Altered transmural contractility in postmenopausal women affected by cardiac syndrome X

Abstract

Background: Cardiac syndrome X (CSX) is characterized by typical angina and abnormal exercise test results, with normal coronary arteries. Cardiovascular magnetic resonance imaging has shown subendocardial hypoperfusion in patients with CSX after adenosine. The aim of this study was to investigate the contribution of separate myocardial layers to global function under stress in women with CSX.

Methods: Twenty-two postmenopausal women with CSX were studied and compared with 20 healthy women matched for age and body mass index. All subjects underwent clinical evaluations and exercise echocardiography. Left ventricular systolic and diastolic parameters were evaluated at rest and at peak exercise. Layer-specific global longitudinal strain (GLS) and strain rate (SR) were assessed from the endocardium, midmyocardium, and epicardium using two-dimensional speckle-tracking echocardiography.

Results: All subjects showed normal contractile function at rest and at peak exercise. Significant increases in GLS and SR in all myocardial layers were observed at peak exercise in the control group, whereas patients with CSX showed significantly lower increases in endocardial GLS and SR compared with the control group (endocardial ΔSR, 0.17 ± 0.19 vs 0.33 ± 0.13 [P < .01]; endocardial ΔGLS, 1.33 ± 2.93 vs 6.64 ± 2.62 [P < .001]). Moreover, significantly impaired diastolic function (ΔE', 1.1 ± 3.3 vs 4.0 ± 2.03) was observed in patients with CSX.

Conclusions: The results of this study show subendocardial impairment of contractile function during exercise in patients with CSX, confirming the existence of reduced myocardial perfusion reserve in patients with CSX and suggesting layer-targeted exercise echocardiography as a sensitive diagnostic tool in the assessment of suspected CSX.

Keywords: CSX; Cardiac syndrome X; Exercise echocardiography; GLS; Global longitudinal strain; LV; Left ventricular; MRI; Magnetic resonance imaging; PET; Positron emission tomography; SR; Speckle-tracking echocardiography; Strain rate.