Relationship of QT interval duration with carotid intima media thickness in a clinically healthy population undergoing cardiovascular risk screening

Abstract

Objectives. To investigate the relationship between cardiac repolarization (QT interval duration) and intima media thickness (IMT) of the carotid arteries as surrogate measures of subclinical atherosclerosis. Design. Prospective study with consecutive subjects enrolled in the SAPHIR program (Salzburg Atherosclerosis Prevention Program in Subjects at High Individual Risk). Setting. The analysis of the material was performed at the departments of medicine and neurology of a university hospital. Subjects. The study cohort comprises a populationbased sample of 1199 clinically healthy subjects (851 men and 348 women; age 39-66 years). Exclusion criteria were cardiovascular disease, diabetes, atrial fibrillation, bundle branch block and use of medication affecting QT interval duration. Main outcome measures. IMT of common (CCA) and internal carotid arteries (ICA) was measured by B-mode ultrasound. QT interval duration was determined in the resting 12-lead electrocardiogram by an automatic analysis program. The QT intervals were corrected for heart rate with five standard equations (QTc-Bazett, -Fridericia, -Framingham, -Hodges and -Rautaharju) and tested for their relationship with carotid IMT after adjustment for clinical and metabolic variables. Results. Females had higher heart rates than males (64 ± 10 b min )1 vs. 60 ± 9 b min )1 , P < 0.0005), with longer mean QT (410 ± 28 ms vs. 404 ± 28 ms, P ¼ 0.003) and QTc intervals in all correction formulae (P < 0.0005). Significant correlations between QT/QTc and ICA IMT (r ¼0.14-0.16) were found in males. In the general linear model the association between QTc (except for Bazett) and ICA IMT remained significant after adjusting for age, BMI and further cardiovascular risk factors. In females the crude correlations between QT/QTc and ICA IMT were lower than those with CCA IMT. Only the correlation between uncorrected QT and CCA IMT (r ¼ 0.15, P ¼ 0.006) remained significant after adjustment for covariates. Conclusions. The results of the present study demonstrate that QT and QTc prolongation are in part associated with IMT of carotid arteries, which is an established risk marker of subclinical atherosclerosis. In men the data support the hypothesis of an association between QTc and ICA IMT. In women a statistically significant relationship was found between the uncorrected QT interval and CCA IMT. These findings suggest that differences in carotid IMT and ventricular repolarization between genders might be related to hormonal and nonhormonal effects.

Response to the letter to the editor “Is neuroticism really associated with increased arrhythmia risk?” by Andrassy et al

“…As for the duration of QT duration in our study, the mean length of QTc interval was in accordance with values observed in other epidemiological studies that aim to investigate the association of QT interval with other predictors of vascular risk, such as carotid intima-media thickness [1] or insulin resistance indexes [2]. It is thus not surprising that the mean duration of QTc in our population was within the normal range, as we focused on a clinically healthy population.…”

QT interval prolongation and the risks of stroke and coronary heart disease in a general Japanese population: the Hisayama study

“…23 QT interval has also been shown to be associated with subclinical arterial disease. [24][25][26] Thus, QT interval prolongation, as a marker of ventricular hypertrophy or subclinical arterial disease, may predict future CVD events.…”

Arterial Stiffness and QT Interval Prolongation in a General Population: The Hisayama Study

“…Ours is the largest study to have investigated the association between subclinical arterial disease and QT interval prolongation, but there have been a few other cross-sectional studies addressing this question using other structural markers of subclinical arterial disease (10)(11)(12). The Insulin Resistance Atherosclerosis Study (IRAS) investigated the association between carotid intima media thickness and QTc in 912 nondiabetic subjects without coronary artery disease and found a close association between carotid atherosclerosis and QT interval prolongation (10).…”

“…Recently, several epidemiological studies have shown that QT interval prolongation predicts the risks of clinical arterial disease (5-9) as well as sudden cardiac death (5). Likewise, a few cross-sectional studies have suggested a positive association between QT interval prolongation and subclinical arterial disease, such as carotid intima media thickness (10)(11)(12). However, there is significant uncertainty about the association between QT interval prolongation and other forms of subclinical arterial disease.…”