Influences of nonselective, beta(1)-selective and vasodilatory beta(1)-selective beta-blockers on arterial pulse wave velocity in normotensive subjects

Mathematical modelling of the influence of ACE I/D polymorphism on blood pressure and antihypertensive therapy

The angiotensin-converting enzyme (ACE) gene (ACE) insertion/deletion (I/D) polymorphism raises the possibility of personalising ACE inhibitor therapy to optimise its efficiency and reduce side effects in genetically distinct subgroups. However, the extent of its influence among these subgroups is unknown. Therefore, we extended our computational model of blood pressure regulation to investigate the effect of the ACE I/D polymorphism on haemodynamic parameters in humans undergoing antihypertensive therapy. The model showed that the dependence of blood pressure on serum ACE activity is a function of saturation and therefore, the lack of association between ACE I/D and blood pressure levels may be due to high ACE activity in specific populations. Additionally, in an extended model simulating the effects of different classes of antihypertensive drugs, we explored the relationship between ACE I/D and the efficacy of inhibitors of the renin-angiotensin-aldosterone system. The model predicted that the response of cardiovascular and renal parameters to treatment directly depends on ACE activity. However, significant differences in parameter changes were observed only between groups with high and low ACE levels, while different ACE I/D genotypes within the same group had similar changes in absolute values. We conclude that a single genetic variant is responsible for only a small fraction of heredity in treatment success and its predictive value is limited.

Comparison of atenolol versus bisoprolol with noninvasive hemodynamic and pulse wave assessment

We aimed to compare atenolol versus bisoprolol regarding general hemodynamics, central-peripheral blood pressure (BP), pulse wave parameters, and arterial stiffness. In this open-label, crossover study, we recruited 19 hypertensives, untreated or with stable monotherapy. Patients were randomized to receive atenolol (25-50 mg) or bisoprolol (2.5-5 mg), and then switched medications after 4 weeks. Studies were performed at baseline and after each drug period. In pulse wave analyses, both drugs significantly increased augmentation index (P < .01) and ejection duration (P < .02), and reduced heart rate (P < .001), brachial systolic BP (P ≤ .01), brachial diastolic BP (P ≤ .001), and central diastolic BP (P ≤ .001), but not central systolic BP (P ≥ .06). Impedance cardiographic assessment showed a significantly increased stroke volume (P ≤ .02). There were no significant differences in the effects between drugs. In conclusion, atenolol and bisoprolol show similar hemodynamic characteristics. Failure to decrease central systolic BP results from bradycardia with increased stroke volume and an earlier reflected aortic wave.

Destiffening effect of valsartan and atenolol: influence of heart rate and blood pressure

OBJECTIVE

We investigated data in 373 patients from the EXPLOR trial to determine the influence of heart rate (HR) and blood pressure (BP) on aortic stiffness in response to beta-blockade or angiotensin 2 type 1 receptor antagonism, administered during 24 weeks.

METHODS

Carotid-femoral pulse wave velocity (PWV) was measured with aplanation tonometry (Sphygmocor ) after 8 (W8) and 24 weeks (W24) of treatment by the single-pill combination valsartan-amlodipine (80/5  mg, then 160/10  mg) or an atenolol-amlodipine combination (50/5  mg, then 100/10  mg) in a prospective, randomized, parallel-groups multicenter trial with PROBE design. Drugs were up-titrated at W8. We analyzed the changes in PWV in relation with the changes in BP and HR, and major covariates, using mixed models in each treatment arm.

RESULTS

The unadjusted reductions in mean BP and PWV were not significantly different between groups. HR was significantly reduced in the atenolol group, but not in the valsartan group. After adjustment on BP and HR, PWV significantly decreased with valsartan [-0.37  m/s (-0.70 to -0.08) at W8 and -0.43 (-0.76 to -0.10) m/s at W24], whereas no significant change was observed after atenolol [-0.16  m/s (-0.49 to 0.17) at W8 and -0.05 (-0.35 to 0.44) m/s at W24].

CONCLUSION

These findings suggest that the reduction in PWV observed after atenolol could be explained by changes in BP and HR, whereas in patients treated by valsartan, about half of the decrease in aortic stiffness was BP-independent.

Effects of Various Antihypertensive Drugs on Arterial Stiffness and Wave Reflections

We reviewed trials that tested the efficacy of antihypertensive drugs in reducing arterial stiffness and wave reflections as assessed by pulse wave velocity and augmentation index, respectively. Regardless of cross-over or parallel-group comparison design, placebo-controlled trials demonstrated that antihypertensive drugs were effective in reducing pulse wave velocity. In actively-controlled parallel-group comparison studies, this effect on arterial stiffness was more evident for angiotensin-converting enzyme inhibitors or angiotensin receptor blockers than other classes of antihypertensive drugs, particularly when brachial-ankle pulse wave velocity was measured. Regardless of cross-over or parallel-group comparison or placebo- or actively-controlled design, the reviewed trials showed that β-blockers were inferior to all the other classes of antihypertensive drugs in reducing augmentation index. However, these studies had a small sample size and a short follow-up time and did not link the changes in measurements of arterial function with cardiovascular events. Whether the superiority or inferiority is clinically relevant for cardiovascular protection and prevention remains to be investigated.

A randomized controlled study on the effects of bisoprolol and atenolol on sympathetic nervous activity and central aortic pressure in patients with essential hypertension

Objective

β-blockers (BBs) with different pharmacological properties may have heterogeneous effects on sympathetic nervous activity (SNA) and central aortic pressure (CAP), which are independent cardiovascular factors for hypertension. Hence, we analyzed the effects of bisoprolol and atenolol on SNA and CAP in hypertensive patients.

Methods

This was a prospective, randomized, controlled study in 109 never-treated hypertensive subjects randomized to bisoprolol (5 mg) or atenolol (50 mg) for 4–8 weeks. SNA, baroreflex sensitivity (BRS) and heart rate (HR) variability (HRV) were measured using power spectral analysis using a Finometer. CAP and related parameters were determined using the SphygmoCor device (pulse wave analysis).

Results

Both drugs were similarly effective in reducing brachial BP. However, central systolic BP (−14±10 mm Hg vs −6±9 mm Hg; P<0.001) and aortic pulse pressure (−3±10 mm Hg vs +3±8 mm Hg; P<0.001) decreased more significantly with bisoprolol than with atenolol. The augmentation index at a HR of 75 bpm (AIxatHR75) was significantly decreased (29%±11% to 25%±12%; P = 0.026) in the bisoprolol group only. Furthermore, the change in BRS in the bisoprolol group (3.99±4.19 ms/mmHg) was higher than in the atenolol group (2.66±3.78 ms/mmHg), although not statistically significant (P>0.05). BRS was stable when RHR was controlled (RHR≤65 bpm), and the two treatments had similar effects on the low frequency/high frequency (HF) ratio and on HF.

Conclusion

BBs seem to have different effects on arterial distensibility and compliance in hypertensive subjects. Compared with atenolol, bisoprolol may have a better effect on CAP.

Trial Registration

ClinicalTrials.gov NCT01762436

Aortic stiffness is reduced beyond blood pressure lowering by short-term and long-term antihypertensive treatment: a meta-analysis of individual data in 294 patients

BACKGROUND

Arterial stiffness is an independent predictor of cardiovascular events and mortality in hypertensive patients. The influence of different antihypertensive drug classes on improving arterial stiffness beyond blood pressure reduction is not widely available. We aimed to determine whether the artery stiffness can be improved because of antihypertensive treatments independently of blood pressure lowering.

METHODS

We conducted a meta-analysis of individual data from 15 randomized, controlled, double-blind, parallel group trials performed in our laboratory between 1987 and 1994. The primary endpoint was the changes of carotid-femoral pulse wave velocity (PWV) after treatment in 294 patients with mild-to-moderate essential hypertension untreated. Treatments tested were placebo (n = 88), angiotensin-converting enzyme inhibitors (ACEIs) (n = 75), calcium antagonists (n = 75), beta-blocker (n = 30), and diuretic (n = 26).

RESULTS

In the short-term and long-term trials, PWV decreased significantly by -0.75 and -1.3 m/s in the active treatment group compared with by +0.17 and -0.44 m/s in the placebo group, respectively. Active treatment was independently related to the changes in PWV and explained 5 and 4% of the variance in the short-term and long-term trials, respectively. In the short-term trials, ACEIs were more effective than calcium antagonists and placebo on improving arterial stiffness. In the long-term trials, ACEI, calcium antagonists, beta-blocker, and diuretic reduced significantly PWV compared to placebo.

CONCLUSION

Our study shows that antihypertensive treatments improve the arterial stiffness beyond their effect on blood pressure.

A comparison of atenolol and nebivolol in isolated systolic hypertension

OBJECTIVES

Some beta-blockers are less effective in reducing central blood pressure than other antihypertensive drugs, which may explain the higher rate of events in subjects randomized to atenolol in recent trials. We hypothesized that nebivolol, a mixed beta-blocker/nitro-vasodilator, would be more effective than atenolol in reducing central blood pressure and augmentation index (AIx). The aim of the present study was to test this in a double-blind, randomized, cross-over study, in a cohort of subjects with isolated systolic hypertension.

METHODS

Following a 2-week placebo run-in, 16 never-treated hypertensive subjects received atenolol (50 mg), nebivolol (5 mg) and placebo, each for 5 weeks, in a random order. Seated brachial blood pressure and heart rate were measured. Aortic blood pressure, AIx and pulse wave velocity (PWV) were assessed non-invasively.

RESULTS

The placebo-corrected fall in brachial pressure was similar between nebivolol and atenolol, as was the reduction in PWV (mean change +/- SEM: -1.0 +/- 0.3 and -1.2 +/- 0.2 m/s; P = 0.2). However, there was less reduction in heart rate (-19 +/- 2 versus -23 +/- 2 beats/min; P < 0.01) and increase in AIx (+6 +/- 1 versus +10 +/- 1%; P = 0.04), following nebivolol. Aortic pulse pressure was significantly lower (50 +/- 2 versus 54 +/- 2 mmHg; P = 0.02) after nebivolol. N-terminal pro-B-type natriuretic peptide (proBNP) rose on both drugs (100 +/- 33 versus 75 +/- 80 pg/ml; P < 0.01 for both, NS for comparison).

CONCLUSIONS

Nebivolol and atenolol have similar effects on brachial blood pressure and aortic stiffness. However, nebivolol reduces aortic pulse pressure more than atenolol, which may be related to a less pronounced rise in AIx and bradycardia. Whether this will translate into differences in clinical outcome requires further investigation.

Association between low plasma levels of ophthalmic timolol and haemodynamics in glaucoma patients

OBJECTIVES

The aims of the study were to assess the correlation between the plasma concentration of ophthalmic timolol and cardiovascular parameters, and the influence of timolol on advanced haemodynamic variables, such as stroke (SI), cardiac (CI) and systemic vascular resistance (SVRI) indices and arterial pulse wave velocity (PWV).

METHODS

Twenty-five glaucoma or ocular hypertensive patients were treated with 0.5% aqueous and 0.1% hydrogel formulations of timolol using a randomised, double-masked, crossover, multicentre design. All the patients were subjected to passive head-up tilt, electrocardiography, exercise test and measurement of plasma concentration of timolol. In the analysis, the data on the two treatments were combined, and the Spearman correlation coefficients between the plasma level of timolol and physiological effects were calculated.

RESULTS

During the head-up tilt test before rising the bed up, the resting heart rate (HR; R=-0.52, P=0.001) and PWV (R=-0.34, P=0.04) were inversely correlated with timolol level. In the upright position, ophthalmic timolol effectively suppressed the rise in HR (R=-0.36, P=0.03). The SI did not change with timolol concentration, while CI diminished as timolol concentration rose (R=-0.39, P=0.02). The SVRI correlated with timolol concentration (R=0.38, P=0.02). In the exercise test, correlation between HR and plasma level of timolol steadily grew stronger as the load increased, reaching R=-0.60 (P<0.0001) at the maximum load. Systolic and diastolic arterial pressures were not associated with the timolol concentration.

CONCLUSION

The plasma concentration of ophthalmic timolol correlates with several haemodynamic effects. As HR decreases, SVRI increases and blood pressure is kept unchanged.

Beyond blood pressure: pulse wave analysis – a better way of assessing cardiovascular risk?

The study of the pulse pressure wave using the technique of applanation tonometry is becoming more popular as a method of studying vascular stiffness. This review aims to present the uses, potential uses, strengths and weaknesses of the technique of applanation tonometry to assess augmentation index and pulse wave velocity. This article shall briefly discuss the practicalities of applanation tonometry, the physiological factors affecting pulse wave velocity and pulse wave analysis, the changes in pulse wave velocity and pulse wave analysis with pharmacological interventions, and the use of applanation tonometry as a prognostic tool. Although the technique of applanation tonometry seems initially promising, several pertinent issues need to be addressed before it can be used reliably as a clinical tool. Importantly, the technique of applanation tonometry to derive the central waveform from noninvasively-acquired peripheral data needs to be prospectively validated. As stated in this review, the transfer function has been extensively validated using invasive data, whilst noninvasive data estimation of the ascending aortic blood pressure is less accurate.

Pulse wave analysis and pulse wave velocity: a critical review of their strengths and weaknesses

The study of the pulse using the technique of applanation tonometry is undergoing a resurgence with the development of new computerized equipment. We aim here to present a critical review of the uses, potential uses, strengths and weaknesses of the technique of applanation tonometry for the assessment of augmentation index and pulse wave velocity. We will review the technique of applanation tonometry, the physiological factors affecting pulse wave velocity and pulse wave analysis, the changes in pulse wave velocity and pulse wave analysis with pharmacological interventions, and the use of the technique of applanation tonometry as a prognostic tool. We conclude that, although the technique of applanation tonometry initially seems promising, several pertinent issues need to be addressed before it can be used reliably as a clinical or research tool. Importantly, use of the technique of applanation tonometry to derive the central waveform from non-invasively acquired peripheral data needs to be validated prospectively.