Roles of ß-adrenoceptor Subtypes and Therapeutics in Human Cardiovascular Disease: Heart Failure, Tachyarrhythmias and Other Cardiovascular Disorders.

ß-Adrenoceptors (ß-ARs) provide an important therapeutic target for the treatment of cardiovascular disease. Three ß-ARs, ß1-AR, ß2-AR, ß3-AR are localized to the human heart. Activation of ß1-AR and ß2-ARs increases heart rate, force of contraction (inotropy) and consequently cardiac output to meet physiological demand. However, in disease, chronic over-activation of ß1-AR is responsible for the progression of disease (e.g. heart failure) mediated by pathological hypertrophy, adverse remodelling and premature cell death. Furthermore, activation of ß1-AR is critical in the pathogenesis of cardiac arrhythmias while activation of ß2-AR directly influences blood pressure haemostasis. There is an increasing awareness of the contribution of ß2-AR in cardiovascular disease, particularly arrhythmia generation. All ß-blockers used therapeutically to treat cardiovascular disease block ß1-AR with variable blockade of ß2-AR depending on relative affinity for ß1-AR vs ß2-AR. Since the introduction of ß-blockers into clinical practice in 1965, ß-blockers with different properties have been trialled, used and evaluated, leading to better understanding of their therapeutic effects and tolerability in various cardiovascular conditions. ß-Blockers with the property of intrinsic sympathomimetic activity (ISA), i.e. ß-blockers that also activate the receptor, were used in the past for post-treatment of myocardial infarction and had limited use in heart failure. The ß-blocker carvedilol continues to intrigue due to numerous properties that differentiate it from other ß-blockers and is used successfully in the treatment of heart failure. The discovery of ß3-AR in human heart created interest in the role of ß3-AR in heart failure but has not resulted in therapeutics at this stage.

Characterization of serum phosphate levels over time with intravenous ferric carboxymaltose versus placebo as treatment for heart failure with reduced ejection fraction and iron deficiency: An exploratory prospective substudy from HEART-FID.

AIMS: Ferric carboxymaltose (FCM) is guideline-recommended for iron deficiency (ID) in heart failure with reduced ejection fraction (HFrEF). Despite a well-established safety profile, the magnitude and clinical significance of FCM-induced hypophosphataemia in HFrEF remains unclear. This pre-specified substudy of HEART-FID evaluated serum phosphate, 1,25-dihydroxyvitamin D, and plasma parathyroid hormone (PTH) subsequent to FCM. METHODS AND RESULTS: HEART-FID was a randomized, double-blind, placebo-controlled trial of ambulatory patients with HFrEF and ID randomized to FCM versus placebo. This substudy assessed mean change from baseline across eight visits over 6 months for the following endpoints: serum phosphate, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and PTH, in addition to the clinical severity of potential hypophosphataemia. Overall, 133 patients (n = 62 FCM, n = 71 placebo) were prospectively enrolled. Mean age was 68 ± 11 years, 55 (41.4%) were women, and 29 (21.8%) had chronic kidney disease. Phosphate levels decreased in 34 (57.6%) patients in the FCM group compared with 7 (10.3%) in the placebo group. Mean change in phosphate levels reached a nadir at day 21 (-0.36 ± 0.27 mmol/L) subsequent to FCM infusion with 28 (51%) having moderate-to-severe hypophosphataemia. Reductions in 1,25-dihydroxyvitamin D were also observed, whilst PTH increased. These biochemical changes returned to baseline levels by day 91. Serum levels of 25-hydroxyvitamin D remained stable throughout the study. No serious adverse events associated with hypophosphataemia were reported. CONCLUSIONS: Transient moderate-to-severe hypophosphataemia was frequent subsequent to FCM infusion, accompanied by 1,25-dihydroxyvitamin D decrease and PTH increase. Serum levels of 25-hydroxyvitamin D remained stable. No evidence of symptomatic hypophosphataemia was reported, collectively indicating FCM-related hypophosphataemia to be clinically benign and transient in HFrEF.

ST Elevation Myocardial Infarction Complicated by Cardiogenic Shock: Systematic Review of Survival Predictors.

Background: Cardiogenic shock complicating acute myocardial infarction is associated with reduced survival despite advancements in the treatment of acute coronary syndromes. Characterizing predictors of morbidity and mortality in this setting is crucial to improving risk stratification and management. Notwithstanding, the interplay of factors determining survival in this condition remains poorly studied. Methods: Embase, MEDLINE, and CINAHL databases were searched for original studies evaluating predictors of short-term (30-day or in-hospital) survival in ST elevation myocardial infarction with cardiogenic shock (STEMI-CS). Included studies were analyzed by way of vote counting, identifying variables that predicted mortality or survival. Results: Twenty-four studies, consisting of 14,735 patients (5649 nonsurvivors and 9086 survivors) were included. All studies were observational by design (17 retrospective and 7 prospective) with clinical and statistical heterogeneity. Unsuccessful revascularization, reduced left ventricular ejection fraction, renal impairment, and other variables were identified as key independent predictors of mortality. Conclusion: Several key variables have been shown to independently increase mortality in STEMI-CS populations. Future prospective studies examining the prognostic role of multivariate scoring systems incorporating these domains are required.