QT interval prolongation in Takotsubo syndrome: a frightening feature with no major prognostic impact

Abstract

Despite the frequent and often severe repolarization abnormalities seen in Takotsubo syndrome (TTS), the underlying mechanism of life-threatening arrhythmias is incompletely understood, and the risk remains uncertain. TTS is considered a potential cause of acquired long QT syndrome; however, there is no robust evidence that QT prolongation has a major prognostic impact on these patients’ outcomes. Our aim was to assess the prevalence and clinical implications of acquired long QT during TTS events and compare in-hospital and long-term outcomes between patients with and without corrected QT interval (QTc) prolongation. This is a retrospective cohort study that included 113 patients admitted to our tertiary care hospital with a diagnosis of TTS. The cohort was divided into two groups: a long QTc group (QTc≥460 milliseconds in any electrocardiogram at admission or during hospitalization) and a normal QTc group. Baseline characteristics, occurrences during hospitalization, and outcome data were obtained from the revision of medical registries and hospital visits. Of the 113 patients, 107 (94.7%) were female. The mean age was 67.6±11.7 years. QTc prolongation was found in 38%. Demographic characteristics, relevant chronic medication, prevalence of cardiovascular risk factors, and other comorbidities were similar between the groups, except for history of atrial fibrillation, which was more common in the long QTc group. Syncope was more prevalent in the long QTc group. In-hospital complications were not statistically different between patients with long and normal QTc (48.8% versus 44.2%, p=0.637), including ventricular arrhythmias and complete atrioventricular block (both 4.7% versus 1.4%, p=0.556). In-hospital mortality was 0.9%, corresponding to one patient in the long QTc group. The mean follow-up time was 4.8±3.8 years. 5-year all-cause mortality and the occurrence of the composite endpoint of major adverse cardiac and cerebrovascular events did not differ between the groups (p=0.511 and p=0.538, respectively). Our study found no association between prolonged QTc interval during TTS events and adverse prognosis, since in-hospital and long-term outcomes were similar between the groups. Our findings suggest that, although QT prolongation is usually a frightening feature on ECG, this repolarization abnormality during the acute phase has no major prognostic implications in the TTS population.

Keywords

• Takotsubo cardiomyopathy
• QT interval
• long QT
• ventricular arrhythmias
• prognosis