Antihypertensive effect of sustained-release isosorbide dinitrate for isolated systolic systemic hypertension in the elderly

Sustained-release isosorbide mononitrate as adjuvant treatment in isolated systolic hypertension in the elderly

Hypertension is one of the main cardiovascular risk factors. In the elderly, the most common form is isolated systolic hypertension, a consequence of the increase in arterial stiffness. None of the antihypertensives currently used affects arterial stiffness, whereas nitrates seem to have an effect. The aim of this work was to assess their effect on elderly patients with uncontrolled isolated systolic hypertension, defined as systolic blood pressure over 140 mmHg and diastolic blood pressure under 90 mmHg. The present study is a phase III, randomized, multicenter, double-blind, placebo-controlled clinical trial, conducted at the University Hospital La Princesa in Madrid. Patients of both sexes, aged 65 years or older, with poorly controlled isolated systolic hypertension, were treated with 40-60 mg of sustained-release isosorbide mononitrate or matching placebo for 12 weeks. The main objective was to assess the effect on clinical pulse pressure (PP); in addition, its effect on vascular function was evaluated. Analysis was performed by intention to treat. The study was registered at the European Union Clinical Trials Register (EUDRACT 2012-002988-10) and was funded by the Spanish Ministry of Health. A total of 58 patients with an average age of 77 years were enrolled, 32 were treated with nitrate, and 26 with placebo. No significant differences were found either in PP decline (5.28 vs 7.49 mmHg, p = 0.79) or in other variables, including parameters of vascular function. There were no differences in adverse events. The results of this study have not confirmed the benefit of nitrate treatment in isolated systolic hypertension or the improvement of vascular function.

A Method to Quantify Mean Hypertension Treatment Daily Dose Intensity Using Health Care System Data

Importance

Simple measures of hypertension treatment, such as achievement of blood pressure (BP) targets, ignore the intensity of treatment once the BP target is met. High-intensity treatment involves increased treatment burden and can be associated with potential adverse effects in older adults. A method was previously developed to identify older patients receiving intense hypertension treatment by low BP and number of BP medications using national Veterans Health Administration and Medicare Part D administrative pharmacy data to evaluate which BP medications a patient is likely taking on any given day.

Objective

To further develop and validate a method to more precisely quantify dose intensity of hypertension treatment using only health system administrative pharmacy fill data.

Design, Setting, and Participants

Observational, cross-sectional study of 319 randomly selected older veterans in the national Veterans Health Administration health care system who were taking multiple BP-lowering medications and had a total of 3625 ambulatory care visits from July 1, 2011, to June 30, 2013. Measure development and medical record review occurred January 1, 2017, through November 30, 2018, and data analysis was conducted from December 1, 2019, to August 31, 2020.

Main Outcomes and Measures

For each BP-lowering medication, a moderate hypertension daily dose (HDD) was defined as half the maximum dose above which no further clinical benefit has been demonstrated by that medication in hypertension trials. Patients' total HDD was calculated using pharmacy data (pharmacy HDDs), accounting for substantial delays in refills (>30 days) when a patient's pill supply was stretched (eg, cutting existing pills in half). As an external comparison, the pharmacy HDDs were correlated with doses manually extracted from clinicians' visit notes (clinically noted HDDs). How well the pharmacy HDDs correlated with clinically noted HDDs was calculated (using C statistics). To facilitate interpretation, HDDs were described in association with the number of medications.

Results

A total of 316 patients (99.1%) were male; the mean (SD) age was 75.6 (7.2) years. Pharmacy HDDs were highly correlated (r = 0.92) with clinically noted HDDs, with a mean (SD) of 2.7 (1.8) for pharmacy HDDs and 2.8 (1.8) for clinically noted HDDs. Pharmacy HDDs correlated with high-intensity, clinically noted HDDs ranging from a C statistic of 92.8% (95% CI, 92.0%-93.7%) for 2 or more clinically noted HDDs to 88.1% (95% CI, 85.5%-90.6%) for 6 or more clinically noted HDDs.

Conclusions and Relevance

This study suggests that health system pharmacy data may be used to accurately quantify hypertension regimen dose intensity. Together with clinic-measured BP, this tool can be used in future health system-based research or quality improvement efforts to fine-tune, manage, and optimize hypertension treatment in older adults.

Central blood pressure: current evidence and clinical importance

Pressure measured with a cuff and sphygmomanometer in the brachial artery is accepted as an important predictor of future cardiovascular risk. However, systolic pressure varies throughout the arterial tree, such that aortic (central) systolic pressure is actually lower than corresponding brachial values, although this difference is highly variable between individuals. Emerging evidence now suggests that central pressure is better related to future cardiovascular events than is brachial pressure. Moreover, anti-hypertensive drugs can exert differential effects on brachial and central pressure. Therefore, basing treatment decisions on central, rather than brachial pressure, is likely to have important implications for the future diagnosis and management of hypertension. Such a paradigm shift will, however, require further, direct evidence that selectively targeting central pressure, brings added benefit, over and above that already provided by brachial artery pressure.

Effect of oral nitrates on pulse pressure and arterial elasticity in patients aged over 65 years with refractory isolated systolic hypertension: study protocol for a randomized controlled trial

Background

Isolated systolic hypertension is a highly prevalent disease among the elderly. The little available evidence on the efficacy of nitrates for treating the disease is based on small experimental studies.

Methods/design

We performed a multicenter, randomized, double-blind, phase III, placebo-controlled trial in 154 patients aged over 65 years with refractory isolated systolic hypertension. Patients were randomized to placebo or 40 mg/day of extended-release isosorbide mononitrate added to standard therapy and titrated to 60 mg/day at week 6 if blood pressure exceeded 140/90 mmHg.

The primary objective was to assess the effect on clinical pulse pressure of extended-release isosorbide mononitrate added to standard therapy in patients aged over 65 years with refractory isolated systolic hypertension after 3 months of treatment.

The secondary objectives were as follows: to quantify the effect of adding the study drug on central blood pressure and vascular compliance using the augmentation index and pulse wave velocity; to evaluate the safety profile by recording adverse effects (frequency, type, severity) and the percentage of patients who had to withdraw from the trial because of adverse events; to quantify the percentage of patients who reach a clinical systolic blood pressure <140 mmHg or <130 mmHg measured by ambulatory blood pressure monitoring; and to quantify the change in pulse pressure measured by ambulatory blood pressure monitoring.

Discussion

Few clinical trials have been carried out to test the effect of oral nitrates on isolated systolic hypertension, even though these agents seem to be effective. Treatment with extended-release isosorbide mononitrate could improve control of systolic blood pressure without severe side effects, thus helping to reduce the morbidity and mortality of the disease.

Trial registration

EUDRACT Number: 2012-002988-10

Regulation of vascular tone and pulse wave velocity in human muscular conduit arteries: selective effects of nitric oxide donors to dilate muscular arteries relative to resistance vessels

Arterial tone in muscular conduit arteries may influence pressure wave reflection through changes in diameter and pulse wave velocity. We examined the relative specificity of vasodilator drugs for radial artery and forearm resistance vessels during intrabrachial arterial infusion. The nitric oxide (NO) donors, nitroglycerine and nitroprusside, and brain natriuretic peptide were compared with the α-adrenergic antagonist phentolamine, calcium-channel antagonist verapamil, and hydralazine. Radial artery diameter was measured by high resolution ultrasound, forearm blood flow by strain gauge plethysmography, and pulse wave velocity by pressure recording cuffs placed over the distal brachial and radial arteries. Norepinephrine was used to constrict the radial artery to generate a greater range of vasodilator tone when examining pulse wave velocity. Despite dilating resistance vasculature, phentolamine and verapamil had little effect on radial artery diameter (mean dilation <9%). By contrast, for comparable actions on resistance vessels, nitroglycerine and nitroprusside but not brain natriuretic peptide had powerful actions to dilate the radial artery (dilations of 31.3 ± 3.6%, 23.6 ± 3.1%, and 9.8 ± 2.0% for nitroglycerine, nitroprusside, and brain natriuretic peptide, respectively). Changes in pulse wave velocity followed those in arterial diameter irrespective of the signaling pathway used to modulate arterial tone (R=-0.89, P<0.05). Basal tone in human muscular arteries is relatively unaffected by α-adrenergic or calcium-channel blockade, but is functionally or directly antagonized by NO donors. The differential response to NO donors suggests that there is potential to manipulate the downstream pathway to confer greater specificity for large arteries with a resultant decrease in pressure wave reflection and systolic blood pressure.

Early vascular aging and the role of central blood pressure

Vascular aging is described as a gradual process involving biochemical, enzymatic, and cellular changes of the vasculature and modification of the signals that modulate them. On the basis of this conception a new pathophysiological model for deeper understanding of cardiovascular risk and its treatment was introduced. The idea of early vascular aging, that is the acceleration of vascular aging seems to be a promising tool for clinical guidance in individuals at increased cardiovascular risk or a strong family history of early cardiovascular manifestations. Increased arterial stiffness, dilation of central elastic arteries, impaired endothelial function and vasodilatation are dominant aspects of this premature process.

Age, hypertension and arterial function

1. Ageing exerts a marked effect on the cardiovascular system and, in particular, the large arteries. Using a variety of techniques to assess arterial stiffness, many cross-sectional studies have demonstrated a significant relationship between age and aortic stiffness, although the age-related changes observed in peripheral arteries appear to be less marked. 2. The relationship between arterial stiffness and hypertension is more complex. The distending, or mean arterial, pressure is an important confounder of measurements of arterial stiffness and, therefore, must be taken into consideration when assessing arterial stiffness in hypertensive subjects or investigating the effect of antihypertensive agents. Current methods for correcting for differences in distending pressure involve pharmacological manipulation, statistical correction or mathematical manipulation of stiffness indices. 3. Many studies have provided evidence that both peripheral (muscular) and central (elastic) arteries are stiffer in subjects with mixed (systolic/diastolic) hypertension compared with normotensive subjects. However, it is unclear to what extent differences in mean arterial pressure explain the observed differences in hypertensive subjects. In contrast, isolated systolic hypertension is associated with increased aortic, but not peripheral artery, stiffness, although the underlying mechanisms are somewhat unclear. 4. Traditional antihypertensive agents appear to reduce arterial stiffness, but mostly via an indirect effect of lowering mean pressure. Therefore, therapies that target the large arteries to reduce stiffness directly are urgently required. Agents such as nitric oxide donors and phosphodiesterase inhibitors may be useful in reducing stiffness via functional mechanisms. In addition, inhibitors or breakers of advanced glycation end-product cross-links between proteins, such as collagen and elastin, hold substantial promise.

High pulse pressure and low mean arterial pressure: two predictors of death after a myocardial infarction

OBJECTIVES

Although the negative prognostic implication of a clinical history of arterial hypertension in myocardial infarction (MI) survivors is well known, the predictive role of the blood pressure (BP) regimen after MI is not well defined. The aim of this study was to investigate the prognostic significance of different BP indices in post-MI.

METHODS AND RESULTS

We evaluated the relationship between baseline systolic, diastolic, pulse and mean arterial pressure (MAP), measured by sphygmomanometry at discharge from hospital or within 3 months of an MI, and total and cardiovascular mortality in 11 116 patients enrolled in the GISSI-Prevenzione trial. Over 3.5 years of follow-up, 999 patients died, 657 of them from cardiovascular causes. Low mean and high pulse pressure were significantly associated with total and cardiovascular mortality after controlling for potential confounders in the multivariate analysis. As compared with patients with less extreme BP values, patients with MAP of 80 mmHg or less (n = 1241; 11.2%) had a 48% higher risk of cardiovascular death [95% confidenceinterval (CI) 1.16-1.87; P = 0.001] and those with pulse pressure greater than 60 mmHg (n = 958; 8.6%) had a 35% higher risk (95% CI 1.09-1.69; P = 0.007); only four subjects (0.04%) had both a high pulse pressure and a low MAP (relative risk of cardiovascular death 3.48; 95% CI 0.48-25.88; P = 0.218).

CONCLUSIONS

Our results show for the first time an additional prognostic importance of two easily measurable components of BP, definitely high pulse pressure (> 60 mmHg) and low MAP (< or = 80 mmHg), in a large sample of non-selected patients surviving MI who entered a modern programme of cardiovascular prevention.

Nitrates as adjunct hypertensive treatment

Isolated systolic hypertension (ISH) is an important cause of strokes and heart failure among the elderly, but it is difficult to control in some elderly patients, even with combination antihypertensive therapy. The presence of a prominent reflection wave in the arterial pulse-wave profile of such patients signifies that adjuvant nitrate therapy may prove effective in lowering pulse pressure. This reflection arises in the muscular arteries and is caused by arterial stiffness associated with hypertension and other cardiovascular risk factors, probably including endothelial dysfunction. By acting directly on the arterial wall, nitrates produce endothelium-independent vasorelaxation. The reflection wave and the contribution this makes to pulse pressure are thereby ablated. Controlled trials of the use of isosorbide mononitrate and isosorbide dinitrate in ISH have shown that these agents decrease systolic blood pressure as well as pulse pressure, and with the mononitrate, efficacy appears to be unimpaired by nitrate tolerance.

Blood Pressure Components in Clinical Hypertension

This review offers a critical evaluation of the remarkable progress in antihypertensive therapy since its inception. Despite the introduction of newer, more sophisticated drugs, treatment results have remained stable. Problems impeding further improvement include limited patient compliance, clinical inertia, incomplete adherence to guidelines, and dependence on brachial artery cuff pressures for diagnosis, risk assessment, and treatment response. Brachial artery systolic and pulse pressures do not reliably represent aortic or carotid artery pressures, which are better risk predictors for the heart and brain. Mean pressure, which is the same throughout the arterial tree, is directly measurable by cuff oscillometry, and might become the best single risk predictor. Available drugs have limited ability to decrease the aortic stiffness that is responsible for the elevated systolic blood pressure of aging. Therefore, to improve risk assessment and therapeutic benefit, we might include mean blood pressure and pulse pressure into blood pressure measurements, pursue efforts to measure central blood pressure, and search for new drugs to reduce arterial stiffness.

Systolic hypertension in the elderly: arterial wall mechanical properties and the renin-angiotensin-aldosterone system

BACKGROUND

Systolic hypertension in the elderly involves an increase of arterial stiffness and early wave reflections, both of them causing a predominant or selective increase of systolic blood pressure. The mechanisms for such alterations remain largely unknown.

DESCRIPTION AND RESULTS

The development of systolic hypertension includes constantly an age-related increase of sodium sensitivity and of endothelial dysfunction, both responsible for phenotypic changes of aortic smooth muscle cells with collagen accumulation and increased stiffness. In the presence of a high sodium diet and under the influence of angiotensin II and aldosterone, a higher number of attachments between vascular smooth muscle cells and collagen fibers develop, causing a supplementary increase in stiffness independent of the mean blood pressure together with the occurrence of early wave reflections. Gene polymorphisms related to the renin-angiotensin system may participate in this evolution.

CONCLUSION

This process contributes to accelerating the increase in pulse pressure and arterial stiffness with age, and therefore to the development of cardiovascular risk.

Systolic and diastolic blood pressure lowering as determinants of cardiovascular outcome

Based on individual patient data, we performed a quantitative overview of trials in hypertension to investigate to what extent lowering of systolic blood pressure (SBP) and diastolic blood pressure (DBP) contributed to cardiovascular prevention. We selected trials that tested active antihypertensive drugs against placebo or no treatment. Our analyses included 12,903 young (30 to 49 years of age) patients randomized in 3 trials and 14,324 old (60 to 79 years of age) and 1209 very old (> or =80 years of age) patients enrolled in 8 trials. Antihypertensive treatment reduced SBP/DBP by 8.3/4.6 mm Hg in young patients, by 10.7/4.2 mm Hg in old patients, and by 9.4/3.2 mm Hg in very old patients, respectively, resulting in ratios of DBP to SBP lowering of 0.55, 0.39, and 0.32, respectively (P=0.004 for trend with age). In spite of the differential lowering of SBP and DBP, antihypertensive treatment reduced the risk of all cardiovascular events, stroke and myocardial infarction in the 3 age strata to a similar extent. Absolute benefit increased with age and with lower ratio of DBP to SBP lowering. Furthermore, in patients with a larger-than-median reduction in SBP, active treatment consistently reduced the risk of all outcomes irrespective of the decrease in DBP or the achieved DBP. These findings remained consistent if the achieved DBP averaged <70 mm Hg. In conclusion, our overview suggests that antihypertensive drug treatment improves outcome mainly through lowering of SBP.

Arterial stiffness, endothelial function and novel pharmacological approaches

1. Despite over half a century of intensive research, cardiovascular disease remains the leading cause of death world wide. Nevertheless, a number of risk factors for cardiovascular disease have been identified, such as hypertension and serum cholesterol, and therapies targeting such factors are effective in reducing cardiovascular and total mortality. Arterial stiffness is an additional independent risk factor for cardiovascular disease and strategies aimed at lowering arterial stiffness may be effective in reducing cardiovascular risk. However, in order to exploit fully the therapeutic potential of this approach, it is necessary first to understand the physiological and pathophysiological factors regulating the stiffness of the large arteries. 2. Until recently, stiffness was thought to depend largely upon structural components within the arterial wall, such as elastin and collagen and the distending pressure. However, we now recognize that arterial smooth muscle also regulates vessel stiffness and that a number of locally derived and circulating factors, including nitric oxide (NO), endothelin-1 and the natriuretic peptides, contribute to the short-term or functional regulation of large artery stiffness. Changes in the balance between these factors and, in particular, a reduction in NO production may well explain why conditions such as hypercholesterolaemia and diabetes are themselves associated with arterial stiffening before the development of manifest atherosclerosis. 3. The importance of smooth muscle in regulating arterial stiffness suggests that direct pharmacological manipulation of stiffness may be possible, thus providing novel therapeutic strategies to reduce cardiovascular risk. Furthermore, differences in the effect of existing drugs on larger artery stiffness may explain, in part, why some drugs produce better clinical outcomes than others.

Mechanisms, pathophysiology, and therapy of arterial stiffness

Arterial stiffness is a growing epidemic associated with increased risk of cardiovascular events, dementia, and death. Decreased compliance of the central vasculature alters arterial pressure and flow dynamics and impacts cardiac performance and coronary perfusion. This article reviews the structural, cellular, and genetic contributors to arterial stiffness, including the roles of the scaffolding proteins, extracellular matrix, inflammatory molecules, endothelial cell function, and reactive oxidant species. Additional influences of atherosclerosis, glucose regulation, chronic renal disease, salt, and changes in neurohormonal regulation are discussed. A review of the hemodynamic impact of arterial stiffness follows. A number of lifestyle changes and therapies that reduce arterial stiffness are presented, including weight loss, exercise, salt reduction, alcohol consumption, and neuroendocrine-directed therapies, such as those targeting the renin-angiotensin aldosterone system, natriuretic peptides, insulin modulators, as well as novel therapies that target advanced glycation end products.

Long-term effectiveness of extended-release nitrate for the treatment of systolic hypertension

Isosorbide mononitrate (ISMN) is effective in the short-term for decreasing systolic blood pressure, pulse pressure, and pulse wave reflection in patients with systolic hypertension. To determine whether tolerance negates the efficacy of this nitrate in the long-term, a placebo-controlled study was performed in which ISMN was withdrawn briefly in a group of patients (n=16) who had received extended-release ISMN 60 to 120 mg once daily for 16 to 109 months. Blood pressure and wave reflection were determined by 24-hour ambulatory recorder and tonometer, respectively. During a 4-hour delay of the regular morning dose of ISMN, mean systolic blood pressure was higher than with the regular ISMN dosing schedule (P<0.0001). The maximum placebo-active difference was 16+/-4 mm Hg. The corresponding difference in augmentation index (a measure of pulse wave reflection) corrected for heart rate was 25+/-4% (P<0.001). The difference in pulse pressure was 13+/-3 mm Hg (P<0.001). There was no significant difference in diastolic blood pressure. For a subgroup (n=12) in which the effects of a single ISMN dose had been determined at the initiation of regular ISMN therapy, the mean change in augmentation index was of similar magnitude to that observed in their initial study. Thus, tolerance does not seriously diminish the antihypertensive efficacy of ISMN used as adjunct therapy in the chronic treatment of systolic hypertension. This agent lowers systolic blood pressure sufficiently to achieve therapeutic goal in some patients refractory to conventional treatment regimens.

Effects of isosorbide mononitrate and AII inhibition on pulse wave reflection in hypertension

The aortic pulse wave contour in isolated systolic hypertension often shows a prominent reflection peak, which combines with the incident wave arising from cardiac ejection so as to widen pulse pressure. We investigated the effects of an extended-release nitrate preparation and of 2 angiotensin II (AII) inhibitors (an AII receptor antagonist and an ACE inhibitor) on the aortic pulse wave contour and systemic blood pressure in hypertensive subjects with high augmentation index caused by exaggerated pulse wave reflection. Two double-blind, randomized, placebo-controlled crossover studies were carried out in a total of 16 elderly patients with systolic hypertension resistant to conventional antihypertensive therapy. In 1 study, pharmacodynamic responses to single doses of placebo, isosorbide mononitrate, eprosartan, and captopril were determined; in the other, single-dose isosorbide mononitrate and placebo were compared in subjects treated with AII inhibitors at baseline. Blood pressure was measured by sphygmomanometry and pulse wave components by applanation tonometry at the radial artery. All 3 agents were shown to decrease brachial systolic blood pressure, aortic systolic blood pressure, and aortic pulse pressure. Qualitative effects on the aortic pulse wave contour differed: augmentation index was not significantly altered by either captopril or eprosartan but was decreased (P<0.0001) by approximately 50% of the placebo value with isosorbide mononitrate in both study groups. We propose that isosorbide mononitrate corrected the magnified wave reflection in systolic hypertension of these elderly patients by an effect that was distinct from that exercised by either acute or chronic AII inhibition.

Improved outcomes with antihypertensive medication in the elderly with isolated systolic hypertension

Isolated systolic hypertension affects over 15% of all individuals aged >60 years. In the elderly, systolic hypertension is a major modifiable cardiovascular risk factor. Systolic blood pressure (SBP) is associated with higher risk of an adverse outcome, whereas diastolic blood pressure (DBP) is inversely correlated with total mortality, independent of SBP, highlighting the role of pulse pressure as a risk factor. Three placebo-controlled outcome trials on antihypertensive drug treatment in older patients with isolated systolic hypertension have been published: the Systolic Hypertension in the Elderly Program (SHEP), the Systolic Hypertension in Europe (Syst-Eur) Trial and the Systolic Hypertension in China (Syst-China) Trial. These 3 trials demonstrated the benefit of antihypertensive drug treatment. A meta-analysis was performed by pooling the patients from these 3 trials with a subset of patients with isolated systolic hypertension from 5 other trials in the elderly. The pooled results of 15,693 older patients with isolated systolic hypertension prove that antihypertensive drug treatment isjustified if on repeated clinic measurements SBP is 160 mm Hg or higher.

Pulse pressure, arterial stiffness, and drug treatment of hypertension

Epidemiological studies in the past decade have stressed the importance of pulse pressure as an independent risk factor for cardiovascular morbidity and mortality. We briefly review the epidemiological evidence and discuss in more detail the pathophysiological basis for this observation and the therapeutic consequences. We focus on the vascular determinants of increased pulse pressure. Both longitudinal and cross-sectional components of the vascular system contribute to the shape of the arterial pressure wave and, thereby, to pulse pressure. The primary longitudinal component is the architecture of the arterial tree, which determines the major reflection sites for the pressure wave. The cross-sectional architecture of the vascular system consists of a geometric (diameter) and a structural (composition vessel wall) component. Both diameter and composition of the vessel wall vary greatly when going from central to more peripheral arteries. We review the implications for the functional properties of various arterial segments. Finally, we discuss the therapeutic consequences of targeting pulse pressure rather than mean blood pressure with various drug classes. Among the antihypertensive agents, nitrates, NO donors, and drugs that interfere with the renin-angiotensin-aldosterone system may offer useful tools to lower pulse pressure, in addition to mean blood pressure. Future developments may include non-antihypertensive agents that target collagen or other components of the arterial wall matrix. However, large-scale clinical trials will have to confirm the therapeutic value of these agents in the treatment of increased pulse pressure and arterial stiffness.

Improvement in blood pressure, arterial stiffness and wave reflections with a very-low-dose perindopril/indapamide combination in hypertensive patient: a comparison with atenolol

International guidelines recommend that antihypertensive drug therapy should normalize not only diastolic (DBP) but also systolic blood pressure (SBP). Therapeutic trials based on cardiovascular mortality have recently shown that SBP reduction requires normalization of both large artery stiffness and wave reflections. The aim of the present study was to compare the antihypertensive effects of the very-low-dose combination indapamide (0.625 mg) and perindopril (2 mg) (Per/Ind) with the beta-blocking agent atenolol (50 mg) to determine whether Per/Ind decreases SBP and pulse pressure (PP) more than does atenolol and, if so, whether this decrease is predominantly due to reduction of aortic pulse wave velocity (PWV) (automatic measurements) and reduction of wave reflections (pulse wave analysis, applanation tonometry). In a double-blind randomized study, 471 patients with essential hypertension were followed for 12 months. For the same DBP reduction, Per/Ind decreased brachial SBP (-6.02 mm Hg; 95% confidence interval, -8.90 to -3.14) and PP (-5.57; 95% confidence interval, -7.70 to -3.44) significantly more than did atenolol. This difference was significantly more pronounced for the carotid artery than for the brachial artery. Whereas the 2 antihypertensive agents decreased PWV to a similar degree, only Per/Ind significantly attenuated carotid wave reflections, resulting in a selective decrease in SBP and PP. The very-low-dose combination Per/Ind normalizes SBP, PP, and arterial function to a significantly larger extent than does atenolol, a hemodynamic profile that is known to improve survival in hypertensive populations with high cardiovascular risk.

Improved arterial compliance by a novel advanced glycation end-product crosslink breaker

BACKGROUND

Arterial stiffening with increased pulse pressure is a leading risk factor for cardiovascular disease in the elderly. We tested whether ALT-711, a novel nonenzymatic breaker of advanced glycation end-product crosslinks, selectively improves arterial compliance and lowers pulse pressure in older individuals with vascular stiffening.

METHODS AND RESULTS

Nine US centers recruited and randomly assigned subjects with resting arterial pulse pressures >60 mm Hg and systolic pressures >140 mm Hg to once-daily ALT-711 (210 mg; n=62) or placebo (n=31) for 56 days. Preexisting antihypertensive treatment (90% of subjects) was continued during the study. Morning upright blood pressure, stroke volume, cardiac output, systemic vascular resistance, total arterial compliance, carotid-femoral pulse wave velocity, and drug tolerability were assessed. ALT-711 netted a greater decline in pulse pressures than placebo (-5.3 versus -0.6 mm Hg at day 56; P=0.034 for treatment effect by repeated-measures ANOVA). Systolic pressure declined in both groups, but diastolic pressure fell less with ALT-711 (P=0.056). Mean pressure declined similarly in both groups (-4 mm Hg; P<0.01 for each group, P=0.34 for treatment effect). Total arterial compliance rose 15% in ALT-711-treated subjects versus no change with placebo (P=0.015 versus ALT-711), an effect that did not depend on reduced mean pressure. Pulse wave velocity declined 8% with ALT-711 (P<0.05 at day 56, P=0.08 for treatment effect). Systemic arterial resistance, cardiac output, and heart rate did not significantly change in either group.

CONCLUSIONS

ALT-711 improves total arterial compliance in aged humans with vascular stiffening, and it may provide a novel therapeutic approach for this abnormality, which occurs with aging, diabetes, and isolated systolic hypertension.

The benefit of treating isolated systolic hypertension

Isolated systolic hypertension affects over 15% of all people older than 60 years of age. In the elderly, systolic hypertension is a major modifiable cardiovascular risk factor. Systolic blood pressure is associated with higher risk of an adverse outcome. Diastolic blood pressure is inversely correlated with total mortality, independent of systolic blood pressure, highlighting the role of pulse pressure as risk factor. Three placebo-controlled outcome trials on antihypertensive drug treatment in older patients with isolated systolic hypertension have been published: the Systolic Hypertension in the Elderly Program (SHEP), the Systolic Hypertension in Europe (Syst-Eur) Trial, and the Systolic Hypertension in China (Syst-China) Trial. These three trials showed the benefit of antihypertensive drug treatment. A meta-analysis was done by pooling the patients from these three trials with a subset of patients with isolated systolic hypertension from five other trials in the elderly. The pooled results of 15,693 older patients with isolated systolic hypertension prove that antihypertensive drug treatment is justified if systolic blood pressure on repeated clinic measurements is 160 mm Hg or higher.

Lowering of blood pressure and coronary blood flow in isolated systolic hypertension

BACKGROUND

In essential hypertension, the lower limit of autoregulation of coronary flow shifts to higher perfusion and the hypertensive ventricle is at a higher than normal risk of ischemia, and less able to tolerate acute reduction of coronary perfusion pressure. Little is known about pattern of coronary flow in isolated systolic hypertension, a pathologic condition in which the elevated systolic blood pressure is associated with a lower than normal vascular compliance and normal or slightly greater than normal mean arterial pressure and vascular resistance.

OBJECTIVE

To evaluate the effects of rapid normalization of blood pressure on coronary blood flow in isolated systolic hypertension.

METHODS

We subjected 20 patients with isolated systolic hypertension to intraoperative hemodynamic and transesophageal echocardiographic monitoring during peripheral vascular surgery. Coronary flow velocity integrals and diameters in the left anterior descending coronary artery were evaluated under baseline conditions and after normalization of blood pressure, which occurred spontaneously during anesthesia (10 cases; group 1A) or was induced by infusion of nitrate (10 cases, group 1B).

RESULTS

After normalization of systolic blood pressure integrals decreased significantly only for patients in group 1A; percentage changes of diameter were significantly greater for patients in group 1B. Therefore, coronary blood flow after normalization of systolic blood pressure increased for patients in group 1B (by 28+/-25%) and decreased for patients in group 1A (by 30+/-21%). Changes in integrals were inversely related to those in diameter (r= -0.72, P < 0.001); for patients in group 1A changes in coronary perfusion pressure and diameter were related to those of integrals (r= 0.94; P < 0.0005).

CONCLUSIONS

In isolated systolic hypertension, despite there being similar changes of the systolic blood pressure, administration of nitrates caused a marked increase of coronary flow through direct effects on coronary circulation, whereas spontaneous normotension was associated with a significant reduction of coronary flow.

Therapeutic studies and arterial stiffness in hypertension: recommendations of the European Society of Hypertension. The Clinical Committee of Arterial Structure and Function. Working Group on Vascular Structure and Function of the European Society of Hypertension

BACKGROUND

Increased pulse pressure and arterial stiffness are identified as predictors of cardiovascular risk in older hypertensive populations, particularly that of myocardial infarction. Because increased pulse pressure involves an increase in systolic (SBP) and a decrease in diastolic blood pressure (DBP), and because the former promotes cardiac hypertrophy and the latter alters coronary perfusion, a drug regimen reducing pulse pressure and decreasing arterial stiffness might further reduce cardiovascular risk. Under conventional treatment, normalization of DBP (< or = 90 mmHg) is not consistently associated with normalization of SBP (< or = 140 mmHg).

THERAPEUTIC DESIGNS

In individuals older than 50 years, the goal of antihypertensive treatment should be, not only to decrease mean blood pressure (to less than 100 mmHg), but also to decrease pulse pressure (to less than 50 mmHg). Using appropriate pharmacological tools, trials should test whether an active decrease in arterial stiffness might produce an attenuation of the age-related increase in SBP and decrease in DBP, thus delaying the age-related increase in pulse pressure and decreasing further cardiovascular risk. This procedure requires concomitant non-invasive evaluations of aortic stiffness.

CONCLUSION

The studies that are required in hypertension should use two different approaches: novel titrations of conventional drugs to achieve a decrease in either SBP or pulse pressure, and development of new drugs acting selectively on the large artery wall, to facilitate the conduct of subsequent controlled trials.

Drug treatment of hypertension: the reduction of pulse pressure does not necessarily parallel that of systolic and diastolic blood pressure

Drug treatment of hypertension reduces systolic and diastolic blood pressure according to a well-established dose-response curve. Whether there is a parallel decrease in mean blood pressure and pulse pressure has not been investigated in the past Recent analysis of the literature and personal work indicates that, during drug treatment of hypertension, a significant decrease in systolic and diastolic blood pressure may be associated with an unchanged pulse pressure, a situation that might contribute to maintaining cardiovascular risk.

Is there a preferred antihypertensive therapy for isolated systolic hypertension and reduced arterial compliance?

Isolated systolic hypertension (ISH) is the most common type of hypertension and the most difficult type to control with antihypertensive therapy. ISH, by definition, is wide pulse pressure hypertension resulting largely from excessive large artery stiffness and representing an independent risk factor for cardiovascular disease in the older aged population. Two major intervention studies of ISH have shown significant benefit in reducing systolic blood pressure with active drug therapy, including thiazide diuretics and calcium receptor antagonists. The optimal treatment strategy is to maximize reduction in systolic blood pressure and to minimize reduction in diastolic blood pressure, thereby reducing pulse pressure. All classes of antihypertensive drugs reduce pulse pressure by means of lowering peripheral resistance, but certain drugs like nitrates, angiotensin converting enzyme inhibitors, and other drugs affecting the renin-angiotensin system have multiple actions that improve large artery stiffness and early wave reflection and are especially useful in treating ISH in the elderly.

Risks of untreated and treated isolated systolic hypertension in the elderly: meta-analysis of outcome trials

BACKGROUND

Previous meta-analysis of outcome trials in hypertension have not specifically focused on isolated systolic hypertension or they have explained treatment benefit mainly in function of the achieved diastolic blood pressure reduction. We therefore undertook a quantitative overview of the trials to further evaluate the risks associated with systolic blood pressure in treated and untreated older patients with isolated systolic hypertension

METHODS

Patients were 60 years old or more. Systolic blood pressure was 160 mm Hg or greater and diastolic blood pressure was less than 95 mm Hg. We used non-parametric methods and Cox regression to model the risks associated with blood pressure and to correct for regression dilution bias. We calculated pooled effects of treatment from stratified 2 x 2 contingency tables after application of Zelen's test of heterogeneity.

FINDINGS

In eight trials 15 693 patients with isolated systolic hypertension were followed up for 3.8 years (median). After correction for regression dilution bias, sex, age, and diastolic blood pressure, the relative hazard rates associated with a 10 mm Hg higher initial systolic blood pressure were 1.26 (p=0.0001) for total mortality, 1.22 (p=0.02) for stroke, but only 1.07 (p=0.37) for coronary events. Independent of systolic blood pressure, diastolic blood pressure was inversely correlated with total mortality, highlighting the role of pulse pressure as risk factor. Active treatment reduced total mortality by 13% (95% CI 2-22, p=0.02), cardiovascular mortality by 18%, all cardiovascular complications by 26%, stroke by 30%, and coronary events by 23%. The number of patients to treat for 5 years to prevent one major cardiovascular event was lower in men (18 vs 38), at or above age 70 (19 vs 39), and in patients with previous cardiovascular complications (16 vs 37).

INTERPRETATION

Drug treatment is justified in older patients with isolated systolic hypertension whose systolic blood pressure is 160 mm Hg or higher. Absolute benefit is larger in men, in patients aged 70 or more and in those with previous cardiovascular complications or wider pulse pressure. Treatment prevented stroke more effectively than coronary events. However, the absence of a relation between coronary events and systolic blood pressure in untreated patients suggests that the coronary protection may have been underestimated.

Stiffness of carotid artery wall material and blood pressure in humans: application to antihypertensive therapy and stroke prevention

BACKGROUND AND PURPOSE

Because epidemiological studies show that increased pulse pressure and carotid wall-material stiffness are predictors of cardiovascular mortality independent of age, atherosclerosis, and conventional risk factors, the relationships between carotid wall stiffness and blood pressure are important to the optimization of cardiovascular prevention.

SUMMARY OF REVIEW

In middle-aged hypertensive patients, mean and pulse pressures are increased, and systolic and diastolic pressures are increased to the same degree as mean pressure. Carotid hypertrophy is associated with normal wall stress, but no increased stiffness of wall material has been reported. With age, the normal wall stress is associated with a larger diameter and a stiffer material of carotid but not peripheral arteries. The stiffer wall involves calcifications, large amounts of collagen, and fragmentation and rupture of elastic tissue, which results in increased pulse-wave velocity and alterations of amplitude and timing of wave reflections and thus causes a disproportionate increase in systolic and pulse pressure. During this period, acutely administered nitrates in elderly subjects are able to reduce selectively systolic and pulse pressures without altering diastolic and mean blood pressure and composition of the carotid wall.

CONCLUSIONS

New therapeutic approaches acting mainly on the wall of large arteries are needed to treat hypertension in elderly patients and prevent stroke and myocardial infarction. These drugs could either selectively lower pulse pressure through changes in wave reflections (as nitrates do) or decrease arterial wall stiffness through modification of the composition of material (such as compounds that act on collagen cross-linking).

The diastolic blood pressure in systolic hypertension

Because antihypertensive therapy is effective in elderly patients with isolated systolic hypertension, attention has been focused on the systolic blood pressure as a predictor of cardiovascular risk. However, it is a normal diastolic pressure that separates patients with isolated systolic hypertension from those with essential hypertension. The normal diastolic and elevated systolic pressures are largely due to age-related stiffening of the aorta. An indistensible aorta causes the pressure pulse to travel faster than normal, where it is quickly reflected off the peripheral resistance. The reflected wave then returns to the central aorta in systole rather than diastole. This augments the systolic pressure further, increasing cardiac work while reducing the diastolic pressure, on which coronary flow is dependent. The potential harm of further reducing the diastolic pressure with antihypertensive therapy, especially in patients with coronary heart disease, underlies the controversial "J curve." By decreasing the blood pressure, all antihypertensive agents improve aortic distensibility, but no agents do so directly; the nitrates come the closest. Such an agent would be useful because any therapeutic increase in aortic distensibility would decrease systolic pressure without greatly reducing diastolic pressure. The problem is complicated by the suspected inaccuracy of the cuff technique in predicting the aortic diastolic pressure. New noninvasive methods to predict the aortic diastolic pressure may help in the future. At present, the combination of a high systolic and normal diastolic pressure-a widened pulse pressure-seems to be the best predictor of cardiovascular risk in patients with hypertension or heart disease. Patients with isolated systolic hypertension should be treated, but marked diastolic hypotension should be avoided.

A controlled study of the effects of isosorbide mononitrate on arterial blood pressure and pulse wave form in systolic hypertension

OBJECTIVE

To determine the effect of an extended-release nitrate preparation on the arterial pulse wave and blood pressure of patients in whom systolic blood pressure was elevated in part by exaggerated pulse-wave reflectance.

DESIGN

A double-blind randomized placebo-controlled crossover study was carried out.

PATIENTS AND METHODS

The subjects were ten elderly patients with systolic hypertension resistant to conventional anti-hypertensive therapy. Pharmacodynamic responses to 2-week courses of placebo/isosorbide mononitrate (ISMN) were assessed in seven subjects by an ambulatory blood pressure monitor, and in all ten subjects by standard sphygmomanometry, arterial pulse-wave analysis and measurement of plasma nitrate concentration during peak and trough.

RESULTS

Ambulatory systolic blood pressure was decreased by ISMN (P < 0.02) between 1000 and 2200 h. Ambulatory diastolic blood pressure fell with ISMN (P < 0.01) during the last 4 h of this period. At peak plasma nitrate levels, ISMN decreased the aortic systolic blood pressure (P < 0.01), ejection peak (P < 0.02) and augmentation component (P < 0.001) of the pulse wave; heart rate increased slightly (P < 0.03).

CONCLUSION

ISMN has a role as an adjunct in the anti-hypertensive therapy of patients with refractory systolic hypertension due to exaggerated pulse-wave reflectance.

Medical treatment of the aorta. II

Because of its elastic properties, the aorta influences left ventricular function and coronary blood flow. The aortic pressure-diameter relationship provides direct estimations of the elastic properties of the aorta in humans. Current research is focused on examining strategies that might improve aortic function. Therapeutic interventions alter the elastic properties of the aorta, and improvement of the elastic properties of the aorta may be beneficial in modifying the natural history of the disease. Certain pharmacological agents that result in improved aortic function have been identified.

Is it possible to develop drugs that act more selectively on large arteries?

BACKGROUND

Patients with high pulse pressures have an increased risk for cardiovascular events. Drugs that selectively decrease high pulse pressure may be of interest for these patients. Such drugs have a more pronounced effect on large arteries than on resistance vessels.

OBJECTIVE

To compare the selectivity to large arteries of the new nitric oxide donor sinitrodil with the classic nitrate isosorbide dinitrate in healthy young men in order to investigate whether it is possible to develop drugs that act more selectively on large arteries.

DESIGN

The study had a double-blind, 5-way cross-over design. In randomized order, subjects received a single oral dose of 10 mg sinitrodil, 20 mg sinitrodil, 40 mg sinitrodil, isosorbide dinitrate and placebo. Measurements were performed before and 45 min after administration of the drugs. Between each drug administration, at least 3 days of wash-out was allowed.

METHODS

The effects of the drugs on large arteries and resistance vessels were assessed by their effects on brachial artery compliance and total peripheral resistance, respectively.

RESULTS

Brachial artery compliance increased gradually with increasing doses of sinitrodil (by 10, 20 and 27% with 10, 20 and 40 mg sinitrodil, respectively). Total peripheral resistance index decreased with isosorbide dinitrate (by 11%) and 40 mg sinitrodil (by 7%), while it remained unchanged with 10 mg and 20 mg sinitrodil.

CONCLUSIONS

The results of this study show that it may be possible to develop drugs with a higher selectivity for large arteries. Such drugs may be good candidates to decrease high pulse pressure without substantially decreasing mean and diastolic blood pressures.

Systolic blood pressure revisited

The clinical importance of systolic blood pressure (SBP) needs no emphasis. Its determinants are well known, but recent studies of one of these determinants, arterial distensibility, have led to results that now have clinical relevance. This review summarizes the role of arterial stiffness in ventricular-vascular coupling in the normal circulation and that disordered by aging and hypertension. The discussion defines the unfamiliar terms of compliance, distensibility and modulus and indicates how they are measured. Such measurements have increased our understanding of the parts played by the inhomogeneity of the arterial tree and reflected pressure waves in governing SBP. Elevated SBP is a recognized risk factor for cardiovascular complications among older patients, but when this elevation is due to a stiffened arterial tree, diastolic blood pressure (DBP) is necessarily reduced. Early epidemiologic studies in hypertension required a DBP > or = 90 mm Hg for hospital admission. They therefore excluded persons with high SBP, low DBP and very wide pulse pressure (PP). More recent inclusion of such patients has shown that elevation of SBP and PP is a strong predictor of cardiovascular risk. These considerations point to a possible redefinition of hypertension to include patients with lower DBP and to the inaccuracy but indispensability of the brachial artery pressure as a surrogate for aortic pressure--the pressure the heart sees. Finally, we review the known effects of available antihypertensive drugs on the arterial wall and indicate possible future directions of research stemming from wider understanding of the role of arterial distensibility in hypertension.

Renin-angiotensin system and cell communication in the failing heart

The influence of heart failure on the process of cell communication was investigated in cell pairs isolated from the ventricle of cardiomyopathic hamsters (11 months old) and the results compared with age-matched normal hamsters. The gap junctional conductance (gj) was measured with two voltage-clamp amplifiers. The results showed two major populations of cell pairs with respect to gj values: one with very low values (0.8 to 2.5 nS) and the other with higher values (7 to 35 nS). In normal hamsters, the most frequent gj values were in the range of 40 to 100 nS. Angiotensin II (Ang 11, 1 microg/mL) caused cell uncoupling in myopathic myocytes with low gj but reduced gj by 53 +/- 6.6 percent (+/- SE) in cell pairs with higher gj values (7 to 35 nS). The effect of Ang II on gj of myopathic cell pairs was suppressed by losartan (10(-7) mol/L). In cardiomyopathic cell pairs with low gj (0.8 to 2.5 nS), enalapril (1 microg/mL) caused an appreciable increase in gj (219 +/- 20.3 percent), whereas in cell pairs with higher gj (7 to 35 nS), the gj increment was smaller (80 +/- 10.8 percent) but still larger than that seen in controls (33 +/- 5.4 percent). Intracellular dialysis of Ang I (10(-8) mol/L) abolished cell communication in myopathic cell pairs with low gj (0.8 to 2.5 nS) and reduced gj by 66 +/- 1.7 percent in the other pairs (7 to 35 nS). The effect of Ang I on gj was greatly reduced by enalaprilat (10(-9) mol/L) added to the cytosol. Dialysis of Ang II (10(-8) mol/L) into the myopathic cell reduced gj by 48 +/- 4.2 percent, an effect abolished by losartan (10(-8) mol/L). The results indicate that the decline in gj seen in the ventricle of cardiomyopathic hamsters is in part due to activation of the cardiac renin-angiotensin system.

Transdermal nitroglycerin patch therapy reduces the extent of exercise-induced myocardial ischemia: results of a double-blind, placebo-controlled trial using quantitative thallium-201 tomography

OBJECTIVES

This study prospectively evaluated whether transdermal nitroglycerin patches could limit the extent of exercise-induced left ventricular ischemia as assessed by quantitative thallium-201 tomography.

BACKGROUND

Although antianginal medications are effective at reducing chest pain symptoms in patients with coronary artery disease, there is limited evidence that these agents can also reduce myocardial ischemia.

METHODS

This was a randomized, double-blind, parallel, placebo-controlled trial evaluating nitroglycerin patch therapy in patients in stable condition with angiographic coronary artery disease and no previous myocardial infarction. All patients were weaned from antianginal agents and had a baseline symptom-limited treadmill test followed by thallium-201 tomography. Forty patients with perfusion defects involving > or = 5% of the left ventricle were randomized to receive either intermittent (12 h on/off) active nitroglycerin patch therapy (0.4 mg/h) or placebo. Exercise tomography was repeated a mean (+/- SD) of 6.1 +/- 1.8 days after randomization.

RESULTS

Patients randomized to receive active patch therapy had a significant reduction in their total perfusion defect size (-8.9 +/- 11.1%) compared with placebo-treated patients (-1.8 +/- 6.1%, p = 0.04), which was most apparent in those with the largest (> or = 20%) baseline perfusion defects (-11.4 +/- 13.4% vs. 1.0 +/- 3.6%, respectively, p < 0.02). Furthermore, 7 (33%) of 21 patients receiving active therapy had a > or = 10% decrease in their perfusion defects compared with only 1 (5%) of 19 patients randomized to receive placebo (p = 0.002). Nitrate therapy did not significantly reduce heart rate, blood pressure or double product, indicating benefit through enhancement of coronary blood flow.

CONCLUSIONS

Short-term, intermittent nitroglycerin patch therapy significantly reduces myocardial ischemia, particularly in patients with large ischemic perfusion defects. Thallium-201 tomography can be used to assess sequential changes in the extent of exercise-induced left ventricular ischemia.

Potassium preserves endothelial function and enhances aortic compliance in Dahl rats

It has recently been proposed that in rat models of genetic hypertension, supplemental dietary potassium preserves release of endothelium-derived relaxing factor independently of its capacity to either attenuate hypertension or increase plasma potassium. To test this hypothesis in Dahl salt-sensitive rats given sodium chloride (4%) for 3 weeks, we supplemented dietary potassium (2.1%) with either KCl (n = 16) or KHCO3 (n = 16). Compared with unsupplemented rats (n = 16), rats supplemented with either potassium salt had a lower mean arterial pressure and a greater release of endothelium-derived relaxing factor, as assessed from acetylcholine-induced relaxation of precontracted aortic rings. However, the maximum relaxation response to acetylcholine correlated inversely with blood pressure (r = -.82, P < .001), not only in the KCl (r = -.68, P < .002) and KHCO3 (r = -.77, P < .001) groups but also in unsupplemented rats (r = -.86, P < .001). With potassium supplementation, plasma potassium concentrations measured between 4 and 6 PM did not increase, but those measured between 4 and 6 AM did increase (P < .05). In isolated ring segments, aortic compliance was greater in both the KCl and KHCO3 groups than in unsupplemented rats (0.015 and 0.017 vs 0.009 mm2/mm Hg) (P < .01). This greater compliance could not be related to differences in blood pressure, plasma potassium, or collagen or elastin content of the aortic wall.(ABSTRACT TRUNCATED AT 250 WORDS)