Hypothesis: EECP improves left ventricular systolic and diastolic function. There is a relationship between d/s ratio and aortic arterial stiffness EECP improves left ventricular diastolic function Standard TTE would be performed prior the EECP procedure, which lasts 60 min., and repeated every 15 minutes. Moreover the investigators would measure pulse wave velocity, a measure of aortic arterial stiffness, in order to investigate the relationship between the d/s ratio and arterial stiffness.