Coronary Artery Bypass Grafting Is Associated with a Significant Worsening of QT Dynamicity and Heart Rate Variability

Abstract

Background: Imbalance in autonomic nervous system and impaired myocardial repolarization has been shown to increase the risk for arrhythmias in patients with coronary artery disease. This study evaluated the effects of coronary artery bypass grafting (CABG) on heart rate variability and QT interval dynamicity in subjects with coronary artery disease undergoing elective CABG surgery. Methods: The study group consisted of 68 consecutive patients (mean age ±SD: 61 ± 9 years) with coronary artery disease who underwent elective CABG. Twenty-four-hour Holter monitoring was performed 2–5 days before cardiac surgery and was repeated 10 days after CABG. ELATEC holter software was used to calculate heart rate variability and QT dynamicity parameters. All subjects had a complete history, laboratory examination and transthoracic echocardiography. Results: All patients had beta-blocking agent medication pre- and postoperatively. Standard deviation of all NN intervals for a selected time period, square root of the mean of the sum of the squares of differences between adjacent RR intervals, the proportion of differences in successive NN intervals greater than 50 ms, normalized low-frequency power, and normalized high-frequency power were significantly decreased after CABG surgery, whereas low-frequency/high-frequency ratio was significantly increased after CABG. QT/RR slopes over 24 h were significantly increased after CABG surgery for QT end and QT apex (QTapex/RR: 0.16 ± 0.13 vs. 0.28 ± 0.19, p < 0.001; QTend/RR: 0.18 ± 0.13 vs. 0.36 ± 0.23, p < 0.001). Conclusion: This prospective study showed for the first time that CABG was associated with a significant worsening of heart rate variability and QT dynamicity parameters in the postoperative period.

Journal

Journal ID (publisher-id): CRD

Journal ID (nlm-ta): Cardiology

Journal ID (doi): 10.1159/issn.0008-6312

Title: Cardiology

Publisher: S. Karger AG

ISSN (Print): 0008-6312

ISSN (Electronic): 1421-9751

Publication date Subscription-year: 2006

Publication date (Print): June 2006

Publication date (Electronic): 03 July 2006

Volume: 106

Issue: 1

Pages: 51-55

Affiliations

Departments of ^aCardiology and ^bCardiothoracic Surgery, Hacettepe University Faculty of Medicine, Ankara, Turkey

Article

Publisher ID: 92599 Other ID: Cardiology 2006;106:51–55

DOI: 10.1159/000092599

PubMed ID: 16612069

Copyright statement: © 2006 S. Karger AG, Basel

License:

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Page count

Figures: 1, Tables: 5, References: 19, Pages: 5

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Categories

Subject: Original Research