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.