Ambulatory Pulse Wave Velocity Is a Stronger Predictor of Cardiovascular Events and All-Cause Mortality Than Office and Ambulatory Blood Pressure in Hemodialysis Patients

Abstract

Arterial stiffness and augmentation of aortic blood pressure (BP) measured in office are known cardiovascular risk factors in hemodialysis patients. This study examines the prognostic significance of ambulatory brachial BP, central BP, pulse wave velocity (PWV), and heart rate–adjusted augmentation index [AIx(75)] in this population. A total of 170 hemodialysis patients underwent 48-hour ambulatory monitoring with Mobil-O-Graph-NG during a standard interdialytic interval and followed-up for 28.1±11.2 months. The primary end point was a combination of all-cause death, nonfatal myocardial infarction, and nonfatal stroke. Secondary end points included: (1) all-cause mortality; (2) cardiovascular mortality; and (3) a combination of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, resuscitation after cardiac arrest, coronary revascularization, or hospitalization for heart failure. During follow-up, 37(21.8%) patients died and 46(27.1%) had cardiovascular events. Cumulative freedom from primary end point was similar for quartiles of predialysis-systolic BP (SBP), 48-hour peripheral-SBP, and central-SBP, but was progressively longer for increasing quartiles for 48-hour peripheral-diastolic BP and central-diastolic BP and shorter for increasing quartiles of 48-hour central pulse pressure (83.7%, 71.4%, 69.0%, 62.8% [log-rank P =0.024]), PWV (93.0%, 81.0%, 57.1%, 55.8% [log-rank P <0.001]), and AIx(75) (88.4%, 66.7%, 69.0%, 62.8% [log-rank P =0.014]). The hazard ratios for all-cause mortality, cardiovascular mortality, and the combined outcome were similar for quartiles of predialysis-SBP, 48-hour peripheral-SBP, and central-SBP, but were increasing with higher ambulatory PWV and AIx(75). In multivariate analysis, 48-hour PWV was the only vascular parameter independently associated with the primary end point (hazard ratios, 1.579; 95% confidence intervals, 1.187–2.102). Ambulatory PWV, AIx(75), and central pulse pressure are associated with increased risk of cardiovascular events and mortality, whereas office and ambulatory SBP are not. These findings further support that arterial stiffness is the prominent cardiovascular risk factor in hemodialysis.

Arterial Stiffness in Chronic Kidney Disease and End-Stage Renal Disease

“…Over a mean follow-up of 50 months, surviving patients were characterized by simultaneous decrease in aortic PWV and BP, that is, “pressure-dependent stiffness.” In non-survivors, despite a similar reduction in BP, the aortic PWV steadily increased, that is, “pressure-independent stiffening.” This observation suggested the hypothesis that modification of arterial stiffness and not BP could be the risk factor associated with the prognosis and outcomes. The recent study by Sarafidis et al [19] supports this hypothesis. In hemodialysis patients, authors compared the value of 48-h ambulatory BP (brachial and central) and 48-h aortic PWV measures for major cardiovascular outcomes and all-cause mortality.…”

“…Premature vascular aging and arterial stiffening are observed with the progression of CKD [16-18]. The most characteristic arterial change observed is the arterial stiffening, more pronounced in the aorta than in peripheral arteries [6, 19]. This condition is responsible for the reduction of the arterial stiffness gradient and impedance mismatch with diminished capacity to lower pulsatile pressure transmission to the peripheral microcirculation [8, 15].…”

“…Arterial remodeling and premature vascular aging are already observed in the early stages of CKD and its progression [16-19]. Compared with normotensive and hypertensive controls, patients with CKD stages 2–5 had significantly higher aortic PWV.…”

Comparison of 24-hour and Office Pulse Wave Velocity for Prediction of Mortality in Hemodialysis Patients

“…Although recent studies could not reproduce a predictive value of predialytic Office-PWV in elderly patients with ESRD [18,19], another study suggested an association of ambulatory 48-hour PWV with cardiovascular events and death in hemodialysis [20]. This discrepancy might be due to methodological issues.…”

Ambulatory Pulse Wave Velocity Monitoring

“…For this reason, the need to improve current techniques or biomarkers for the assessment of vascular properties has led to new concepts and approaches. One step forward is achieved by the ambulatory monitoring of arterial stiffness, which was proven in the study of Sarafidis et al 7 to be superior for the prediction of cardiovascular events and allcause mortality in hemodialysis patients compared with traditional hemodynamic measures. Another step forward might be the assessment of total arterial compliance instead of indices measuring local or segmental arterial properties.…”