inverted T waves. Rates of adverse events during hospitalization among patients of group 1 and 2 were different although not significantly (20% vs 6%, P  = 0.22). After 647 days follow‐up, patients of group 1 presented higher risk of cardiovascular rehospitalization (31% vs 6%, P  = 0.013; log‐rank, P  < 0.01). At multivariate analysis, including age and gender, a prolonged QTc interval at admission was significantly associated with higher risk of rehospitalization at follow‐up (hazard ratio: 1.07 every 10 ms, 95% confidence interval: 1.003‐1.14, P  = 0.04). Conclusions Prolonged QTc intervals at admission during a TTC episode could be associated with a higher risk of cardiovascular rehospitalization at follow‐up. Dynamic increase of QTc intervals after admission are characterized by a trend toward a better prognosis.