Low Flow States Research Articles

Fever Prevention and Neurological Recovery in In-Hospital Cardiac Arrest Survivors at a Limited-Resource Setting.

Temperature management plays a critical role in the neurological recovery of cardiac arrest survivors. While advanced device-based temperature control systems are prevalent in high-resource settings, their implementation in low-resource environments remains a challenge. This study aimed to examine the impact of fever prevention on neurological outcomes in cardiac arrest survivors managed without device-based temperature control. We conducted a retrospective study of adult in-hospital cardiac arrest survivors at an academic institution from 2013 to 2020. Patients were included if they were ≥18 years old, survived for at least 72 hours post-return of spontaneous circulation (ROSC), and experienced cardiac arrest in inpatient wards, intensive care units, or the emergency department. Fever was defined as a rectal temperature ≥37.5°C, and neurological outcomes were assessed using the Cerebral Performance Category (CPC) scale at 1 month post-ROSC. A good neurological outcome was defined as CPC 1 or 2. Statistical analyses included chi-square tests and logistic regression to identify predictors of outcomes. Of the 427 patients included, 58.8% experienced fever, and 12.8% achieved a good neurological outcome. Patients with fever were significantly less likely to have favorable outcomes (p < 0.01). Logistic regression revealed that each 1°C increase in body temperature beyond 37.5°C was associated with a 31% reduction in the likelihood of a good outcome (p < 0.01). Other predictors of poor outcomes included prolonged low-flow states and higher pre-arrest frailty scores. Fever is strongly associated with poor neurological outcomes in cardiac arrest survivors, particularly in low-resource settings without device-based temperature management. Effective fever prevention strategies, such as intravenous antipyretics and physical cooling methods, should be prioritized to improve outcomes.

Bivalirudin in Extracorporeal Membrane Oxygenation.

Extracorporeal membrane oxygenation (ECMO) is a mechanical support treatment modality used in patients with refractory cardiac and/or pulmonary failure. Bleeding and thrombotic complications associated with ECMO are inherent concerns that require careful management. Anticoagulation optimization may help mitigate these risks by providing more adequate therapeutic anticoagulation and lessen the bleed risk. Heparin, the most used anticoagulant, carries concerns for heparin-induced thrombocytopenia and possible resistance given its dependence on cofactors and circulating proteins to exert its pharmacologic effect. In contrast, bivalirudin, a direct thrombin inhibitor, exerts its effect independent of cofactors or plasma proteins, and possesses thrombin-binding and metabolism features that may confer advantages in ECMO management. This review of the evidence for bivalirudin utilization in ECMO suggests favorable outcomes in circuit-related thrombosis, bleeding, and dosing reliability. In addition, blood product utilization, circuit interventions, and success in ECMO decannulation and survival were positive findings associated with bivalirudin that merit consideration. Common questions and concerns relative to bivalirudin utilization, including laboratory monitoring, utilization in low-flow states, dosing considerations in renal replacement therapy, reversibility, and cost are also discussed in this review. Moreover, this review suggests that bivalirudin utilization presents the opportunity for ECMO management simplification.

Abstract 4119619: Congruency of Stated Aortic Stenosis Severity and Reported Doppler Exam Values in a Large Health Care System Based on ACC/ASE Guidelines

Background: Peak aortic valve Doppler velocity, mean aortic valve gradient, and Doppler estimated aortic valve area are key measures recommended for assessing aortic stenosis severity. Discordance often occurs among these measures, posing diagnostic challenges. Failure to accurately diagnose severe aortic stenosis is critical. This study focuses on the discordance between reported aortic valve area (AVA) and stenosis severity, comparing guidelines from the ASE and ACC seen in Table 1. Goals: Assess the incidence of discordance between reported AVA and severity of aortic stenosis and compare how the differing guideline recommendations of the ASE versus ACC for defining severe AS by AVA would affect reporting severity in a large clinical practice. Methods: A query of all transthoracic echocardiograms obtained in patients 18 years of age and above was performed in a large multi-hospital healthcare system between Jan 1 and Jun 30 of 2023. This group was then filtered to include only exams in which the reported aortic valve area was 1 cm2 or less, excluding all cases with prosthetic aortic valves. This group was then further filtered to contain only those patients in whom the physician did NOT report severe aortic stenosis. Results: Between Jan and June 2023, 16,675 subjects ages 18-95 (avg 74) underwent transthoracic echocardiograms in our healthcare system, with 190 (1.1%) reported as having an AVA ≤ 1 cm2. Of those exams, 63 (33% of those with AVA ≤ 1) were not reported as having severe aortic stenosis. Of those 63 exams, 35 (56%) had a reported SVI &lt; 35 ml/m2 compatible with a low flow state. However, only 1 of those 35 cases mentioned flow-status in labeling the stenosis severity in the report. Based on the ASE Doppler AVA definition of severe AS (&lt; 1.0 cm2 (≤ 0.94 )) vs ACC (≤ 1 cm2 (≤1.04), the AV Doppler and SVI data contained in the reports should have led to the grading of the aortic valve as being ”Severe” or “Moderate” aortic stenosis as described in Table 2. Conclusion: Discordance in labeling severe aortic stenosis relates to differing AVA criteria. Cases are often termed "moderate to severe" under ACC criteria. The majority (56%) of cases failing to describe severe AS despite meeting AVA criteria were in low flow states, suggesting this phenomenon is not well understood in clinical practice. Various factors contribute to these findings, warranting further investigation.

Abstract 4136136: Left Ventricular Global Longitudinal Strain: An Imaging Marker Associated with Improved Survival in Paradoxical Low-Flow, Low-Gradient Severe Aortic Stenosis

Background: The optimal clinical management and timing of intervention are less well defined in paradoxical low-flow, low-gradient severe aortic stenosis (PLFLG AS). Left ventricular global longitudinal strain (LV-GLS) has been shown to predict outcomes in high flow severe AS, but there is lack of data in patients with PLFLG AS. Given the exaggerated LV hypertrophy and remodeling pattern in PLFLG AS, LV-GLS may be a mechanistic imaging marker for worse outcomes. Hypothesis: In patients with PLFLG AS, LV-GLS is associated with adverse clinical outcomes by detecting subclinical myocardial fibrosis resulting from myocardial remodeling due to LV pressure overload. Methods: We examined patients with PLFLG AS defined as AVA &lt;1cm 2 , mean gradient &lt;40mmHg and preserved left ventricular ejection fraction (LVEF) ≥50%, with low-flow state defined as transvalvular flow rate (Q) ≤210 ml/sec. Exclusion criteria included moderate or greater mitral or aortic regurgitation and presence of atrial fibrillation at the time of echocardiogram. LV strain analysis was performed using 2D-strain imaging software (TomTec, Chicago, IL). Clinical outcome data were obtained via the electronic health record. The primary outcome was defined as all-cause mortality. Patients were stratified by LV-GLS above and below the median value. Results: A total of 198 patients were included in the analysis, with a median LV-GLS of -12.3% [IQR: (-9.8,-16.3)]. Over a median follow-up time of 1.2 years, 130 deaths (65.6%) were identified. Patients with less negative LV-GLS (n=101) had worse survival than those with more negative LV-GLS (n=97; 22 vs 38%; p=0.02) (Fig 1). After multivariable adjustment for potential confounders (stroke volume index, aortic valve mean gradient, relative wall thickness, age, sex, heart failure, hypertension, coronary artery disease, and diabetes), less negative LV-GLS was independently associated with adverse outcomes (HR 1.56; 95% CI (1.03-2.38); p=0.04). Conclusions: In patients with PLFLG AS as defined by a transvalvular flow rate (Q) ≤210 ml/sec, reduced LV-GLS is associated with increased all-cause mortality. LV-GLS may serve as an imaging marker to help guide clinical decision making in PLFLG AS.

Severe Mitral Regurgitation in Paradoxical Low-Flow Low-Gradient Severe Aortic Stenosis.

Patients with paradoxical low-flow, low-gradient severe aortic stenosis (LFLGAS) exhibit low transvalvular flow rate (Q), while maintaining preserved left ventricular ejection fraction (LVEF). Concomitant severe mitral regurgitation (MR) contributes to the low flow state, adding complexity to diagnosis and management. This study aimed to examine the impact of severe MR on outcomes in paradoxical LFLGAS. Data from an institutional echo database identified 1,189 patients with adjudicated severe aortic stenosis (AVA≤1.0 cm 2 ), low transaortic gradients (mean gradient<40 mmHg), preserved LVEF (≥50%), and low flow rate (Q≤210 ml/sec), to confirm paradoxical LFLGAS. Subgroups were based on MR severity (severe and non-severe). Clinical outcomes included all-cause mortality, aortic valve replacement (AVR), heart failure hospitalizations, and a composite outcome. In the severe MR group (n=80), patients had lower flow rates, increased LV dimensions and a more eccentric hypertrophy pattern compared to non-severe MR (n=1,109). Over a median 5-year follow-up, severe MR correlated with higher all-cause mortality (p=0.02) and AVR rates (p=0.012). After adjustment, severe MR was independently associated with increased all-cause mortality risk (HR=1.43, p=0.011) and composite outcome (HR=1.64, p<0.001). AVR significantly reduced mortality at every MR degree, with the most substantial impact in severe MR (HR=0.18, p<0.001). Propensity-adjusted models demonstrated a stronger AVR impact with increasing MR degree (p-for-interaction=0.044). Severe MR in paradoxical LFLGAS is associated with adverse outcomes and distinctive LV remodeling. Aortic valve replacement improves survival across all MR grades, with greater impact in severe MR.

Laparoscopic Cholecystectomy in Cardiogenic Shock And Heart Failure.

Background: Patients with cardiogenic shock (CS) or heart failure can develop ischemic cholecystitis from a systemic low-flow state. Cholecystectomy in high-risk patients is controversial. Percutaneous cholecystostomy tube (PCT) is often the chosen intervention; however, data on PCT as definitive treatment are conflicting. Data on cholecystectomy in these patients are limited. This study discusses outcomes following laparoscopic cholecystectomy (LC) in this patient population. Methods: This is a retrospective review of patients who underwent LC from 2015 to 2019 while hospitalized for CS or heart failure. Surgical services are provided by fellowship-trained minimally invasive surgeons at a single, academic, tertiary-care center. Patient characteristics are reported as frequencies' percentages for categorical variables. Odds ratio is used to determine the association between comorbidities and complications. Results: Twenty-four patients underwent LC. Around 83% were white and 79% were male. Many were anticoagulated (88%), with Class IV heart failure (63%), and required vasopressors (46%) at the time of surgery. Fourteen of 24 (58%) had at least one circulatory device at the time of surgery: extracorporeal membrane oxygenation, left ventricular assist device, Impella, tandem heart, and total artificial heart. Four patients (17%) had PCT preoperatively. Fifteen days were the average interval between diagnosis and surgery. Pneumoperitoneum was tolerated by all, and 0% converted to open. Most common complication was bleeding (52%). Nine patients (37.5%) underwent 21 reoperations, one of which (4%) was related to cholecystectomy. Mortality occurred in 5 patients (20.8%); interval between cholecystectomy and mortality ranged 6-30 days. Conclusion: Although high risk, LC is a treatment option in patients with ischemic cholecystitis at risk for death from sepsis.

Feasibility of a 4 French resuscitative endovascular balloon occlusion of the aorta (REBOA) device for nontraumatic cardiac arrest in a randomized controlled study using a large porcine model

AimThe objectives of this study were to assess the return of spontaneous circulation rates and hemodynamic response of large swine (>65Kg) during cardiopulmonary resuscitation after nontraumatic cardiac arrest using the COBRA-OS® aortic occlusion balloon and to address limitations of large swine closed-chest cardiopulmonary resuscitation by comparing closed-chest vs. open-chest cardiopulmonary resuscitation. MethodsYorkshire pigs (n = 10) weighing >65 kg were anesthetized and ventilated. After 7 min of untreated ventricular fibrillation (VF), animals were randomized to receive mechanical closed-chest cardiopulmonary resuscitation or open-chest cardiac massage. Following a 5-minute low-flow state, advanced cardiac life support algorithms were started and the COBRA-OS® was inflated in the thoracic aorta. Animals that achieved return of spontaneous circulation were re-started on mechanical ventilation and medications, CPR, defibrillation, and aortic occlusion were discontinued. The primary outcome was return of spontaneous circulation and secondary outcomes were mean arterial pressures generated in the low flow and aortic occlusion states before return of spontaneous circulation. Groups were compared with a t-test or Mann-Whitney U test for normal and non-parametric data, respectively, while categorical data was compared with the chi square test. ResultsReturn of spontaneous circulation was obtained in 4 animals (80%) in the open cardiac massage group and none in the mechanical closed-chest CPR group (p < 0.05). The COBRA-OS® successfully occluded all aortas and animals experienced higher mean arterial pressures in both groups with aortic occlusion (median 15 mm Hg, IQR 13–23 mm Hg), but with a higher MAP difference in the open cardiac massage group (−12.2 mm Hg, [−2.581, −21.819]). ConclusionsConsideration should be given to intra-thoracic cardiac massage to increase cardiopulmonary resuscitation effectiveness and therefore return of spontaneous circulation rates in large (>65 kg) swine models of nontraumatic cardiac arrest. The COBRA-OS® demonstrated feasibility for use in this model.The Keenan Research Center, Li Ka Shing Knowledge Institute of St. Michael’s Hospital Animal Care Committee: ACC Protocol #726.

Patients with Acute Lower Limb Ischemia Continue to Have Significant Morbidity and Mortality

The treatment of acute lower limb ischemia (ALLI) has evolved over the last several decades with the availability of several new treatment modalities. This study was undertaken to evaluate the contemporary presentation and outcomes of ALLI patients. We retrospectively analyzed data from a prospectively collected database of all patients who presented to our tertiary referral hospital with acute ischemia of the lower extremity between May 2016 and October 2020. The cause of death was obtained from the Michigan State Death Registry. During the study period, 233 patients (251 lower limbs) were evaluated for ALLI. Seventy-three percent had thrombotic occlusion, 24% had embolic occlusion, and 3% due to a low flow state. Rutherford classification of ischemia severity was 7%, 49%, 40%, and 4% for Rutherford grade I, IIA, IIB, and III, respectively. Five percent underwent primary amputations, and 6% received medical therapy only. The mean length of stay was 11±9days. Nineteen percent of patients were readmitted within 30days of discharge. At 30days postoperatively, mortality was 9% and limb loss was 19%. On multivariate analysis, 1 or no vessel runoff to the foot postoperatively was associated with higher 30-day limb loss. Patients with no run-off vessels postoperatively had significantly higher 30-day mortality. Cardiovascular complications accounted for most deaths (48%). At 1-year postoperatively, mortality and limb loss reached 17% and 34%, respectively. Despite advances in treatment modalities and cardiovascular care, patients presenting with ALLI continue to have high mortality, limb loss, and readmission rates at 30days.

Stroke volume index (SVI) predicts all-cause mortality following transcatheter aortic valve replacement (TAVR)

BackgroundLeft ventricular systolic dysfunction in patients with severe aortic stenosis (AS) may result in low transvalvular gradients and underestimation of AS severity. A low-flow state may occur with reduced LVEF. Little is known about the implications of low compared to normal flow in patients with reduced LVEF undergoing transcatheter aortic valve replacement (TAVR). ObjectivesWe compared survival rates with degree of flow across stenosed aortic valves and left ventricular dysfunction. We hypothesized that the stroke volume index (SVI) offers essential information regarding survival following TAVR. MethodsWe retrospectively reviewed patients with LVEF <50 % undergoing TAVR at the Gates Vascular Institute in Buffalo, New York, from 2012 to 2017. We performed Receiver Operator Characteristics to examine the value of SVI in predicting the postoperative outcome of patients. Kaplan-Meier and Cox regression analyses were used to investigate the effect of a low-flow state on five-year survival in patients with systolic dysfunction undergoing TAVR. ResultsFive-year survival following TAVR was decreased in patients with low-flow AS (SVI <35 mL/m2) compared to patients with normal flow. Seventy-four percent (n = 50) of patients with low-flow compared to 43 % (n = 22) of patients with normal flow were deceased five years post-TAVR (p ≤0.001). ROC curve indicated SVI to be a clinical predictor of five year survival (AUC 0.732, 95 % CI: 0.641–0.823, p < 0.001). ConclusionPatients with systolic dysfunction and low transvalvular flow AS had increased mortality five years following TAVR. These findings highlight a better prognosis in patients with normal flow and LV systolic dysfunction. Condensed abstractLow-flow aortic stenosis can occur with reduced left ventricular function. We compared survival rates of patients with known reduced left ventricular function in low-flow and normal flow aortic stenosis. This retrospective single-center study examined mortality rates following transcatheter aortic valve replacement. The mean gradient was not a predictor of mortality. This study shows patients with low-flow aortic stenosis have decreased five-year survival following valve replacement.

Impact of Elevated Gradients After Transcatheter Aortic Valve Implantation for Degenerated Surgical Aortic Valve Bioprostheses.

Elevated aortic valve gradients are common after transcatheter aortic valve implantation for degenerated surgical aortic valve replacement bioprostheses, but their clinical impact is uncertain. A total of 12 122 patients who underwent transcatheter aortic valve implantation-in-surgical aortic valve replacement from November 2011 to December 2019 in the Society of Thoracic Surgery/American College of Cardiology Transvalvular Therapeutics Registry were included. The primary outcome was a composite of 1-year all-cause mortality, stroke, myocardial infarction, or valve reintervention. Secondary outcomes included 1-year all-cause mortality, readmission, and change from baseline 12-question self-administered Kansas City Cardiomyopathy Questionnaire-Overall Summary Score. Due to nonlinearity observed with restricted cubic splines analysis, a Cox regression analysis with aortic valve mean gradient modeled as a spline-continuous variable (with 20 mm Hg as a cutoff) was used to study the 1-year composite outcome and mortality. The composite outcome occurred most frequently in patients with aortic valve mean gradient ≥30 and <10 mm Hg, as compared with those with 10 to 20 and 20 to 30 mm Hg ranges (unadjusted rates, 13.9%, 12.1%, 7.5%, and 6.5%, respectively; P=0.002). When the mean aortic valve gradient was ≥20 mm Hg, higher gradients were associated with greater risk of the 1-year composite outcome (adjusted hazard ratio, 1.02 [1.02-1.03] per mm Hg; P<0.001) and 1-year mortality (adjusted hazard ratio, 1.02 [1.00-1.03] per mm Hg; P=0.007). Whereas when the mean aortic valve gradient was <20 mm Hg, higher gradients were not significantly associated with the composite outcome (adjusted hazard ratio, 0.99 [0.98-1.003] per mm Hg; P=0.12) but were associated with lower 1-year mortality (adjusted hazard ratio, 0.98 [0.97-0.99] per mm Hg; P=0.007). The relationship between postprocedural aortic valve mean gradient after transcatheter aortic valve implantation-in-surgical aortic valve replacement and clinical outcomes is complex and nonlinear, with relatively greater adverse events occurring at low and high gradient extremes. Further study of factors mediating the relationship between postprocedural gradients and clinical outcomes, including low-flow states, is necessary.

Investigation of swirler effect on combustion and exergy efficiency of hydrogen/chlorine combustor based on entropy generation analysis

Inefficient reagent reaction limits the development of compact combustion-based HCl synthesis production. To address this issue, a non-premixed HCl synthesis combustor that combines a swirler at the hydrogen channel with a porous nozzle at the chlorine channel is proposed. A three-dimensional non-premixed combustion model is used to investigate the effects of this combustor structure on the combustion efficiency, exergy efficiency, and pressure loss coefficient. The entropy generation analysis is employed to evaluate multiple irreversible losses for different structures and flow states. Through experimental validation and numerical simulation analysis, the effects of the swirler installation, inlet flow rate, and H2/Cl2 equivalence ratio on the combustion and heat transfer characteristics are investigated. The results demonstrate that the combustor with the swirler and porous nozzle improves exergy efficiency, leading to higher HCl purity and a reduced flame height for faster reactions under low-flow states. Chemical reactions contribute to over 96 % of entropy generation during combustion, with the swirler reducing total entropy by approximately 5 %. Optimal heat transfer effects and minimized entropy generation are achieved when the swirler is installed below the combustor spray hole. The installation of the swirler can increase the exergy efficiency of the H2/Cl2 combustor to approximately 43.73 %.

Extracorporeal Cardiopulmonary Resuscitation(ECPR) - the Future?

In recent years, invasive resuscitation methods utilizing veno-arterial extracorporeal membrane oxygenation (VA-ECMO) have gained significant attention. Despite advances in traditional resuscitation measures, out-of-hospital cardiac arrest (OHCA) mortality remains high. In the context of extracorporeal cardiopulmonary resuscitation (ECPR), VA-ECMO therapy offers a promising approach by providing circulatory support during cardiac arrest, allowing time for diagnostic evaluation and targeted therapy. However, patient selection for ECPR remains a challenge, relying on various factors including initial rhythm, duration of no-flow and low-flow states, as well as presence of reversible causes.Recent studies such as the ARREST, Prague OHCA and INCEPTION trials have investigated the efficacy of ECPR in OHCA patients, yielding mixed results. While the ARREST trial demonstrated a survival benefit with ECPR, the Prague OHCA and INCEPTION trials showed varying outcomes, reflecting the complexity of patient selection and treatment strategies. Despite inherent risks and complications associated with ECPR, it may offer a potential survival advantage under optimal conditions.Future directions in ECPR involve the development of innovative treatment protocols such as the CARL therapy, which incorporates specialized ECMO systems and tailored perfusion solutions. Early studies indicate promising outcomes with CARL therapy, emphasizing the importance of a well-coordinated and structured approach to ECPR implementation.In summary, ECPR shows promise in improving survival rates for OHCA patients within a well-organized healthcare system. However, further research is needed to refine patient selection criteria and optimize treatment protocols, ultimately enhancing patient outcomes in cardiac arrest scenarios.

Heart failure — An unexplored risk factor for infective endocarditis after pacemaker implantation

BackgroundWith the widespread use of permanent pacemakers (PPM), and increased mortality associated with pacemaker endocarditis, it is essential to evaluate comorbidities that could potentially increase the risk of infective endocarditis (IE). Heart failure (HF), a common comorbidity, has not been well studied as an independent risk factor for development of IE in individuals with PPM. MethodsThe US National Inpatient Sample database was used to sample individuals with PPM. Patients with concomitant implantable cardioverter defibrillator, acute heart failure, history of endocarditis, intravenous drug use, prosthetic heart valves, or central venous catheter infection were excluded. Propensity matching was performed to match patients with and without HF. Pre- and post-match logistic regression was performed to assess HF as an independent risk factor for IE. A subgroup analysis was performed comparing IE rates between patients with HF with reduced (HFrEF) vs preserved (HFpEF) ejection fraction. ResultsOut of 333,571 patients with PPM included in the study, 121,862 (37 %) had HF. HF patients were older and had a higher prevalence of females. All comorbidities except for dental disease and cancer were more prevalent in the HF group. Patients with HF were 1.30 times more likely to develop IE [OR: 1.30 (1.16–1.47); p < 0.001]. The two cohorts were then matched for age, gender, and 20 comorbidities using a 1:1 propensity score matching algorithm. After matching, HF was still independently associated with increased risk of IE [OR: 1.62 (1.36–1.93); p < 0.001]. In our sub-group analysis, HFrEF and HFpEF patients had similar IE rates. ConclusionIn PPM population, HF was associated with an increased risk of IE compared to those without HF. We hypothesize that HF being a low-flow and high-inflammatory state might have contributed to this increased risk. Larger studies are required to corroborate our findings and evaluate the need for antimicrobial prophylaxis for this population.

On the existence of multiple states of low flows in catchments in southeast Australia

This study investigates whether low flow events in a catchment exhibit a possibility of switching regimes. If this happens, it can result in a catchment experiencing a flow anomaly that is even more extreme than what was historically considered a conventional low flow event. A Hidden Markov Modeling approach was used to identify shifts in the intensity of low flow events in catchments in southeast Australia. We found very strong evidence of low flow intensity exhibiting two distinct states (viz., a normal and an intensified state) for several catchments, providing convincing reasons to believe that low flows can and have undergone regime changes. The periods when the catchments exist in an intensified low flow state were associated with higher maximum and average monthly temperature (Δ≈+2.1,+1°C, respectively) and lower precipitation (Δ≈−25mm, a decline of 30%) compared to periods when these exist in their normal state.

Cardiac Damage and Conduction Disorders after Transcatheter Aortic Valve Implantation.

Recently, a staging system using 4 grades has been proposed to quantify the extent of cardiac damage associated with aortic stenosis (AS), namely AS-related cardiac damage staging (ASCDS). ASCDS is independently associated with all-cause mortality and important clinical outcomes. To evaluate whether it might be associated with the occurrence of conduction system disorders after TAVI, a total of 119 symptomatic patients with severe AS who underwent a TAVI were categorized according to ASCDS: group 1 (13.5%): no or LV damage; group 2 (58.8%): left atrial/mitral valve damage, atrial fibrillation (AF); group 3 (27.7%): low-flow state, pulmonary vasculature/tricuspid valve/RV damage. After TAVI, 34% of patients exhibited LBBB and 10% high-degree atrioventricular block (HD-AVB). No patient in group 1 developed HD-AVB whereas new LBBB was frequent in groups 2 and 3. Twenty-one patients presented with paroxysmal AF with a higher rate for each group increment (group 1: n = 0, 0%; group 2: n = 11, 15.7%; group 3: n = 10, 30.3%) (p = 0.012). Patients in group 3 had the higher rate of permanent pacemaker implantation (PPMI) (group 1: n = 1, 6.3%; group 2: n = 7, 10%; group 3: n = 9, 27.3%) (p = 0.012). In conclusion, ASCDS might help identify patients at higher risk of conduction disorders and PPMI requirement after TAVI.

Aortic stenosis assessment from the 3-chamber cine: Ratio of balanced steady-state-free-precession (bSSFP) blood signal between the aorta and left ventricle predicts severity

BackgroundCardiovascular magnetic resonance (CMR) imaging is an important tool for evaluating the severity of aortic stenosis (AS), co-existing aortic disease, and concurrent myocardial abnormalities. Acquiring this additional information requires protocol adaptations and additional scanner time, but is not necessary for the majority of patients who do not have AS. We observed that the relative signal intensity of blood in the ascending aorta on a balanced steady state free precession (bSSFP) 3-chamber cine was often reduced in those with significant aortic stenosis. We investigated whether this effect could be quantified and used to predict AS severity in comparison to existing gold-standard measurements. MethodsMulti-centre, multi-vendor retrospective analysis of patients with AS undergoing CMR and transthoracic echocardiography (TTE). Blood signal intensity was measured in a ∼1 cm2 region of interest (ROI) in the aorta and left ventricle (LV) in the 3-chamber bSSFP cine. Because signal intensity varied across patients and scanner vendors, a ratio of the mean signal intensity in the aorta ROI to the LV ROI (Ao:LV) was used. This ratio was compared using Pearson correlations against TTE parameters of AS severity: aortic valve peak velocity, mean pressure gradient and the dimensionless index. The study also assessed whether field strength (1.5 T vs. 3 T) and patient characteristics (presence of bicuspid aortic valves (BAV), dilated aortic root and low flow states) altered this signal relationship. Results314 patients (median age 69 [IQR 57–77], 64% male) who had undergone both CMR and TTE were studied; 84 had severe AS, 78 had moderate AS, 66 had mild AS and 86 without AS were studied as a comparator group. The median time between CMR and TTE was 12 weeks (IQR 4–26). The Ao:LV ratio at 1.5 T strongly correlated with peak velocity (r = −0.796, p = 0.001), peak gradient (r = −0.772, p = 0.001) and dimensionless index (r = 0.743, p = 0.001). An Ao:LV ratio of < 0.86 was 84% sensitive and 82% specific for detecting AS of any severity and a ratio of 0.58 was 83% sensitive and 92% specific for severe AS. The ability of Ao:LV ratio to predict AS severity remained for patients with bicuspid aortic valves, dilated aortic root or low indexed stroke volume. The relationship between Ao:LV ratio and AS severity was weaker at 3 T. ConclusionsThe Ao:LV ratio, derived from bSSFP 3-chamber cine images, shows a good correlation with existing measures of AS severity. It demonstrates utility at 1.5 T and offers an easily calculable metric that can be used at the time of scanning or automated to identify on an adaptive basis which patients benefit from dedicated imaging to assess which patients should have additional sequences to assess AS.

Treatment of Refractory Cardiac Arrest by Controlled Reperfusion of the Whole Body: A Multicenter, Prospective Observational Study.

Background: Survival following cardiac arrest (CA) remains poor after conventional cardiopulmonary resuscitation (CCPR) (6-26%), and the outcomes after extracorporeal cardiopulmonary resuscitation (ECPR) are often inconsistent. Poor survival is a consequence of CA, low-flow states during CCPR, multi-organ injury, insufficient monitoring, and delayed treatment of the causative condition. We developed a new strategy to address these issues. Methods: This all-comers, multicenter, prospective observational study (69 patients with in- and out-of-hospital CA (IHCA and OHCA) after prolonged refractory CCPR) focused on extracorporeal cardiopulmonary support, comprehensive monitoring, multi-organ repair, and the potential for out-of-hospital cannulation and treatment. Result: The overall survival rate at hospital discharge was 42.0%, and a favorable neurological outcome (CPC 1+2) at 90 days was achieved for 79.3% of survivors (CPC 1+2 survival 33%). IHCA survival was very favorable (51.7%), as was CPC 1+2 survival at 90 days (41%). Survival of OHCA patients was 35% and CPC 1+2 survival at 90 days was 28%. The subgroup of OHCA patients with pre-hospital cannulation showed a superior survival rate of 57.1%. Conclusions: This new strategy focusing on repairing damage to multiple organs appears to improve outcomes after CA, and these findings should provide a sound basis for further research in this area.

Prognostic value of flow-status in severe aortic stenosis patients undergoing percutaneous intervention

PurposeLow-flow status is a mortality predictor in severe aortic stenosis (SAS) patients, including after transcatheter aortic valve implantation (TAVI) treatment. However, the best parameter to assess flow is unknown. Recent studies suggest that transaortic flow rate (FR) is superior to currently used stroke volume index (SVi) in defining low-flow states. Therefore, we aimed to evaluate the prognostic value of FR and SVi in patients undergoing TAVI.MethodsA single-centre retrospective analysis of all consecutive patients treated with TAVI for SAS between 2011 and 2019 was conducted. Low-FR was defined as < 200 mL/s and low-SVi as < 35 mL/m2. Primary endpoint was all-cause five-year mortality, analyzed using Kaplan-Meier curves and Cox regression models. Secondary endpoint was variation of NYHA functional class six months after procedure. Patients were further stratified according to ejection fraction (EF < 50%).ResultsOf 489 cases, 59.5% were low-FR, and 43.1% low-SVi. Low-flow patients had superior surgical risk, worse renal function, and had a higher prevalence of coronary artery disease. Low-FR was associated with mortality (hazard ratio 1.36, p = 0.041), but not after adjustment to EuroSCORE II. Normal-SVi was not associated with survival, despite a significative p-trend for its continuous value. No associations were found for flow-status and NYHA recovery. When stratifying according to preserved and reduced EF, both FR and SVi did not predict all-cause mortality.ConclusionIn patients with SAS undergoing TAVI, a low-FR state was associated with higher mortality, as well as SVi, but not at a 35 mL/m2 cut off.

Abstract 15667: The Transvalvular Pressure Gradient to Valve Area Ratio: A Novel, Simple Doppler Echocardiographic Parameter to Adjudicate Low-Gradient Aortic Stenosis Severity

Background: In patients with low-gradient (LG) aortic stenosis (AS), dobutamine stress echocardiography (DSE) or aortic valve calcium scoring (AVCS) by computed tomography is required to confirm AS severity and the indication for intervention. Hypothesis: We hypothesized that the mean transvalvular gradient to effective orifice area ratio (MG/EOA, in mmHg/cm 2 ) measured during rest echocardiography predicts true-severe AS (TSAS) and clinical outcomes in LG-AS patients. The present study aimed to assess the diagnostic accuracy and prognostic value of the MG/EOA ratio in LG-AS patients. Methods: The diagnostic accuracy of the MG/EOA ratio to predict TSAS was assessed in: i) an in vitro dataset obtained in a circulatory model, and ii) an in vivo dataset collected in 198 patients recruited in the prospective observational cohort TOPAS study (NCT01835028), using receiver operating characteristic (ROC) curve analysis. The prognostic value of this parameter was assessed using spline curve analysis and multivariate Cox regression, using a composite of aortic valve replacement or all-cause mortality at 2-years as clinical endpoint. Results: The MG/EOA ratio at rest predicted TSAS with an area under the ROC curve of 0.99 [0.98-1.00] in the in vitro dataset and 0.92 [0.87-0.95] in the in vivo dataset of LG-AS patients. In the in vivo dataset predominantly composed of patients with a low flow state, the optimal cut-off of MG/EOA ratio was 29 mmHg/cm 2 with a normal flow state (percentage of correct classification: 95%) and 25 mmHg/cm 2 with a low flow state (85%). In LG-AS patients, a MG/EOA ratio ≥ 23 mmHg/cm 2 was associated with increased risk of the composite endpoint (unadjusted HR=2.16 [1.58-3.06], p&lt;0.001; adjusted HR=2.80 [1.94-4.03], p&lt;0.001). The net reclassification index (NRI) of the resting parameter MG/EOA was 0.57 (p&lt;0.001), which was similar to projected EOA (NRI=0.61, p&lt;0.001) measured by DSE. Conclusion: We propose a new, easily obtainable parameter from standard echocardiography that outperforms other rest echocardiographic parameters and is non-inferior to DSE with respect to diagnostic accuracy and prognostic value. The MG/EOA ratio can be useful in LG-AS to confirm AS severity and may thus avoid the use of additional tests such as DSE or AVCS.

Abstract 15718: Valvulo-Arterial Impedance in ESKD Patients With Aortic Stenosis: Echocardiographic Correlates and Outcomes

Introduction: Higher values of valvulo-arterial impedance (Zva), a marker of global hemodynamic load, are associated with worse outcomes in patients with aortic stenosis (AS). No studies have evaluated the impact of Zva on outcomes in end stage kidney disease (ESKD) patients with AS. Objectives We aim to evaluate clinical outcomes associated with Zva and echocardiographic correlates of Zva in patients with AS and ESKD. Methods: Consecutive ESKD patients on dialysis with AS on echocardiography from a single center between January 2000 and March 2021. AS severity was defined using AHA guideline recommendations. Zva [units: mmHg/ml/m 2 ] was calculated as (systolic arterial pressure + aortic valve mean gradient) divided by indexed stroke volume. The association of high Zva with the combined primary outcome of aortic valve replacement (AVR) or mortality was assessed using Cox proportional hazard analysis. Results: The cohort included 94 patients with co-prevalent ESKD and AS; mean age 66 years, 71% male; 43% Black, 24% severe AS. Patients with Zva&gt;4 mmHg/ml/m2 (median value; Table ) associated with lower indexed aortic valve area (0.52 vs. 0.71 cm 2 /m 2 , p&lt;0.001), lower stroke volume (66 vs. 84 ml; p&lt;0.001), lower cardiac output (5.3 vs. 6.1 L/min; p=0.005); Figure . Zva did not associate with the combined incidence of AVR or mortality (p=0.2). Conclusion: In ESKD patients with AS, high Zva was associated with smaller AVA and measures of low flow state; but not with the primary outcome of AVR or mortality. These findings should be validated in a larger cohort. Differences in prognostic information from Zva and flow states in the context of AS between ESKD vs non-ESKD patients deserve further study.