Cochrane corner: beta-blockers for hypertension

Effect of Beta-Blocker Consumption on the Severity and Extension of Perfusion Defects in Dipyridamole Myocardial Perfusion Single-Photon Emission Computed Tomography

Background  Regarding the less-known effects of beta-blocker consumption on the diagnostic value of the myocardial perfusion scan with dipyridamole stress in coronary artery disease (CAD), we aimed to compare the findings of the scans done on the beta-blocker consumption course and after discontinuation of this medications. Materials and Methods  Thirty patients with probably CAD and abnormal myocardial perfusion scans (presence of reversible defect), who had been treated with beta-blockers for at least 3 months, were studied. Dipyridamole stress phase of myocardial perfusion single-photon emission computed tomography (SPECT) was performed two times with an interval of about 1 week, once after discontinuation of all antianginal and anti-ischemic medications, statins, and beta-blockers for 72 hours prior to the study, and again after discontinuation of all these medications except for beta-blockers. Imaging was done with the same protocol, radiopharmaceutical dose, and imaging parameters. Summed stress score (SSS), summed stress rest, and summed difference scores (SDS), total perfusion deficit (TPD), severity, and extension of myocardial perfusion defects in three coronary artery territories were analyzed, using quantitative perfusion SPECT software. Results  Most variables such as SSS, SDS, TPD, severity, and extension of defects showed a significant difference between the two conditions including beta-blocker consumption and after discontinuing beta-blocker consumption before stress imaging ( p  < 0.05). Moreover, in patients on treatment with metoprolol, all studied factors including SSS, SDS, TPD, severity, and extension of perfusion defects were significantly reduced when patients consumed beta-blockers before SPECT evaluation ( p  < 0.05). Conclusion  Beta-blocker consumption can lead to a decrease in the severity and extent of myocardial perfusion defects and therefore probably a decrease in the sensitivity of myocardial scans. Discontinuation of beta-blocker prior to the dipyridamole myocardial perfusion scan can improve diagnostic accuracy.

Angiotensin-Converting Enzyme and Hypertension: A Systemic Analysis of Various ACE Inhibitors, Their Side Effects, and Bioactive Peptides as a Putative Therapy for Hypertension

Hypertension is a major risk factor for heart attack, produce atherosclerosis (hardening of the arteries), congestive heart failure, stroke, kidney infection, blindness, end-stage renal infection, and cardiovascular diseases. Many mechanisms are involved in causing hypertension, i.e., via calcium channels, alpha and beta receptors, and the renin-angiotensin system (RAS). RAS has an important role in blood pressure control and is also involved in the metabolism of glucose, homeostasis, and balance of electrolytes in the body. The components of RAS that are involved in the regulation of blood pressure are angiotensinogen, Ang I (angiotensin I), Ang II (angiotensin II), ACE (angiotensin-converting enzyme), and ACE 2 (angiotensin-converting enzyme 2). These components provide for relevant therapeutic targets for the treatment of hypertension, and various drugs are commercially available that target individual components of RAS. Angiotensin receptor blockers (ARBs) and ACE inhibitors are the most popular among these drugs. ACE is chosen in this review as it makes an important target for blood pressure control because it converts Ang I into Ang II and also acts on the vasodilator, bradykinin, to degrade it into inactive peptides. This review highlights various aspects of blood pressure regulation in the body with a focus on ACE, drugs targeting the components involved in regulation, their associated side effects, and a need to shift to alternative therapy for putative hypertension treatment in the form of bioactive peptides from food.

Beta Blockers can mask not only Hypoglycemia, but also Hypotension

Background:

Beta-adrenergic (β-AR) receptor blockers (BBs) are an essential class of drugs as they have numerous indications. On the other hand, they have numerous unwanted effects which decrease the compliance, adherence, and persistence of this very useful group of drugs.

Objective:

The paper aims to analyze the possibility that an unnoticed side effect may contribute to a less favorable pharmacologic profile of BBs, e.g., a diminished reaction to a sudden fall in BP.

Methods:

We searched two medical databases for abstracts and citations (Medline and SCOPUS). Moreover, we searched the internet for drug prescription leaflets (of the individual BBs).

Results:

Whichever cause of stress is considered, the somatic manifestations of stress will be (partially) masked if a patient takes BB. Stress–induced hypercatecholaminemia acts on β-AR of cardiomyocytes; it increases heart rate and contractility, effects suppressed by BBs. The answers of the organism to hypoglycemia and hypotension share the main mechanisms such as sympathetic nervous system activation and hypercatecholaminemia. Thus, there is a striking analogy: BBs can cover up symptoms of both hypoglycemia (which is widely known) and of hypotension (which is not recognized). It is widely known that BBs can cause hypotension. However, they can also complicate recovery by spoiling the defense mechanisms in hypotension as they interfere with the crucial compensatory reflex to increase blood pressure in hypotension.

Conclusion:

Beta blockers can cause hypotension, mask it, and make recovery more difficult. This is clinically important and deserves to be more investigated and probably to be stated as a warning.

Neurocardiac regulation: from cardiac mechanisms to novel therapeutic approaches

Cardiac sympathetic overactivity is a well-established contributor to the progression of neurogenic hypertension and heart failure, yet the underlying pathophysiology remains unclear. Recent studies have highlighted the importance of acutely regulated cyclic nucleotides and their effectors in the control of intracellular calcium and exocytosis. Emerging evidence now suggests that a significant component of sympathetic overactivity and enhanced transmission may arise from impaired cyclic nucleotide signalling, resulting from compromised phosphodiesterase activity, as well as alterations in receptor-coupled G-protein activation. In this review, we address some of the key cellular and molecular pathways that contribute to sympathetic overactivity in hypertension and discuss their potential for therapeutic targeting.

Racial and Sex Differences in the Response to First-Line Antihypertensive Therapy

Objective: As compared to whites, the black population develops hypertension (HTN) at an earlier age, has a greater frequency and severity of HTN, and has poorer control of blood pressure (BP). Traditional practices and treatment efforts have had minor impact on these disparities, with over a 2-fold higher death rate currently for blacks as compared to whites. The University of Mississippi Medical Center (UMC) is located in the southeastern US and the Stroke Belt, which has higher rates of HTN and related diseases as compared to the rest of the country. Methods: We retrospectively analyzed the UMC's Research Data Warehouse, containing >30 million electronic health records from >900,000 patients to determine the initial BP response following the first prescribed antihypertensive drug. Results: There were 5,973 white (45% overall HTN prevalence) and 10,731 black (57% overall HTN prevalence) patients who met criteria for the study. After controlling for age, BMI, and drug dosage, black males were overall less likely to have controlled BP (defined as < 140/90 mmHg) and were associated with smaller falls in BP as compared to whites and black females. Blockers of the renin-angiotensin system (RAS) failed to significantly improve odds of HTN control vs. the untreated group in black patients. However, our data suggests that these drugs do provide significant benefit in blacks when combined with THZ, as compared to untreated and as compared to THZ alone. Conclusion: These data support the use of a single-pill formulation with ARB or ACE inhibitor with a thiazide in blacks for initial first-line HTN therapy and suggests that HTN treatment strategies should consider both race and gender. Our study gives a unique insight into initial antihypertensive responses in actual clinical practice and could have an impact in BP control efficiency in a state with prevalent socioeconomic and racial disparities.

Genome-Wide Meta-Analysis of Blood Pressure Response to β1-Blockers: Results From ICAPS (International Consortium of Antihypertensive Pharmacogenomics Studies)

BackgroundThere exists a wide interindividual variability in blood pressure (BP) response to β₁-blockers. To identify the genetic determinants of this variability, we performed a pharmacogenomic genome-wide meta-analysis of genetic variants influencing β₁-blocker BP response.Methods and ResultsGenome-wide association analysis for systolic BP and diastolic BP response to β₁-blockers from 5 randomized clinical trials consisting of 1254 patients with hypertension of European ancestry were combined in meta-analysis and single nucleotide polymorphisms (SNPs) with P<10^-4 were tested for replication in 2 independent randomized clinical trials of β₁-blocker-treated patients of European ancestry (n=1552). Regions harboring the replicated SNPs were validated in a β₁-blocker-treated black cohort from 2 randomized clinical trials (n=315). A missense SNP rs28404156 in BST1 was associated with systolic BP response to β₁-blockers in the discovery meta-analysis (P=9.33×10^-5, β=-3.21 mm Hg) and replicated at Bonferroni significance (P=1.85×10^-4, β=-4.86 mm Hg) in the replication meta-analysis with combined meta-analysis approaching genome-wide significance (P=2.18×10^-7). This SNP in BST1 is in linkage disequilibrium with several SNPs with putative regulatory functions in nearby genes, including CD38, FBXL5, and FGFBP1, all of which have been implicated in BP regulation. SNPs in this genetic region were also associated with BP response in the black cohort.ConclusionsData from randomized clinical trials of 8 European ancestry and 2 black cohorts support the assumption that BST1 containing locus on chromosome 4 is associated with β₁-blocker BP response. Given the previous associations of this region with BP, this is a strong candidate region for future functional studies and potential use in precision medicine approaches for BP management and risk prediction.

The role of the pharmacist in hypertension management

PURPOSE OF REVIEW

Hypertension remains a vital, modifiable risk factor in the prevention of cardiovascular disease. However, many patients do not achieve their therapeutic goals for numerous reasons which can include poor disease insight and nonadherence. Pharmacists can be key players in controlling hypertension, given their medication knowledge and patient counseling skills, yet they remain an underutilized resource in the management of chronic disease states. Various models exist that allow pharmacists to provide direct patient-centered care but practices differ from state to state since pharmacists are not recognized nationally as healthcare providers. This article aims to provide an update on the proven methods in which pharmacists contribute to the management of hypertensive patients.

RECENT FINDINGS

Several recently published studies demonstrate the positive impact of pharmacist intervention and care on patient outcomes in ambulatory and community settings. These practice models include medication therapy management, collaborative drug therapy management, telehealth and team-based care.

SUMMARY

The role of the pharmacist in hypertension encompasses medication management, disease state education and patient counseling and is most successful when integrated into the patient's care team. Further validation through larger, prospective trials and evaluation of long-term outcomes, such as mortality, remain viable research opportunities.

Neurotransmitter Switching Coupled to β-Adrenergic Signaling in Sympathetic Neurons in Prehypertensive States

Single or combinatorial administration of β-blockers is a mainstay treatment strategy for conditions caused by sympathetic overactivity. Conventional wisdom suggests that the main beneficial effect of β-blockers includes resensitization and restoration of β1-adrenergic signaling pathways in the myocardium, improvements in cardiomyocyte contractility, and reversal of ventricular sensitization. However, emerging evidence indicates that another beneficial effect of β-blockers in disease may reside in sympathetic neurons. We investigated whether β-adrenoceptors are present on postganglionic sympathetic neurons and facilitate neurotransmission in a feed-forward manner. Using a combination of immunocytochemistry, RNA sequencing, Förster resonance energy transfer, and intracellular Ca2+ imaging, we demonstrate the presence of β-adrenoceptors on presynaptic sympathetic neurons in both human and rat stellate ganglia. In diseased neurons from the prehypertensive rat, there was enhanced β-adrenoceptor-mediated signaling predominantly via β2-adrenoceptor activation. Moreover, in human and rat neurons, we identified the presence of the epinephrine-synthesizing enzyme PNMT (phenylethanolamine-N-methyltransferase). Using high-pressure liquid chromatography with electrochemical detection, we measured greater epinephrine content and evoked release from the prehypertensive rat cardiac-stellate ganglia. We conclude that neurotransmitter switching resulting in enhanced epinephrine release, may provide presynaptic positive feedback on β-adrenoceptors to promote further release, that leads to greater postsynaptic excitability in disease, before increases in arterial blood pressure. Targeting neuronal β-adrenoceptor downstream signaling could provide therapeutic opportunity to minimize end-organ damage caused by sympathetic overactivity.