Is QT interval a marker of subclinical atherosclerosis in nondiabetic subjects? The Insulin Resistance Atherosclerosis Study (IRAS).
OBJECTIVE
We studied the relationship of heart rate-corrected QT interval with subclinical atherosclerosis, as determined by ultrasonographic measurement of carotid intima-media thickness (IMT) in nondiabetic subjects in the Insulin Resistance Atherosclerosis Study (IRAS). Prolonged heart rate-corrected QT interval is an unfavorable prognostic factor of cardiovascular morbidity and mortality, and QT interval prolongation may be the result of atherosclerosis.


METHODS
B-mode ultrasound imaging of the carotid artery IMT was performed in a large, triethnic, nondiabetic population free of clinical coronary artery disease (n=912). QT interval was measured on resting electrocardiograms with use of a computer program and corrected for heart rate with standard equations.


RESULTS
IMT of the common carotid artery correlated significantly with heart rate-corrected QT interval duration (r=0.15 for QT(60) and r=0.14 for QTc), whereas no relationship between IMT of the internal carotid artery and QT interval was found (r=-0.01). The association was somewhat stronger in women than in men. In a multiple regression analysis adjusting for demographic variables, the association of common carotid artery IMT to heart rate-corrected QT interval remained highly significant, but adjustment for cardiovascular risk factors weakened the relationship.


CONCLUSIONS
We found a significant relation of heart rate-corrected QT interval to carotid atherosclerosis in nondiabetic subjects that was stronger in women and partly mediated by cardiovascular risk factors, including hypertension. QT interval may therefore serve as a marker for clinically undetected ("subclinical") atherosclerotic disease.
Festa
A
A
Department of Medicine, Division of Clinical Epidemiology, University of Texas Health Science Center at San Antonio, USA. festa@uthscsa.edu
D'Agostino
R
R
Rautaharju
P
P
O'Leary
D H
DH
Rewers
M
M
Mykkänen
L
L
Haffner
S M
SM
D001161:Arteriosclerosis / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D044383:Black People; D001786:Blood Glucose / Q000378:metabolism; D002340:Carotid Artery Diseases / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D004562:Electrocardiography; D005260:Female; D005951:Glucose Tolerance Test; D006339:Heart Rate; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D017395:Plasminogen Activator Inhibitor 1 / Q000097:blood; D011379:Prognosis; D012737:Sex Factors; D011795:Surveys and Questionnaires; D014280:Triglycerides / Q000097:blood; D044465:White People
D001786:Blood Glucose; D007328:Insulin; D017395:Plasminogen Activator Inhibitor 1; D014280:Triglycerides