The antiatherogenic effects of antihypertensive drugs: experimental and clinical evidence

Do all antihypertensive drugs improve carotid intima-media thickness? A network meta-analysis of randomized controlled trials

The many clinical trials investigating the effect of various antihypertensive drugs on carotid intima-media thickness (CIMT) produced conflicting results. We used meta-analysis to evaluate CIMT changes and network meta-analysis to rank drugs according to the magnitude of these changes. We identified 31 randomized controlled trials listed in three databases as of January 2008. Using a random-effects model, we found a significant CIMT decrease with antihypertensive drugs compared to placebo (-0.10 [-0.16; -0.04]). Overall effect sizes vs. placebo were significant for angiotensin-converting enzyme (ACE) inhibitors (-0.08 [-0.14; -0.02]), and a trend was found for beta-blockers (-0.09 [-0.19; 0.01]). The data did not allow other direct comparisons vs. placebo. Significant benefits were found for calcium-channel blockers (CCBs) compared to both ACE inhibitors (0.37 [0.20; 0.54]), as well as for angiotensin II receptor blockers (ARBs) compared to beta-blockers (0.42 [0.29; 0.55]). Diuretics were less efficient than CCBs (-0.09 [-0.16; -0.02]). Indirect comparisons with network meta-analysis showed significant effects of CCBs and ARBs vs. placebo (both P < 0.05) and vs. diuretics (both P < 0.001). The CIMT decrease with ACE inhibitors and beta-blockers was greater than with diuretics (both P < 0.05) but was not different from the placebo effect. In subgroup analyses, significant benefits occurred with lower baseline CIMT values and shorter treatment durations but were unrelated to the size of the blood pressure decrease. In conclusion, among antihypertensive drugs, CCBs and ARBs have the greatest effect on CIMT.

Simvastatin combined with nifedipine enhances endothelial cell protection by inhibiting ROS generation and activating Akt phosphorylation

AIM

To investigate the protective effects of simvastatin (Sim) combined with nifedipine (Nif) on endothelial cells and elucidate the action mechanism.

METHODS

Human umbilical vein endothelial cells (HUVEC) were used. mRNA and protein levels were measured by using reverse-transcription polymerase chain reaction (RT-PCR) and Western blotting, respectively. Intracellular calcium and reactive oxygen species (ROS) were detected using confocal microscopy. The Griess assay was used to evaluate nitric oxide (NO) release.

RESULTS

Treatment of HUVEC with H(2)O(2) 100 micromol/L for 30 min inhibited the mRNA and protein expression of endothelial nitric oxide synthase (eNOS). With increased concentrations of Nif, eNOS mRNA and protein levels increased (P<0.05). Combined treatment with Sim 1.0 micromol/L and Nif 1.0 micromol/L significantly increased the mRNA and protein expression of eNOS and NO release compared with Sim or Nif alone (P<0.05). The combination significantly lowered the intracellular ROS level (P<0.05), which was correlated with the increase in eNOS and NO, but there was no visible change in intracellular calcium (P>0.05). Compared with individual drug treatment, Akt phosphorylation and the ratio of p-eNOS/eNOS were up-regulated in the combination group, and this effect was inhibited by the phosphatidylinositol 3-kinase (PI3K) inhibitors wortmannin and LY294002.

CONCLUSION

The Sim-Nif combination effectively protects HUVEC against H(2)O(2) injury by inhibiting intracellular ROS generation, increasing the ratio of p-eNOS/eNOS and up-regulating Akt phosphorylation.

Effects of amlodipine and lisinopril on intima-media thickness in previously untreated, elderly hypertensive patients (the ELVERA trial)

OBJECTIVE

To compare the effects of the calcium channel blocker amlodipine and the angiotensin-converting enzyme inhibitor lisinopril on intima-media thickness (IMT) in elderly, previously untreated hypertensive individuals.

DESIGN

A double-blind randomized parallel-group trial (the ELVERA trial).

PATIENTS

The study population comprised 166 newly diagnosed hypertensive individuals (aged 60-75 years) with diastolic blood pressure between 95 and 115 mmHg or systolic blood pressure between 160 and 220 mmHg, or both.

INTERVENTION

Patients were allocated randomly to groups to receive amlodipine 5-10 mg or lisinopril 10-20 mg for 2 years.

MAIN OUTCOME MEASURES

Before and after 1 and 2 years of treatment, IMT was measured in three carotid and two femoral arterial sites by B-mode ultrasound. The primary endpoint was the change from baseline of the combined mean maximum far wall IMT of carotid and femoral arteries, evaluated by repeated measurement analysis of the treatment effect in an intention-to-treat analysis.

RESULTS

After 2 years of treatment, amlodipine decreased IMT by 0.089 mm [95% confidence interval (CI) 0.144 to 0.037]. Lisinopril decreased IMT by 0.065 mm (95% CI 0.124 to 0.010). No differences between the two drugs were found (P = 0.18). Both treatment regimens achieved the greatest reduction of IMT after 1 year, with a slight increase after the second year, whereas the reduction in blood pressure was maintained. Comparing the carotid and femoral arteries, a significant treatment difference in the change from baseline in favour of amlodipine was observed in the IMT of the elastic common carotid artery (P < 0.05). The effects of the two drugs on the muscular common femoral artery were not different.

CONCLUSION

In a long-term study, amlodipine and lisinopril reduce IMT to a similar extent in newly diagnosed elderly hypertensive patients. It is suggested that the two drugs have different effects on arteries that are not prone to atherosclerosis.

The renin-angiotensin hypothesis for the pathogenesis of cardiac allograft vasculopathy

The precise molecular mechanism for the development of cardiac allograft vasculopathy (CAV) after heart transplantation is not known. We, thus, hypothesize that increased activity of renin-angiotensin system (RAS) is important for the progression of CAV. There is evidence to support this concept. RAS via its principal effector molecule, angiotensin II exerts multitude of actions on vascular structure and function including regulation of vasomotor tone, cell growth/apoptosis, fibrosis and inflammation, which are particularly relevant to the genesis of atherosclerotic lesions. Risk factors, which increase predisposition to CAD, are known to activate tissue RAS and thus influence its progression. Importantly, CAD risk factors are also associated with accelerated CAV progression after transplantation. Whereas angiotensin converting enzyme (ACE) gene polymorphism increases the predisposition, pharmacological inhibition of RAS seems to reduce the incidence of CAV. These observations may support our hypothesis, provide a plausible explanation for the molecular mechanisms underlying the development of accelerated CAV and has predictions that can be tested.

Anti-lipid deposition effect of HMG-CoA reductase inhibitor, pitavastatin, in a rat model of hypertension and hypercholesterolemia

Since the rat is an atherosclerosis-resistant species, the study of atherosclerosis using rats is limited. The present study was undertaken to develop an atherosclerotic model in rats, to investigate the effect of nitric oxide (NO) inactivation and hyperlipidemia, and to evaluate the effect of pitavastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) inhibitor, on NO inactivation and on hyperlipidemia-induced changes in the cardiovascular system. Four-month-old male spontaneously hypertensive hyperlipidemic rats (SHHR) and Sprague-Dawley (SD) rats were used to study 1) the effect of the period of treatment with N(G)-nitro-L-arginine methyl ester (L-NAME, 100 mg/L) on high fat diet (HFD)-treated SHHR and SD rats, and 2) the effect of pitavastatin (Pit, 0.3 mg/kg/day) on the changes in the aorta of L-NAME- and HFD-treated SHHR and SD rats. L-NAME administration for 1 month then HFD feeding for 2 months markedly increased the deposition of lipids and the thickness of the endothelium in SHHR. Continuous L-NAME treatment with HFD produced severe injury and stripped of endothelium in both strains. The plasma total cholesterol of L-NAME + HFD-treated and L-NAME + HFD + Pit-treated SHHR was significantly higher than that of control SHHR. Lipid deposition, however, was comparatively less in the aorta of L-NAME + HFD + Pit-treated SHHR. The concentration of cholesterol in the aorta of control SHHR was significantly lower than that in the aorta of L-NAME + HFD-treated SHHR, whereas that of L-NAME + HFD + Pit-treated SHHR was the same as that in control SHHR. These data indicated that Pit blocked lipid deposition in the aorta of L-NAME + HFD treated SHHR without changing plasma lipid profiles. In conclusion, NO inactivation and HFD induce lipid deposition in the endothelium, and the HMG-CoA reductase inhibitor blocks the deposition in SHHR.

Systolic and pulse blood pressures (but not diastolic blood pressure and serum cholesterol) are associated with alterations in carotid intima-media thickness in the moderately hypercholesterolaemic hypertensive patients of the Plaque Hypertension Lipid Lowering Italian Study. PHYLLIS study group

OBJECTIVE

The Plaque Hypertension Lipid Lowering Italian Study (PHYLLIS), is the first study in patients with hypertension (diastolic blood pressure (DBP) 95-115 mmHg; systolic blood pressure (SBP) 150-210 mmHg), moderate hypercholesterolaemia (LDL-cholesterol 4.14-5.17 mmol/l (160-200 mg/dl) and initial carotid artery alterations (maximum intima-media thickness (IMT) Tmax > or = 1.3 mm). The primary objective of PHYLLIS is investigating whether in these patients administration of an angiotensin converting enzyme inhibitor, fosinopril, and a statin, pravastatin, is more effective than administration of a diuretic and a lipid-lowering diet in retarding or regressing alterations in carotid IMT. While the study is in progress, baseline data are here reported to clarify the association of various risk factors with carotid IMT in these medium-high risk hypertensive patients.

METHODS

Patients numbering 508 have been randomized to PHYLLIS by 13 peripheral units, in Italy. Age was (mean +/- SD) 58.4 +/- 6.7 years, males were 40.2%, current smokers 16.5%, means +/- SD of serum total, low-density lipoprotein (LDL), high-density lipoprotein (HDL) cholesterol and triglycerides concentrations were 6.79 +/- 0.67, 4.69 +/- 0.51, 1.37 +/- 0.38, 1.59 +/- 0.64 mmol/l (262.4 +/- 25.8, 181.3 +/- 19.8, 53.0 +/- 14.6, 141.0 +/- 56.7 mg/ dl). Means +/- SD of clinic sitting SBP/DBP were 159.8 +/- 9.0/98.3 +/- 4.2 mmHg. 483 of the 508 patients also had 24 h ambulatory BP monitoring, edited and read at a centralized unit (mean +/- SD 24 h SBP/DBP averages 136.3 +/- 14.1/84.0 +/- 10.0 mmHg). Quantitative B-mode ultrasound (Biosound 2000 II 5A, Biosound, Indianapolis, Indiana, USA) recordings of carotid arteries were taken by certified sonographers in the peripheral units and tracings were all read at a central unit. CBMmax (mean IMT of eight sites at common carotids and bifurcations) was 1.21 +/- 0.17; Mmax (mean of 12 sites also including internal carotids) 1.16 +/- 0.17, and Tmax (single maximum) 1.85 +/- 0.48 mm.

RESULTS

Ambulatory SBP and pulse pressure (PP) (24 h, daytime, night-time averages) and their variability indices (24 h SD) were always significantly correlated with CBMmax and Mmax (P0.01 -0.001), and the correlations remained significant after adjustment for age, gender and smoking. No measurement of DBP was ever associated with any IMT measurement. Likewise, no lipid variable was found associated with any IMT measurement.

CONCLUSIONS

Baseline data from PHYLLIS indicate that in this population of hypertensive patients with moderate hypercholesterolaemia, SBP and PP are with age among the most significant factors associated with carotid artery alterations. However, the narrow range of inclusion LDL-cholesterol and DBP values may have obscured an additional role of these variables.

Comparative effects of different dihydropyridines on the expression of adhesion molecules induced by TNF-alpha on endothelial cells

OBJECTIVE

Lacidipine has already been demonstrated to reduce the expression of some adhesion molecules induced by pro-oxidant signals on endothelial cells. In order to verify if this effect is a peculiarity of this molecule, or belongs to other dihydropyridinic compounds (DHPs), the activity of lacidipine was compared with that of lercanidipine, amlodipine, nimodipine and nifedipine.

DESIGN AND METHODS

The compounds were incorporated in human umbilical vein endothelial cells (HUVECs) using native low-density lipoprotein as a carrier. The drug concentrations in HUVECs were measured by mass spectrometry. Human recombinant tumour necrosis factor-alpha was then incubated with HUVECs for 7 h at 37 degrees C for adhesion molecule expression.

RESULTS

The cellular amount of lacidipine, lercanidipine and amlodipine was similar, while nimodipine and nifedipine were almost undetectable or undetectable, respectively. Lacidipine, at any concentration, determined a dose-dependent significant decrease of the expression of intercellular adhesion molecule-1 (ICAM-1) ICAM-1, vascular cell adhesion molecule-1 (VCAM-1) VCAM-1 and E-selectin (P < 0.01). Lercanidipine and amlodipine determined variable decreases of adhesion molecules at the intermediate and highest concentrations. Nimodipine and nifedipine determined no effect on ICAM-1, VCAM-1 and E-selectin. The lowest IC50, i.e. the concentration determining the 50% reduction of ICAM-1, VCAM-1 and E-selectin expression was obtained with lacidipine for all the adhesion molecules considered (P < 0.01).

CONCLUSIONS

It is concluded that the effect of the DHPs used in this study on adhesion molecule expression is determined first by their lipophilicity and then by their intrinsic antioxidant activity.

Carotid artery wall alterations as intermediate end points

Carotid artery wall alterations can now be measured in a quantitative, well reproducible way by B-mode ultrasound. The thickness of the intima-media complex (IMT) is commonly measured at three levels along the carotid tree. Well standardized protocols to use in randomized prospective trials are available. It is argued that IMT measurements can be used as intermediate end points of antihypertensive treatment trials as 1) IMT alterations are frequent in hypertension and closely correlated to systolic and pulse pressures; 2) IMT alterations are predictive of an increased risk of cardiovascular events; 3) changes in IMT occur during antihypertensive treatment; 4) at least one study has shown differential effects of different antihypertensive agents on IMT (VHAS: verapamil better than chlorthalidone); 5) in this study a greater effect on IMT has been accompanied by a reduced cardiovascular event rates. Larger studies are desirable to confirm these conclusions.

Risk factors associated with alterations in carotid intima-media thickness in hypertension: baseline data from the European Lacidipine Study on Atherosclerosis

BACKGROUND

The possibility that calcium antagonists exert an anti-atherosclerotic action at least partly independently of the blood-pressure-lowering effect is supported by results of a large number of experimental studies and can now be investigated by quantitative B-mode ultrasound imagining of the carotid artery walls.

DESIGN

The European Lacidipine Study on Atherosclerosis (ELSA) is a prospective, randomized, double-blind, multinational trial comparing effects of 4-year treatment based on the long-acting, highly lipophilic calcium antagonist lacidipine with those of treatment based on the beta-blocker atenolol on the development of carotid artery wall alterations in patients (aged 45-75 years) with mild-to-moderate hypertension (systolic blood pressure 150-210 mmHg and diastolic blood pressure 95-115 mmHg). While the intervention study is progressing, this article summarizes baseline data obtained from the whole cohort of 2259 patients randomly allocated to treatment.

METHODS

Baseline ultrasound data were obtained from two replicate examinations performed shortly before random allocation to treatment by certified sonographers at 23 referral centres and read at the ultrasound coordinating centre at the Wake Forest University School of Medicine. Intima-media thickness was measured at up to 12 different sites in the carotid artery tree and expressed as the mean of the maxima at these sites (Mmax), the mean of the maxima at four sites in the distal common carotid artery and bifurcation (CBMmax) and the maximum intima-media thickness (Tmax). Baseline demographic and clinical measurements were performed by investigators in 410 peripheral clinical units and 24 h ambulatory blood pressure monitorings read and validated by members of a centralized unit at the University of Milan. The statistical analysis centre at the Technische Universität München received and analysed all baseline data, by calculating means +/- SD, medians and ranges and performing correlation (Spearman correlation coefficients) and multiple regression analyses.

RESULTS

Prevalence of carotid artery wall alterations among the hypertensive patients randomly allocated to treatment in the ELSA was very high: 82% had Tmax > or = 1.3 mm ('plaques' according to protocol) and 17% had Tmax > or = 1.0 and < 1.3 mm ('thickening'), with a median of two plaques per patient. We found significant correlations between ultrasound measurements and the following demographic and clinical variables: age, sex, systolic blood pressure and pulse pressure (both clinic and ambulatory), concentrations of total, high-density lipoprotein and low-density lipoprotein cholesterol and triglycerides, smoking habit and duration of hypertension. We found no significant correlation to diastolic blood pressure and glucose concentration. A multiple regression analysis indicated significant variables in the following rank order: age, 24 h ambulatory pulse pressure, sex, low-density lipoprotein cholesterol concentration, triglyceride concentration, smoking and clinic systolic blood pressure.

CONCLUSIONS

Analysis of baseline data from the ELSA has shown that there is an extremely marked prevalence of carotid artery wall alterations among mild-to-moderate, middle-aged hypertensive patients. In addition to age, systolic blood pressure and pulse pressure, particularly if they are accurately measured by ambulatory monitoring, play a major role, somewhat greater than those of sex, low-density lipoprotein cholesterol concentration and smoking, in influencing intima-media thickness.

Antihypertensive therapy: how to evaluate the benefits

For more than 30 years, the benefits of antihypertensive therapy have been assessed in randomized trials that monitor cardiovascular events. Even greater benefits can result if prevention of (1) congestive heart failure, (2) left ventricular hypertrophy, and (3) progression to more severe hypertension is taken into consideration. However, quantifying the benefits in order to calculate the cost-effectiveness of treatment is not easy. Taking absolute risk and benefit as the only guide to treatment decisions may result in limiting therapy only to elderly hypertensive patients and hypertensive patients with complications. Furthermore, randomized trials, of which the duration is necessarily short, are likely to underestimate treatment benefits. An alternative to such an approach is the actuarial approach: treatment benefits are calculated from the actuarial data showing the reduction in life expectancy associated with any given blood pressure increase. The cost of antihypertensive therapy per year of life gained calculated in this way is much lower than the cost calculated from randomized trials. In an uncertain area such as that of cost-effectiveness evaluation, it is important that both approaches are taken into consideration by physicians, patients, politicians, and officers of national health systems.

Antiatherosclerotic effects of antihypertensive drugs: recent evidence and ongoing trials

The issue as to whether antihypertensive drugs may exert some antiatherosclerotic effect, at least partly independent of blood pressure lowering, has been explored in several experimental models of atherosclerosis, and a large body of evidence has been obtained in favor of a specific antiatherosclerotic action of calcium antagonists and ACE-inhibitors. On the clinical side, several studies are investigating the problem in hypertensive patients in whom progression of carotid intima-media thickness (IMT) and atherosclerotic plaques is explored by sensitive quantitative B-mode ultrasound techniques. The MIDAS has indicated a slower progression, at least in the first six months, of carotid plaques in isradipine treated patients than in diuretic-treated ones. However, MIDAS as a pioneer study has been particularly valuable in giving information on the rate of growth of IMT in hypertensive patients and on the best end-point to use in carotid ultrasound trials. Baseline data of the ongoing studies ELSA and VHAS have so far provided evidence of the very high prevalence of carotid atherosclerosis among hypertensive patients, an observation that makes the evaluation of the antiatherosclerotic action of some antihypertensive agents even more important. Finally, the PHYLLIS trial using a factorial design, beside exploring the antiatherosclerotic action of an ACE-inhibitor vs a diuretic, intends to evaluate the possible benefits of associating antihypertensive therapy with lipid lowering by a statin on the progression of carotid atherosclerosis.