2.1 Study population
We prospectively evaluated 60 consecutive CKD patients 40-75 years old who were followed-up at the CKD outpatient clinic of the University Hospital of Ioannina, Greece, between January 2013 and December 2014. The study protocol was previously approved by the local ethics committee. Exclusion criteria were: 1) history of coronary artery disease (CAD) and other established atherosclerotic disease i.e. cerebrovascular and peripheral arterial disease, 2) LV ejection fraction <50%, 3) any moderate-severevalvular heart disease (VHD), 4) atrial fibrillation, 5) advanced atrioventricular conduction disorder, 6) poor acoustic window during echocardiographic examination, 7) history of congestive heart failure, cardiomyopathy or constrictive pericarditis and 8) known allergy to dipyridamole or history of asthma/severe chronic obstructive pulmonary disease (COPD).
From a total of 106 patients attending the CKD outpatient clinic of our hospital, 46 patients were excluded at the time of study enrollment, due to poor acoustic window (16 patients), moderate-severe VHD (8 patients), presence of not previously known atrial fibrillation (6 patients), history of asthma/severe COPD (4 patients), asymptomatic (not previously known) CAD (8 patients), allergic reaction during dipyridamole infusion (1 patient) and denial to participate to the protocol (3 patients). The remaining patients (n=60) were divided and analyzed in two subgroups according to a cut-off at the age of 60 years. In the current study 30 healthy controls (40-60 years old) that were age- and gender-matched to younger CKD patients (i.e. <60 years old), were also enrolled. Finding healthy subjects in the specific age span without any known risk factor and without taking any medication was more difficult than originally thought. All patients (CKD and healthy controls) underwent a thorough physical examination and a detailed echocardiographic assessment. The study complied with the Declaration of Helsinki. All participants provided a written informed consent.