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Open Access Highly Accessed Original investigation

Insulin resistance and subclinical abnormalities of global and regional left ventricular function in patients with aortic valve sclerosis

Hiroto Utsunomiya, Hideya Yamamoto*, Eiji Kunita, Takayuki Hidaka and Yasuki Kihara

Author Affiliations

Department of Cardiovascular Medicine, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan

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Cardiovascular Diabetology 2014, 13:86  doi:10.1186/1475-2840-13-86

Published: 27 April 2014

Abstract

Background

Insulin resistance, as a key mediator of metabolic syndrome, is thought to be associated with pathogenesis of calcific aortic valve disease and altered left ventricular (LV) function and structure. However, in patients with aortic valve sclerosis (AVS), the association between insulin resistance and subclinical impairment of LV function is not fully elucidated.

Methods

We studied 57 patients (mean age 70 ± 8 years, 22 women) with asymptomatic AVS but normal LV ejection fraction in echocardiography. LV longitudinal and circumferential strain and strain rate was analyzed using two-dimensional speckle tracking echocardiography. Patients with uncontrolled hypertension and diabetes mellitus, chronic kidney disease, and concomitant coronary artery disease were excluded. They were divided into the insulin-resistant group (AVS+IR; N = 28) and no insulin-resistant group (AVS-IR; N = 29) according to the median value of homeostatic model assessment index. Computed tomography scans were also performed to measure the aortic valve calcium score and the visceral adipose tissue (VAT) area. In addition, age- and sex- adjusted 28 control subjects were recruited for the comparison.

Results

There were no significant differences in LV ejection fraction or mass index among the groups. The AVS+IR group had a higher aortic valve calcium score (median 94 versus 21, P = 0.022) and a larger VAT area (113 ± 42 cm2 versus 77 ± 38 cm2, P = 0.001) than the AVS-IR group. Notably, LV global longitudinal strain, strain rate (SR), and early diastolic SR were significantly lower in the AVS+IR group than in the AVS-IR group and in control subjects (strain: -16.2 ± 1.6% versus -17.2 ± 1.2% and -18.9 ± 0.8%; SR: -1.18 ± 0.26 s-1 versus -1.32 ± 0.21 s-1 and -1.52 ± 0.08 s-1; early diastolic SR: -1.09 ± 0.23 s-1 versus -1.23 ± 0.18 s-1 and -1.35 ± 0.12 s-1; P < 0.05 for all comparison), whereas circumferential function were not significantly different. Multiple linear regression analyses revealed insulin resistance as an independent determinant of LV longitudinal strain (P = 0.017), SR (P = 0.047), and early diastolic SR (P = 0.049) regardless of LV mass index or VAT area.

Conclusions

Insulin resistance is a powerful independent predictor of subclinical LV dysfunction regardless of concomitant visceral obesity and LV hypertrophy. Thus, it may be a novel therapeutic target to prevent subsequent heart failure in patients with AVS.

Keywords:
Aortic valve sclerosis; Cardiac function; Insulin resistance; Speckle-tracking echocardiography; Visceral adipose tissue