The circulating renin-angiotensin system during treatment with metoprolol or captopril in patients with heart failure due to non-ischaemic dilated cardiomyopathy

Arrhythmias after COVID-19 Vaccination: Have We Left All Stones Unturned?

SARS-CoV-2 vaccination offered the opportunity to emerge from the pandemic and, thereby, worldwide health, social, and economic disasters. However, in addition to efficacy, safety is an important issue for any vaccine. The mRNA-based vaccine platform is considered to be safe, but side effects are being reported more frequently as more and more people around the world become treated. Myopericarditis is the major, but not the only cardiovascular complication of this vaccine; hence it is important not to underestimate other side effects. We report a case series of patients affected by cardiac arrhythmias post-mRNA vaccine from our clinical practice and the literature. Reviewing the official vigilance database, we found that heart rhythm disorders after COVID vaccination are not uncommon and deserve more clinical and scientific attention. Since the COVID vaccine is the only vaccination related to this side effect, questions arose about whether these vaccines could affect heart conduction. Although the risk-benefit ratio is clearly in favor of vaccination, heart rhythm disorders are not a negligible issue, and there are red flags in the literature about the risk of post-vaccination malignant arrhythmias in some predisposed patients. In light of these findings, we reviewed the potential molecular pathways for the COVID vaccine to impact cardiac electrophysiology and cause heart rhythm disorders.

Hypertension and its management in countries in Africa and the Middle East, with special reference to the place of β-blockade

BACKGROUND

The prevalence and clinical consequences of hypertension in countries in Africa and the Middle East have not been studied as well as in other regions.

SCOPE

We have reviewed the literature on the epidemiology and management of hypertension and related cardiovascular complications in countries within Africa and the Middle East. A PubMed search for countries in the region and 'hypertension' was supplemented by articles identified from reviews, and by literature suggested by the authors.

FINDINGS

The prevalence of hypertension is >20% in some countries in the Middle East and Africa, despite an average population age that is some 10-15 years lower than those of developed countries. Hypertension in these countries is associated with an increased risk of cardiovascular risk factors and cardiovascular disease, as elsewhere. Awareness rates of hypertension are low. Hypertension and its complications are undertreated, and mortality rates from cardiovascular disease are higher than in developed countries.

CONCLUSION

Available resources should be brought to bear on the management of hypertension in these countries. In particular, a recent downgrading of the importance of β-blockers in hypertension management guidelines needs to be reassessed. These agents are as effective as other antihypertensive classes both on blood pressures and on cardiovascular event rates. General concerns over an increased rate of new-onset diabetes with β-blockers have been overstated, although these agents should be avoided in metabolic syndrome.

Direct effects of 3 combinations of enalapril, metoprolol, and spironolactone on cardiac remodeling in dilated cardiomyopathic hamsters

BACKGROUND

In congestive heart failure, enalapril (E), metoprolol (M), and spironolactone (S) improve survival. Their direct effects on cardiac remodeling, when administered in combination, remain to be assessed.

METHODS AND RESULTS

One hundred and five cardiomyopathic hamsters were divided into 5 groups (control, E, E-M, E-S, E-M-S) and treated from 150 to 240 days of age (E: 3 mg/kg, M: 1 mg/kg, S: 20 mg/kg). Cardiac and systemic hemodynamics, and cardiac remodeling were investigated. There was no difference between groups on blood pressure. Compared with C, both S-treated groups significantly increased cardiac index (E-S: +49%; E-M-S: +46%). Compared with C, E significantly decreased left ventricular (LV) cavity area (-10%). Compared with E, all combinations significantly decreased LV cavity area (E-M: -13%, E-S: -22%, E-M-S: -19%) and right ventricular (RV) collagen density (E-M: -18%, E-S: -30%, E-M-S: -34%), and the tri-therapy significantly decreased LV collagen density (-18%). Compared with bi-therapies, the tri-therapy significantly decreased LV (-19% vs. E-M, -16% vs. E-S) and RV (-20% vs. E-M) collagen densities.

CONCLUSION

At subdepressor doses, both bi-therapies induced similar effects on myocardial remodeling, enhancing the effects of E on LV cavity area and reducing RV collagen density. Compared with bi-therapies, the tri-therapy induced additional effects on LV and RV collagen densities.

Sympathetic cardiac influence and arterial blood pressure instability

Previous studies have suggested that sympathetic cardiac blockade enhances baroreflex function, whereas parasympathetic blockade diminishes baroreflex sensitivity and elicits arterial blood pressure (ABP) instability. The aim of this project was to test the hypothesis that sympathetic cardiac blockade was beneficial in maintaining ABP stability during orthostatic challenge. In 8 young healthy subjects, measurements were taken before and after sympathetic cardiac blockade (beta1-adrenoceptor blockade via metoprolol) in combination with or without parasympathetic blockade (atropine) at rest and during lower body negative pressure (LBNP). Arterial blood samples were obtained to evaluate plasma renin activity (PRA) and norepinephrine (NE). Power spectral analyses were performed on heart rate (HR) and ABP variability. LBNP -50 Torr significantly decreased systolic blood pressure (SBP, -6+/-3 mm Hg) and increased PRA (from 0.72+/-0.23 to 1.75+/-0.24 ng ml(-1) h(-1)) and NE (from 1.02+/-0.11 to 2.13+/-0.32 pg ml(-1)). Low frequency (LF, 0.04-0.12 Hz) SBP and diastolic blood pressure (DBP) variability were significantly augmented by LBNP (4.1+/-1.6 vs. 10.8+/-3.0 mm Hg2, and 3.1+/-1.0 vs. 7.9+/-1.9 mm Hg2, respectively). Following metoprolol, arterial baroreflex sensitivity (assessed by the slope of HR interval to SBP during injection with 1 mug kg(-1) phenylephrine) increased significantly (9.9+/-2.2 to 19.6+/-4.1 ms mm Hg(-1)). With beta1-adrenoceptor blockade, LBNP still decreased SBP (-10+/-2 mm Hg) and increased NE, but did not significantly augment PRA (0.59+/-0.22 vs. 1.03+/-0.18 ng ml(-1) h(-1)), or LF SBP and DBP variability (3.3+/-0.6 vs. 5.7+/-1.3 mm Hg2, and 3.1+/-0.7 vs. 5.4+/-1.1 mm Hg2, respectively). The increased PRA during LBNP remained non-significant following metoprolol combined with atropine, whereas the augmented LF SBP (2.6+/-0.7 vs. 9.9+/-2.8 mm Hg2) and DBP (2.5+/-0.7 vs. 11.1+/-3.0 mm Hg2) variability were significantly accentuated compared to both metoprolol alone and control conditions, accompanied by a greater delta SBP (-17+/-7 mm Hg) and significantly diminished baroreflex gain (0.91+/-0.05 ms/mm Hg). These data suggested that removal of sympathetic cardiac influence improved cardiovascular stability as indicated by a diminished LF ABP variability, which was related to an enhanced cardiac responsiveness.

Importance of the renin-angiotensin system in the regulation of arterial blood pressure in conscious mice and rats

AIM

The present experiments were designed to determine the mechanism(s) for increased sensitivity to blockade of the renin-angiotensin system in mice in comparison with rats.

METHODS

Mice and rats, with indwelling femoral arterial and venous catheters, were chronically administered angiotensin II or pharmacological inhibitors of the renin-angiotensin system as sodium intake was altered.

RESULTS

Increasing sodium intake led to suppression of circulating renin, angiotensin II, and aldosterone in rats and mice in the absence of alterations in arterial blood pressure. Additional experiments demonstrated that continuous intravenous infusion of angiotensin II (20 ng kg(-1) min(-1)) significantly increased arterial blood pressure by approximately 35 mmHg in conscious rats at all levels of sodium intake (n = 6). In contrast, arterial pressure was unaffected by angiotensin II infusion in conscious mice under conditions of low sodium intake, although arterial pressure was increased by 16 mmHg when mice were administered a high sodium intake while infused with angiotensin II (n = 6). In comparison, blockade of the endogenous renin-angiotensin system led to significantly greater effects on arterial pressure in mice than rats. Continuous infusion of captopril (30 microg kg(-1) min(-1)) or losartan (100 microg kg(-1) min(-1)) resulted in a 55-90% greater fall in blood pressure in conscious mice in comparison with conscious rats.

CONCLUSION

The present studies indicate that arterial pressure in mice is more dependent upon the endogenous renin-angiotensin system than it is in rats, but mice are more resistant to the hypertensive effects of exogenous angiotensin II.

NT-proBNP in severe chronic heart failure: rationale, design and preliminary results of the COPERNICUS NT-proBNP substudy

BACKGROUND

Neither profiles nor prognostic value of cardiac N-terminal proBNP (NT-proBNP) have been prospectively evaluated in a sufficient number of patients with severe chronic heart failure (CHF) treated with carvedilol or placebo.

METHODS

Baseline and follow-up plasma concentrations of NT-proBNP were measured in the European part of the COPERNICUS Trial. This study enrolled patients with an ejection fraction <25% and symptoms of CHF at rest or on minimal exertion, equally randomized to placebo or carvedilol.

RESULTS

NT-proBNP concentrations were increased at baseline (mean+/-S.D.=579+/-822 pmol/l, median=322.5 pmol/l) with a marked decrease during follow-up in the carvedilol, but not in the placebo group. One-year mortality rates were 3.9, 12 and 27.9% in the lower, middle and upper tertiles of NT-proBNP, respectively. When mortality was calculated separately in the placebo and carvedilol group, rates were 0.8, 6.3 and 19.1% in the carvedilol treated but 6.7, 17.9 and 36.9% in the placebo treated patients.

CONCLUSIONS

NT-proBNP was a powerful predictor of subsequent all-cause mortality in patients with severe CHF. This marker should therefore be further evaluated for risk stratification and monitoring of therapy in CHF.

Acute decompensated heart failure: a contemporary approach to pharmacotherapeutic management

Hospital admissions for acute decompensated heart failure (ADHF) have increased precipitously during the past few decades and are projected to continue to increase in the future. To optimize patient outcomes and reduce the costs associated with this disorder, evidenced-based pharmacotherapy is essential. Continuous infusions of loop diuretic therapy rather than bolus dosing may enhance efficacy and reduce the extent of diuretic resistance. Nesiritide is a pharmacologically novel preload and afterload reducer but based on clinical trial evidence should be reserved for those unable to take or with resistance to intravenous nitrate therapy. Catecholamine- and phosphodiesterase-based inotropic therapies are efficacious, but the increased risk of arrhythmogenesis and the potential for negative survival effects limit their use. The experimental agent levosimendan is a positive inotropic agent but does not increase myocyte calcium concentrations as do catecholamines or phosphodiesterase inhibitors. Clinical trial evidence demonstrates a positive survival benefit for levosimendan versus dobutamine.

Combined effects of metoprolol and spironolactone in dilated cardiomyopathic hamsters

The use of beta-blockers reduces angiotensin II levels, but could not adequately suppress aldosterone production. Thus, the combination of a beta-blocker with an aldosterone receptor antagonist could exert additive effects. The effects of metoprolol and spironolactone and their combination on hemodynamics and cardiac remodeling in cardiomyopathic hamsters (CMH) were investigated. The Bio TO-2 dilated strain of CMH was treated orally with metoprolol (10 mg/kg/day), spironolactone (20 mg/kg/day), or both according to a 2 x 2 factorial design (24 animals per group) from 120 days of age and during 120 days. As compared to corresponding untreated groups, metoprolol significantly decreased mean blood pressure (-7%), and metoprolol and spironolactone significantly increased cardiac output (18% and 19%, respectively), mesenteric blood flow (11% and 14%), and femoral blood flow (13% and 17%), and significantly decreased systemic (-24% and -15%), mesenteric (-14% and -13%) and femoral (-19% and -10%) vascular resistances. Metoprolol significantly increased renal blood flow (22%) and significantly decreased renal vascular resistance (-23%). Metoprolol and spironolactone significantly decreased the cavity area of the left ventricle (-21% and -32%, respectively) and the collagen density of the left (-36% and -39%) and right (-38% and -43%) ventricles. Although the combination did not induce stronger effects than each drug alone on the systemic and most regional hemodynamic variables, it did have a stronger effect on the cardiac remodeling (compared to control group: -24%, -34%, and -46% for the left ventricle cavity area, -33%, -35%, and -62% for collagen density in the left ventricle, and -52%, -57%, and -59% for collagen density in the right ventricle, respectively, in the metoprolol, spironolactone, and metoprolol + spironolactone groups). In CMH, metoprolol and spironolactone combined did not improve hemodynamics more than each drug alone, but did exert additive effects on cardiac remodeling.

Mediators of chronic heart failure: how drugs work

OBJECTIVE

To critically review the pathophysiology of chronic heart failure at the neurohormonal level, and discuss the effect of present and future therapeutic options on these neurohormones.

DATA SOURCES

A MEDLINE search (1986-November 2000) was used to identify important primary literature and reviews. Additional references were obtained from these articles.

DATA SYNTHESIS

Chronic heart failure is a common, progressive disorder with high morbidity and mortality. Progression is due in large part to several redundant neurohormonal responses. The neurohormones include angiotensin II, norepinephrine, aldosterone, endothelin-1, arginine vasopressin, and tumor necrosis factor. These responses are initially adaptive, but become maladaptive in the long term, impairing the function of the heart, vasculature, and kidneys. Counter-regulatory hormones, such as bradykinin and natriuretic peptides, are insufficient to offset the adverse effects of the other neurohormones. Most drugs used to treat chronic heart failure, such as angiotensin-converting enzyme inhibitors, beta-adrenergic antagonists, and spironolactone, achieve their benefits through altering the neurohormonal pathways. New agents that affect more or different neurohormones may soon be available.

CONCLUSIONS

Multiple agents are required for treatment of chronic heart failure, as no single agent can counteract all of the various adverse pathways. The appropriate prescription and use of such inherently complex regimens require significant physician and patient education.

Protection against ischemia/reperfusion injury and myocardial dysfunction by antisense-oligodeoxynucleotide directed at angiotensin-converting enzyme mRNA

Angiotensin-converting enzyme (ACE) activity in the myocardium and angiotensin-II (Ang-II) levels in plasma increase after myocardial ischemia, which lead to exacerbation of myocardial injury and cardiac dysfunction. We examined the protective role of novel antisense-oligodeoxynucleotide (AS-ODN) directed at ACE mRNA in myocardial ischemic injury. Sprague-Dawley rats were treated with ACE-AS-ODN (200 microg per rat, n = 8, i.v.) or inverted-ODN (IN-ODN, 200 microg per rat, n = 8, i.v.), given with 600 microg per rat of liposome DOTAP/DOPE. Hearts from AS-ODN- or IN-ODN-treated rats were excised, perfused in vitro, and subjected to 25 min of global ischemia followed by 30 min of reperfusion. Parallel groups of rats were given ACE inhibitor captopril (5 mg/kg, n = 8) or saline (n = 8) before excising the hearts. Ischemia/reperfusion resulted in myocardial dysfunction (increase in coronary perfusion pressure and LV end-diastolic pressure and a decrease in developed LV pressure) in the saline-treated rats. Myocardial dysfunction was associated with evidence of lipid peroxidation and enzyme leakage (MDA and LDH levels in the myocardium) and up-regulation of ACE protein expression. Administration of AS-ODN or captopril, but not IN-ODN, reduced Ang-II levels in the plasma, decreased ischemia/reperfusion-mediated cardiac functional deterioration and lipid peroxidation, and preserved LDH in the myocardium (all P < 0.05 versus the saline group). AS-ODN and captopril had equipotent effects on cardiac dynamics. ACE protein expression (western blot) was decreased in the hearts of the AS-ODN-treated group, but not in IN-ODN-treated rat hearts. In contrast, ACE protein expression was significantly increased in captopril-treated rat hearts. These observations suggest that AS-ODN directed at ACE mRNA can ameliorate myocardial dysfunction and injury after ischemia/reperfusion, and its use is associated with decreased expression of ACE protein in the ischemic myocardium.