Related Experiment Video
Updated: Apr 3, 2026

High-Resolution Endocardial and Epicardial Optical Mapping in a Sheep Model of Stretch-Induced Atrial Fibrillation
Published on: July 29, 2011
Time-Dependent Changes in QT Dynamics after Initiation and Termination of Paroxysmal Atrial Fibrillation
Yoshiaki Yamaguchi1, Koichi Mizumaki2, Kunihiro Nishida1
1Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, Toyama, Japan.
Background:
Little is known about time-dependent changes in QT dynamics after initiation of atrial fibrillation (AF) and after restoration of sinus rhythm (SR) in patients with paroxysmal AF.
Methods:
Beat-to-beat QT and RR intervals in CM5 lead were measured automatically in 13 patients with both AF and SR on the single 24-hour Holter electrocardiology recording. QT-RR relation was analyzed at six periods of time: 1 hour before AF onset (Pre(0-1h)), 0-1 hour and 4-5 hours after AF onset (AF(0-1h) and AF(4-5h)), and 0-1 hour, 2-3 hours, and 4-5 hours after the restoration of SR (SR(0-1h), SR(2-3h), and SR(4-5h)).
Results:
QT-RR slope was gradually decreased after AF onset and gradually returned to the baseline level after restoration of SR. The slope became greater at SR(4-5h) than at AF(4-5h) and AF(0-1h). In patients receiving antiarrhythmic drugs (AADs; n = 5), QT-RR slope was greater at SR(4-5h) than in those not receiving AADs (n = 8).
Conclusion:
In patients with paroxysmal AF, bradycardia-dependent QT prolongation was attenuated during AF, and was corrected and gradually augmented along with continuation of SR, especially in patients receiving AADs. This could increase the risk of developing torsade de pointes.
Related Concept Videos
Dysrhythmias III: Characteristics of Dysrhythmias
ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias
Dysrhythmias IV: Characteristics of Bradyarrhythmias
Disturbances in Heart Rhythm
Arrhythmias are categorized by their speed, rhythm, and origin. A slow heart...
Correlation between ECG and Cardiac Cycle
A cardiac action potential originates in the SA node and spreads throughout the atria and the AV node in approximately 0.03 seconds. This results in the P wave in an ECG and triggers atrial contraction. The action potential is then briefly slowed at the AV node, allowing the atria to contract and fill the ventricles with blood before...
Dysrhythmias II: Classification of Tachyarrhythmias

