Elevated sympathetic-mediated vasoconstriction at rest but intact functional sympatholysis during exercise in heart failure with reduced ejection fraction.

Patients with heart failure with reduced ejection fraction (HFrEF) have exaggerated sympathoexcitation and impaired peripheral vascular conductance. Evidence demonstrating consequent impaired functional sympatholysis is limited in HFrEF. This study aimed to determine the magnitude of reduced limb vascular conductance during sympathoexcitation and whether functional sympatholysis would abolish such reductions in HFrEF. Twenty patients with HFrEF and 22 age-matched controls performed the cold pressor test (CPT) [left foot 2-min in -0.5 (1)°C water] alone and with right handgrip exercise (EX + CPT). Right forearm vascular conductance (FVC), forearm blood flow (FBF), and mean arterial pressure (MAP) were measured. Patients with HFrEF had greater decreases in %ΔFVC and %ΔFBF during CPT (both P < 0.0001) but not EX + CPT (P = 0.449, P = 0.199) compared with controls, respectively. %ΔFVC and %ΔFBF decreased from CPT to EX + CPT in patients with HFrEF (both P < 0.0001) and controls (P = 0.018, P = 0.015), respectively. MAP increased during CPT and EX + CPT in both groups (all P < 0.0001). MAP was greater in controls than in patients with HFrEF during EX + CPT (P = 0.025) but not CPT (P = 0.209). In conclusion, acute sympathoexcitation caused exaggerated peripheral vasoconstriction and reduced peripheral blood flow in patients with HFrEF. Handgrip exercise abolished sympathoexcitatory-mediated peripheral vasoconstriction and normalized peripheral blood flow in patients with HFrEF. These novel data reveal intact functional sympatholysis in the upper limb and suggest that exercise-mediated, local control of blood flow is preserved when cardiac limitations that are cardinal to HFrEF are evaded with dynamic handgrip exercise.NEW & NOTEWORTHY Patients with HFrEF demonstrate impaired peripheral blood flow regulation, evidenced by heightened peripheral vasoconstriction that reduces limb blood flow in response to physiological sympathoexcitation (cold pressor test). Despite evidence of exaggerated sympathetic vasoconstriction, patients with HFrEF demonstrate a normal hyperemic response to moderate-intensity handgrip exercise. Most importantly, acute, simultaneous handgrip exercise restores normal limb vasomotor control and vascular conductance during acute sympathoexcitation (cold pressor test), suggesting intact functional sympatholysis in patients with HFrEF.

Autonomic cardiovascular reflex control of hemodynamics during exercise in heart failure with reduced ejection fraction and the effects of exercise training.

Heart failure with reduced ejection fraction is associated with increased exercise intolerance, morbidity, and mortality. Importantly, exercise intolerance in heart failure with reduced ejection fraction is a key factor limiting patient quality of life and survival. Exercise intolerance in heart failure with reduced ejection fraction stems from a multi-organ failure to maintain homeostasis at rest and during exercise, including the heart, skeletal muscle, and autonomic nervous system, lending itself to a system constantly trying to "catch-up". Hemodynamic control during exercise is regulated primarily by the autonomic nervous system, whose operation, in turn, is partly regulated via reflexive information from exercise-stimulated receptors throughout the body (e.g., arterial baroreflex, central and peripheral chemoreceptors, and the muscle metabo- and mechanoreflexes). Persons with heart failure with reduced ejection fraction exhibit malfunctioning autonomic reflexes, which lead to exaggerated sympathoexcitation and attenuated parasympathetic tone. Chronic elevation of sympathetic activity is associated with increased morbidity and mortality. In this review, we provide an overview of how each main exercise-related autonomic reflex is changed in heart failure with reduced ejection fraction, and the role of exercise training in attenuating or reversing the counterproductive changes.

Mechanical circulatory support in cardiogenic shock.

PURPOSE OF REVIEW: Cardiogenic shock remains a complex clinical syndrome with high morbidity and mortality. The purpose of this article is to review important landmark trials as well as the relevant recent literature for percutaneous mechanical circulatory support following acute myocardial infarction. RECENT FINDINGS: The sole use of intraaortic balloon pumps for cardiogenic shock following acute myocardial infarction continues to be questioned with downgrading of its recommendation in recent years, there however may remain a role in patients with mechanical complications of their myocardial infarction. The combined use of extracorporeal circulatory support and a ventricular unloading device appears to be promising with increasing data supporting this strategy. SUMMARY: Given the complex and heterogeneous nature of cardiogenic shock there remains somewhat limited robust data to guide clinical practice. Ongoing research is needed to help guide improvements in patient outcomes.

Secondary mitral regurgitation: percutaneous edge-to-edge repair on the cutting edge?

PURPOSE OF REVIEW: Secondary mitral regurgitation commonly complicates heart failure. Although the evidence for its management is most robust for treating the underlying cardiomyopathy, treatment aimed at additionally reducing the severity of mitral regurgitation with a percutaneous edge-to-edge device, MitraClip, has recently emerged. RECENT FINDINGS: Despite the use of contemporary evidence-based heart failure therapies, patients with secondary mitral regurgitation and heart failure continue to remain at high risk for adverse clinical events; in both the MITRA-FR and COAPT trials, an extremely high event rate was evident in the medically managed arms over the respective 12-24-month follow-up. Data supporting the use of MitraClip to mitigate adverse outcomes in secondary mitral regurgitation is, however, conflicting. In MITRA-FR no difference was noted between MitraClip compared with the medically managed arm for the composite of all-cause death or heart failure hospitalization at 12 months. However, in COAPT, a significant reduction in the rate of heart failure re-hospitalization over 2 years was evident with MitraClip compared with medical therapy alone. SUMMARY: Recommendations exist for the use of MitraClip in patients with primary mitral regurgitation and prohibitive surgical risk. However, with the divergent results of two recent high-quality randomized trials, its role in patients with secondary mitral regurgitation remains controversial.

Update on revascularization in patients with heart failure and coronary artery disease.

PURPOSE OF REVIEW: The review explores the recent findings surrounding the evaluation and the treatment of patients with heart failure and coronary artery disease. It also shed the light on the gaps in this area. RECENT FINDINGS: Surgical revascularization in patients with ischemic cardiomyopathy has the potential to offer symptomatic and survival benefits. SUMMARY: Patients with heart failure and coronary artery disease should be considered candidates for revascularization on the basis of their symptoms, extent of the disease, and comorbidities. Surgical revascularization in these patients provides a symptomatic relief, and a survival benefit.

Chemotherapy-related cardiac dysfunction: grey area in type I and type II classification.

PURPOSE OF REVIEW: The main aim of this review is to address and challenge an old nomenclature of reversible versus irreversible chemotherapy-induced cardiomyopathy. RECENT FINDINGS: Chemotherapy-related cardiac dysfunction (CRCD) has been often characterized as type I or type II. Type I CRCD (e.g., anthracycline) represents a group of chemotherapeutic agents that has often been correlated with irreversible cardiac dysfunction. Conversely, type II CRCD (e.g., trastuzumab) represents a group of anticancer agents that has been considered as reversible. Recent evidence suggests that this nomenclature may not hold true, thus affecting clinical prognosis as well as timely management. It is prudent to address this concern so that physicians are armed with appropriate information, thus providing our oncological patients with informed care. The purpose is to highlight the grey area in this dichotomous classification. SUMMARY: Type I CRCD can be reversible if cardioprotective medications are administered in a timely manner. Conversely, a small proportion of type II CRCD may develop irreversible dysfunction and therefore, will require a long-term follow-up. Therefore, every case should be dealt on an individual basis and an appropriate prognosis should be given to patients based on the clinical evidence on hand.

The impact of obesity on heart failure.

PURPOSE OF REVIEW: Obesity, a growing global health problem, contributes to the development of heart failure. However, increased BMI seems protective for those with established disease, a phenomenon known as the 'obesity paradox'. In this review, we outline the mechanism through which obesity can contribute to the development of heart failure, explore the concept of obesity paradox, and highlight the challenges that obesity presents for advanced heart failure therapy. RECENT FINDINGS: Although the mechanism underlying the obesity paradox is complex, meta-analysis shows that intentional weight loss through bariatric surgery can indeed improve cardiac structure and function. With regard to ventricular assist device therapy in obese patients, recent studies demonstrate that while obesity was indeed associated with higher likelihood of complications, there were no statistically significant differences in terms of mortality or delisting from cardiac transplant waiting list. SUMMARY: Obesity is strongly associated with the development of heart failure, through direct and indirect mechanisms. Although clear consensus regarding weight reduction in this patient population is lacking, there is mounting clinical evidence that intentional weight loss may be beneficial, in spite of the well-recognized obesity paradox, particularly as the presence of obesity presents unique challenges in the advanced therapy of heart failure patients.

Genetic testing in cardiomyopathies: an update on indications and benefits.

PURPOSE OF REVIEW: As rapid genetic testing has become increasingly accessible in a timely fashion, more genetic mutations are identified in inherited conditions such as cardiomyopathies. Understanding when to consider genetic testing is an important part of the management of patients whose presentations vary from decompensated heart failure to sudden cardiac death. RECENT FINDINGS: We describe the benefits of genetic testing for risk stratification of family members, prognostication of probands, and identification of novel disease-causing mutations and examine the possible role of genetic predisposition in seemingly acquired cardiomyopathies such as peripartum and anthracycline-induced cardiomyopathy. SUMMARY: Genetic screening for the recognition of family members who have inherited a cardiomyopathy is important, and testing may identify patients at higher risk of sudden death. However, genetic testing does have its limitations, such as the identification of variants of unknown significance that often complicate the clinical picture.

Effects of Xanthine Oxidase Inhibition in Hyperuricemic Heart Failure Patients: The Xanthine Oxidase Inhibition for Hyperuricemic Heart Failure Patients (EXACT-HF) Study.

BACKGROUND: Oxidative stress may contribute to heart failure (HF) progression. Inhibiting xanthine oxidase in hyperuricemic HF patients may improve outcomes. METHODS AND RESULTS: We randomly assigned 253 patients with symptomatic HF, left ventricular ejection fraction ≤40%, and serum uric acid levels ≥9.5 mg/dL to receive allopurinol (target dose, 600 mg daily) or placebo in a double-blind, multicenter trial. The primary composite end point at 24 weeks was based on survival, worsening HF, and patient global assessment. Secondary end points included change in quality of life, submaximal exercise capacity, and left ventricular ejection fraction. Uric acid levels were significantly reduced with allopurinol in comparison with placebo (treatment difference, -4.2 [-4.9, -3.5] mg/dL and -3.5 [-4.2, -2.7] mg/dL at 12 and 24 weeks, respectively, both P<0.0001). At 24 weeks, there was no significant difference in clinical status between the allopurinol- and placebo-treated patients (worsened 45% versus 46%, unchanged 42% versus 34%, improved 13% versus 19%, respectively; P=0.68). At 12 and 24 weeks, there was no significant difference in change in Kansas City Cardiomyopathy Questionnaire scores or 6-minute walk distances between the 2 groups. At 24 weeks, left ventricular ejection fraction did not change in either group or between groups. Rash occurred more frequently with allopurinol (10% versus 2%, P=0.01), but there was no difference in serious adverse event rates between the groups (20% versus 15%, P=0.36). CONCLUSIONS: In high-risk HF patients with reduced ejection fraction and elevated uric acid levels, xanthine oxidase inhibition with allopurinol failed to improve clinical status, exercise capacity, quality of life, or left ventricular ejection fraction at 24 weeks. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00987415.

Heart rate and heart failure.

PURPOSE OF REVIEW: Resting heart rate has long been thought to be a risk factor in cardiovascular disease and a prognostic factor in heart failure. ß-Blockers were originally used in heart failure for their heart rate control abilities. However, they also have negative inotropic effects contributing to their overall benefit. The role of isolated heart rate modification is unclear in left ventricular systolic dysfunction. RECENT FINDINGS: Two recent studies looked at the heart rate-lowering effects of the If, or funny current inhibitor ivabradine and its potential role in heart failure therapy. At the doses chosen for the studies, ivabradine is presumed to have only effects on heart rate with no other cardiotropic effects. Thus, the cardiovascular outcome benefits are presumed to be secondary to heart rate modification. SUMMARY: The two recent trials showed both heart rate and cardiovascular events to be significantly lower in the ivabradine-treated group of patients with left ventricular systolic dysfunction and initial heart rate at least 70 beats/min. However, neither of these trials proved causality. Hence, the link between heart rate and improved cardiovascular outcomes still remains muddled.

Heart failure and sleep-disordered breathing.

PURPOSE OF REVIEW: Sleep-disordered breathing, which includes both obstructive and central sleep apnoea (OSA and CSA, respectively), is highly prevalent in patients with heart failure. In this review, we outline our current understanding of the bidirectional relationship between these disorders and heart failure. We also explore the role of recent advances in therapeutics. RECENT FINDINGS: Although early studies suggest promise of adaptive servoventilation in treating sleep-disordered breathing, particularly CSA with associated Cheyne-Stokes respiration, the recent clinical trial in the heart failure patient population has demonstrated worse cardiovascular outcome in symptomatic patients. SUMMARY: Both OSA and CSA are highly prevalent in patients with heart failure. Effective treatment of OSA with continuous positive airway pressure can improve cardiovascular outcome in these patients. However, recent evidence suggests that adaptive servoventilation cannot be safely recommended as a therapy for CSA in the context of heart failure, as a result of increased risk of cardiovascular mortality.

Effects of short-term continuous positive airway pressure on myocardial sympathetic nerve function and energetics in patients with heart failure and obstructive sleep apnea: a randomized study.

BACKGROUND: Heart failure with reduced ejection fraction and obstructive sleep apnea (OSA), 2 states of increased metabolic demand and sympathetic nervous system activation, often coexist. Continuous positive airway pressure (CPAP), which alleviates OSA, can improve ventricular function. It is unknown whether this is due to altered oxidative metabolism or presynaptic sympathetic nerve function. We hypothesized that short-term (6-8 weeks) CPAP in patients with OSA and heart failure with reduced ejection fraction would improve myocardial sympathetic nerve function and energetics. METHODS AND RESULTS: Forty-five patients with OSA and heart failure with reduced ejection fraction (left ventricular ejection fraction 35.8±9.7% [mean±SD]) were evaluated with the use of echocardiography and 11C-acetate and 11C-hydroxyephedrine positron emission tomography before and ≈6 to 8 weeks after randomization to receive short-term CPAP (n=22) or no CPAP (n=23). Work metabolic index, an estimate of myocardial efficiency, was calculated as follows: (stroke volume index×heart rate×systolic blood pressure÷Kmono), where Kmono is the monoexponential function fit to the myocardial 11C-acetate time-activity data, reflecting oxidative metabolism. Presynaptic sympathetic nerve function was measured with the use of the 11C-hydroxyephedrine retention index. CPAP significantly increased hydroxyephedrine retention versus no CPAP (Δretention: +0.012 [0.002, 0.021] versus -0.006 [-0.013, 0.005] min(-1); P=0.003). There was no significant change in work metabolic index between groups. However, in those with more severe OSA (apnea-hypopnea index>20 events per hour), CPAP significantly increased both work metabolic index and systolic blood pressure (P<0.05). CONCLUSIONS: In patients with heart failure with reduced ejection fraction and OSA, short-term CPAP increased hydroxyephedrine retention, indicating improved myocardial sympathetic nerve function, but overall did not affect energetics. In those with more severe OSA, CPAP may improve cardiac efficiency. Further outcome-based investigation of the consequences of CPAP is warranted. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT00756366.

Anticoagulation strategies for left ventricular assist devices.

PURPOSE OF REVIEW: Pump thrombosis can be a devastating complication in patients with a left ventricular assist device (LVAD). Treatment options with intravenous anticoagulation can lead to further complications. The present review discusses the current antithrombotic and anticoagulation strategies following LVAD implantation and during suspected pump thrombosis. RECENT FINDINGS: Recently, a significant increase in pump thrombosis (HeartMate II) at 3 months after LVAD implantation starting in March 2011 has been observed. This observation is likely multifaceted; however, recent changes in perioperative anticoagulation, accepting lower target international normalized ratios and lack of heparin bridging may play a substantial role. The International Society for Heart and Lung Transplantation published guidelines surrounding LVAD anticoagulation and management options in the setting of pump thrombosis. SUMMARY: Recommendations for thromboprophylaxis in patients with LVADs are scarce. The International Society for Heart and Lung Transplantation has put together minimum criteria for perioperative anticoagulation; however, this is on the basis of poor level of evidence (observational studies and expert opinion). Ultimately, clinicians will need to individualize the intensity and timing of anticoagulation following LVAD implantation to ensure adequate thromboprophylaxis while simultaneously minimizing bleeding.

An update in the management of acute decompensated heart failure.

PURPOSE OF REVIEW: This review will provide an overview of recent advances in the management of acute decompensated heart failure, focusing on major publications from the past few years. RECENT FINDINGS: There have been several publications investigating different strategies in the management of acute decompensated heart failure. Trials have investigated the role of ultrafiltration, diuretic infusions and recombinant B-type natriuretic peptide for the treatment of these patients. SUMMARY: In patients with acute decompensated heart failure, the use of ultrafiltration in place of diuretics, diuretic infusions, and B-type natriuretic peptide has not shown benefit in recent trials. Unfortunately, there have been no major advances in the management of patients with acute decompensated heart failure.

Contemporary Outcomes of Acute Coronary Syndromes in Indigenous Compared with Non-Indigenous Patients: A Northern Saskatchewan Perspective.

BACKGROUND: In patients presenting with an acute coronary syndrome (ACS), the impact of efforts leveraged at bridging historical care gaps between Indigenous and non-Indigenous patients remains limited. METHODS: For consecutive ACS presentations (STEMI and NSTEMI/UA, respectively) at the Royal University Hospital, Saskatoon, we compared between self-identified Indigenous and non-Indigenous patients their demographics, treatments and all-cause mortality (in-hospital and 3-years). We used propensity score-inverse probability weighting to mitigate confounding, and Cox regression models to estimate the adjusted hazard (aHR, 95% confidence intervals) for all-cause mortality. RESULTS: Of 3946 ACS patients, 37.2% (n=1468) were STEMI of whom 11.3% (n=166) were Indigenous. Of the NSTEMI/UA (n=2478), 12.6% (n=311) were Indigenous. Overall, Indigenous compared with non-Indigenous patients were likely to be younger, female, have higher risk burden, and lived more remotely; Indigenous STEMI patients triaged to primary PCI had longer first medical contact-to-device times, while Indigenous NSTEMI/UA patients more likely to present with heart failure, cardiac arrest and/or cardiogenic shock. No significant differences were noted for in-hospital mortality (STEMI 8.4% vs 5.7%, p= 0.16; NSTEMI/UA 1.9% vs 1.6%, p=0.68), however, in follow-up, Indigenous STEMI patients associated with a higher all-cause mortality risk (aHR 1.98, 95% CI 1.19, 3.31, p=0.009) with no between-group differences evident for NSTEMI/UA (aHR 1.03, 95% CI 0.63 1.69, p=0.91). CONCLUSIONS: Indigenous compared with non-Indigenous patients presenting with an ACS had higher cardiovascular risk profiles, and consequently residual mortality risk. Improving primary care and intensifying secondary risk reduction, and particularly so for Indigenous patients, will substantially modify ACS outcomes in Saskatchewan.

Depression in heart failure.

PURPOSE OF REVIEW: This review aims to provide a general overview of the recent advances in understanding of depression as it pertains to heart failure. The focus is to impart an up to date knowledge in this field. RECENT FINDINGS: The mortality associated with heart failure remains high despite recent pharmacologic interventions that have improved survival. The situation is complicated by recent recognition of depression being widespread in this population. Depression is a hard diagnosis, as some of the features coincide with the symptoms of heart failure. Recently the psychological sequelae of depression have been under major scrutiny, as it has been associated with increased morbidity. In addition, current data are quite compelling on prevalence of depression in heart failure patients. Therefore, it is imperative to highlight the recent challenges and to recognize areas requiring future research. SUMMARY: Despite the prevalence of depression in heart failure, we remain abysmal in detecting, diagnosing and treating depression, which remains an independent predictor of mortality. Therefore, more research and more awareness are required in this arena.

The role of vitamin D in chronic heart failure.

PURPOSE OF REVIEW: Despite advanced medical and device-based therapies, congestive heart failure (CHF) remains a major medical problem, associated with significant morbidity and mortality. Vitamin D deficiency is prevalent in CHF and is associated with poor outcomes. In this manuscript we review the evidence linking vitamin D deficiency and CHF and discuss potential mechanisms involved, as well the clinical data on vitamin D supplementation in CHF patients. RECENT FINDINGS: A clear relationship has been established between Vitamin D deficiency and increased mortality and morbidity in CHF. However, the mechanism involved is not clearly understood. Recent clinical and experimental evidence have identified the renin-angiotensin-aldosterone system and inflammatory cytokines as likely mediators that can lead to poor clinical outcomes via the cardiorenal syndrome. Clinical data on vitamin D supplementation also remain unestablished, with potential clinical benefits recently reported in patients with vitamin D deficiency. Nonetheless, large-scale randomized clinical trials are lacking. SUMMARY: Vitamin D is an emerging agent with tremendous potential and may represent a novel target for therapy in CHF. Further studies are needed to identify the mechanism(s) involved in the pathophysiology as well as to adequately examine the role of Vitamin D measurement and supplementation in patients with CHF.

Do high doses of AT(1)-receptor blockers attenuate central sympathetic outflow in humans with chronic heart failure?

In patients with CHF (chronic heart failure) sympathetic activity increases as cardiac performance decreases and filling pressures increase. We hypothesized that in patients with mild-to-moderate CHF, higher than conventional doses of an AT1-receptor [AngII (angiotensin II) type 1 receptor] antagonist would achieve greater central AT1-receptor blockade, resulting in diminished MSNA (muscle sympathetic nerve activity) and augmented MSNA variability, two indices of central effects on sympathetic outflow. In total, 13 patients with ischaemic cardiomyopathy [NYHA (New York Heart Association) class II-III] were weaned off all pharmacological RAS (renin-angiotensin system) modifiers, and then randomized to receive a low (50 mg/day) or high (200 mg/day) dose of losartan. Central haemodynamics, MSNA and its variability, plasma catecholamines, AngI (angiotensin I) and AngII and aldosterone were assessed both before and 3 months after randomization. Neither dose altered BP (blood pressure), PCWP (pulmonary capillary wedge pressure) or CI (cardiac index) significantly. Compared with 50 mg daily, losartan 200 mg/day decreased MSNA significantly (P<0.05), by approximately 15 bursts/min, and increased MSNA variability within the 0.27-0.33 Hz high-frequency range by 0.11 units(2)/Hz (P=0.06). PNE [plasma noradrenaline (norepinephrine)] fell in parallel with changes in MSNA (r=0.62; P<0.05). These findings support the hypothesis that higher than conventional doses of lipophilic ARBs (AT1-receptor blockers) can modulate the intensity and variability of central sympathetic outflow in patients with CHF. The efficacy and safety of this conceptual change in the therapeutic approach to heart failure merits prospective testing in clinical trials.

Stroke in heart failure in sinus rhythm: the Warfarin versus Aspirin in Reduced Cardiac Ejection Fraction trial.

BACKGROUND: The Warfarin versus Aspirin in Reduced Cardiac Ejection Fraction trial found no difference between warfarin and aspirin in patients with low ejection fraction in sinus rhythm for the primary outcome: first to occur of 84 incident ischemic strokes (IIS), 7 intracerebral hemorrhages or 531 deaths. Prespecified secondary analysis showed a 48% hazard ratio reduction (p = 0.005) for warfarin in IIS. Cardioembolism is likely the main pathogenesis of stroke in heart failure. We examined the IIS benefit for warfarin in more detail in post hoc secondary analyses. METHODS: We subtyped IIS into definite, possible and noncardioembolic using the Stroke Prevention in Atrial Fibrillation method. Statistical tests, stratified by prior ischemic stroke or transient ischemic attack, were the conditional binomial for independent Poisson variables for rates, the Cochran-Mantel-Haenszel test for stroke subtype and the van Elteren test for modified Rankin Score (mRS) and National Institute of Health Stroke Scale (NIHSS) distributions, and an exact test for proportions. RESULTS: Twenty-nine of 1,142 warfarin and 55 of 1,163 aspirin patients had IIS. The warfarin IIS rate (0.727/100 patient-years, PY) was lower than for aspirin (1.36/100 PY, p = 0.003). Definite cardioembolic IIS was less frequent on warfarin than aspirin (0.22 vs. 0.55/100 PY, p = 0.012). Possible cardioembolic IIS tended to be less frequent on warfarin than aspirin (0.37 vs. 0.67/100 PY, p = 0.063) but noncardioembolic IIS showed no difference: 5 (0.12/100 PY) versus 6 (0.15/100 PY, p = 0.768). Among patients experiencing IIS, there were no differences by treatment arm in fatal IIS, baseline mRS, mRS 90 days after IIS, and change from baseline to post-IIS mRS. The warfarin arm showed a trend to a lower proportion of severe nonfatal IIS [mRS 3-5; 3/23 (13.0%) vs. 16/48 (33.3%), p = 0.086]. There was no difference in NIHSS at the time of stroke (p = 0.825) or in post-IIS mRS (p = 0.948) between cardioembolic, possible cardioembolic and noncardioembolic stroke including both warfarin and aspirin groups. CONCLUSIONS: The observed benefits in the reduction of IIS for warfarin compared to aspirin are most significant for cardioembolic IIS among patients with low ejection fraction in sinus rhythm. This is supported by trends to lower frequencies of severe IIS and possible cardioembolic IIS in patients on warfarin compared to aspirin.

Muscle metaboreflex control of left ventricular systolic function in heart failure with reduced ejection fraction.

Heart failure with reduced ejection fraction (HFrEF) exhibits exaggerated sympathoexcitation and altered cardiac and vascular responses to muscle metaboreflex activation (MMA). However, left ventricular (LV) responses to MMA are not well studied in patients with HFrEF. The purpose of this study was to examine LV function during MMA using cardiac magnetic resonance imaging (MRI) in patients with HFrEF. Thirteen patients with HFrEF and 18 healthy age-matched controls underwent cardiac MRI during rest and MMA. MMA protocol included 6 min of isometric handgrip exercise followed by 6-min of brachial postexercise circulatory occlusion. LV stroke volume index (SVi), end-systolic volume index (ESVi), end-diastolic volume index (EDVi), and global longitudinal strain (GLS) were measured by two- and four-chamber cine images. Volumes were indexed to body surface area. Heart rate (via ECG) and brachial mean arterial pressure (MAP) were recorded. Cardiac output and total peripheral resistance (TPR) were calculated. SVi decreased during MMA in HFrEF (P = 0.037) but not in controls (P = 0.392). ESVi (P = 0.007) and heart rate (P < 0.001) increased during MMA in HFrEF but not controls (P ≥ 0.170). TPR (P = 0.021) and MAP (P < 0.001) increased during MMA in both groups. Cardiac output (P = 0.946), EDVi (P = 0.177), and GLS (P = 0.619) were maintained from rest to MMA in both groups. Despite similarly maintained cardiac output, LV strain, and increased TPR in HFrEF and control groups, SVi decreased, and heart rate increased during MMA in patients with HFrEF. These findings suggest an impaired contractility reserve in response to increased TPR during MMA in HFrEF.NEW & NOTEWORTHY Stroke volume decreases and end-systolic volume increases during muscle metaboreflex activation in patients with heart failure with reduced ejection fraction (HFrEF), suggesting impaired contractile reserve during muscle metaboreflex activation in patients with HFrEF. Total peripheral resistance increases similarly during muscle metaboreflex activation in patients with HFrEF compared to controls, indicating normal levels of peripheral vasoconstriction during muscle metaboreflex activation in patients with HFrEF.