<qa>  What is the main determinant of pulse pressure in patients with CRF?Arterial stiffness: Large conduit arteries buffer the changes in pressure resulting from intermittent ventricular ejection. Stiffening of the arteries loss of arterial compliance leads to increased systolic and pulse pressure; indeed arterial stiffness is the principal determinant of pulse pressure in patients with CRF. It is also closely associated with LVH and its progression over time. Recent prospective studies have demonstrated that measures of aortic stiffness, such as aortic pulse wave velocity PWV, and augmentation of central aortic pressure by early wave reflections AIx, are independent and powerful predictors of all-cause and cardiovascular mortality in patients on dialysis. Indeed, in a recent prospective study, lowering aortic PWV, mainly by use of an ACE-inhibitor, was associated with an improved survival in dialysis patients. This reduction in aortic PWV was associated with a parallel reduction in mean arterial and pulse pressure in survivors. In contrast, in those who died from cardiovascular events, although mean arterial pressure was lowered to the same extent as in survivors; neither pulse pressure nor aortic PWV was significantly modified by ACE inhibition. These findings suggest that arterial stiffness is not merely a marker of arterial damage but a potentially reversible factor contributing to mortality. 