Relation of systemic blood pressure, left ventricular mass, insulin sensitivity, and coronary artery disease to QT interval duration in nondiabetic and type 2 diabetic subjects☆

https://doi.org/10.1016/S0002-9149(00)01170-XGet rights and content

Abstract

A prolonged QT interval has been identified as a risk factor for cardiovascular disease; however, knowledge about etiologic factors is limited. We studied determinants of QT interval duration in the Insulin Resistance Atherosclerosis Study, a large, triethnic population (n = 1,577) with varying degrees of glucose tolerance. In particular, we sought to investigate the relation of QT interval with blood pressure (BP), left ventricular (LV) mass, estimated using electrocardiographic criteria, and insulin sensitivity, directly measured by a frequently sampled intravenous glucose tolerance test. QT interval was measured electronically on electrocardiograms at rest and corrected for heart rate using standard equations. The QT interval was related to various components of the insulin resistance syndrome, including BP and insulin sensitivity. Multivariate analyses showed that BP and LV mass were the main determinants of the QT interval in diabetic and nondiabetic subjects. Additionally, prevalent coronary artery disease was related to the QT interval in subjects with newly diagnosed diabetes. In conclusion, we found that BP and LV mass were the strongest and most consistent determinants of the QT interval in nondiabetic and diabetic subjects. Additional factors potentially contributing to QT interval prolongation in diabetic patients include insulin sensitivity and prevalent coronary artery disease.

Section snippets

Study subjects and methods

The Insulin Resistance Atherosclerosis Study (IRAS) is a multicenter, epidemiologic study aiming to explore relations between insulin resistance, cardiovascular risk factors, and disease across different ethnic groups and varying states of glucose tolerance. A full description of the design and methods of the IRAS has been published previously.11 Recruitment was tailored to yield approximately equal numbers of participants by ethnicity, sex, and glucose tolerance categories (type 2 diabetes,

Statistical analysis

Statistical analyses were performed using the SAS statistical software system (SAS, Cary, North Carolina).25Table 1 shows descriptive data stratified by diabetic status. We assessed significant determinants of QT interval in the overall population using analysis of variance and covariance (ANCOVA), unadjusted and partial Spearman rank correlation analyses, and finally stepwise multiple linear regression analyses. We tested (1) demographic variables (gender, ethnicity [Table 2], and age), then

Results

Table 1 shows descriptive data stratified by diabetic status.

Discussion

The present study yielded several important observations. First, in a large population with varying degrees of glucose tolerance, the QT interval duration was mainly determined by BP and LV mass, as assessed electrocardiographically. Second, QT interval was prolonged in type 2 diabetes, even in newly diagnosed diabetes; the differences remained significant after adjusting for cardiovascular risk factors including hypertension as well as insulin sensitivity. Third, prevalent CAD in newly

Acknowledgements

We thankfully acknowledge the contributions and expertise of Professor C. Nicholas Hales, Cambridge, United Kingdom, and of Professor Rusell P. Tracy, Burlington, Vermont, in the fields of proinsulin metabolism and hemostasis, respectively.

References (29)

  • M.J. Carella et al.

    Obesity, adiposity, and lengthening of the QT intervalimprovement after weight loss

    Int J Obes

    (1996)
  • J. Karjalainen et al.

    QT interval as a cardiac risk factor in a middle aged population

    Heart

    (1997)
  • F. Bellavere et al.

    Prolonged QT period in diabetic autonomic neuropathya possible role in sudden cardiac death?

    Br Heart J

    (1988)
  • J.M. Dekker et al.

    QTc duration is associated with levels of insulin and glucose tolerance. The Zutphen Elderly Study

    Diabetes

    (1996)

    • Cited by (0)

    ☆

    This work was supported by Grants HL47887, HL47889, HL47890, HL47892, HL47902, and HL55208 from the National Heart, Lung and Blood Institute, Bethesda, Maryland; and Grants NCRR GCRC, M01 RR431, and M01 RR01346 from the General Clinic Research Centers Program. Manuscript received December 15, 1999; revised manuscript received and accepted May 24, 2000.

    View full text
    Copyright © 2000 Excerpta Medica Inc. All rights reserved.