Prevalence and severity of QT prolongation and other ECG abnormalities in takotsubo syndrome.

Background: The prevalence and severity of QT interval prolongation (long QT, LQT) in takotsubo syndrome (TS) is not well described.

Methods: This is a retrospective cohort study of all patients admitted in our Centre between January 2019 and December 2023 with confirmed TS. QT interval corrected for heart rate (QTc) (Bazzett formula) was measured manually in all available ECGs. Presence of other ECG abnormalities (T-wave inversion (TWI), ST segment elevation (STE), ST segment depression (STD)) were also recorded.

Results: Fifty-eight patients were included, all women (68 ± 11 years). Fifty-six patients (96.6 %) had classical, apical ballooning form of TS. Symptoms included chest pain (93.1 %), dyspnoea (10.3 %), and others (5.2 %). Triggers were present in 70.7 % of patients. Three-hundred-and-thirty ECGs were analysed. LQT was infrequent in the first 3 h after symptom onset (23.5 % of patients), and was only mild. However, between 24 and 48 h after symptom onset, 90.9 % of patients developed LQT, which was severe (≥500 ms) in 63.6 % of patients. LQT prevalence decreased afterwards but QTc did not return to normal in 40.0 % of patients, and remained severely prolonged in 11.4 % of patients beyond 96 h. ECG was normal in 40.5 % of patients in the first 6 h. TWI was the predominant ECG change, and its prevalence increased from 16.7 % within the first 6 h to 76.9 % after 7 days. STE was present in 31.4 % of patients in the first 96 h, but was rare in isolation. Isolated STD did not occur.

Conclusion: LQT is almost universally seen in patients with TS within the first 96 h after symptom onset, and is severe in the majority. ECGs abnormalities in TS are highly dynamic, but ECGs are frequently normal in the first 6 h after symptom onset. Patients should be monitored for at least 96 h after symptom onset, and until QTc falls below 500 ms.