Obesity/cardiometabolic phenotype of heart failure with preserved ejection fraction: mechanisms to recent trials

PURPOSE OF REVIEW

Heart failure with preserved ejection fraction (HFpEF) is a leading and growing cause of morbidity and mortality globally. Of the various phenotypes identified, the obesity (or cardiometabolic) phenotype appears to be most common. The purpose of this review is to provide the clinician with an abridged understanding of recent developments that have elucidated obesity/visceral adiposity as a central mechanism linking inflammation/immune dysregulation to the development of the HFpEF syndrome. Recent clinical trials examining the efficacy of pharmacological treatments that target obesity in HFpEF will also be discussed.

RECENT FINDINGS

Recent data indicate that visceral adiposity and insulin resistance in HFpEF serve as key mechanisms driving inflammation and immune dysregulation, which play a critical role in the development of cardiac stiffness, diastolic dysfunction and fibrosis in HFpEF. In obesity, alterations in macrophage polarization, changes in innate and adaptive immune systems and altered myocardial energetics promote metabolic inflammation in HFpEF. Finally, emerging data suggest that inflammatory biomarkers, specifically, IL-6, may provide useful information about HFpEF severity and symptom burden in obesity.

SUMMARY

The obesity phenotype of HFpEF is seen in upward of 80% with HFpEF. Obesity is not just a bystander, but plays an essential role in the pathobiology and clinical course of HFpEF. Targeting overweight/obesity in HFpEF with GLP-1 receptor agonists holds promise in these patients.

Efficacy and Safety of Empagliflozin According to Background Diuretic Use in HFrEF: Post-Hoc Analysis of EMPEROR-Reduced

BACKGROUND

The EMPEROR-Reduced (EMPagliflozin outcomE tRial in Patients With chrOnic heaRt Failure With Reduced Ejection Fraction) trial established the efficacy of empagliflozin in reducing heart failure (HF) outcomes among patients with heart failure with reduced ejection fraction (HFrEF).

OBJECTIVES

The authors examined the outcomes of EMPEROR-Reduced as a function of background diuretic therapy.

METHODS

The EMPEROR-Reduced trial was a double-blind, randomized controlled trial of placebo vs empagliflozin 10 mg among 3,730 HFrEF patients. Herein, the population was stratified into 4 groups: no diuretic and diuretic dose equivalent to furosemide <40, 40, and >40 mg daily at baseline.

RESULTS

A total of 3,656 patients from the EMPEROR-Reduced trial were available for analysis. Of those patients, 482 (13.2%) were receiving no diuretic therapy, and 731 (20.0%), 1,411 (38.6%), and 1,032 (28.2%) were receiving <40 mg, 40 mg, and >40 mg, respectively. The efficacy of empagliflozin on the primary outcome (time to first event of hospitalization for HF or cardiovascular [CV] death) was consistent regardless of background diuretic therapy (>40 mg: HR: 0.88 [95% CI: 0.71-1.10]; 40 mg: HR: 0.65 [95% CI: 0.51-0.82]; <40 mg: HR: 0.65 [95% CI: 0.46-0.92]); no diuretic agents: HR: 0.78 [95% CI: 0.47-1.29]; Ptrend test = 0.192). Baseline diuretic doses did not influence the effect of empagliflozin on body weight, systolic blood pressure, NT-proBNP, or hematocrit at 52 weeks. The safety profile of empagliflozin vs placebo was unaffected by baseline diuretic dose; however, independently of treatment allocation, total rates of adverse events were higher among patients with higher baseline doses of diuretic agents.

CONCLUSIONS

Empagliflozin exhibits a consistent effect on time to CV death or HF hospitalization and an unaltered safety profile regardless of baseline diuretic therapy. (EMPagliflozin outcomE tRial in Patients With chrOnic heaRt Failure With Reduced Ejection Fraction [EMPEROR-Reduced]; NCT03057977).

Age period cohort analysis of rheumatic heart disease in high-income countries

INTRODUCTION

Rheumatic heart disease is considered well-controlled in high-income countries; however, its actual trends in mortality remain unclarified. We analyzed trends in mortality from rheumatic heart disease in association with age, period, and birth cohort.

METHODS

We analyzed the WHO mortality database to determine trends in mortality from rheumatic heart disease in the UK, Germany, France, Italy, Japan, Australia, USA, and Canada from 2000 to 2020. We used age-cohort-period modeling to estimate cohort and period effects. Net drift (overall annual percentage change), local drift (annual percentage change in each age group) and heterogeneity were calculated.

RESULTS

In the most recent year, crude mortality rates and age-standardized mortality rates ranged from 1.10 in the USA to 6.17 in Germany, and 0.32 (95% CI 0.31-0.34) in Japan and 1.70 (95% CI 1.65-1.75) in Germany, respectively. During the observation period, while Germany had a constant trend in overall annual percentage change, all the other countries had significant decreasing trends (p < 0.0001, respectively). Annual percent change was not homogeneous across each group in all 8 countries (pheterogeneity < 0.0001), with 2 peaks in the younger and older age categories. In Germany, Italy, Australia, and Canada, we found increasing mortality rates among older patients. Improving period and cohort risks for rheumatic heart disease mortality were generally observed, excluding Germany where the period effect was worsening and the cohort effect was constant.

CONCLUSIONS

Mortality trends from rheumatic heart disease were decreasing in the study high-income countries except for Germany where higher mortality and two peaks in annual percentage change in younger and older age groups warrant further investigation.

A big STEP for treatment of heart failure with preserved ejection fraction

In the STEP-HFpEF trial, 2.4 mg semaglutide produced marked improvements in heart failure-related symptoms, physical limitations, and exercise function, and reduced inflammation and body weight in individuals with obesity HFpEF phenotype. These data usher in a new paradigm of targeting obesity as a therapeutic strategy in HFpEF.

Chronic heart failure management in adult patients with congenital heart disease

PURPOSE OF REVIEW

A growing number of adult patients with congenital heart disease (ACHD) are entering the healthcare system as a result of advances in the diagnosis and management of congenital heart defects. Heart failure is a common final pathway for this diverse patient population, representing the leading cause of mortality in ACHD patients. Herein, we review present guideline-directed management of heart failure in ACHD patients.

RECENT FINDINGS

There exists a dearth of data to guide management of ACHD-related heart failure. Given this gap, recent guidelines have been limited in the recommendations they can provide for this patient population, with practitioners being consequently forced to generalize findings from studies of acquired heart disease patients based on mechanistic plausibility. The small number of studies directly assessing ACHD patients have been largely limited in their clinical relevance through being negative, small, observational, limited to specific subsets of ACHD patients or assessing nonvalidated outcomes.

SUMMARY

Despite the prevalence and impact of ACHD-related heart failure, there are limited evidence-based therapies for its management. Given the rising burden of this clinical problem, definitive trials assessing newer therapies are required to establish their potential role in heart failure amongst ACHD patients.

Risk Factors for Postrepair Elevated Mitral Gradient: A Post-hoc Analysis of a Randomized Trial

BACKGROUND

Predischarge elevated mean mitral gradients (>5 mm Hg) may occur after repair for degenerative mitral regurgitation. We sought to identify risk factors associated with elevated gradients and to evaluate its impact on functional outcomes at 12 months in this subanalysis of the Canadian Mitral Research Alliance CardioLink-2 trial.

METHODS

One hundred four patients with degenerative mitral regurgitation undergoing mitral repair were randomized to either a leaflet resection or preservation strategy. Logistic regression was used to identify risk factors associated with an elevated gradient. Functional outcomes at 12 months were compared between participants with and without elevated gradients.

RESULTS

Elevated gradients was identified in 15 participants (14.4%), which was not significantly different based on allocation to each repair strategy (P = .10). Patients with elevated gradients were more likely to be women (odds ratio [OR], 4.28; 95% confidence interval [CI], 1.29-14.19; P = .02) and to have a lower preoperative hemoglobin level (OR, 0.93; 95% CI, 0.89-0.98; P = .01) and smaller intercommissural diameter (OR, 0.86; 95% CI, 0.76-0.97; P = .02) and mitral annuloplasty size (OR, 0.71; 95% CI, 0.57-0.87; P = .001). The ratio of intercommissural diameter-to-annuloplasty size was similar between those with and without elevated gradients (both 0.8 ± 0.1, P = .69). At 12 months those with elevated gradients had a worse New York Heart Association functional status (P = .0001), lower peak oxygen saturation in exercise test (P = .01), smaller body weight-walk distance product (P = .02), and higher Borg scale (P = .01) in the 6-minute walk test.

CONCLUSIONS

Female gender, smaller mitral anatomy sizes, and lower preoperative hemoglobin levels were associated with postoperative elevated mitral gradients, which was in turn were associated with reduced functional status. Further research is warranted to investigate these potential risk factors.

Cardiopulmonary bypass and cardiac surgery associated pulmonary hypertension: The need for proactivity and reactivity

Pulmonary hypertension remains an important postcardiac surgical problem requiring prompt identification and management. In this edition of the Journal of Cardiac Surgery, Fayad and colleagues provide a detailed review of this topic, including epidemiology, mechanistic underpinnings, and available treatment options. In addition to responding to postoperative pulmonary hypertension, however, proactive measures including optimal timing of intervention are paramount to preventing the development of pulmonary hypertension and its associated complications.

Stage-based approach to predict left ventricular reverse remodeling after mitral repair

Background

Although predictors of reverse left ventricular (LV) remodeling postmitral valve repair are critical for guiding perioperative decision‐making, there remains a paucity of randomized, prospective data to support the criteria that potential predictor variables must meet.

Methods and Results

The CAMRA CardioLink‐2 randomized trial allocated 104 patients to either leaflet resection or preservation strategies for mitral repair. The correlation of indexed left ventricular end‐systolic volume (LVESVI), indexed left ventricular end‐diastolic volume (LVEDVI), and left ventricular ejection fraction (LVEF) were tested with univariate analysis and subsequently with multivariate analysis to determine independent predictors of reverse remodeling at discharge and at 12 months postoperatively. At discharge, both LVESVI and LVEDVI were independently associated with their preoperative values (p < .001 for both) and LVEF by preoperative LVESVI (p < .001). Mitral ring size was favorably associated with the change in LVESVI (p < .05) and LVEF (p < .01) from predischarge to 12 months, while the mean mitral valve gradient after repair was adversely associated with the change in LVESVI (p < .05) and LVEDVI (p < .05). No significant associations were found between reverse remodeling and coaptation height nor mitral repair technique.

Conclusions

Beyond confirming the lack of impact of mitral repair technique on reverse remodeling, this investigation suggests that recommending surgery before significant LV dilatation or dysfunction, as well as higher postoperative mitral valve hemodynamic performance, may enhance remodeling capacity following mitral repair.

Aortic valve neocuspidization and its technical nuance

Aortic valve neocuspidization or Ozaki procedure represents an advanced surgical strategy for the management of patients with aortic valvulopathy. It has been shown to have clinical and hemodynamic outcomes that compare favorably with aortic valve replacement as it restores physiological aortic valve function and left ventricular remodeling. There are, however, a new set of issues including structural valve deterioration, leaflet tear/perforation, and need for reoperation. A keen understanding of the technical nuances involved with the Ozaki procedure may help in reducing the incidence of such adverse outcomes.

An Arrow Through the Heart

A 54-year-old man suffered a self-inflicted penetrating chest wound from an automated crossbow used for hunting large animals. The arrow was in the plane of the diaphragm and penetrated the left ventricle, although no hemopericardium, hemothorax, or pneumothorax were identified. Intraoperative transesophageal echocardiography showed no significant mitral regurgitation despite the proximity of the arrow to the base of a papillary muscle. This case details his subsequent successful treatment with the assistance of cardiopulmonary bypass.

Routine left atrial appendage occlusion in patients undergoing cardiac surgery: a narrative review

PURPOSE OF REVIEW

New evidence suggests a greater prevalence of protracted postoperative atrial fibrillation (POAF) than previously recognized. The left atrial appendage (LAA) is the most common source of embolism in patients with nonvalvular atrial fibrillation. In this review, we ask whether there is evidence to support routine LAA occlusion (LAAO) in patients without preexisting atrial fibrillation undergoing cardiac surgery.

RECENT FINDINGS

Overall, available studies are small, inconsistent and have varying proportions of patients with and without preexisting atrial fibrillation. There is considerable discrepancy with respect to the efficacy of LAAO in reducing the risk of POAF-related stroke. Only one study reported a lower rate of stroke in the LAAO group compared with no LAAO. Two studies included a subgroup analysis of patients that developed POAF and report a significantly higher rate of stroke in patients that developed POAF and did not undergo LAAO. There are three clinical trials ongoing that are investigating prophylactic LAAO in patients undergoing cardiac surgery: ATLAS, LAA-CLOSURE and LAACS-2.

SUMMARY

There is currently insufficient evidence to recommend routine addition of LAAO to lower the risk of postoperative stroke. Ongoing clinical trials will provide important insight into the role of routine LAAO in all patients undergoing cardiac surgery.

Sodium-glucose cotransporter 2 inhibitors in heart failure with reduced or preserved ejection fraction: a meta-analysis

Aims

Sodium‐glucose cotransporter 2 (SGLT2) inhibitors have been shown to be an effective therapy in improving heart failure outcomes. We conducted a meta‐analysis of randomized controlled trials to evaluate the efficacy of SGLT2 inhibitors in heart failure patients with either a reduced or preserved ejection fraction.

Methods and results

We searched MEDLINE and EMBASE for large (≥1000 patients) randomized controlled trials evaluating the effects of SGLT2 inhibitors compared with placebo in the setting of heart failure until September 2021. Our primary outcome was the composite of heart failure hospitalization and cardiovascular death, and secondary outcomes included all‐cause mortality and total heart failure hospitalizations. We pooled hazard ratios and risk ratios and evaluated risk of bias with the Cochrane Collaboration tool. Four randomized controlled trials (DAPA HF, EMPEROR‐Preserved, EMPEROR‐Reduced, and SOLOIST‐WHF) were included (n = 15 684); two of which evaluated patients with a reduced LVEF, one of which evaluated patients with a preserved LVEF, and one of which included both. Treatment with SGLT2 inhibitors resulted in a significant reduction in the composite of CV death and heart failure hospitalization (HR: 0.76, 95% CI: 0.70, 0.82, I²: 0%, P < 0.00001). This was consistent in sub‐groups of patients with LVEF ≤40% (n = 9199, HR: 0.74, 95% CI: 0.68, 0.81, I²: 0%) and LVEF >40% (n = 6482, HR: 0.78, 95% CI: 0.68, 0.89, I²: 0%, P‐for‐interaction: 0.57), as well as in sub‐groups of patients with and without diabetes mellitus at baseline (P‐for‐interaction: 0.81). SGLT2 inhibitors were associated with a significant reduction in cardiovascular death (HR: 0.87, 95% CI: 0.79, 0.97, I²: 0%, P < 0.00001) and total heart failure hospitalization (RR: 0.71, 95% CI: 0.67, 0.76, I²: 0%, P < 0.00001); although a potential trend towards reduced all‐cause mortality was noted with SGLT2 inhibitors, no statistically significant difference was observed (HR: 0.91, 95% CI: 0.83, 1.00, I²: 14%, P = 0.05).

Conclusions

Sodium‐glucose cotransporter 2 inhibitors reduce cardiovascular death and heart failure hospitalization among patients with heart failure, regardless of LVEF status.

Empagliflozin in the treatment of heart failure with reduced ejection fraction in addition to background therapies and therapeutic combinations (EMPEROR-Reduced): a post-hoc analysis of a randomised, double-blind trial

BACKGROUND

It is important to evaluate whether a new treatment for heart failure with reduced ejection fraction (HFrEF) provides additive benefit to background foundational treatments. As such, we aimed to evaluate the efficacy and safety of empagliflozin in patients with HFrEF in addition to baseline treatment with specific doses and combinations of disease-modifying therapies.

METHODS

We performed a post-hoc analysis of the EMPEROR-Reduced randomised, double-blind, parallel-group trial, which took place in 520 centres (hospitals and medical clinics) in 20 countries in Asia, Australia, Europe, North America, and South America. Patients with New York Heart Association (NYHA) classification II-IV with an ejection fraction of 40% or less were randomly assigned (1:1) to receive the addition of either oral empagliflozin 10 mg per day or placebo to background therapy. The primary composite outcome was cardiovascular death and heart failure hospitalisation; the secondary outcome was total heart failure hospital admissions. An extended composite outcome consisted of inpatient and outpatient HFrEF events was also evaluated. Outcomes were analysed according to background use of angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs) or angiotensin receptor neprilysin inhibitors (ARNIs), as well as β blockers and mineralocorticoid receptor antagonists (MRAs) at less than 50% or 50% or more of target doses and in various combinations. This study is registered with ClinicalTrials.gov, NCT03057977.

FINDINGS

In this post-hoc analysis of 3730 patients (mean age 66·8 years [SD 11·0], 893 [23·9%] women; 1863 [49·9%] in the empagliflozin group, 1867 [50·1%] in the placebo group) assessed between March 6, 2017, and May 28, 2020, empagliflozin reduced the risk of the primary outcome (361 in 1863 participants in the empagliflozin group and 462 of 1867 in the placebo group; HR 0·75 [95% CI 0·65-0·86]) regardless of background therapy or its target doses for ACE inhibitors or ARBs at doses of less than 50% of the target dose (HR 0·85 [0·69-1·06]) and for doses of 50% or more of the target dose (HR 0·67 [0·52-0·88]; p_interaction=0·18). A similar result was seen for β blockers at doses of less than 50% of the target dose (HR 0·66 [0·54-0·80]) and for doses of 50% or more of the target dose (HR 0·81 [0·66-1·00]; p_interaction=0·15). Empagliflozin also reduced the risk of the primary outcome irrespective of background use of triple therapy with an ACE inhibitor, ARB, or ARNI plus β blocker plus MRA (given combination HR 0·73 [0·61-0·88]; not given combination HR 0·76 [0·62-0·94]; p_interaction=0·77). Similar patterns of benefit were observed for the secondary and extended composite outcomes. Empagliflozin was well tolerated and rates of hypotension, symptomatic hypotension, and hyperkalaemia were similar across all subgroups.

INTERPRETATION

Empagliflozin reduced serious heart failure outcomes across doses and combinations of disease-modifying therapies for HFrEF. Clinically, these data suggest that empagliflozin might be considered as a foundational therapy in patients with HFrEF regardless of their existing background therapy.

FUNDING

Boehringer Ingelheim and Eli Lilly and Company.

Icosapent Ethyl Reduces Ischemic Events in Patients With a History of Previous Coronary Artery Bypass Grafting: REDUCE-IT CABG

BACKGROUND

Despite advances in surgery and pharmacotherapy, there remains significant residual ischemic risk after coronary artery bypass grafting surgery.

METHODS

In REDUCE-IT (Reduction of Cardiovascular Events With Icosapent Ethyl-Intervention Trial), a multicenter, placebo-controlled, double-blind trial, statin-treated patients with controlled low-density lipoprotein cholesterol and mild to moderate hypertriglyceridemia were randomized to 4 g daily of icosapent ethyl or placebo. They experienced a 25% reduction in risk of a primary efficacy end point (composite of cardiovascular death, myocardial infarction, stroke, coronary revascularization, or hospitalization for unstable angina) and a 26% reduction in risk of a key secondary efficacy end point (composite of cardiovascular death, myocardial infarction, or stroke) when compared with placebo. The current analysis reports on the subgroup of patients from the trial with a history of coronary artery bypass grafting.

RESULTS

Of the 8179 patients randomized in REDUCE-IT, a total of 1837 (22.5%) had a history of coronary artery bypass grafting, with 897 patients randomized to icosapent ethyl and 940 to placebo. Baseline characteristics were similar between treatment groups. Randomization to icosapent ethyl was associated with a significant reduction in the primary end point (hazard ratio [HR], 0.76 [95% CI, 0.63-0.92]; P=0.004), in the key secondary end point (HR, 0.69 [95% CI, 0.56-0.87]; P=0.001), and in total (first plus subsequent or recurrent) ischemic events (rate ratio, 0.64 [95% CI, 0.50-0.81]; P=0.0002) compared with placebo. This yielded an absolute risk reduction of 6.2% (95% CI, 2.3%-10.2%) in first events, with a number needed to treat of 16 (95% CI, 10-44) during a median follow-up time of 4.8 years. Safety findings were similar to the overall study: beyond an increased rate of atrial fibrillation/flutter requiring hospitalization for at least 24 hours (5.0% vs 3.1%; P=0.03) and a nonsignificant increase in bleeding, occurrences of adverse events were comparable between groups.

CONCLUSIONS

In REDUCE-IT patients with a history of coronary artery bypass grafting, treatment with icosapent ethyl was associated with significant reductions in first and recurrent ischemic events. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01492361.

Surgical Treatment for Gerbode Defect Caused by Infective Endocarditis

In this case illustration, a Gerbode defect in a 52-year-old woman caused by infective endocarditis was closed with autologous pericardium. Postoperative echocardiographic findings were satisfactory without residual shunt flow or perivalvular leak. Her postoperative recovery was uneventful without infection recurrence. Gerbode defect is a rare complication of infective endocarditis and careful preoperative echocardiographic work-up is imperative for successful repair.

Stuck between a rock and a hard place: The clinical conundrum of managing cardiac surgical patients during the SARS-CoV-2 pandemic

Deferring nonemergent cardiac surgery became the strategy of choice for several international healthcare systems afflicted by high case burdens of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2/COVID‐19) to both conserve valuable healthcare resources and protect patients from possible exposure. Missing from the available dataset to help guide policy development has been a clear understanding of the extent to which COVID‐19 infection modulates cardiac surgery outcomes. In their investigation, Bonalumi et al. uncovered an inpatient COVID‐19 positivity rate of almost 10 times higher than that of the general Italian population, as well as a mortality rate over 20 times higher amongst cardiac surgery patients with perioperative COVID‐19 infection compared to those COVID‐negative. While the summation of available evidence points to the serious consideration cardiac surgeons must give to delaying surgeries during the COVID‐19 pandemic, recognition must be given to the risks that postponing cardiac surgery may have on patient outcomes. Emerging data is beginning to demonstrate the efficacy of vaccination in preventing postoperative COVID‐19 infection and morbidity.

SGLT2 inhibitors and cardiac remodelling: a systematic review and meta-analysis of randomized cardiac magnetic resonance imaging trials

Aims

Recent large randomized controlled trials (RCTs) have demonstrated efficacy of sodium‐glucose cotransporter‐2 inhibitors (SGLT2i) in both preventing and treating heart failure (HF). SGLT2i‐induced reversal of left ventricular remodelling has been proposed as a mechanism contributing to this effect.

Methods and results

We performed a systematic review and meta‐analysis of RCTs to compare SGLT2i versus placebo (treatment duration >3 months) on cardiac remodelling parameters as measured by cardiac magnetic resonance imaging (cMRI) in patients with HF and/or diabetes. The PubMed and ClinicalTrials.gov databases were searched until 15 June 2021. Our primary outcome was change in absolute left ventricular mass (LVM) from baseline to study endpoint. Secondary outcomes included changes in LVM indexed to body surface area, left ventricular end‐systolic volume (LVESV), left ventricular end‐diastolic volume (LVEDV), and left ventricular ejection fraction (LVEF) from baseline to study endpoint. The Cochrane Collaboration's tool was used to assess risk of bias. Five studies representing 408 patients were included. SGLT2i was associated with greater LVM regression compared to placebo (MD, −5.76 g; 95% CI, −10.87 g to −0.64 g, I² = 73%; overall effect, P < 0.03; four RCTs). Statistical subgroup differences were not observed in our sensitivity analysis focusing on HF with reduced ejection fraction (P = 0.37) and were observed in our sensitivity analysis focusing on diabetes (P < 0.001). SGLT2i was not associated with statistical changes in LV mass indexed to body surface area (I² = 75%; P = 0.16; five RCTs), LVESV (I² = 87%; P = 0.07; five RCTs), LVEDV (I² = 81%; P = 0.20; five RCTs), nor LVEF (I² = 85%; P = 0.19; five RCTs) versus placebo. Sixty per cent of RCTs had low risk of bias.

Conclusions

Sodium‐glucose cotransporter‐2 inhibitors treatment was associated with a reduction in left ventricular mass as assessed by cMRI.

Ticagrelor use and practice patterns among Canadian cardiac surgeons

BACKGROUND AND AIM

The P2Y12 platelet receptor inhibitor ticagrelor is widely used in patients following acute coronary syndromes or in those who have received coronary stents. Bentracimab is a monoclonal antibody-based reversal agent that is being formally evaluated in a Phase 3 clinical trial. Here, we probe the knowledge, attitudes, and practice patterns of cardiac surgeons regarding their perioperative management of ticagrelor and potential application of a ticagrelor reversal agent.

METHODS

A questionnaire was developed by a working group of cardiac surgeons to inquire into participants' practices and beliefs regarding ticagrelor and disseminated to practicing, Canadian-trained cardiac surgeons.

RESULTS

A total of 70 Canadian-trained cardiac surgeons participated. Bleeding risk was identified as the most significant consideration when surgically revascularizing ticagrelor-treated patients (90%). There is variability in the duration of withholding ticagrelor before coronary artery bypass graft procedure in a stable patient; 44.3% wait 3 days and 32.9% wait 4 days or longer. Currently, 15.7% of cardiac surgeons prophylactically give platelet transfusions and fresh frozen plasma intraoperatively following protamine infusion in patients who have recently received ticagrelor. Interestingly, 47.1% of surveyed surgeons were aware of a reversal agent for ticagrelor, 91.4% of cardiac surgeons would consider utilizing a ticagrelor reversal agent if available, and 51.4% acknowledged that the introduction of such an agent would be a major advance in clinical practice.

CONCLUSIONS

The present survey identified ticagrelor-related bleeding as a major concern for cardiac surgeons. Surgeons recognized the significant unmet need that a ticagrelor reversal agent would address.

Synaptic development in semi-dissociated cultures of rat retina

Cultured neurons provide a simpler and more accessible environment to study the synaptic physiology. However, it is not clear if development of synapses in culture is similar to that in the in vivo condition. We studied the developmental sequence and morphological differentiation of chemical synapses in semi-dissociated rat retinal cultures that consisted of dissociated neurons as well as undissociated retinal aggregates. Synapses were quantified by synaptophysin immunoreactive puncta. During second week of in vitro development the average number of chemical synapses on the cell body decreased while that on the neurites increased significantly. Conventional synapses appeared both in aggregate and in dissociated neurons, with the developmental profile similar to that reported for in vivo retina. In contrast, the development of ribbon synapses was adversely affected by the in vitro microenvironment as suggested by following observations. The ribbon synapses were more frequently found in aggregate than in dissociated neurons, and were not associated with dyadic or triadic synaptic arrangement. The photoreceptor ribbons did not contact a postsynaptic process while bipolar ribbons made single (monadic) synapses. Further, photoreceptor ribbons in dissociated neurons were late to form and took more time to mature as compared to those in the aggregate cultures. Most of the rod bipolar cells, identified by their immunoreactivity to protein kinase C (PKC), had three or more neurites. Unlike in the in vivo retina, the dissociated rod bipolar cells did not show any PKC immunoreactive varicosities, suggesting that they failed to develop a well-differentiated synaptic terminal. Interestingly, we did not find any parvalbumin positive AII amacrine cells that are normally postsynaptic to rod bipolar cells. These results show that the conventional synapses of retina, which are similar to chemical synapses in other parts of the brain, develop normally both in aggregate and dissociated neurons. However, the highly specialized ribbon synapses have more stringent developmental requirements, and their normal development may require the presence of postsynaptic neurons in their close vicinity.

Cytochrome oxidase activity in rat retinal ganglion cells during postnatal development

In this study, the metabolic activity of rat retinal ganglion cells during postnatal development has been examined in vivo using cytochrome oxidase histochemistry. The intensity of staining was measured by optical densitometry. The activity of cytochrome oxidase in retinal ganglion cells progressively increased from postnatal day 0 (P0) and reached a peak during the second week of postnatal development (P10-P14) and declined thereafter. Our data show that the increased levels of cytochrome oxidase seen in developing retinal ganglion cells occur at the same time, when neuronal maturity and synaptogenesis reach their peaks.

Role of monoamine oxidase type A and B on the dopamine metabolism in discrete regions of the primate brain

The role of monoamine oxidase (MAO) type A and B on the metabolism of dopamine (DA) in discrete regions of the monkey brain was studied. Monkeys were administered (-)-deprenyl (0.25 mg/kg) or clorgyline (1.0 mg/kg) or deprenyl and clorgyline together by intramuscular injections for 8 days. Levels of DA and its metabolites, dihydroxy phenylacetic acid (DOPAC) and homovanillic acid (HVA) were estimated in frontal cortex (FC), motor cortex (MC), occipital cortex (OC), entorhinal cortex (EC), hippocampus (HI), hypothalamus (HY), caudate nucleus (CN), globus pallidus (GP) and substantia nigra (SN). (-)-Deprenyl administration significantly increased DA levels in FC, HY, CN, GP and SN (39-87%). This was accompanied by a reduction in the levels of DOPAC (37-66%) and HVA (27-79%). Clorgyline administration resulted in MAO-A inhibition by more than 87% but failed to increase DA levels in any of the brain regions studied. Combined treatment of (-)-deprenyl and clorgyline inhibited both types of MAO by more than 90% and DA levels were increased (57-245%) in all brain regions studied with a corresponding decrease in the DOPAC (49-83%) and HVA (54-88%) levels. Our results suggest that DA is metabolized preferentially, if not exclusively by MAO-B in some regions of the monkey brain.

Chronic (-) deprenyl administration increases dendritic arborization in CA3 neurons of hippocampus and AChE activity in specific regions of the primate brain

The mechanism by which (-) deprenyl enhances cognitive function in Alzheimer's disease (AD) is not yet understood. (-) Deprenyl (0.2 mg/kg/day) was administered intramuscularly to adult male monkeys (n = 6) for 25 days. Control monkeys (n = 6) received physiological saline by the same route. The activity of acetylcholinesterase (AChE) in different brain regions and the dendritic arborization in CA3 pyramidal neurons of hippocampus were analysed. (-) Deprenyl-treated monkeys showed a significant increase in the AChE activity by 43% (p < 0.001) in the frontal cortex, by 39% (p < 0.025) in the motor cortex, by 66% (p < 0.001) in the hippocampus and by 26% (p < 0.05) in the striatum compared to controls. The branching points and the intersections of both apical and basal dendrites of CA3 hippocampal pyramidal neurons were also significantly increased in (-) deprenyl-treated monkeys. Enhanced AChE activity may increase dendritic arborization in the hippocampus and it may also play a role in improving cognitive functions observed in AD, following (-) deprenyl treatment.

Developmental expression of synaptophysin, synapsin I and syntaxin in the rat retina

Expression of synaptophysin, synapsin I and syntaxin was studied immunocytochemically in the developing rat retina using indirect immunoperoxidase technique. In the inner plexiform layer (IPL), syntaxin immunoreactivity appeared at postnatal day 1 (P1) whereas synaptophysin and synapsin I staining were first observed at P2. In the outer plexiform layer (OPL), synaptophysin appeared at P4, while synapsin I and syntaxin appeared at P8. In the case of synaptophysin, a punctate pattern of staining was observed from the time of its appearance (P4) in the OPL and from P12 onwards in the IPL. Synapsin I and syntaxin immunoreactivity in the OPL were of a low intensity throughout the development and in the adult stage. These findings are discussed in relation to synaptogenesis in the rat retina.

Selective reduction of monoamine oxidase A and B in the frontal cortex of subordinate rats

We have previously shown that subordination causes a reduction in the levels of 5-hydroxytryptamine and dopamine selectively in the frontal cortex [6]. These monoamines are catabolised mainly by the enzyme monoamine oxidase (MAO) which exists in two isoforms; MAO-A and MAO-B. The present study was carried out to determine whether there is any change in the activity of these two iso-enzymes induced by subordination and if any such alteration is confined to the frontal cortex. The animal model of dominance-subordination used was a worker-parasite paradigm in male Wistar rats. The enzyme activities were measured in five brain regions, the frontal cortex, entorhinal cortex, hippocampus, hypothalamus and striatum, using kynuramine as the substrate. Clorgyline and L-deprenyl were used in vitro to block the activities of MAO-A and MAO-B, respectively. There was a significant (P < 0.001) reduction in the activity of MAO-A as well as MAO-B selectively in the frontal cortex of the subordinate animals. This finding may suggest a reduced neurotransmitter turnover in the serotonergic and dopaminergic neurons terminating in the frontal cortex.

Subordination induced decrease in 5-hydroxytryptamine and dopamine levels in the frontal cortex--a study using worker-parasite relationship in rats as a model

Competition for a limited resource appears to be an important factor in natural selection. Such competition when elicited experimentally, leads to the establishment of dominant-subordinate (D-S) relationship between the competitors. The present study was carried out to analyse the effect of D-S relationship on the levels of monoamines, namely, dopamine (DA), 5-hydroxytryptamine (5-HT) and norepinephrine (NE) in various brain regions. The model of D-S relationship selected for this work was a modified worker-parasite paradigm in adult male Wistar rats. The levels of monoamines were estimated in the frontal cortex, the entorhinal cortex, the hippocampus and the septum of the two competitors and a non-competitor control, using high pressure liquid chromatography (HPLC). Levels of DA and 5-HT, but not NE, were found to be lower (P < 0.05) only in the frontal cortex of the subordinate as compared to that of the dominant or the control. These findings are comparable with similar neurochemical changes reported to be caused by some of the known stressors.