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Heart Rhythm. 2017 May;14(5):654-660. doi: 10.1016/j.hrthm.2017.02.005. Epub 2017 Feb 9.

Electrocardiographic intervals associated with incident atrial fibrillation: Dissecting the QT interval.

Author information

1
Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, Western University, London, Ontario, Canada. Electronic address: jason.roberts@lhsc.on.ca.
2
Epidemiological Cardiology Research Center, Wake Forest University School of Medicine, Winston Salem, North Carolina.
3
Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, Georgia.
4
Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California.
5
Cardiovascular Division, University of Minnesota Medical School, Minneapolis, Minnesota.
6
Department of Epidemiology, University of North Carolina, Chapel Hill, North Carolina.
7
Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, California. Electronic address: greg.marcus@ucsf.edu.

Abstract

BACKGROUND:

Prolongation of the QT interval has been associated with an increased risk of developing atrial fibrillation (AF), but the responsible mechanism remains unknown.

OBJECTIVES:

The aims of this study were to subdivide the QT interval into its components and identify the resultant electrocardiographic interval(s) responsible for the association with AF.

METHODS:

Predefined QT-interval components were assessed for association with incident AF in the Atherosclerosis Risk in Communities study using Cox proportional hazards models. Hazard ratios (HRs) were calculated per 1-SD increase in each component. Among QT-interval components exhibiting significant associations, additional analyses evaluating long extremes, defined as greater than the 95th percentile, were performed.

RESULTS:

Of the 14,625 individuals, 1505 (10.3%) were diagnosed with incident AF during a mean follow-up period of 17.6 years. After multivariable adjustment, QT-interval components involved in repolarization, but not depolarization, exhibited significant associations with incident AF, including a longer ST segment (HR 1.27; 95% confidence interval [CI] 1.14-1.41; P < .001) and a prolonged T-wave onset to T-wave peak (T-onset to T-peak) (HR 1.13; 95% CI 1.07-1.20; P < .001). Marked prolongation of the ST segment (HR 1.31; 95% CI 1.04-1.64; P = .022) and T-onset to T-peak (HR 1.36; 95% CI 1.09-1.69; P = .006) was also associated with an increased risk of incident AF.

CONCLUSION:

The association between a prolonged QT interval and incident AF is primarily explained by components involved in ventricular repolarization: prolongation of the ST segment and T-onset to T-peak. These observations suggest that prolongation of phases 2 and 3 of the cardiac action potential drives the association between the QT interval and AF risk.

KEYWORDS:

Arrhythmia; Atrial fibrillation; Electrocardiography; Epidemiology; QT interval

PMID:
28189824
DOI:
10.1016/j.hrthm.2017.02.005
[Indexed for MEDLINE]

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