Analysis of 24-h Rhythm in Ventricular Repolarization Identifies QT Diurnality As a Novel Clinical Parameter Associated with Previous Ventricular Arrhythmias in Heart Failure Patients

Figure 1. Flowchart of retrospective analyses. LVEF, Left Ventricular Ejection Fraction; ICD, Implantable Cardioverter/Defibrillator; LQTS2, Long QT Syndrome Type 2; PVI, Pulmonary Vein Isolation; SVT, Supraventricular Arrhythmia; VT/VF, Ventricular Tachycardia/Ventricular Fibrillation.

Figure 2. Depicted is a 24-h rhythm in QT of one of the patients. From hourly averages, an optimal fitting cosine curve with a period of 24-h was calculated. 24-h average, peak time, and diurnality were derived from this curve.

Figure 3. Comparison of 24-h Holter parameters in post-infarct systolic heart failure patients subdivided in two groups based on history of ventricular arrhythmias. In arrhythmia patients, QT(c) diurnality (QTd and QTcd, respectively) were two-fold higher compared to non-arrhythmia controls. VT/VF, Ventricular Tachycardia/Ventricular Fibrillation. *p < 0.05 vs. no arrhythmia.

Figure 4. 24-h QT and QTc diurnality (QTd and QTcd, respectively) is higher in patients using Sotalol compared to the same patients without anti-arrhythmic drugs. Red line indicates average of all subjects. *P < 0.05 for difference between no Sotalol and Sotalol.

Figure 5. Comparison of 24-h Holter parameters between controls, Sotalol users, and LQTS2 patients. QT and QTc diurnality are increased in Sotalol users and LQTS2 patients. *indicates p < 0.05 compared to controls.