QT Prolongation and In-Hospital Ventricular Arrhythmic Complications in Patients With Apical Ballooning Takotsubo Syndrome.

BACKGROUND

Takotsubo syndrome is associated with life threatening arrhythmias, and the apical ballooning pattern is characterized by a peculiar QT prolongation and particularly high-risk of arrhythmias.

OBJECTIVES

The aim of the study was to determine the association of QT interval on electrocardiogram for ventricular arrhythmic complications in patients with apical ballooning Takotsubo syndrome in a diverse population at a large urban hospital in the U.S.

METHODS

We reviewed 105 cases of apical ballooning Takotsubo syndrome in patients admitted between 2011 and 2017. Two cardiologists reviewed the electrocardiograms to measure QT interval, adjusted for rate using the Fridericia formula (QTCF), and ventricular arrhythmic complications during the hospitalization. Data are reported as median and interquartile range or number and percentage.

RESULTS

Of the 105 patients, 86 (82%) were female, and 34 (32%) were self-reported Black or African American. The mean age was 65 years (range: 58-72 years). Left ventricular ejection fraction was 25% (range: 25%-35%). Heart rate was 101 beats/min (range: 83-121 beats/min). Ten (11%) patients experienced a ventricular arrhythmic complication and had significantly longer QTCF (470 [range: 422-543] milliseconds) than did those without complications (417 [range: 383-456] milliseconds, P = 0.031). The area under the curve for QTCF was 0.708 (95% CI: 0.536-0.880; P = 0.031). Twenty-eight (27%) patients had a QTCF ≥460 milliseconds and significantly more arrhythmic complications (21% vs 5%, odds ratio 4.997 [95% CI: 1.288-19.237], P = 0.021). QTCF was an independent predictor of ventricular arrhythmias: odds ratio 1.090 for each 10-millisecond increase in QTCF (95% CI: 1.004-1.183; P = 0.040, corrected for sex).

CONCLUSIONS

In a diverse population of patients with apical ballooning Takotsubo syndrome admitted to a large urban hospital in the United States, QTCF at admission ≥460 milliseconds identifies patients at high risk for in-hospital arrhythmic complications. Further studies are needed to determine strategies aimed at shortening QT interval to potentially prevent life-threatening arrhythmic events.