When QTc Shrinks After Rhythm Conversion

Authors

• Mohammed Hussein Kamareddine, Thomas Jefferson University
• Alyssa Zakala, Thomas Jefferson University
• Farid Farkouh
• Ibrahim Alameh
• Gan-Xin Yan, Thomas Jefferson UniversityFollow

Document Type

Report

Publication Date

5-20-2026

Comments

This article is the author’s final published version in JACC: Case Reports, Volume 31, Issue 20, 2026, Article number 107936.

The published version is available at https://doi.org/10.1016/j.jaccas.2026.107936. Copyright © 2026 The Authors.

Abstract

CASE SUMMARY: An 83-year-old man with a history of atrial fibrillation on amiodarone therapy was admitted for direct-current cardioversion because of recurrent atrial fibrillation with a ventricular rate of approximately 105 beats per minute. Cardioversion successfully restored sinus rhythm. Postcardioversion 12-lead electrocardiography revealed an unexpectedly short QTc of 344 ms despite chronic treatment with a QT-prolonging agent. This finding was attributed to QT hysteresis, reflecting delayed adaptation of ventricular repolarization to the abrupt reduction in heart rate after rhythm conversion.

TAKE-HOME MESSAGE: QT hysteresis can result in transient QTc shortening and has important implications for interpretation of QT intervals during antiarrhythmic therapy.

Recommended Citation

Hussein Kamareddine, Mohammed; Zakala, Alyssa; Farkouh, Farid; Alameh, Ibrahim; and Yan, Gan-Xin, "When QTc Shrinks After Rhythm Conversion" (2026). Department of Medicine Faculty Papers. Paper 571.
https://jdc.jefferson.edu/medfp/571

Creative Commons License

This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

PubMed ID

42165479

Language

English