Leveraging metabolism for better outcomes in heart failure.

Whilst metabolic inflexibility and substrate constraint have been observed in heart failure for many years, their exact causal role remains controversial. In parallel, many of our fundamental assumptions about cardiac fuel use are now being challenged like never before. For example, the emergence of sodium glucose cotransporter 2 inhibitor (SGLT2i) therapy as one of the four "pillars" of heart failure therapy is causing a revisit of metabolism as a key mechanism and therapeutic target in heart failure. Improvements in the field of cardiac metabolomics will lead to a far more granular understanding of the mechanisms underpinning normal and abnormal human cardiac fuel use, an appreciation of drug action, and novel therapeutic strategies. Technological advances and expanding biorepositories offer exciting opportunities to elucidate the novel aspects of these metabolic mechanisms. Methodologic advances include comprehensive and accurate substrate quantitation such as metabolomics and stable-isotope fluxomics, improved access to arterio-venous blood samples across the heart to determine fuel consumption and energy conversion, high quality cardiac tissue biopsies, biochemical analytics, and informatics. Pairing these technologies with recent discoveries in epigenetic regulation, mitochondrial dynamics, and organ-microbiome metabolic crosstalk will garner critical mechanistic insights in heart failure. In this state-of-the-art review, we focus on new metabolic insights, with an eye on emerging metabolic strategies for heart failure. Our synthesis of the field will be valuable for a diverse audience with an interest in cardiac metabolism.

Long term safety and outcomes after atrial shunting for heart failure with preserved or mildly reduced ejection fraction: 5-year and 3-year follow-up in the REDUCE LAP-HF I and II trials.

BACKGROUND: There is a little evidence regarding long-term safety and efficacy for atrial shunt devices in heart failure (HF). METHODS: The REDUCE LAP-HF I (n = 44) and II (n = 621) trials (RCT-I and -II) were multicenter, randomized, sham-controlled trials of patients with HF and ejection fraction >40%. Outcome data were analyzed from RCT-I, a mechanistic trial with 5-year follow-up, and RCT-II, a pivotal trial identifying a responder group (n = 313) defined by exercise PVR <1.74 WU and no cardiac rhythm management device with 3-year follow-up. RESULTS: At 5 years in RCT I, there were no differences in cardiovascular (CV) mortality, HF events, embolic stroke, or new-onset atrial fibrillation between groups. After 3 years in RCT II, there was no difference in the primary outcome (hierarchical composite of CV mortality, stroke, HF events, and KCCQ) between shunt and sham in the overall trial. Compared to sham, those with responder characteristics in RCT-II had a better outcome with shunt (win ratio 1.6 [95% CI 1.2-2.2], P = .006; 44% reduction in HF events [shunt 9 vs. control 16 per 100 patient-years], P = .005; and greater improvement in KCCQ overall summary score [+17.9 ± 20.0 vs. +7.6 ± 20.4], P < .001), while nonresponders had significantly more HF events. Shunt treatment at 3 years was associated with a higher rate of ischemic stroke (3.2% vs. 0%, 95% CI 2%-6.1%, P = .032) and lower incidence of worsening kidney dysfunction (10.7% vs. 19.3%, P = .041). CONCLUSIONS: With up to 5 years of follow up, adverse events were low in patients receiving atrial shunts. In the responder group, atrial shunt treatment was associated with a significantly lower HF event rate and improved KCCQ compared to sham through 3 years of follow-up. GOV REGISTRATION: NCT02600234, NCT03088033.

Prehospital factors predicting mortality in patients with shock: state-wide linkage study.

BACKGROUND: Patients with shock treated by emergency medical services (EMS) have high morbidity and mortality. Knowledge of prehospital factors predicting outcomes in patients with shock remains limited. We aimed to describe the prehospital predictors of mortality in patients with non-traumatic shock transported to hospital by EMS. METHOD: This is a retrospective cohort study of consecutive ambulance attendances for non-traumatic shock in Victoria, Australia (January 2015-June 2019) linked with government-held administrative data (emergency, admissions and mortality records). Predictors of 30-day mortality were assessed using Cox proportional regressions. The primary outcome was 30-day all-cause mortality. RESULTS: Overall, 21 334 patients with non-traumatic shock (median age 69 years, 54.8% female) were successfully linked with state administrative records. Among this cohort, 9 149 (43%) patients died within 30-days. Compared with survivors, non-survivors had a longer median on-scene time: 60 (35-98) versus 30 (19-50), p <0.001. Non-survivors were more likely to be older (median age in years: 74 (61-84) vs 65 (47-78), p<0.001), had prehospital cardiac arrest requiring cardiopulmonary resuscitation (adjusted HR (aHR)=6.26, 95% CI 5.87, 6.69) and had prehospital intubation (aHR=1.07, CI 1.00, 1.14). Reduced 30-day mortality was associated with administration of epinephrine (aHR=0.66, CI 0.62, 0.71) and systolic blood pressures above 80 mm Hg in the prehospital setting. CONCLUSION: The 30-day mortality from non-traumatic shock is high at 43%. Independent predictors of mortality included age, prehospital cardiac arrest and endotracheal intubation. Interventions that target reversible causes of short-term mortality in patients with non-traumatic shock are a high priority.

Reversible cerebral vasoconstriction syndrome post-cardiac transplantation: a therapeutic dilemma: case report.

BACKGROUND: Reversible cerebral vasoconstriction syndrome (RCVS) is characterized by diffuse, multifocal segmental narrowing of cerebral arteries and can result in ischaemic stroke. Causal factors, identified in 60% of cases, include immunosuppressant pharmacotherapy. The few reports following heart transplantation are almost all in Asian recipients. We report on a Caucasian Australian patient with immunotherapy induced RCVS post heart transplantation to highlight the state of knowledge of the condition and the treatment dilemma it poses. CASE PRESENTATION: A 51-year-old female underwent orthotopic heart transplantation at our institution. Induction immunotherapy comprised basiliximab, mycophenolate mofetil and methylprednisolone. On day 6 post-transplantation the patient was transitioned to oral prednisolone and tacrolimus. On day 7 the patient began to experience bilateral, severe, transient occipital and temporal headaches. On day 9 tacrolimus dose was up-titrated. A non-contrast computed tomography brain (CTB) was normal. Endomyocardial biopsy on day 12 demonstrated moderate Acute Cellular Rejection (ACR), which was treated with intravenous methylprednisolone. That evening the patient experienced a 15-minute episode of expressive dysphasia. The following morning she became confused, aphasic, and demonstrated right sided neglect and right hemianopia. A CT cerebral perfusion scan demonstrated hypoperfusion in the left middle cerebral artery (MCA) territory and cerebral angiography revealed widespread, focal multi-segmental narrowing of the anterior and posterior circulations. A diagnosis of RCVS was made, and nimodipine was commenced. As both steroids and tacrolimus are potential triggers of RCVS, cyclosporin replaced tacrolimus and methylprednisolone dose was reduced. A further CTB demonstrated a large left MCA territory infarct with left M2 MCA occlusion. The patient made steady neurological improvement. She was discharged 34 days post-transplantation with mild residual right lower limb weakness and persistent visual field defect on verapamil, cyclosporine, everolimus, mycophenolate mofetil and prednisolone. CONCLUSION: Reversible cerebral vasoconstriction syndrome is rare after orthotopic heart transplantation. Until now, RCVS has been almost exclusively described in Asian recipients, and is typically caused by immunotherapy. The condition may lead to permanent neurological deficits, and in the absence of definitive treatments, early recognition and imaging based diagnosis is essential to provide the opportunity to remove the causal agent(s). Co-existent ACR, can pose unique treatment difficulties.

Comparison of Pressure vs Volume Overload Ventricular Wall Stress in Patients With Valvular Heart Disease.

BACKGROUND: Aortic stenosis (AS) and mitral regurgitation (MR) result in different patterns of left ventricular remodeling and hypertrophy. OBJECTIVES: We characterized left ventricular wall stress (LVWS) profiles in pressure and volume-overloaded systems, examined the relationship between baseline LVWS and cardiac remodeling, and assessed the acute effects of valve intervention on LVWS using invasive pressures combined with cardiac magnetic resonance (CMR) imaging measures of left ventricular volumes/mass. METHODS: A total of 47 patients with severe AS undergoing transcatheter aortic valve replacement (TAVR) and 15 patients with severe MR undergoing MitraClip (MC) underwent a 6-minute walk test (6MWT), transthoracic echocardiogram, and CMR before their procedures. Catheters in the left ventricle were used to record hemodynamic changes before and after valve/clip deployment. This was integrated with CMR data to calculate LVWS before and after intervention. RESULTS: The TAVR group demonstrated significant reductions in systolic LVWS post procedure (median 24.7 Pa [IQR: 14 Pa] pre vs median 17.3 Pa [IQR: 12 Pa] post; P < 0.001). The MC group demonstrated significant reductions in diastolic LVWS (median 6.4 Pa [IQR: 5 Pa] pre vs median 4.3 Pa [IQR: 4.1 Pa] post; P = 0.021) with no significant change in systolic LVWS (30.6 ±1.61 pre vs 33 ±2.47 Pa post; P = 0.16). There was an inverse correlation between baseline systolic LVWS and 6MWT in the TAVR group (r = -0.31; P = 0.04). CONCLUSIONS: TAVR results in significant reductions in systolic LVWS acutely. MC results in significant reductions in diastolic LVWS. Higher baseline systolic LVWS in TAVR is associated with shorter 6MWT suggesting that in AS, LVWS may be a useful marker of early decompensation.

The cost-effectiveness of semaglutide in reducing cardiovascular risk among people with overweight and obesity and existing cardiovascular disease, but without diabetes.

BACKGROUND AND AIMS: The Semaglutide Effects on Cardiovascular Outcomes in People with Overweight or Obesity (SELECT) trial demonstrated significant reductions in cardiovascular outcomes in people with cardiovascular disease (CVD) and overweight or obesity (but without diabetes). However, the cost of the medication has raised concerns about its financial viability and accessibility within healthcare systems. This study explored whether use of semaglutide for the secondary prevention of CVD in overweight or obesity is cost-effective from the Australian healthcare perspective. METHODS: A Markov model was developed based on the SELECT trial to model the clinical outcomes and costs of a hypothetical population treated with semaglutide versus placebo, in addition to standard care, and followed up over 20 years. With each annual cycle, subjects were at risk of having non-fatal CVD events or dying. Model inputs were derived from SELECT and published literature. Costs were obtained from Australian sources. All outcomes were discounted by 5% annually. The main outcome of interest was the incremental cost-effectiveness ratio (ICER) in terms of cost per year of life saved (YoLS) and cost per quality-adjusted life year (QALY) gained. RESULTS: With an annual estimated cost of semaglutide of A${\$}$4175, the model resulted in ICERs of A${\$}$99 853 (US${\$}$143 504; £40 873) per YoLS and A${\$}$96 055 (US${\$}$138 046; £39 318) per QALY gained. CONCLUSIONS: Assuming a willingness-to-pay threshold of A${\$}$50 000, semaglutide is not considered cost-effective at the current price. A price of ≤ A${\$}$2000 per year or more targeted use in high-risk patients would be needed for it to be considered cost-effective in the Australian setting.

Current surgical management of chronic thromboembolic pulmonary disease.

Chronic thromboembolic pulmonary disease (CTEPD) with or without pulmonary hypertension (PH) is an important potential consequence of venous thromboembolic disease. Untreated CTEPD with pulmonary hypertension (CTEPH) is associated with high rates of morbidity and mortality. Several treatment options are now available for patients with CTEPD and CTEPH, including pulmonary endarterectomy (PEA), balloon pulmonary angioplasty, medical therapy or a combination of therapies. Choice of treatment depends on the location of the thromboembolic disease burden, presence and severity of PH and patient factors, including frailty, parenchymal lung disease and other comorbidities. PEA is a complex surgery that can result in excellent outcomes and resolution of disease, but also comes with the risk of serious perioperative complications. This manuscript examines the history of PEA and its place in Australasia, and reports on outcomes from the main Australasian CTEPH expert centre. It provides a summary of up-to-date guidance on how PEA should be utilised in the overall management of these patients and describes opportunities and challenges for the future diagnosis and management of this disease, particularly in the Australasian setting.

The burden of atrial fibrillation on emergency medical services: A population-based cohort study.

BACKGROUND: Atrial fibrillation (AF) is a growing burden on healthcare resources, despite improvements in prevention and management. AF is a common cause of hospitalisation, and Emergency Medical Services (EMS) use. However, there is a paucity of data describing the burden of AF on EMS. We aimed to determine the prevalence, characteristics, and outcomes of patients presenting with AF to EMS using a large population-based sample. METHODS: Consecutive attendances for AF in Victoria, Australia (January 2015-June 2019) were included if patients had a diagnosis of "AF" or "arrhythmia" with AF on electrocardiogram. Data were individually linked to emergency, hospital, and mortality records. RESULTS: Of 2,613,056 EMS attendances, 16,525 were a first attendance for AF and linked to hospital records. Median (IQR) age was 76 (67,84) years (43% female). Seventy-eight percent had high thromboembolic risk (CHA2DS2-VASc score ≥ 2), and 72% had a heart rate ≥ 100 bpm. Forty-two percent of patients received no treatment by paramedics and 99.4% were transported to hospital. Fifty-three percent were discharged from ED. Median length of hospital stay was 2 days. Of 2542 cases reattended for AF, 19% occurred within 30 days, with increased odds for females and those of low socioeconomic status. Overall, 24% died during the study period, 12% within 30 days. Increasing age, heart failure, stroke, COPD, and low socioeconomic status increased the odds of 30-day mortality. CONCLUSIONS: EMS utilisation for AF is common and associated with frequent reattendance. Further studies are required to investigate novel pathways of care to reduce AF burden on healthcare systems.

Actual Cost of Extracorporeal Cardiopulmonary Resuscitation: A Time-Driven Activity-Based Costing Study.

OBJECTIVES: To determine the actual cost and drivers of the cost of an extracorporeal cardiopulmonary resuscitation (E-CPR) care cycle. PERSPECTIVE: A time-driven activity-based costing study conducted from a healthcare provider perspective. SETTING: A quaternary care ICU providing around-the-clock E-CPR service for out-of-hospital cardiac arrest (OHCA) and in-hospital cardiac arrest (IHCA) in Australia. METHODS: The E-CPR care cycle was defined as the time from initiating E-CPR to hospital discharge or death of the patient. Detailed process maps with discrete steps and probabilistic decision nodes accounting for the complex trajectories of E-CPR patients were developed. Data about clinical and nonclinical resources and timing of activities was collected multiple times for each process . Total direct costs were calculated using the time estimates and unit costs per resource for all clinical and nonclinical resources. The total direct costs were combined with indirect costs to obtain the total cost of E-CPR. RESULTS: From 10 E-CPR care cycles observed during the study period, a minimum of 3 observations were obtained per process. The E-CPR care cycle's mean (95% CI) cost was $75,014 ($66,209-83,222). Initiation of extracorporeal membrane oxygenation (ECMO) and ECMO management constituted 18% of costs. The ICU management (35%) and surgical costs (20%) were the primary cost determinants. IHCA had a higher mean (95% CI) cost than OHCA ($87,940 [75,372-100,570] vs. 62,595 [53,994-71,890], p < 0.01), mainly because of the increased survival and ICU length of stay of patients with IHCA. The mean cost for each E-CPR survivor was $129,503 ($112,422-147,224). CONCLUSIONS: Significant costs are associated with E-CPR for refractory cardiac arrest. The cost of E-CPR for IHCA was higher compared with the cost of E-CPR for OHCA. The major determinants of the E-CPR costs were ICU and surgical costs. These data can inform the cost-effectiveness analysis of E-CPR in the future.

Early Use of Aspirin for Coronary Allograft Prophylaxis in Heart Transplant Recipients.

BACKGROUND: Coronary allograft vasculopathy (CAV) remains a significant cause of morbidity and mortality after heart transplantation. The use of aspirin for CAV prophylaxis has recently garnered interest as a possible therapeutic adjunct in this setting. METHODS: This 2-center retrospective cohort study included 372 patients who underwent heart transplantation between January 2009 and March 2018 and were stratified according to the commencement of aspirin during their index transplant admission. The primary outcome was the development of moderate or severe CAV (International Society for Heart and Lung Transplantation grade ≥2) at surveillance coronary angiography. Secondary endpoints included mortality at follow-up. RESULTS: There were no differences in age, sex, and cause of heart failure. In the early aspirin group, the preponderant risk factors included use of ventricular assist devices, pretransplant smoking, and mild or moderate rejection. Multivariable analyses to assess for independent predictors of CAV development and mortality demonstrated that aspirin was associated with reduced mortality (adjusted hazard ratio = 0.19; 95% confidence interval, 0.08-0.47, P < 0.01) and a trend toward a protective effect against the development of moderate or severe CAV (adjusted hazard ratio = 0.24; 95% confidence interval, 0.54-1.19; P = 0.08). CONCLUSIONS: In this retrospective risk-adjusted 2-center cohort study, early aspirin administration was associated with reduced risk of death and a trend toward a protective effect against CAV development. These findings warrant validation in prospective randomized trials.

HeartMate 3 for Heart Failure with Preserved Ejection Fraction: In Vitro Hemodynamic Evaluation and Anatomical Fitting.

Heart failure with preserved ejection fraction (HFpEF) constitutes approximately 50% of heart failure (HF) cases, and encompasses different phenotypes. Among these, most patients with HFpEF exhibit structural heart changes, often with smaller left ventricular cavities, which pose challenges for utilizing ventricular assist devices (VADs). A left atrial to aortic (LA-Ao) VAD configuration could address these challenges, potentially enhancing patient quality of life by lowering elevated mean left atrial pressure (MLAP). This study assessed the anatomical compatibility and left atrial unloading capacity using a simulated VAD-supported HFpEF patient. A HeartMate3-supported HFpEF patient in an LA-Ao configuration was simulated using a cardiovascular simulator. Hemodynamic parameters were recorded during rest and exercise at seven pump flow rates. Computed tomography scans of 14 HFpEF (NYHA II-III) and six heart failure with reduced ejection fraction patients were analysed for anatomical comparisons. HFpEF models were independently assessed for virtual anatomical fit with the HM3 in the LA-Ao configuration. Baseline MLAP was reduced from 15 to 11 mmHg with the addition of 1 L/min HM3 support in the rest condition. In an exercise simulation, 6 L/min of HM3 support was required to reduce the MLAP from 29 to 16 mmHg. The HM3 successfully accommodated six HFpEF patients without causing interference with other cardiac structures, whereas it caused impingement ranging from 4 to 14 mm in the remaining patients. This study demonstrated that the HM3 in an LA-Ao configuration may be suitable for unloading the left atrium and relieving pulmonary congestion in some HFpEF patients where size-related limitations can be addressed through pre-surgical anatomical fit analysis.

The Efficacy of Risk Factor Modification Compared to NAD+ Repletion in Diastolic Heart Failure.

Heart failure (HF) with left ventricular diastolic dysfunction is a growing global concern. This study evaluated myocardial oxidized nicotinamide adenine dinucleotide (NAD+) levels in human systolic and diastolic HF and in a murine model of HF with preserved ejection fraction, exploring NAD+ repletion as therapy. We quantified myocardial NAD+ and nicotinamide phosphoribosyltransferase levels, assessing restoration with nicotinamide riboside (NR). Findings show significant NAD+ and nicotinamide phosphoribosyltransferase depletion in human diastolic HF myocardium, but NR successfully restored NAD+ levels. In murine HF with preserved ejection fraction, NR as preventive and therapeutic intervention improved metabolic and antioxidant profiles. This study underscores NAD+ repletion's potential in diastolic HF management.

Effect of COVID-19 Pandemic Lockdown on Emergency Medical Service Utilisation, and Percutaneous Coronary Intervention Volume-An Australian Perspective.

BACKGROUND: Acute coronary syndrome (ACS) admissions and percutaneous coronary intervention (PCI) volume declined during periods of COVID-19 lockdown internationally in 2020. The effect of lockdown on emergency medical service (EMS) utilisation, and PCI volume during the initial phase of the pandemic in Australia has not been well described. METHOD: We analysed data from the Victorian Cardiac Outcomes Registry (VCOR), a state-wide PCI registry, linked with the Ambulance Victoria EMS registry. PCI volume, 30-day major adverse cardiovascular and cerebrovascular events (MACCE; composite of mortality, myocardial infarction, stent thrombosis, unplanned revascularisation, and stroke), and EMS utilisation were compared over four time periods: lockdown (26 Mar 2020-12 May 2020); pre-lockdown (26 Feb 2020-25 Mar 2020); post-lockdown (13 May 2020-10 Jul 2020); and the year prior (26 Mar 2019-12 May 2019). Interrupted time series analysis was performed to assess PCI trends within and between consecutive periods. RESULTS: The EMS utilisation for ACS during lockdown was higher compared with other periods: lockdown 39.4% vs pre-lockdown 29.7%; vs post-lockdown 33.6%; vs year prior 27.1%; all p<0.01. Median daily PCI cases were similar: 31 (IQR 10, 38) during lockdown; 39 (15, 49) pre-lockdown; 39.5 (11, 44) post-lockdown; and, 42 (10, 49) the year prior; all p>0.05. Median door-to-procedure time for ACS indication during lockdown was shorter at 3 hours (1.2, 20.6) vs pre-lockdown 3.9 (1.7, 21); vs post-lockdown 3.5 (1.5, 21.26); and, the year prior 3.5 (1.5, 23.7); all p<0.05. Lockdown period was associated with lower odds for 30-day MACCE compared to pre-lockdown (odds ratio [OR] 0.55 [0.33-0.93]; p=0.026); post-lockdown (OR 0.66; [0.40-1.06]; p=0.087); and the year prior (OR 0.55 [0.33-0.93]; p=0.026). CONCLUSIONS: Contrary to international trends, EMS utilisation for ACS increased during lockdown but PCI volumes remained similar throughout the initial stages of the pandemic in Victoria, with no observed adverse effect on 30-day MACCE during lockdown. These data suggest that the public health response in Victoria was not associated with poorer quality cardiovascular care in patients receiving PCI.

Heart failure with preserved ejection fraction: The role of inflammation.

Heart failure (HF) is a debilitating clinical syndrome affecting 64.3 million patients worldwide. More than 50% of HF cases are attributed to HF with preserved ejection fraction (HFpEF), an entity growing in prevalence and mortality. Although recent breakthroughs reveal the prognostic benefits of sodium-glucose co-transporter 2 inhibitors (SGLT2i) in HFpEF, there is still a lack of effective pharmacological therapy available. This highlights a major gap in medical knowledge that must be addressed. Current evidence attributes HFpEF pathogenesis to an interplay between cardiometabolic comorbidities, inflammation, and renin-angiotensin-aldosterone-system (RAAS) activation, leading to cardiac remodelling and diastolic dysfunction. However, conventional RAAS blockade has demonstrated limited benefits in HFpEF, which emphasises that alternative therapeutic targets should be explored. Presently, there is limited literature examining the use of anti-inflammatory HFpEF therapies despite growing evidence supporting its importance in disease progression. Hence, this review aims to explore current perspectives on HFpEF pathogenesis, including the importance of inflammation-driven cardiac remodelling and the therapeutic potential of anti-inflammatory therapies.

An evidence-based screening tool for heart failure with preserved ejection fraction: the HFpEF-ABA score.

Heart failure with preserved ejection fraction (HFpEF) is under-recognized in clinical practice. Although a previously developed risk score, termed H2FPEF, can be used to estimate HFpEF probability, this score requires imaging data, which is often unavailable. Here we sought to develop an HFpEF screening model that is based exclusively on clinical variables and that can guide the need for echocardiography and further testing. In a derivation cohort (n = 414, 249 women), a clinical model using age, body mass index and history of atrial fibrillation (termed the HFpEF-ABA score) showed good discrimination (area under the curve (AUC) = 0.839 (95% confidence interval (CI) = 0.800-0.877), P < 0.0001). The performance of the model was validated in an international, multicenter cohort (n = 736, 443 women; AUC = 0.813 (95% CI = 0.779-0.847), P < 0.0001) and further validated in two additional cohorts: a cohort including patients with unexplained dyspnea (n = 228, 136 women; AUC = 0.840 (95% CI = 0.782-0.900), P < 0.0001) and a cohort for which HF hospitalization was used instead of hemodynamics to establish an HFpEF diagnosis (n = 456, 272 women; AUC = 0.929 (95% CI = 0.909-0.948), P < 0.0001). Model-based probabilities were also associated with increased risk of HF hospitalization or death among patients from the Mayo Clinic (n = 790) and a US national cohort across the Veteran Affairs health system (n = 3076, 110 women). Using the HFpEF-ABA score, rapid and efficient screening for risk of undiagnosed HFpEF can be performed in patients with dyspnea using only age, body mass index and history of atrial fibrillation.

2-Year Outcomes of an Atrial Shunt Device in HFpEF/HFmrEF: Results From REDUCE LAP-HF II.

BACKGROUND: The REDUCE LAP-HF II (Reduce Elevated Left Atrial Pressure in Patients With Heart Failure II) trial found that, compared with a sham procedure, the Corvia Atrial Shunt did not improve outcomes in heart failure with preserved or mildly reduced ejection fraction. However, after 12-month follow-up, "responders" (peak-exercise pulmonary vascular resistance <1.74 WU and absence of a cardiac rhythm management device) were identified. OBJECTIVES: This study sought to determine: 1) the overall efficacy and safety of the atrial shunt vs sham control after 2 years of follow-up; and 2) whether the benefits of atrial shunting are sustained in responders during longer-term follow-up or are offset by adverse effects of the shunt. METHODS: The study analyzed 2-year outcomes in the overall REDUCE LAP-HF II trial, as well as in responder and nonresponder subgroups. The primary endpoint was a hierarchical composite of cardiovascular death or nonfatal ischemic/embolic stroke, total heart failure events, and change in health status. RESULTS: In 621 randomized patients, there was no difference between the shunt (n = 309) and sham (n = 312) groups in the primary endpoint (win ratio: 1.01 [95% CI: 0.82-1.24]) or its individual components at 2 years. Shunt patency at 24 months was 98% in shunt-treated patients. Cardiovascular mortality and nonfatal ischemic stroke were not different between the groups; however, major adverse cardiac events were more common in those patients assigned to the shunt compared with sham (6.9% vs 2.7%; P = 0.018). More patients randomized to the shunt had an increase in right ventricular volume of ≥30% compared with the sham control (39% vs 28%, respectively; P < 0.001), but right ventricular dysfunction was uncommon and not different between the treatment groups. In responders (n = 313), the shunt was superior to sham (win ratio: 1.36 [95% CI: 1.02-1.83]; P = 0.037, with 51% fewer HF events [incidence rate ratio: 0.49 [95% CI: 0.25-0.95]; P = 0.034]). In nonresponders (n = 265), atrial shunting was inferior to sham (win ratio: 0.73 [95% CI: 0.54-0.98]). CONCLUSIONS: At 2 years of follow-up in REDUCE LAP-HF II, there was no difference in efficacy between the atrial shunt and sham groups in the overall trial group. The potential clinical benefit identified in the responder group after 1 and 2 years of follow-up is currently being evaluated in the RESPONDER-HF (Re-Evaluation of the Corvia Atrial Shunt Device in a Precision Medicine Trial to Determine Efficacy in Mildly Reduced or Preserved Ejection Fraction Heart Failure) trial. (Reduce Elevated Left Atrial Pressure in Patients With Heart Failure II [REDUCE LAP-HF II]; NCT03088033).

Hyperlactataemia is a marker of reduced exercise capacity in heart failure with preserved ejection fraction.

AIMS: Heart failure with preserved ejection fraction (HFpEF) is associated with an array of central and peripheral haemodynamic and metabolic changes. The exact pathogenesis of exercise limitation in HFpEF remains uncertain. Our aim was to compare lactate accumulation and central haemodynamic responses to exercise in patients with HFpEF, non-cardiac dyspnoea (NCD), and healthy volunteers. METHODS AND RESULTS: Right heart catheterization with mixed venous blood gas and lactate measurements was performed at rest and during symptom-limited supine exercise. Multivariable analyses were conducted to determine the relationship between haemodynamic and biochemical parameters and their association with exercise capacity. Of 362 subjects, 198 (55%) had HFpEF, 103 (28%) had NCD, and 61 (17%) were healthy volunteers. This included 139 (70%) females with HFpEF, 77 (75%) in NCD (P = 0.41 HFpEF vs. NCD), and 31 (51%) in healthy volunteers (P < 0.001 HFpEF vs. volunteers). The median age was 71 (65, 75) years in HFpEF, 66 (57, 72) years in NCD, and 49 (38, 65) years in healthy volunteers (HFpEF vs. NCD or volunteer, both P < 0.001). Peak workload was lower in HFpEF compared with healthy volunteers [52 W (interquartile range 31-73), 150 W (125-175), P < 0.001], but not NCD [53 W (33, 75), P = 0.85]. Exercise lactate indexed to workload was higher in HFpEF at 0.08 mmol/L/W (0.05-0.11), 0.06 mmol/L/W (0.05-0.08; P = 0.016) in NCD, and 0.04 mmol/L/W (0.03-0.05; P < 0.001) in volunteers. Exercise cardiac index was 4.5 L/min/m2 (3.7-5.5) in HFpEF, 5.2 L/min/m2 (4.3-6.2; P < 0.001) in NCD, and 9.1 L/min/m2 (8.0-9.9; P < 0.001) in volunteers. Oxygen delivery in HFpEF was lower at 1553 mL/min (1175-1986) vs. 1758 mL/min (1361-2282; P = 0.024) in NCD and 3117 mL/min (2667-3502; P < 0.001) in the volunteer group during exercise. Predictors of higher exercise lactate levels in HFpEF following adjustment included female sex and chronic kidney disease (both P < 0.001). CONCLUSIONS: HFpEF is associated with reduced exercise capacity secondary to both central and peripheral factors that alter oxygen utilization. This results in hyperlactataemia. In HFpEF, plasma lactate responses to exercise may be a marker of haemodynamic and cardiometabolic derangements and represent an important target for future potential therapies.