Michel E. Safar

Impact of Aortic Stiffness on Survival in End-Stage Renal Disease

BACKGROUND Damage to large arteries is a major factor in the high cardiovascular morbidity and mortality of patients with end-stage renal disease (ESRD). Increased arterial stiffness and intima-media thickness, together with increased pulse pressure, are the principal arterial alterations. Whether increased aortic pulse-wave velocity (PWV), a classic marker of increased arterial stiffness, may predict all-cause and/or cardiovascular mortality has never been investigated. METHODS AND RESULTS A cohort of 241 patients with ESRD undergoing hemodialysis was studied between April 1987 and April 1998. The mean duration of follow-up was 72+/-41 months (mean+/-SD). Mean age at entry was 51.5+/-16.3 years. Seventy-three deaths occurred, including 48 cardiovascular and 25 noncardiovascular fatal events. At entry, together with standard clinical and biochemical analyses, patients underwent echocardiography and aortic PWV measured by Doppler ultrasonography. On the basis of Cox analyses, 2 factors emerged as predictors of all-cause and cardiovascular mortality: age and aortic PWV. Hemoglobin and low diastolic pressure interfered to a smaller extent. After adjustment for all the confounding factors, an OR for PWV >12. 0 versus <9.4 m/s was 5.4 (95% CI, 2.4 to 11.9) for all-cause mortality and 5.9 (95% CI, 2.3 to 15.5) for cardiovascular mortality. For each PWV increase of 1 m/s in our study population, all-cause mortality-adjusted OR was 1.39 (95% CI, 1.19 to 1.62). CONCLUSIONS These results provide the first direct evidence that in patients with ESRD, increased aortic stiffness determined by measurement of aortic PWV is a strong independent predictor of all-cause and mainly cardiovascular mortality.

Pulse Pressure A Predictor of Long-term Cardiovascular Mortality in a French Male Population

Studies on the usefulness of blood pressure as a prognostic factor in cardiovascular disease have more often involved investigations of the levels of diastolic or systolic blood pressure. However, blood pressure may be divided into two other components: steady (mean pressure) and pulsatile (pulse pressure). In this study, the relationship of pulse pressure to cardiovascular mortality was investigated in 19 083 men 40 to 69 years old who were undergoing a routine systematic health examination and were being followed up after a mean period of 19.5 years. Subjects were divided into four groups according to age (40 to 54 and 55 to 69 years) and mean arterial pressure (<107 and > or =107 mm Hg). Each group was further divided into four subgroups according to the pulse pressure level. A wide pulse pressure (evaluated according to the quartile group or as a continuous quantitative variable) was an independent and significant predictor of all-cause, total cardiovascular, and, especially, coronary mortality in all age and mean pressure groups. No significant association between pulse pressure and cerebrovascular mortality was observed. In conclusion, in a large population of men with a relatively low cardiovascular risk, a wide pulse pressure is a significant independent predictor of all-cause, cardiovascular, and, especially, coronary mortality.

Current Perspectives on Arterial Stiffness and Pulse Pressure in Hypertension and Cardiovascular Diseases

Blood pressure (BP) is a powerful cardiovascular (CV) risk factor that acts on the arterial wall and is responsible in part for various CV events, such as cerebrovascular accidents and ischemic heart disease. In clinical practice, 2 specific and arbitrary points of the BP curve, peak systolic BP (SBP) and end-diastolic BP (DBP), are used to define the CV risk factor. Because the goal of drug treatment of hypertension is to prevent CV complications, it appears likely that the totality of the BP curve, not simply 2 specific and arbitrary points, should be considered to act mechanically on the arterial wall and therefore should be used to propose an adequate definition of high BP. A current approach consists of considering the BP curve as the summation of a steady component, mean blood pressure (MBP), and a pulsatile component, pulse pressure (PP).1 MBP, the product of cardiac output multiplied by total peripheral resistance, is the pressure for the steady flow of blood and oxygen to peripheral tissues and organs. The pulsatile component, PP, is the consequence of intermittent ventricular ejection from the heart. PP is influenced by several cardiac and vascular factors, but it is the role of large conduit arteries, mainly the aorta, to minimize pulsatility. In addition to the pattern of left ventricular ejection, the determinants of PP (and SBP) are the cushioning capacity of arteries and the timing and intensity of wave reflections.1 The former is influenced by arterial stiffness, usually expressed in the quantitative terms of compliance and distensibility.1 The latter result from the summation of a forward wave coming from the heart and propagating at a given speed (pulse wave velocity, or PWV) toward the origin of resistance vessels and a backward wave returning toward the heart from particular sites characterized by specific …

Impact of Aortic Stiffness Attenuation on Survival of Patients in End-Stage Renal Failure

Background —Aortic pulse wave velocity (PWV) is a predictor of mortality in patients with end-stage renal failure (ESRF). The PWV is partly dependent on blood pressure (BP), and a decrease in BP can attenuate the stiffness. Whether the changes in PWV in response to decreases in BP can predict mortality in ESRF patients has never been investigated. Methods and Results —One hundred fifty ESRF patients (aged 52±16 years) were monitored for 51±38 months. From entry until the end of follow-up, the changes of PWV in response to decreased BP were measured ultrasonographically. BP was controlled by adjustment of “dry weight” and, when necessary, with ACE inhibitors, calcium antagonists, and/or &bgr;-blockers, in combination if necessary. Fifty-nine deaths occurred, including 40 cardiovascular and 19 noncardiovascular events. Cox analyses demonstrated that independent of BP changes, the predictors of all-cause and cardiovascular mortality were as follows: absence of PWV decrease in response to BP decrease, increased left ventricular mass, age, and preexisting cardiovascular disease. Survival was positively associated with ACE inhibitor use. After adjustment for all confounding factors, the risk ratio for the absence of PWV decrease was 2.59 (95% CI 1.51 to 4.43) for all-cause mortality and 2.35 (95% CI 1.23 to 4.41) for cardiovascular mortality. The risk ratio for ACE inhibitor use was 0.19 (95% CI 0.14 to 0.43) for all-cause mortality and 0.18 (95% CI 0.06 to 0.55) for cardiovascular mortality. Conclusions —These results indicate that in ESRF patients, the insensitivity of PWV to decreased BP is an independent predictor of mortality and that use of ACE inhibitors has a favorable effect on survival that is independent of BP changes.

Relationship between aortic stiffening and microvascular disease in brain and kidney: cause and logic of therapy.

A close relationship has been established between microvascular damage in brain and kidney and indices of age and hypertension (pulse pressure, aortic pulse wave velocity, and augmentation index). The mechanism of such association has not been established, nor has rationale for prevention and treatment of microvascular damage. A logical pathophysiological explanation can be offered on the basis of differential input impedance in the brain and kidney compared with other systemic vascular beds. Torrential flow and low resistance to flow in these organs exposes small arterial vessels to the high-pressure fluctuations that exist in the carotid, vertebral, and renal arteries. Such fluctuations, measurable as central pulse pressure, increase 3- to 4-fold with age. Exposure of small vessels to highly pulsatile pressure and flow explains microvascular damage and resulting renal insufficiency and intellectual deterioration, according to the mechanism established by Byrom >50 years ago. The logical approach to prevention and treatment requires reduction of central pulse pressure. Because the aorta and large arteries are not directly affected by drugs, this entails reduction of wave reflection by dilation of conduit arteries elsewhere in the body. This can be accomplished by regular exercise and by drugs such as nitrates, calcium channel blockers, angiotensin-converting enzyme inhibitors, and angiotensin receptor blockers. The explanation given here accounts for greater and earlier vascular damage in diabetes mellitus (relative microvascular fragility) and is similar to that given for vascular changes of pulmonary hypertension caused by ventricular septal defects and other congenital vascular shunts.

Prediction of cardiovascular events and all-cause mortality with central haemodynamics: a systematic review and meta-analysis.

AIMS To calculate robust quantitative estimates on the predictive value of central pressures and derived central haemodynamic indices for cardiovascular (CV) outcomes and all-cause mortality by meta-analysis of longitudinal studies. METHODS AND RESULTS We meta-analysed 11 longitudinal studies that had employed measures of central haemodynamics and had followed 5648 subjects for a mean follow-up of 45 months. The age- and risk-factor-adjusted pooled relative risk (RR) of total CV events was 1.088 (95% CI 1.040-1.139) for a 10 mmHg increase of central systolic pressure, 1.137 (95% CI 1.063-1.215) for a 10 mmHg increase of central pulse pressure (PP), and 1.318 (95% CI 1.093-1.588) for a 10% absolute increase of central augmentation index (AIx). Furthermore, we found that a 10% increase of central AIx was associated with a RR of 1.384 (95% CI 1.192-1.606) for all-cause mortality. When compared with brachial PP, central PP was associated with marginally but not significantly higher RR of clinical events (P = 0.057). CONCLUSION Central haemodynamic indexes are independent predictors of future CV events and all-cause mortality. Augmentation index predicts clinical events independently of peripheral pressures, while central PP has a marginally but not significantly (P = 0.057) better predictive ability when compared with peripheral PP.

Arterial Wave Reflections and Survival in End-Stage Renal Failure

The increased effect of arterial wave reflections on central arteries like the common carotid artery seen in end-stage renal failure (ESRF) patients favors myocardial hypertrophy and oxygen consumption and alters coronary blood flow distribution. Nevertheless, the impact of wave reflection on the outcome and end points such as mortality remains to be demonstrated. One hundred eighty ESRF patients (age, 54±16 years) were monitored for 52±36 months (mean±SD). Seventy deaths, including 40 cardiovascular (CV) and 30 non-CV events, occurred. At entry, patients, in addition to standard clinical and biochemical analyses, underwent aortic pulse wave velocity measurement and determination of arterial wave reflexion by applanation tonometry on the common carotid artery that was expressed as augmentation index. Cox analyses demonstrated that predictors of all-cause and CV mortality were age, aortic pulse wave velocity, low diastolic blood pressure, preexisting CV disease, and increased augmentation index, whereas the prescription of an ACE inhibitor had a favorable effect on survival. After adjustment for all confounding factors, the risk ratio for each 10% increase in augmentation index was 1.51 (95% confidence interval, 1.23 to 1.86;P <0.0001) for all-cause mortality and 1.48 (95% confidence interval, 1.16 to 1.90;P <0.0001) for CV mortality. These results provide the first direct evidence that in ESRF patients increased effect of arterial wave reflections is an independent predictor of all-cause and CV mortality.

Carotid Arterial Stiffness as a Predictor of Cardiovascular and All-Cause Mortality in End-Stage Renal Disease

Damage of large arteries is a major contributory factor to the high pulse pressure observed in patients with end-stage renal disease. Whether incremental modulus of elasticity (Einc), a classic marker of arterial stiffness, can predict cardiovascular mortality has never been investigated. A cohort of 79 patients with end-stage renal disease undergoing hemodialysis was studied between September 1995 and January 1998. Mean age at entry was 58+/-15 years. The duration of follow-up was 25+/-7 months, during which 10 cardiovascular and 8 noncardiovascular fatal events occurred. At entry, carotid Einc was calculated from measurements of diameter, thickness (echo-tracking technique), and pulse pressure (tonometry). Based on Cox analyses, 2 dominant factors emerged as predictors of all-cause and cardiovascular mortality: increased Einc and decreased diastolic blood pressure. Lipid abnormalities and the presence of previous cardiovascular events interfered to a smaller extent. After adjustment for confounding variables, the odds ratio for Einc >/=1 kPa-3 was 9.2 (95% confidence interval, 2.4 to 35.0) for all-cause mortality. These results provide the first direct evidence that in patients with end-stage renal disease undergoing hemodialysis, arterial alterations, as determined from carotid Einc, are strong independent predictors of all-cause and cardiovascular mortality.

Central Blood Pressure Measurements and Antihypertensive Therapy. A Consensus Document

The 2003 European Society of Hypertension/European Society of Cardiology guidelines for the management of arterial hypertension1 included 2 important novel recommendations: assessment of the total cardiovascular risk should be taken into account in the management of the hypertensive patient, and quantification of risk should include subclinical target organ damage. These guidelines acknowledged that central (aortic) blood pressure (BP), which is the pressure exerted on the heart and brain, may be different from the pressure that is measured at the arm. They also recognized that central pressure may be predictive of outcome in specific populations2 and differently affected by antihypertensive drugs. However, although these guidelines accepted that central augmentation index and pulse wave velocity may be important as measures of subclinical organ damage, they also stressed the need for prospective trials to establish their predictive values given that such studies were lacking at that time (2003). After publication of these guidelines, additional data have strengthened the pathophysiological importance of central BP. Clinical studies have indicated that central BP may have predictive value independent of the corresponding peripheral (brachial) BP. More importantly, recent large-scale trials have shown that central hemodynamics may provide a worthwhile treatment target. In addition, central hemodynamics can now be reliably assessed noninvasively with a number of devices. Accordingly, because arterial stiffening and central hemodynamics are markers and manifestations of organ damage, the pertinent key question is whether the balance of evidence on their importance and issues related to clinical practice allows for implementation in patient management. Central (aortic and carotid) pressures are pathophysiologically more relevant than peripheral pressures for the pathogenesis of cardiovascular disease.3,4 It is aortic systolic pressure that the left ventricle encounters during systole (afterload), and the aortic pressure during diastole is a determinant of coronary perfusion. Furthermore, the distending pressure in the …

Calcium Antagonist Lacidipine Slows Down Progression of Asymptomatic Carotid Atherosclerosis Principal Results of the European Lacidipine Study on Atherosclerosis (ELSA), a Randomized, Double-Blind, Long-Term Trial

Background—Most cardiovascular events associated with hypertension are complications of atherosclerosis. Some antihypertensive agents influence experimental models of atherosclerosis through mechanisms independent of blood pressure lowering. Methods and Results—The European Lacidipine Study on Atherosclerosis (ELSA) was a randomized, double-blind trial in 2334 patients with hypertension that compared the effects of a 4-year treatment based on either lacidipine or atenolol on an index of carotid atherosclerosis, the mean of the maximum intima-media thicknesses (IMT) in far walls of common carotids and bifurcations (CBMmax). This index has been shown by epidemiological studies to be predictive of cardiovascular events. A significant (P <0.0001) effect of lacidipine was found compared with atenolol, with a treatment difference in 4-year CBMmax progression of −0.0227 mm (intention-to-treat population) and −0.0281 mm (completers). The yearly IMT progression rate was 0.0145 mm/y in atenolol-treated and 0.0087 mm/y in lacidipine-treated patients (completers, 40% reduction;P =0.0073). Patients with plaque progression were significantly less common, and patients with plaque regression were significantly more common in the lacidipine group. Clinic blood pressure reductions were identical with both treatments, but 24-hour ambulatory systolic/diastolic blood pressure changes were greater with atenolol (−10/−9 mm Hg) than with lacidipine (−7/−5 mm Hg). No significant difference between treatments was found in any cardiovascular events, although the relative risk for stroke, major cardiovascular events, and mortality showed a trend favoring lacidipine. Conclusion—The greater efficacy of lacidipine on carotid IMT progression and number of plaques per patient, despite a smaller ambulatory blood pressure reduction, indicates an antiatherosclerotic action of lacidipine independent of its antihypertensive action.