1. INTRODUCTION
Patients with chronic kidney disease (CKD) are at a higher risk for
cardiovascular disease (CVD) compared to the general population; CVD is
responsible for about 50% of deaths in CKD patients
[1]. The interrelation between kidney
and heart function has long been recognized and current research effort
is focused in delineating the exact mechanisms behind this complex
pathophysiology. Increased cardiovascular risk in individuals with CKD
is due partly to the high prevalence of traditional risk factors, such
as hypertension and diabetes, but also to non-traditional cardiac risk
factors that are particularly relevant to patients with chronic kidney
disease, including decreased glomerular filtration and albuminuria.
Early atherosclerosis progression and endothelial cell dysfunction,
uraemia and kidney failure, neurohormonal dysregulation, anaemia and
iron disorders, mineral metabolic derangements and inflammatory pathways
may all contribute to the phenotype of cardio-renal syndrome
[2-6].
Non-invasive and widely available diagnostic methods that may detect
preclinical functional and structural myocardial abnormalities are
needed in order to identify CKD patients at higher risk for CVD
[7-9]. Echocardiography is an
essential tool for the assessment of cardiac structure and function in
several patient groups, including CKD patients, while various
echocardiographic indices have been shown to predict adverse CVD
outcomes. Classic echocardiographic indices of left ventricular (LV)
systolic and diastolic function may not be sensitive enough in detecting
early myocardial deterioration in CKD patients
[10,
11]. Two-dimensional speckle tracking
echocardiography (2DSTE) is a semi-automated modality for quantification
of LV systolic as well as diastolic function in an operator-independent
manner. LV myocardial deformation may be assessed in the longitudinal,
radial and circumferential plane but peak global longitudinal strain
(GLS) has been shown to be the most important load-independent index
that gives an efficient and rather objective measurement of LV systolic
and diastolic function with many prognostic implications
[10,
12-17].
Dipyridamole stress echocardiography (DIPSE) is mostly used to measure
coronary flow reserve (CFR) in a non-invasive way. CFR is used for
evaluating both the presence of significant epicardial stenosis and the
microcirculatory function in the left anterior descending artery (LAD)
territory; a CFR value <2 is correlated to significant
microvascular dysfunction and is proposed to be a strong predictor of
epicardial coronary artery disease (CAD)
[18]. Impaired CFR has been also
advocated as an adverse prognosticator for CVD
[19,
20].
The aim of the current study was to investigate differences in classic,
2DSTE-related indices, CFR and other DIPSE-induced changes in various
echocardiographic parameters between: 1) healthy controls and
age-matched younger CKD patients, 2) younger versus older CKD patients
with similar clinical characteristics.