Rationale, design and patient baseline characteristics of OlmeSartan and calcium antagonists randomized (OSCAR) study: a study comparing the incidence of cardiovascular events between high-dose angiotensin II receptor blocker (ARB) monotherapy and combination therapy of ARB with calcium channel blocker in Japanese elderly high-risk hypertensive patients (ClinicalTrials. gov no. NCT00134160)

Involvement of Angiotensin II Type 1 Receptor and Calcium Channel in Vascular Remodeling and Endothelial Dysfunction in Rats with Pressure Overload

Vascular remodeling is an adaptive response to various stimuli, including mechanical forces, inflammatory cytokines and hormones. In the present study, we investigated the role of angiotensin II type 1 receptor (AT1R) and calcium channel in carotid artery remodeling in response to increased biomechanical forces by using the transverse aortic constriction (TAC) rat model. TAC was induced on ten-week-old male Sprague-Dawley rats and these models were treated with AT1R blocker olmesartan (1 mg/kg/day) or/and calcium channel blocker (CCB) amlodipine (0.5 mg/kg/day) for 14 days. After the treatment, the right common carotid artery proximal to the band (RCCA-B) was collected for further assay. Results showed that olmesartan, but not amlodipine, significantly prevented TAC-induced adventitial hyperplasia. Similarly, olmesartan, but not amlodipine, signifcantly prevented vascular infammation, as indicated by increased tumor necrosis factor α (TNF-α) and increased p65 phosphorylation, an indicator of nuclear factor κ-light-chain-enhancer of activated B cells (NFκB) activation in RCCA-B. In contrast, both olmesartan and amlodipine reversed the decreased expression of endothelial nitric oxidase synthase (eNOS) and improved endothelium-dependent vasodilation, whereas combination of olmesartan and amlodipine showed no further synergistic protective effects. These results suggest that AT1R was involved in vascular remodeling and inflammation in response to pressure overload, whereas AT1R and subsequent calcium channel were involved in endothelial dysfunction.

Methods of Blood Pressure Assessment Used in Milestone Hypertension Trials

In the present review, we summarized the blood pressure (BP) measurement protocols of contemporary outcome trials in hypertension. In all these trials, clinic BP was used for the diagnosis and therapeutic monitoring of hypertension. In most trials, BP was measured in the sitting position with mercury sphygmomanometers or automated electronic BP monitors by trained observers. BP readings were taken on each occasion at least twice with a 30-to-60-s interval after 5 min of rest. Details regarding the arm side, cuff size, and the timing of BP measurement were infrequently reported. If clinic BP continues being used in future hypertension trials, the measurement should strictly follow current guidelines. The observers must be trained and experienced, and the device should be validated by automated electronic BP monitors. On each occasion, BP readings should be taken 2-3 times. The time interval between successive measurements has to be 30-60 s, and the resting period before the measurement should be at least 5 min in the supine or seated position and 1-3 min standing. BP should usually be measured in the seated position. The higher arm side and an appropriate size cuff should be chosen and noted. BP should be measured at defined trough hours. Automated office BP measurement has recently been used and seems to have less white-coat effect. The out-of-office BP measurement, either ambulatory or home BP monitoring, was only used in a subset of study participants of few hypertension trials. Future trials should consider these novel office or out-of-office BP measurements in guiding the therapy and preventing cardiovascular events.

Addition of a renin-angiotensin-aldosterone system inhibitor to a calcium channel blocker ameliorates arterial stiffness

BACKGROUND

The aim of controlling hypertension is to protect against arteriosclerosis. Calcium channel blockers (CCBs) and renin-angiotensin-aldosterone system (RAAS) inhibitors have been reported to have antihypertensive effects, but their effect on the progression of arteriosclerosis is not fully understood. The cardio-ankle vascular index (CAVI) was developed to estimate arterial stiffness, which reflects arteriosclerosis. In this study, we investigated the longer term effects of CCBs and RAAS inhibitors on the progression of arteriosclerosis by monitoring the CAVI.

METHODS

Our subjects were 115 consecutive, non-smoking hypertensive patients on oral treatment with a CCB and/or RAAS inhibitor for at least 3 years in whom the CAVI was measured on two occasions approximately 1 year apart during the period from January 2009 to December 2011. Changes in CAVI were evaluated in patients administered a CCB alone (group C), an RAAS inhibitor (group R) alone, or both drugs together (group B). Changes in laboratory findings, blood pressure, and ankle-brachial index were similarly evaluated.

RESULTS

No significant change in laboratory findings, blood pressure, or ankle-brachial index was noted in any of the groups. The CAVI decreased slightly in group R (first recording 8.80±1.03, second recording 8.57±0.97, P=0.517) and increased significantly in group C (first 8.45±0.92, second 8.95±1.04, P=0.038), but showed no significant change in group B (first 9.01±1.26, second 9.05±1.35, P=0.851).

CONCLUSION

Long-term administration of a CCB alone increased the CAVI, but this effect was offset by the concomitant use of a RAAS inhibitor, indicating that a RAAS inhibitor might protect against arteriosclerosis.

Differential effectiveness of ARB plus CCB therapy and high-dose ARB therapy in high-risk elderly hypertensive patients: subanalysis of the OSCAR study

The OSCAR study was a multicenter prospective randomized study that examined the relative benefit of combined ARB (olmesartan 20 mg per day) plus calcium channel blocker (CCB) therapy vs. high-dose ARB monotherapy (olmesartan 40 mg per day) for prevention of cardiovascular events in elderly Japanese hypertensive patients. The present subanalysis of patients enrolled in the OSCAR study (n = 1078) was performed to assess whether baseline eGFR coupled with cardiovascular disease (CVD) could predict the relative benefit of these two treatments. Patients with baseline CVD (n = 769) and patients without baseline CVD (n = 309) were divided into two groups based on baseline eGFR; (i) patients with eGFR of < 60 ml min(-1) 1.73 m(-)(2) and (ii) those with eGFR of ⩾ 60 ml min(-1) 1.73 m(-2). There was a significant treatment-subgroup interaction among these four subgroups in relation to the incidence of primary outcome events(P = 0.007 for interaction). In patients with CVD and with eGFR of <60 ml min(-1) 1.73 m(-2), ARB plus CCB therapy was associated with a lower incidence of primary events than high-dose ARB therapy and the difference of the relative risk was statistically significant (hazard ratio: 3.525, 95% confidence interval (CI): 1.676-7.412, P < 0.001). The greater benefit of ARB plus CCB therapy vs. high-dose ARB therapy in this subgroup was associated with less visit-to-visit variability of systolic BP and diastolic BP. In conclusion, baseline eGFR coupled with baseline CVD seems to be a predictor of the relative efficacy of ARB plus CCB therapy vs. high-dose ARB therapy in the elderly hypertensive patients. ARB plus CCB therapy appears to be superior to high-dose ARB therapy for preventing cardiovascular events in the patients with CVD and with eGFR of <60 ml min(-1) 1.73 m(-2).

Sex differences in response to angiotensin II receptor blocker-based therapy in elderly, high-risk, hypertensive Japanese patients: a subanalysis of the OSCAR study

The OlmeSartan Calcium Antagonists Randomized (OSCAR) study is a multicenter, prospective, randomized, open-label, blinded, end point study of elderly hypertensive Japanese patients that compared the efficacy of a high-dose angiotensin II receptor blocker (ARB) treatment to an ARB plus calcium channel blocker (CCB) combination. In this pre-specified subgroup analysis, we compared the response to such therapy according to sex. A total of 1164 patients (515 (44%) men and 649 (56%) women) were included, and each gender was split into two nearly equal treatment groups. The primary end point was a composite of cardiovascular events and non-cardiovascular death. The baseline characteristics between the two treatment groups in each sex were similar, except for some variables. Male patients had lower systolic and higher diastolic blood pressure than female patients (156.8/85.7 vs. 158.5/84.2 mm Hg). At the end of the study, the mean systolic pressure was higher in the ARB group (134.4 mm Hg) than in the ARB plus CCB group (131.5 mm Hg; P=0.03) for men but not for women (135.4 vs. 133.4 mm Hg; P=0.12). For men, the primary outcome events tended to be higher in the ARB group than in the ARB plus CCB group (hazard ratio (HR)=1.66; P=0.055) but not for women (HR=0.97; P=0.92). This difference in men was due to cardiovascular events (HR=1.86; P=0.03). The interaction between sex and treatment group was not significant (P=0.17). These findings suggest that, in addition to blood pressure control, appropriate patient risk assessment is important for the treatment of hypertension, especially in male patients, as opposed to possible sex differences in treatment effects.

An angiotensin II receptor blocker-calcium channel blocker combination prevents cardiovascular events in elderly high-risk hypertensive patients with chronic kidney disease better than high-dose angiotensin II receptor blockade alone

The OSCAR study was a multicenter, prospective randomized open-label blinded end-point study of 1164 Japanese elderly hypertensive patients comparing the efficacy of angiotensin II receptor blocker (ARB) uptitration to an ARB plus calcium channel blocker (CCB) combination. In this prospective study, we performed prespecified subgroup analysis according to baseline estimated glomerular filtration rate (eGFR) with chronic kidney disease (CKD) defined as an eGFR <60 ml/min per 1.73 m². Blood pressure was lower in the combined therapy than in the high-dose ARB cohort in both groups with and without CKD. In patients with CKD, significantly more primary events (a composite of cardiovascular events and noncardiovascular death) occurred in the high-dose ARB group than in the combination group (30 vs. 16, respectively, hazard ratio 2.25). Significantly more cerebrovascular and more heart failure events occurred in the high-dose ARB group than in the combination group. In patients without CKD, however, the incidence of primary events was similar between the two treatments. The treatment-by-subgroup interaction was significant. Allocation to the high-dose ARB was a significant independent prognostic factor for primary events in patients with CKD. Thus, the ARB plus CCB combination conferred greater benefit in prevention of cardiovascular events in patients with CKD compared with high-dose ARB alone. Our findings provide new insight into the antihypertensive strategy for elderly hypertensive patients with CKD.

Angiotensin II receptor blocker-based therapy in Japanese elderly, high-risk, hypertensive patients

BACKGROUND

It is unknown whether high-dose angiotensin II receptor blocker therapy or angiotensin II receptor blocker + calcium channel blocker combination therapy is better in elderly hypertensive patients with high cardiovascular risk. The objective of the study was to compare the efficacy of these treatments in elderly, high-risk Japanese hypertensive patients.

METHODS

The OlmeSartan and Calcium Antagonists Randomized (OSCAR) study was a multicenter, prospective, randomized, open-label, blinded-end point study of 1164 hypertensive patients aged 65 to 84 years with type 2 diabetes or cardiovascular disease. Patients with uncontrolled hypertension during treatment with olmesartan 20 mg/d were randomly assigned to receive 40 mg/d olmesartan (high-dose angiotensin II receptor blocker) or a calcium channel blocker + 20 mg/d olmesartan (angiotensin II receptor blocker + calcium channel blocker). The primary end point was a composite of cardiovascular events and noncardiovascular death.

RESULTS

During a 3-year follow-up, blood pressure was significantly lower in the angiotensin II receptor blocker + calcium channel blocker group than in the high-dose angiotensin II receptor blocker group. Mean blood pressure at 36 months was 135.0/74.3 mm Hg in the high-dose angiotensin II receptor blocker group and 132.6/72.6 mm Hg in the angiotensin II receptor blocker + calcium channel blocker group. More primary end points occurred in the high-dose angiotensin II receptor blocker group than in the angiotensin II receptor blocker + calcium channel blocker group (58 vs 48 events, hazard ratio [HR], 1.31, 95% confidence interval, 0.89-1.92; P=.17). In patients with cardiovascular disease at baseline, more primary events occurred in the high-dose angiotensin II receptor blocker group (HR, 1.63, P=.03); in contrast, fewer events were observed in the subgroup without cardiovascular disease (HR, 0.52, P=.14). This treatment-by-subgroup interaction was significant (P=.02).

CONCLUSION

The angiotensin II receptor blocker and calcium channel blocker combination lowered blood pressure more than the high-dose angiotensin II receptor blocker and reduced the incidence of primary end points more than the high-dose angiotensin II receptor blocker in patients with cardiovascular disease. The addition of a second antihypertensive agent is more effective at lowering blood pressure than simply doubling the dose of an existing agent.

Rationale for triple fixed-dose combination therapy with an angiotensin II receptor blocker, a calcium channel blocker, and a thiazide diuretic

Hypertension is a growing global health problem, and is predicted to affect 1.56 billion people by 2025. Treatment remains suboptimal, with control of blood pressure achieved in only 20%-35% of patients, and the majority requiring two or more antihypertensive drugs to achieve recommended blood pressure goals. To improve blood pressure control, the European hypertension guidelines recommend that angiotensin II receptor blockers (ARBs) or angiotensin-converting enzyme inhibitors (ACEIs) are combined with calcium channel blockers (CCBs) and/or thiazide diuretics. The rationale for this strategy is based, in part, on their different effects on the renin-angiotensin system, which improves antihypertensive efficacy. Data from a large number of trials support the efficacy of ACEIs or ARBs in combination with CCBs and/or hydrochlorothiazide (HCTZ). Combining two different classes of antihypertensive drugs has an additive effect on lowering of blood pressure, and does not increase adverse events, with the ARBs showing a tolerability advantage over the ACEIs. Among the different ARBs, olmesartan medoxomil is available as a dual fixed-dose combination with either amlodipine or HCTZ, and the increased blood pressure-lowering efficacy of these two combinations is proven. Triple therapy is required in 15%-20% of treated uncontrolled hypertensive patients, with a renin-angiotensin system blocker, CCB, and thiazide diuretic considered to be a rational combination according to the European guidelines. Olmesartan, amlodipine, and HCTZ are available as a triple fixed-dose combination, and significant blood pressure reductions have been observed with this regimen compared with the possible dual combinations. The availability of these fixed-dose combinations should lead to improvement in blood pressure control and aid compliance with long-term therapy, optimizing the management of this chronic condition.

Cardio classics revisited: focus on the role of amlodipine

Amlodipine is a long-acting, dihydropyridine calcium antagonist now widely used for lowering of elevated blood pressure. In recent years it has been shown to be effective in reducing both blood pressure and risk of cardiovascular (CV) events when used in combination with other antihypertensive agents of different classes. Strong evidence of cardiovascular benefit has been attained for combination of amlodipine with diuretics or angiotensin converting enzyme (ACE) inhibitors in a number of high-risk CV groups, including those with established coronary artery disease, diabetes, and at risk of renal disease. Combination therapies of amlodipine with other agents eliciting renin-angiotensin-aldosterone system blockade (angiotensin II receptor blockers or renin inhibitors) have been shown to be effective blood pressure-lowering strategies, but await the results of ongoing trials for direct evidence of benefit for renal disease progression and CV morbidity and mortality.

Hydrochlorothiazide versus calcium channel blockers: what is the best add-on to a renin-angiotensin system blocker for treating hypertension in patients with renal disease?

Hypertension remains an important problem that increases the risk of cardiovascular disease and is a leading cause of mortality worldwide. Achieving long-term control of arterial hypertension, which has an estimated prevalence of 28% in the US adult population, would translate into a significant reduction in cardiovascular events. Specific causes can be identified and treated for certain forms of secondary hypertension, but often it is multifactorial. Therefore, it makes sense to attain blood pressure control by addressing more than one pressor mechanism. Several clinical studies have demonstrated that combination antihypertensive therapy is more effective than monotherapy, and a review of currently published data suggests that approximately 75% of hypertensive individuals will require some form of combination therapy to achieve target blood pressure (BP) goals. To this end, the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of Blood Pressure (JNC 7) has recommended that antihypertensive therapy should start with two drugs when a patient presents with systolic blood pressure (SBP) more than 20 mm Hg above target levels, diastolic blood pressure (DBP) more than 10 mm Hg above target levels, or both. This review attempts to analyze the current evidence in published medical literature to answer the question of whether hydrochlorothiazide or a calcium channel blocker is a better add-on to a renin-angiotensin system blocker for treating hypertension in patients with renal disease.

Reappraisal of role of angiotensin receptor blockers in cardiovascular protection

Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) have shown cardioprotective and renoprotective properties. These agents are recommended as first-line therapy for the treatment of hypertension and the reduction of cardiovascular risk. Early studies pointed to the cardioprotective and renoprotective effects of ARBs in high-risk patients. The ONgoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial (ONTARGET) established the clinical equivalence of the cardioprotective and renoprotective effects of telmisartan and ramipril, but did not find an added benefit of the combination over ramipril alone. Similar findings were observed in the Telmisartan Randomized AssessmeNt Study in aCE INtolerant subjects with cardiovascular Disease (TRANSCEND) trial conducted in ACEI-intolerant patients. In ONTARGET, telmisartan had a better tolerability profile with similar renoprotective properties compared with ramipril, suggesting a potential clinical benefit over ramipril. The recently completed Olmesartan Reducing Incidence of Endstage Renal Disease in Diabetic Nephropathy Trial (ORIENT) and Olmesartan and Calcium Antagonists Randomized (OSCAR) studies will further define the role of ARBs in cardioprotection and renoprotection for high-risk patients.

Role of olmesartan in combination therapy in blood pressure control and vascular function

Angiotensin receptor blockers have emerged as a first-line therapy in the management of hypertension and hypertension-related comorbidities. Since national and international guidelines have stressed the need to control blood pressure to <140/90 mmHg in uncomplicated hypertension and <130/80 mmHg in those with associated comorbidities such as diabetes or chronic kidney disease, these goal blood pressures can only be achieved through combination therapy. Of several drugs that can be effectively combined to attain the recommended blood pressure goals, fixed-dose combinations of angiotensin receptor blockers and the calcium channel blocker amlodipine provide additive antihypertensive effects associated with a safe profile and increased adherence to therapy. In this article, we review the evidence regarding the beneficial effects of renin–angiotensin system blockade with olmesartan medoxomil and amlodipine in terms of blood pressure control and improvement of vascular function and target organ damage.