The Combination of Beta-Blockers and ACE Inhibitors Across the Spectrum of Cardiovascular Diseases

Cardiovascular disease is the leading cause of mortality worldwide, affecting a wide range of patients at different stages across the cardiovascular continuum. Hypertension is one of the earliest risk factors in this continuum and can be controlled in most patients with currently available antihypertensive agents. However, goals are often not met because treatments are not optimized in terms of tailoring therapy to individual patients based on their hypertension subclass and cardiovascular risk profile and initiating early use of adapted-dose, single-pill combinations. In this context, beta-blockers in combination with angiotensin-converting enzyme (ACE) inhibitors are of special interest as a result of their complementary actions on the sympathetic nervous system and renin-angiotensin-aldosterone system, two interlinked pathways that influence cardiovascular risk and disease outcomes. In addition to their antihypertensive actions, beta-blockers are used to manage arrhythmias and treat angina pectoris and heart failure, while ACE inhibitors provide cardioprotection in patients with acute coronary syndromes and treat congestive heart failure. A broad range of patients may therefore receive the combination in routine clinical practice. This paper examines the supporting evidence for beta-blockers and ACE inhibitors in each of the above indications and considers the rationale for combining these agents into a single pill, using data from bisoprolol and perindopril randomized controlled trials as supporting evidence. Combining these established antihypertensive agents into a single pill continues to provide effective blood pressure lowering and improved cardiovascular outcomes while allowing a greater proportion of patients to rapidly achieve treatment targets.

Blood pressure reduction and clinical outcomes with angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers: protocol for a systematic review and meta-regression analysis

BACKGROUND

Angiotensin-converting enzyme inhibitors (ACEis) and angiotensin II receptor blockers (ARBs) efficaciously reduce systolic blood pressure (BP), a well-established risk factor for myocardial infarction (MI). Both inhibit the renin-angiotensin system, albeit through different mechanisms, and produce similar reductions in BP. However, in parallel meta-analyses of ACEi and ARB trials, ACEis reduce risk of MI whereas ARBs do not-a phenomenon described as the 'ARB-MI paradox'. In addition, ACEis reduce all-cause mortality, whereas ARBs do not, which appears to be independent of BP lowering. The divergent cardiovascular effects of ACE inhibitors and ARBs, despite similar BP reductions, are counter-intuitive. This systematic review aims to ascertain the extent to which clinical outcomes in randomised trials of ACEi and ARBs are attributable to reductions in systolic BP.

METHODS

A comprehensive search of bibliographic databases will be performed to identify all randomised studies of agents of the ACEi and ARB class. Placebo and active comparator-controlled studies that report clinical outcomes, with greater than 500 person-years of follow-up in each study arm, will be included. Two independent reviewers will screen study records against a priori-defined eligibility criteria and perform data extraction. The Cochrane Risk of Bias Tool will be applied to all included studies. Studies retracted subsequent to initial publication will be excluded. Primary outcomes of interest include MI and all-cause mortality; secondary outcomes include stroke, heart failure, revascularisation and cardiovascular mortality. Meta-regression will be performed, evaluating the relationship between attained reduction in systolic BP and relative risk of each outcome, stratified by drug class. Where a BP-dependent effect exists (two-tailed p value < 0.05), relative risks, standardised per 10 mmHg difference in BP, will be reported for each study outcome. Publication bias will be examined using Funnel plots, and calculation of Egger's statistic.

DISCUSSION

This systematic review will provide a detailed synthesis of evidence regarding the relationship between BP reduction and clinical outcomes with ACEi and ARBs. Greater understanding of the dependency of the effect of each class on BP reduction will advance insight into the nature of the ARB-MI paradox and guide the future usage of these agents.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42017072988.

The Divergent Cardiovascular Effects of Angiotensin-Converting Enzyme Inhibitors and Angiotensin II Type 1 Receptor Blockers in Adult Patients With Type 2 Diabetes Mellitus

The renin angiotensin aldosterone system (RAAS) plays a central role in the pathophysiology of hypertension and vascular disease. Angiotensin-converting enzyme inhibitors (ACEi's) suppress angiotensin II (ANG II) concentrations, whereas angiotensin II type 1 (AT₁) receptor blockers (ARBs) block the binding of ANG II to AT₁ receptors. ACEi's and ARBs are both effective antihypertensive agents and produce similar risk reductions for stroke, a blood pressure-dependent phenomenon. ACEi's also reduce the risk for myocardial infarction (MI) and all-cause mortality in high-risk hypertensive patients as well as in people with diabetes, vascular disease and congestive heart failure. ARBs, in contrast, do not reduce the risk for MI or death in randomized clinical trials when assessed vs. placebo. Systematic reviews of ARBs that include meta-analyses or metaregression analyses confirm that ARBs lack the cardiovascular-protective effects of ACEi's. Practice guidelines, especially those for high-risk patients, such as those with diabetes mellitus, should reflect the evidence that ACEi's and ARBs have divergent cardiovascular effects: ACEi's reduce mortality, whereas ARBs do not. ACEi's should remain the preferred RAAS inhibitor for patients at high risk.

More about the "ARB MI paradox"

"Logic dictates that angiotensin converting enzyme inhibitors should remain the preferred drug across the entire spectrum of cardiometabolic disease"

Cardiac effects of prazosin in chronic aortic insufficiency

Eight patients with chronic moderate to severe aortic insufficiency were assessed by radionuclide angiography at rest and during maximal bicycle exercise after six weeks of placebo, six weeks of prazosin titration up to 10 mg bid and 12 weeks of prazosin maintenance therapy. Prazosin was well tolerated and the final dose amounted to 18.6 +/- 0.7 mg/day. Exercise performance tended to increase (from 8.9 +/- 1.1 to 9.6 +/- 0.8 mins). Resting and exercise blood pressure and heart rate were not affected by prazosin. Left ventricular volumes were decreased and exercise ejection fraction increased by prazosin. Total left ventricular output decreased, whereas regurgitant index improved. The authors conclude that in patients with chronic moderate to severe aortic insufficiency, chronic prazosin therapy causes persistent improvements in left ventricular anatomy and function both at rest and during exercise.

The role of cardiac beta-1 receptors in the hemodynamic response to a beta-2 agonist

The role of beta 1-receptors in the hemodynamic response to beta 2-stimulation was assessed in seven healthy subjects by infusion of the selective beta 2-agonist terbutaline both with and without selective beta 1-blockade by atenolol (50 mg). Infusion of terbutaline increased heart rate (+28 bpm) and indices of left ventricular (LV) performance associated with a marked decrease in LV end-systolic wall stress. The LV end-diastolic dimension remained unchanged despite the tachycardia, suggesting that venous return had increased. Systolic blood pressure increased, whereas total peripheral resistance and diastolic blood pressure decreased. Atenolol pretreatment caused the hemodynamic changes expected of beta 1-blockade but did not blunt the effects of terbutaline on heart rate, peripheral resistance, or venous return. Increases after terbutaline in LV performance and systolic blood pressure were significantly blunted by atenolol. Stimulation of beta 1-receptors therefore appears to play no role in the chronotropic and only a moderate role in the inotropic response after infusion of a beta 2-agonist. Alternative mechanisms for the cardiac changes with terbutaline include (1) withdrawal of vagal tone, (2) decrease in afterload, and (3) stimulation of cardiac beta 2-receptors.