QT Prolongation and Clinical Outcomes in Patients with Takotsubo Cardiomyopathy

Takotsubo cardiomyopathy (TCM) has been associated with repolarization abnormalities including QT prolongation and acquired long QT syndrome. However, the association between QT prolongation and clinical outcomes in patients with TCM remains unclear. The aim of this study is to examine the association between QT prolongation and ventricular arrhythmias, cardiogenic shock, and death in patients with TCM.

Forty-six patients with TCM met our inclusion criteria in an ongoing prospective cohort database from 2010 to May 2015. We assigned the patients to a long QT group or a normal QT group, and created a composite outcome consisting of ventricular arrhythmias, cardiogenic shock, or death.

The mean age of the participants was 59.7 ± 16 years, 67% were women, and 63% had hypertension. Median follow-up time was 3.1 years (interquartile range: 2.0-3.8), with a total of 133.8 person-years. The mean left ventricular ejection fraction at diagnosis was 27.2% ± 1.4%. The mean QTc on diagnosis was 484 ms ± 10.2 ms for men, and 488 ms ± 8.6 ms for women. The long QT group had a 4.1-times higher odds of having the composite clinical outcome as compared to the normal QT group (95% confidence interval: 1.1, 16.1, P = 0.04) after adjusting for age and race in logistic regression.

Patients with TCM who have a long QT interval or develop acquired long QT syndrome due to TCM may be more likely to be intubated; require vasopressors; and develop shock, ventricular arrhythmias, and death than those with a normal QT interval.