Accuracy and consistency of online large language model-based artificial intelligence chat platforms in answering patients' questions about heart failure

BACKGROUND

Heart failure (HF) is a prevalent condition associated with significant morbidity. Patients may have questions that they feel embarrassed to ask or will face delays awaiting responses from their healthcare providers which may impact their health behavior. We aimed to investigate the potential of large language model (LLM) based artificial intelligence (AI) chat platforms in complementing the delivery of patient-centered care.

METHODS

Using online patient forums and physician experience, we created 30 questions related to diagnosis, management and prognosis of HF. The questions were posed to two LLM-based AI chat platforms (OpenAI's ChatGPT-3.5 and Google's Bard). Each set of answers was evaluated by two HF experts, independently and blinded to each other, for accuracy (adequacy of content) and consistency of content.

RESULTS

ChatGPT provided mostly appropriate answers (27/30, 90%) and showed a high degree of consistency (93%). Bard provided a similar content in its answers and thus was evaluated only for adequacy (23/30, 77%). The two HF experts' grades were concordant in 83% and 67% of the questions for ChatGPT and Bard, respectively.

CONCLUSION

LLM-based AI chat platforms demonstrate potential in improving HF education and empowering patients, however, these platforms currently suffer from issues related to factual errors and difficulty with more contemporary recommendations. This inaccurate information may pose serious and life-threatening implications for patients that should be considered and addressed in future research.

Differences in Donor Heart Acceptance by Race and Gender of Patients on the Transplant Waiting List

Importance

Barriers to heart transplant must be overcome prior to listing. It is unclear why Black men and women remain less likely to receive a heart transplant after listing than White men and women.

Objective

To evaluate whether race or gender of a heart transplant candidate (ie, patient on the transplant waiting list) is associated with the probability of a donor heart being accepted by the transplant center team with each offer.

Design, Setting, and Participants

This cohort study used the United Network for Organ Sharing datasets to identify organ acceptance with each offer for US non-Hispanic Black (hereafter, Black) and non-Hispanic White (hereafter, White) adults listed for heart transplant from October 18, 2018, through March 31, 2023.

Exposures

Black or White race and gender (men, women) of a heart transplant candidate.

Main Outcomes and Measures

The main outcome was heart offer acceptance by the transplant center team. The number of offers to acceptance was assessed using discrete time-to-event analyses, nonparametrically (stratified by race and gender) and parametrically. The hazard probability of offer acceptance for each offer was modeled using generalized linear mixed models adjusted for candidate-, donor-, and offer-level variables.

Results

Among 159 177 heart offers with 13 760 donors, there were 14 890 candidates listed for heart transplant; 30.9% were Black, 69.1% were White, 73.6% were men, and 26.4% were women. The cumulative incidence of offer acceptance was highest for White women followed by Black women, White men, and Black men (P < .001). Odds of acceptance were less for Black candidates than for White candidates for the first offer (odds ratio [OR], 0.76; 95% CI, 0.69-0.84) through the 16th offer. Odds of acceptance were higher for women than for men for the first offer (OR, 1.53; 95% CI, 1.39-1.68) through the sixth offer and were lower for the 10th through 31st offers.

Conclusions and Relevance

The cumulative incidence of heart offer acceptance by a transplant center team was consistently lower for Black candidates than for White candidates of the same gender and higher for women than for men. These disparities persisted after adjusting for candidate-, donor-, and offer-level variables, possibly suggesting racial and gender bias in the decision-making process. Further investigation of site-level decision-making may reveal strategies for equitable donor heart acceptance.

Clinical Significance of Coronary Arterial Dominance: A Review of the Literature

Coronary dominance describes the anatomic variation of coronary arterial supply, notably as it relates to perfusion of the inferior cardiac territories. Differences in the development and outcome in select disease states between coronary dominance patterns are increasingly recognized. In particular, observational studies have identified higher prevalence of poor outcomes in left coronary dominance in the setting of ischemic, conduction, and valvular disease. In this qualitative literature review, we summarize anatomic, physiologic, and clinical implications of differences in coronary dominance to highlight current understanding and gaps in the literature that should warrant further studies.

A roadmap for therapeutic discovery in pulmonary hypertension associated with left heart failure. A scientific statement of the Heart Failure Association (HFA) of the ESC and the ESC Working Group on Pulmonary Circulation & Right Ventricular Function

Pulmonary hypertension (PH) associated with left heart failure (LHF) (PH-LHF) is one of the most common causes of PH. It directly contributes to symptoms and reduced functional capacity and negatively affects right heart function, ultimately leading to a poor prognosis. There are no specific treatments for PH-LHF, despite the high number of drugs tested so far. This scientific document addresses the main knowledge gaps in PH-LHF with emphasis on pathophysiology and clinical trials. Key identified issues include better understanding of the role of pulmonary venous versus arteriolar remodelling, multidimensional phenotyping to recognize patient subgroups positioned to respond to different therapies, and conduct of rigorous pre-clinical studies combining small and large animal models. Advancements in these areas are expected to better inform the design of clinical trials and extend treatment options beyond those effective in pulmonary arterial hypertension. Enrichment strategies, endpoint assessments, and thorough haemodynamic studies, both at rest and during exercise, are proposed to play primary roles to optimize early-stage development of candidate therapies for PH-LHF.

A multicenter evaluation of the HeartMate 3 risk score

BACKGROUND

The Heartmate 3 (HM3) risk score (HM3RS) was derived and validated internally from within the Multicenter Study of MagLev Technology in Patients Undergoing Mechanical Circulatory Support Therapy with HeartMate 3 (MOMENTUM 3) trial population and provides 1- and 2-year mortality risk prediction for patients in those before HM3 left ventricular assist device (LVAD) implantation. We aimed to evaluate the HM3RS in nontrial unselected patients, including those not meeting inclusion criteria for MOMENTUM 3 trial enrollment.

METHODS

Patients who underwent HM3 LVAD implant at 1 of 7 US centers between 2017 and 2021, with at least 1-year follow-up, were included in this analysis. Patients were retrospectively assessed for their eligibility for the MOMENTUM 3 trial based on study inclusion and exclusion criteria. HM3RS risk discrimination was evaluated using time-dependent receiver operating characteristic curve analysis for 1-year mortality for all patients and further stratified by MOMENTUM 3 trial eligibility. Kaplan-Meier curves were constructed using the HM3RS-based risk categories.

RESULTS

Of 521 patients included in the analysis, 266 (51.1%) would have met enrollment criteria for MOMENTUM 3. The 1- and 2-year survival for the total cohort was 85% and 81%, respectively. There was no statistically significant difference in survival between those who met and did not meet enrollment criteria at 1 (87% vs 83%; p = 0.21) and 2 years postimplant (80% vs 78%; p = 0.39). For the total cohort, HM3RS predicted 1-year survival with an area under the curve (AUC) of 0.63 (95% confidence interval [CI]: 0.57-0.69, p < 0.001). HM3RS performed better in the subset of patients meeting enrollment criteria: AUC 0.69 (95% CI:0.61-0.77, p < 0.001) compared to the subset that did not: AUC 0.58 (95% CI: 0.49-0.66, p = 0.078).

CONCLUSIONS

In this real-world evidence, multicenter cohort, 1- and 2-year survival after commercial HM3 LVAD implant was excellent, regardless of trial eligibility. The HM3RS provided adequate risk discrimination in "trial-like" patients, but predictive value was reduced in patients who did not meet trial criteria.

Management of Pulmonary Hypertension in the Context of Heart Failure with Preserved Ejection Fraction

PURPOSE OF REVIEW

To review the current evidence and modalities for treating pulmonary hypertension (PH) in heart failure with preserved ejection fraction (HFpEF).

RECENT FINDINGS

In recent years, several therapies have been developed that improve morbidity in HFpEF, though these studies have not specifically studied patients with PF-HFpEF. Multiple trials of therapies specifically targeting the pulmonary vasculature such as phosphodiesterase (PDE) inhibitors, prostacyclin analogs, endothelin receptor antagonists (ERA), and soluble guanylate cyclase stimulators have also been conducted. However, these therapies demonstrated lack of consistency in improving hemodynamics or functional outcomes in PH-HFpEF. There is limited evidence to support the use of pulmonary vasculature-targeting therapies in PH-HFpEF. The mainstay of therapy remains the treatment of the underlying HFpEF condition. There is emerging evidence that newer HF therapies such as sodium-glucose transporter 2 inhibitors and angiotensin-receptor-neprilysin inhibitors are associated with improved hemodynamics and quality of life of patients with PH-HFpEF. There is also a growing realization that more robust phenotyping PH and right ventricular (RV) function may hold promise for therapeutic strategies for patients with PH-HFpEF.

Occult right ventricular dysfunction and right ventricular-vascular uncoupling in left ventricular assist device recipients

BACKGROUND

Detecting right heart failure post left ventricular assist device (LVAD) is challenging. Sensitive pressure-volume loop assessments of right ventricle (RV) contractility may improve our appreciation of post-LVAD RV dysfunction.

METHODS

Thirteen LVAD patients and 20 reference (non-LVAD) subjects underwent comparison of echocardiographic, right heart cath hemodynamic, and pressure-volume loop-derived assessments of RV contractility using end-systolic elastance (Ees), RV afterload by effective arterial elastance (Ea), and RV-pulmonary arterial coupling (ratio of Ees/Ea).

RESULTS

LVAD patients had lower RV Ees (0.20 ± 0.08 vs 0.30 ± 0.15 mm Hg/ml, p = 0.01) and lower RV Ees/Ea (0.37 ± 0.14 vs 1.20 ± 0.54, p < 0.001) versus reference subjects. Low RV Ees correlated with reduced RV septal strain, an indicator of septal contractility, in both the entire cohort (r = 0.68, p = 0.004) as well as the LVAD cohort itself (r = 0.78, p = 0.02). LVAD recipients with low RV Ees/Ea (below the median value) demonstrated more clinical heart failure (71% vs 17%, p = 0.048), driven by an inability to augment RV Ees (0.22 ± 0.11 vs 0.19 ± 0.02 mm Hg/ml, p = 0.95) to accommodate higher RV Ea (0.82 ± 0.38 vs 0.39 ± 0.08 mm Hg/ml, p = 0.002). Pulmonary artery pulsatility index (PAPi) best identified low baseline RV Ees/Ea (≤0.35) in LVAD patients ((area under the curve) AUC = 0.80); during the ramp study, change in PAPi also correlated with change in RV Ees/Ea (r = 0.58, p = 0.04).

CONCLUSIONS

LVAD patients demonstrate occult intrinsic RV dysfunction. In the setting of excess RV afterload, LVAD patients lack the RV contractile reserve to maintain ventriculo-vascular coupling. Depression in RV contractility may be related to LVAD left ventricular unloading, which reduces septal contractility.

Changes in heart transplant outcomes of elderly patients in the new allocation era

OBJECTIVE

Studies demonstrate that heart transplantation can be performed safely in septuagenarians. We evaluate the outcomes of septuagenarians undergoing heart transplantation after the US heart allocation change in 2018.

METHODS

The United Network for Organ Sharing registry was used to identify heart transplant recipients aged 70 years or more between 2010 and 2021. Primary outcomes were 90-day and 1-year mortality. Kaplan-Meier, multivariable Cox proportional hazards, and accelerated failure time models were used for unadjusted and risk-adjusted analyses.

RESULTS

A total of 27,403 patients underwent heart transplantation, with 1059 (3.9%) aged 70 years or more. Patients aged 70 years or more increased from 3.7% before 2018 to 4.5% after 2018 (P = .003). Patients aged 70 years or more before 2018 had comparable 90-day and 1-year survivals relative to patients aged less than 70 years (90 days: 93.8% vs 94.2%, log-rank P = .650; 1 year: 89.4% vs 91.1%, log-rank P = .130). After 2018, septuagenarians had lower 90-day and 1-year survivals (90 days: 91.4% vs 95.0%, log-rank P = .021; 1 year: 86.5% vs 90.9%, log-rank P = .018). Risk-adjusted analysis showed comparable 90-day mortality (hazard ratio, 1.29; 0.94-1.76, P = .110) but worse 1-year mortality (hazard ratio, 1.32; 1.03-1.68, P = .028) before policy change. After policy change, both 90-day and 1-year mortalities were higher (90 days: HR, 1.99; 1.23-3.22, P = .005; 1 year: hazard ratio, 1.71; 1.14-2.56, P = .010). An accelerated failure time model showed comparable 90-day (0.42; 0.16-1.44; P = .088) and 1-year (0.48; 0.18-1.26; P = .133) survival postallocation change.

CONCLUSIONS

Septuagenarians comprise a greater proportion of heart transplant recipients after the allocation change, and their post-transplant outcomes relative to younger recipients have worsened.

Guide to Lung-Protective Ventilation in Cardiac Patients

The incidence of acute respiratory insufficiency has continued to increase among patients admitted to modern-day cardiovascular intensive care units. Positive pressure ventilation (PPV) remains the mainstay of treatment for these patients. Alterations in intrathoracic pressure during PPV has distinct effects on both the right and left ventricles, affecting cardiovascular performance. Lung-protective ventilation (LPV) minimizes the risk of further lung injury through ventilator-induced lung injury and, hence, an understanding of LPV and its cardiopulmonary interactions is beneficial for cardiologists.

Ventricular Assist Device using a Thoracotomybased Implant Technique: Multi-center HeartMate 3 SWIFT Study

OBJECTIVES

The HeartMate 3 (HM3) left ventricular assist device (LVAD) provides substantial improvement in long-term morbidity and mortality in advanced heart failure patients. The SWIFT study compares thoracotomy-based implantation clinical outcomes with standard median sternotomy.

METHODS

We conducted a prospective, multicenter, single-arm study in patients eligible for HM3 implantation with thoracotomy-based surgical technique (bilateral thoracotomy or partial upper sternotomy with left thoracotomy). The composite primary endpoint was survival free of disabling stroke (Modified Rankin Score > 3), or reoperation to remove or replace a malfunctioning device, or conversion to median sternotomy at 6-months post-implant (elective transplants were treated as a success). The primary end point (non-inferiority, -15% margin) was assessed with >90% power compared to a propensity-matched cohort (ratio 1:2) derived from MOMENTUM 3 Continued Access Protocol (CAP).

RESULTS

The study enrolled 102 patients between December 2020 and July 2022 in the thoracotomy-based arm at 23 North American Centers. Follow-up concluded in December 2022. In the SWIFT group non-inferiority criteria was met (absolute between-group difference, -1.2%; Farrington Manning lower, one-sided 95%CI: -9.3%, P<0.0025) and event-free survival was not different (85.0% versus 86.2%; HR 1.01, 95%CI 0.58-2.10). Length of stay with thoracotomy-based implant was longer (median 20 versus 17 days, p=0.03). No differences were observed for blood product utilization, adverse events (including right heart failure), functional status, and quality of life between cohorts.

CONCLUSION

Thoracotomy-based implantation of the HM3 LVAD is non-inferior to implantation via standard full sternotomy. This study supports thoracotomy-based implantation as an additional standard for surgical implantation of the HM3 LVAD.

Risk Factors for 1-Year Mortality After Heart Transplant in Obese Patients Bridged With an LVAD

BACKGROUND

Heart transplantation is relatively contraindicated in morbidly obese patients because of increased morbidity and mortality. This study identified risk factors for post-heart transplantation mortality in obese patients with a left ventricular assist device (LVAD).

METHODS

The United Network for Organ Sharing database was used to identify patients with a body mass index ≥35 kg/m2 who had a durable LVAD at the time of isolated heart transplantation between 2010 and 2021. The primary outcome was post-heart transplantation 1-year mortality. Multivariable Cox regression modeling was used to identify significant risk factors for 1-year mortality. Receiver-operating characteristic analyses were performed to identify optimal thresholds for continuous variables associated with the primary outcome. Patients were stratified by the number of risk factors, and Kaplan-Meier analysis was used to compare survival.

RESULTS

A total of 1222 obese patients were bridged to heart transplantation with a durable LVAD. Six risk factors were identified as significantly associated with 1-year post-heart transplantation mortality: recipient age >62.5 years, body mass index >36.6 kg/m2, bilirubin level >0.95 mg/dL, cold ischemic time >3.7 hours, recipient-donor sex mismatch, and pretransplantation mechanical ventilation. The distribution of cumulative risk factors was as follows: 8.6% with 0, 30.6% with 1, 37.0% with 2, and 23.8% patients with ≥3 risk factors. The 1-year survival rate decreased significantly from 96.0% in those patients with 0 risk factors to 77.6% in those with 3 or more risk factors.

CONCLUSIONS

These data provide a useful guide for risk stratification and patient selection in obese LVAD candidates being considered for heart transplantation.

Right Ventricular Contractility and Pulmonary Arterial Coupling After Less Invasive Left Ventricular Assist Device Implantation

Right ventricular failure contributes significantly to morbidity and mortality after left ventricular assist device implantation. Recent data suggest a less invasive strategy (LIS) via thoracotomy may be associated with less right ventricular failure than conventional median sternotomy (CMS). However, the impact of these approaches on load-independent right ventricular (RV) contractility and RV-pulmonary arterial (RV-PA) coupling remains uncertain. We hypothesized that the LIS approach would be associated with preserved RV contractility and improved RV-PA coupling compared with CMS. We performed a retrospective study of patients who underwent durable, centrifugal left ventricular assist device implantation and had paired hemodynamic assessments before and after implantation. RV contractility (end-systolic elastance [Ees]), RV afterload (pulmonary effective arterial elastance [Ea]), and RV-PA coupling (Ees/Ea) were determined using digitized RV pressure waveforms. Forty-two CMS and 21 LIS patients were identified. Preimplant measures of Ees, Ea, and Ees/Ea were similar between groups. After implantation, Ees declined significantly in the CMS group (0.60-0.40, p  = 0.008) but not in the LIS group (0.67-0.58, p  = 0.28). Coupling (Ees/Ea) was unchanged in CMS group (0.54-0.59, p  = 0.80) but improved significantly in the LIS group (0.58-0.71, p  = 0.008). LIS implantation techniques may better preserve RV contractility and improve RV-PA coupling compared with CMS.

Donor utilization in heart transplant with donation after circulatory death in the United States

Heart transplantation using donation after circulatory death (DCD) was recently adopted in the United States. This study aimed to characterize organ yield from adult (≥18 years) DCD heart donors in the United States using the United Network for Organ Sharing registry. The registry does not identify potential donors who do not progress to circulatory death, and only those who progressed to death were included for analysis. Outcomes included organ recovery from the donor operating room and organ utilization for transplant. Multiple logistic regression was used to identify predictors of heart recovery and utilization. Among 558 DCD procurements, recovery occurred in 89.6%, and 92.5% of recovered hearts were utilized for transplant. Of 506 DCD procurements with available data, 65.0% were classified as direct procurement and perfusion and 35.0% were classified as normothermic regional perfusion (NRP). Logistic regression identified that NRP, shorter agonal time, younger donor age, and highest volume of organ procurement organizations were independently associated with increased odds for heart recovery. NRP independently predicted heart utilization after recovery. DCD heart utilization in the United States is satisfactory and consistent with international experience. NRP procurements have a higher yield for DCD heart transplantation compared with direct procurement and perfusion, which may reflect differences in donor assessment and acceptance criteria.

Clinical and functional relevance of right ventricular contraction patterns in pulmonary hypertension

BACKGROUND

The right ventricle has a complex contraction pattern of uncertain clinical relevance. We aimed to assess the relationship between right ventricular (RV) contraction pattern and RV-pulmonary arterial (PA) coupling defined by the gold-standard pressure-volume loop-derived ratio of end-systolic/arterial elastance (Ees/Ea).

METHODS

Prospectively enrolled patients with suspected or confirmed pulmonary hypertension underwent three-dimensional echocardiography, standard right heart catheterization, and RV conductance catheterization. RV-PA uncoupling was categorized as severe (Ees/Ea < 0.8), moderate (Ees/Ea 0.8-1.29), and none/mild (Ees/Ea ≥ 1.3). Clinical severity was determined from hemodynamics using a truncated version of the 2022 European Society of Cardiology/European Respiratory Society risk stratification scheme.

RESULTS

Fifty-three patients were included, 23 with no/mild, 24 with moderate, and 6 with severe uncoupling. Longitudinal shortening was decreased in patients with moderate vs no/mild uncoupling (p <0.001) and intermediate vs low hemodynamic risk (p < 0.001), discriminating low risk from intermediate/high risk with an optimal threshold of 18% (sensitivity 80%, specificity 87%). Anteroposterior shortening was impaired in patients with severe vs moderate uncoupling (p = 0.033), low vs intermediate risk (p = 0.018), and high vs intermediate risk (p = 0.010), discriminating high risk from intermediate/low risk with an optimal threshold of 15% (sensitivity 100%, specificity 83%). Left ventricular (LV) end-diastolic volume was decreased in patients with severe uncoupling (p = 0.035 vs no/mild uncoupling).

CONCLUSIONS

Early RV-PA uncoupling is associated with reduced longitudinal function, whereas advanced RV-PA uncoupling is associated with reduced anteroposterior movement and LV preload, all in a risk-related fashion.

CLINICALTRIALS

GOV: NCT04663217.

Standardization of the Right Heart Catheterization and the Emerging Role of Advanced Hemodynamics in Heart Failure

The accurate assessment of hemodynamics is paramount to providing timely and efficacious care for patients presenting in cardiogenic shock. Recently, the regular use of the pulmonary artery catheter in cardiogenic shock has had a resurgence with emerging data indicating improved survival in the modern era. Optimal multidisciplinary management of advanced heart failure and cardiogenic shock relies on our ability to effectively communicate and understand the complete hemodynamic assessment. Standardization of data acquisition and a renewed focus on the physiological processes, and thresholds driving disease progression, including the coupling ratio and myocardial reserve, are needed to fully understand and interpret the hemodynamic assessment. This State-of-the-Art review discusses best practices in the cardiac catheterization laboratory as well as emerging data on the prognostic role of emerging advanced hemodynamic parameters.

Durable Mechanical Circulatory Support: JACC Scientific Statement

Despite advances in medical therapy for patients with stage C heart failure (HF), survival for patients with advanced HF is <20% at 5 years. Durable left ventricular assist device (dLVAD) support is an important treatment option for patients with advanced HF. Innovations in dLVAD technology have reduced the risk of several adverse events, including pump thrombosis, stroke, and bleeding. Average patient survival is now similar to that of heart transplantation at 2 years, with 5-year dLVAD survival now approaching 60%. Unfortunately, greater adoption of dLVAD therapy has not been realized due to delayed referral of patients to advanced HF centers, insufficient clinician knowledge of contemporary dLVAD outcomes (including gains in quality of life), and deprioritization of patients with dLVAD support waiting for heart transplantation. Despite these challenges, novel devices are on the horizon of clinical investigation, offering smaller size, permitting less invasive surgical implantation, and eliminating the percutaneous lead for power supply.

Decoupling of Hemodynamics and Congestive Symptoms in Obese Patients With Heart Failure

BACKGROUND

Prior studies indicate significant physiological differences between obese and nonobese patients with heart failure (HF), but none have evaluated differences in hemodynamic patterns in these patient populations during treatment for acute decompensated HF (ADHF).

OBJECTIVES

In this study, we assessed differences in hemodynamic trends between obese and nonobese patients during treatment for ADHF.

METHODS

Obese (body mass index (BMI) >30, n = 63) and nonobese (BMI < 25, n = 69) patients with ADHF in the Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness (ESCAPE) study who had pulmonary artery catheterization data available through the duration of treatment were evaluated. Hemodynamics were analyzed at baseline and optimal day. Changes in BNP levels, weight, creatinine, BUN, 6MWT, orthopnea and dyspnea scores were assessed.

RESULTS

Despite similar baseline hemodynamics, obese patients had significantly less absolute and relative pulmonary arterial wedge pressure (PAWP) reduction (-16 ± 28 vs -32 ± 29%; P = 0.03) during treatment. Obese patients also had higher PAWPs (19.9 + 8 vs 15.5 + 6.8 mmHg; P = 0.01) and PA pressures at optimization compared with nonobese patients. Obese and nonobese patients had similar relative improvements in weight, BNP, 6-minute walk test distance, dyspnea and orthopnea scores, and similar changes in creatinine and BUN levels.

CONCLUSIONS

Obese patients treated for ADHF display less reduction in invasively measured left heart filling pressures, despite similar improvements in symptoms, weight loss, and noninvasive surrogates of congestion. Our findings suggest a degree of decoupling between left heart filling pressures and congestive symptoms in obese patients undergoing treatment for ADHF.

Impact of Donor Hemodynamics on Recipient Survival in Heart Transplantation

BACKGROUND

Heart transplantation is the gold-standard therapy for end-stage heart failure, but rates of donor-heart use remain low due to various factors that are often not evidence based. The impact of donor hemodynamics obtained via right-heart catheterization on recipient survival remains unclear.

METHODS

The United Network for Organ Sharing registry was used to identify donors and recipients from September 1999-December 2019. Donor hemodynamics data were obtained and analyzed using univariate and multivariable logistical regression, with the primary endpoints being 1- and 5-year post-transplant survival.

RESULTS

Of the 85,333 donors who consented to heart transplantation during the study period, 6573 (7.7%) underwent right-heart catheterization, of whom 5531 eventually underwent procurement and transplantation. Donors were more likely to undergo right-heart catheterization if they had high-risk criteria. Recipients who had donor hemodynamic assessment had 1- and 5-year survival rates similar to those without donor hemodynamic assessment (87% vs 86%, 1 year). Abnormal hemodynamics were common in donor hearts but did not impact recipient survival rates, even when risk-adjusted in multivariable analysis.

CONCLUSIONS

Donors with abnormal hemodynamics may represent an opportunity to expand the pool of viable donor hearts.

Echocardiographic evaluation of right ventricular diastolic function in pulmonary hypertension

Background

Right ventricular (RV) diastolic dysfunction may be prognostic in pulmonary hypertension (PH). However, its assessment is complex and relies on conductance catheterisation. We aimed to evaluate echocardiography-based parameters as surrogates of RV diastolic function, provide validation against the gold standard, end-diastolic elastance (Eed), and define the prognostic impact of echocardiography-derived RV diastolic dysfunction.

Methods

Patients with suspected PH who underwent right heart catheterisation including conductance catheterisation were prospectively recruited. In this study population, an echocardiography-based RV diastolic function surrogate was derived. Survival analyses were performed in patients with precapillary PH in the Giessen PH Registry, with external validation in patients with pulmonary arterial hypertension at Sapienza University (Rome).

Results

In the derivation cohort (n=61), the early/late diastolic tricuspid inflow velocity ratio (E/A) and early tricuspid inflow velocity/early diastolic tricuspid annular velocity ratio (E/e') did not correlate with Eed (p>0.05). Receiver operating characteristic analysis revealed a large area under the curve (AUC) for the peak lateral tricuspid annulus systolic velocity/right atrial area index ratio (S'/RAAi) to detect elevated Eed (AUC 0.913, 95% confidence interval (CI) 0.839-0.986) and elevated end-diastolic pressure (AUC 0.848, 95% CI 0.699-0.998) with an optimal threshold of 0.81 m2·s-1·cm-1. Subgroup analyses demonstrated a large AUC in patients with preserved RV systolic function (AUC 0.963, 95% CI 0.882-1.000). Survival analyses confirmed the prognostic relevance of S'/RAAi in the Giessen PH Registry (n=225) and the external validation cohort (n=106).

Conclusions

Our study demonstrates the usefulness of echocardiography-derived S'/RAAi for noninvasive assessment of RV diastolic function and prognosis in PH.

How to Select Patients for Left Ventricular Assist Devices? A Guide for Clinical Practice

In recent years, a significant improvement in left ventricular assist device (LVAD) technology has occurred, and the continuous-flow devices currently used can last more than 10 years in a patient. Current studies report that the 5-year survival rate after LVAD implantation approaches that after a heart transplant. However, the outcome is influenced by the correct selection of the patients, as well as the choice of the optimal time for implantation. This review summarizes the indications, the red flags for prompt initiation of LVAD evaluation, and the principles for appropriate patient screening.

Substrate Imaging Before Catheter Ablation of Ventricular Tachycardia: Risk Prediction for Acute Hemodynamic Decompensation

BACKGROUND

The PAINESD (Pulmonary disease, Age, Ischemic cardiomyopathy, NYHA functional class, Ejection fraction, Storm, Diabetes mellitus) risk score has been validated as a predictor of periprocedural acute hemodynamic decompensation (AHD) in patients undergoing ventricular tachycardia (VT) ablation. Whether the addition of total scar volume (TSV) determined by preprocedure computed tomography imaging provides additional risk stratification has not been previously investigated.

OBJECTIVES

The purpose of this study was to evaluate the impact of TSV on the risk of AHD and its adjunctive benefit to the PAINESD score newly modified as Pulmonary disease, Age, Ischemic cardiomyopathy, NYHA class, Ejection fraction, Storm, Scar volume, Diabetes mellitus (PAINES2D) based on the addition of scar volumes.

METHODS

This was a retrospective analysis of all index VT ablations at a quaternary care center from 2017 to 2022. Associations between TSV and AHD were evaluated among patients with structural heart disease.

RESULTS

Among 61 patients with TSV data, 13 (21%) had periprocedural AHD. TSV and PAINESD were independently associated with AHD risk. Both TSV and PAINESD were associated with AHD (P = 0.016 vs P = 0.053, respectively). The highest TSV tertile (≥37.30 mL) showed significant association with AHD (P = 0.018; OR: 4.80) compared to the other tertiles. The PAINESD and PAINES2D scores had significant impact on AHD (P = 0.046 and P = 0.010, respectively). The PAINES2D score had a greater impact on AHD compared to PAINESD (area under the curve: 0.73; P = 0.011; 95% CI: 0.56-0.91 and area under the curve: 0.67; P = 0.058; 95% CI: 0.49-0.85, respectively).

CONCLUSIONS

Addition of TSV to a modified PAINESD score, PAINES2D, enhances risk prediction of AHD. Further prospective study is needed to assess benefit in various cardiomyopathy populations undergoing VT ablation.

Elevated Pulmonary Arterial Compliance Is Associated with Survival in Pulmonary Hypertension: Results from a Novel Network Medicine Analysis

Rationale: Predictors of adverse outcome in pulmonary hypertension (PH) are well established; however, data that inform survival are lacking. Objectives: We aim to identify clinical markers and therapeutic targets that inform the survival in PH. Methods: We included data from patients with elevated mean pulmonary artery pressure (mPAP) diagnosed by right heart catheterization in the U.S. Veterans Affairs system (October 1, 2006-September 30, 2018). Network medicine framework was used to subgroup patients when considering an N of 79 variables per patient. The results informed outcome analyses in the discovery cohort and a sex-balanced validation right heart catheterization cohort from Vanderbilt University (September 24, 1998-December 20, 2013). Measurements and Main Results: From an N of 4,737 complete case patients with mPAP of 19-24 mm Hg, there were 21 distinct subgroups (network modules) (all-cause mortality range = 15.9-61.2% per module). Pulmonary arterial compliance (PAC) drove patient assignment to modules characterized by increased survival. When modeled continuously in patients with mPAP ⩾19 mm Hg (N = 37,744; age, 67.2 yr [range = 61.7-73.8 yr]; 96.7% male; median follow-up time, 1,236 d [range = 570-1,971 d]), the adjusted all-cause mortality hazard ratio was <1.0 beginning at PAC ⩾3.0 ml/mm Hg and decreased progressively to ∼7 ml/mm Hg. A protective association between PAC ⩾3.0 ml/mm Hg and mortality was also observed in the validation cohort (N = 1,514; age, 60.2 yr [range = 49.2-69.1 yr]; 48.0% male; median follow-up time, 2,485 d [range = 671-3,580 d]). The association was strongest in patients with precapillary PH at the time of catheterization, in whom 41% (95% confidence interval, 0.55-0.62; P < 0.001) and 49% (95% confidence interval, 0.38-0.69; P < 0.001) improvements in survival were observed for PAC ⩾3.0 versus <3.0 ml/mm Hg in the discovery and validation cohorts, respectively. Conclusions: These data identify elevated PAC as an important parameter associated with survival in PH. Prospective studies are warranted that consider PAC ⩾3.0 ml/mm Hg as a therapeutic target to achieve through proven interventions.

Late Right Heart Failure After Left Ventricular Assist Device Implantation: Contemporary Insights and Future Perspectives

Late right heart failure (RHF) is increasingly recognized in patients with long-term left ventricular assist device (LVAD) support and is associated with decreased survival and increased incidence of adverse events such as gastrointestinal bleeding and stroke. Progression of right ventricular (RV) dysfunction to clinical syndrome of late RHF in patients supported with LVAD is dependent on the severity of pre-existing RV dysfunction, persistent or worsening left- or right-sided valvular heart disease, pulmonary hypertension, inadequate or excessive left ventricular unloading, and/or progression of the underlying cardiac disease. RHF likely represents a continuum of risk with early presentation and progression to late RHF. However, de novo RHF develops in a subset of patients leading to increased diuretic requirement, arrhythmias, renal and hepatic dysfunction, and heart failure hospitalizations. The distinction between isolated late RHF and RHF due to left-sided contributions is lacking in registry studies and should be the focus of future registry data collection. Potential management strategies include optimization of RV preload and afterload, neurohormonal blockade, LVAD speed optimization, and treatment of concomitant valvular disease. In this review, the authors discuss definition, pathophysiology, prevention, and management of late RHF.

Outcomes of Combined Heart-Kidney Transplantation in Older Recipients

Objectives

The upper limit of recipient age for combined heart-kidney transplantation (HKT) remains controversial. This study evaluated the outcomes of HKT in patients aged ≥65 years.

Methods

The United Network of Organ Sharing (UNOS) was used to identify patients undergoing HKT from 2005 to 2021. Patients were stratified by age at transplantation: <65 and ≥ 65 years. The primary outcome was one-year mortality. Secondary outcomes included 90-day and 5-year mortality, postoperative new-onset dialysis, postoperative stroke, acute rejection prior to discharge, and rejection within one-year of HKT. Survival was compared using Kaplan-Meier analysis, and risk adjustment for mortality was performed using Cox proportional hazards modeling.

Results

HKT in recipients aged ≥65 significantly increased from 5.6% of all recipients in 2005 to 23.7% in 2021 (p=0.002). Of 2,022 HKT patients in the study period, 372 (18.40%) were aged ≥65. Older recipients were more likely to be male and white, and fewer required dialysis prior to HKT. There were no differences between cohorts in unadjusted 90-day, 1-year, or 5-year survival in Kaplan-Meier analysis. These findings persisted after risk-adjustment, with an adjusted hazard for one-year mortality for age ≥65 of 0.91 (95% CI (0.63-1.29), p=0.572). As a continuous variable, increasing age was not associated with one-year mortality (HR 1.01 (95% CI (1.00-1.02), p=0.236) per year). Patients aged ≥65 more frequently required new-onset dialysis prior to discharge (11.56% vs. 7.82%, p=0.051). Stroke and rejection rates were comparable.

Conclusion

Combined HKT is increasing in older recipients, and advanced age ≥65 should not preclude HKT.

Metabolic profiling of in vivo right ventricular function and exercise performance in pulmonary arterial hypertension

Right ventricular (RV) adaptation is the principal determinant of outcomes in pulmonary arterial hypertension (PAH), however, RV function is challenging to assess. RV responses to hemodynamic stressors are particularly difficult to interrogate without invasive testing. This study sought to identify metabolomic markers of in vivo right ventricular function and exercise performance in PAH. Consecutive subjects with PAH (n = 23) underwent rest and exercise right heart catheterization with multibeat pressure volume loop analysis. Pulmonary arterial blood was collected at rest and during exercise. Mass spectrometry-based targeted metabolomics were performed, and metabolic associations with hemodynamics and comprehensive measures of RV function were determined using sparse partial least squares regression. Metabolite profiles were compared with N-terminal prohormone of B-type natriuretic peptide (NT-proBNP) measurements for accuracy in modeling ventriculo-arterial parameters. Thirteen metabolites changed in abundance with exercise, including metabolites reflecting increased arginine bioavailability, precursors of catecholamine and nucleotide synthesis, and branched-chain amino acids. Higher resting arginine bioavailability predicted more favorable exercise hemodynamics and pressure-flow relationships. Subjects with more severe PAH augmented arginine bioavailability with exercise to a greater extent than subjects with less severe PAH. We identified relationships between kynurenine pathway metabolism and impaired ventriculo-arterial coupling, worse RV diastolic function, lower RV contractility, diminished RV contractility with exercise, and RV dilation with exercise. Metabolite profiles outperformed NT-proBNP in modeling RV contractility, diastolic function, and exercise performance. Specific metabolite profiles correspond to RV functional measurements only obtainable via invasive pressure-volume loop analysis and predict RV responses to exercise. Metabolic profiling may inform discovery of RV functional biomarkers.NEW & NOTEWORTHY In this cohort of patients with pulmonary arterial hypertension (PAH), we investigate metabolomic associations with comprehensive right ventricular (RV) functional measurements derived from multibeat RV pressure-volume loop analysis. Our results show that tryptophan metabolism, particularly the kynurenine pathway, is linked to intrinsic RV function and PAH pathobiology. Findings also highlight the importance of arginine bioavailability in the cardiopulmonary system's response to exercise stress. Metabolite profiles selected via unbiased analysis outperformed N-terminal prohormone of B-type natriuretic peptide (NT-proBNP) in predicting load-independent measures of RV function at rest and cardiopulmonary system performance under stress. Overall, this work suggests the potential for select metabolites to function as disease-specific biomarkers, offers insights into PAH pathobiology, and informs discovery of potentially targetable RV-centric pathways.

Characteristics and Predictors of Late Right Heart Failure After Left Ventricular Assist Device Implantation

Late right heart failure (LRHF) following left ventricular assist device (LVAD) implantation remains poorly characterized and challenging to predict. We performed a multicenter retrospective study of LRHF in 237 consecutive adult LVAD patients, in which LRHF was defined according to the 2020 Mechanical Circulatory Support Academic Research Consortium guidelines. Clinical and hemodynamic variables were assessed pre- and post-implant. Competing-risk regression and Kaplan-Meier survival analysis were used to assess outcomes. LRHF prediction was assessed using multivariable logistic and Cox proportional hazards regression. Among 237 LVAD patients, 45 (19%) developed LRHF at a median of 133 days post-LVAD. LRHF patients had more frequent heart failure hospitalizations ( p < 0.001) alongside other complications. LRHF patients did not experience reduced bridge-to-transplant rates but did suffer increased mortality (hazard ratio 1.95, 95% confidence interval [CI] 1.11-3.42; p = 0.02). Hemodynamically, LRHF patients demonstrated higher right atrial pressure, mean pulmonary arterial pressure, and pulmonary vascular resistance (PVR), but no difference in pulmonary arterial wedge pressure. History of early right heart failure, blood urea nitrogen (BUN) > 35 mg/dl at 1 month post-LVAD, and diuretic requirements at 1 month post-LVAD were each significant, independent predictors of LRHF in multivariable analysis. An LRHF prediction risk score incorporating these variables predicted LRHF with excellent discrimination (log-rank p < 0.0001). Overall, LRHF post-LVAD is more common than generally appreciated, with significant morbidity and mortality. Elevated PVR and precapillary pulmonary pressures may play a role. A risk score using early right heart failure, elevated BUN, and diuretic requirements 1 month post implant predicted the development of LRHF.

Outcomes of Over 1000 Heart Transplants Using Hepatitis C-Positive Donors in the Modern Era

BACKGROUND

Advances in hepatitis C virus (HCV) treatment and the ongoing opioid epidemic have made HCV-positive donors increasingly available for heart transplantation (HT). This analysis reports outcomes of over 1000 HCV-positive HTs in the United States in the modern era.

METHODS

The United Network of Organ Sharing registry was used to identify HTs between 2015 and 2021. Recipients were grouped by donor HCV status and by nucleic acid amplification test (NAT) positivity. The primary outcome was 1-year mortality, and secondary outcomes included 3-year mortality. A subanalysis compared HCV-positive HT outcomes between NAT-positive and NAT-negative donors. Risk adjustment was performed using Cox regression. Kaplan-Meier analysis was used to estimate survival.

RESULTS

The frequency of HCV-positive HT increased from 0.12% of HTs in 2015 to 12.9% in 2021 (P < .001). Of 16,648 HTs, 1170 (7.0%) used an organ from an HCV-positive donor. Recipients of HCV-positive organs were more likely to be HCV seropositive, older, and White. Unadjusted 1- and 3-year survival rates were not significantly different between recipients of HCV-negative and HCV-positive organs. After risk adjustment HCV-positive donor status was not associated with an elevated risk for 1-year (hazard ratio, 0.92; 95% CI, 0.71-1.19; P = .518) or 3-year mortality. Among HCV-positive HTs 772 (61.7%) were NAT positive. After risk adjustment NAT positivity did not impact 1-year mortality.

CONCLUSIONS

The proportion of HCV-positive HTs has increased over 100-fold in recent years. This analysis of the US experience demonstrates that recipients of HCV-positive hearts, including those that are NAT positive, have acceptable outcomes with similar early to midterm survival as recipients of HCV-negative organs.

Cardiac output assessment methods in left ventricular assist device patients: A problem of heteroscedasticity

Equipoise remains about how best to measure cardiac output (CO) in patients with left ventricular assist devices (LVAD). In this study, direct Fick CO was compared with thermodilution (TD) and indirect Fick (iFick) CO in 61 LVAD patients. TD and LaFarge iFick showed moderate correlation with direct Fick (R² = 0.49 and R² = 0.38, p < 0.001 for both), while Dehmer and Bergstra iFick showed poor correlation with direct Fick (R² = 0.29 and R² = 0.31, p < 0.001 for both). Absolute bias between all CO estimation techniques and direct Fick CO was lowest for TD compared to iFick methods but significant for all methods. All methods tended to overestimate CO compared to direct Fick, with greatest overestimation present in those with the lowest measured direct Fick CO. Bias and frequency of significant discrepancy were least using TD and Lafarge iFick CO estimation methods in this study, with TD CO demonstrating modestly better correlation and less heteroscedasticity compared to Lafarge.

Use of Levosimendan in Patients with Pulmonary Hypertension: What is the Current Evidence?

Pulmonary hypertension, defined as an increase in mean arterial pressure > 20 mmHg, is a chronic and progressive condition with high mortality and morbidity. Drug therapy of patients with pulmonary hypertension is based on the distinctive pathophysiologic aspect that characterizes the different groups. However, recently, levosimendan, a calcium-sensitizing agent with inotropic, pulmonary vasodilator, and cardioprotective properties, has been shown to be an effective and safe therapeutic strategy for patients with pulmonary arterial hypertension (in addition to specific drugs) and pulmonary hypertension associated with left heart disease (as possible treatment). This review provides a comprehensive overview of the current evidence on the use of levosimendan in patients with pulmonary hypertension.

Effects of Body Mass Index on Presentation and Outcomes of COVID-19 among Heart Transplant and Left Ventricular Assist Device Patients: A Multi-Institutional Study

The coronavirus disease 2019 (COVID-19) pandemic continues to pose a significant threat to patients receiving advanced heart failure therapies. The current study was undertaken to better understand the relationship between obesity and outcomes of SARS-CoV-2 infection in patients with a left ventricular assist device (LVAD) or heart transplant. We performed a retrospective review of patients with a heart transplant or LVAD who presented to one of the participating 11 institutions between April 1 and November 30, 2020. Patients were grouped by body mass index (BMI) into obese (BMI ≥ 30 k/m2) and nonobese cohorts (BMI < 30 kg/m2). Multivariable logistic regression models were used to estimate effects of obesity on outcomes of interest. Across all centers, 162 heart transplant and 81 LVAD patients were identified; 54 (33%) and 38 (47%) were obese, respectively. Obese patients tended to have more symptoms at presentation. No differences in rates of hospitalization or ICU admission were noted. Obese patients with LVADs were more likely to require mechanical ventilation (39% vs. 8%, p < 0.05). No differences in renal failure or secondary infection were noted. Mortality was similar among heart transplant patients (11% [obese] vs. 16% [nonobese], p = 0.628) and LVAD patients (12% vs. 15%, p = 1.0). BMI was not associated with increased adjusted odds of mortality, ICU admission, or mechanical ventilation (all p > 0.10). In summary, acute presentations of SARS-CoV-2 among heart transplant and LVAD recipients carry a significantly higher mortality than the general population, although BMI does not appear to impact this. Further studies on the longer-term effects of COVID-19 on this population are warranted.

Hemodynamic reserve predicts early right heart failure after LVAD implantation

BACKGROUND

Early right heart failure (RHF) remains a major source of morbidity and mortality after left ventricular assist device (LVAD) implantation, yet efforts to predict early RHF have proven only modestly successful. Pharmacologic unloading of the left ventricle may be a risk stratification approach allowing for assessment of right ventricular and hemodynamic reserve.

METHODS

We performed a multicenter, retrospective analysis of patients who had undergone continuous-flow LVAD implantation from October 2011 to April 2020. Only those who underwent vasodilator testing with nitroprusside during their preimplant right heart catheterization were included (n = 70). Multivariable logistic regression was used to determine independent predictors of early RHF as defined by Mechanical Circulatory Support-Academic Research Consortium.

RESULTS

Twenty-seven patients experienced post-LVAD early RHF (39%). Baseline clinical characteristics were similar between patients with and without RHF. Patients without RHF, however, achieved higher peak stroke volume index (SVI) (30.1 ± 8.8 vs 21.7 ± 7.4 mL/m2; p < 0.001; AUC: 0.78; optimal cut-point: 22.1 mL/m2) during nitroprusside administration. Multivariable analysis revealed that peak SVI was significantly associated with early RHF, demonstrating a 16% increase in risk of early RHF per 1 ml/m2 decrease in SVI. A follow up cohort of 10 consecutive patients from July 2020 to October 2021 resulted in all patients being categorized appropriately in regards to early RHF versus no RHF according to peak SVI.

CONCLUSION

Peak SVI with nitroprusside administration was independently associated with post-LVAD early RHF while resting hemodynamics were not. Vasodilator testing may prove to be a strong risk stratification tool when assessing LVAD candidacy though additional prospective validation is needed.

The HeartMate 3 left ventricular assist device as a strategy to bridge to transplant

PURPOSE

Recent changes in the market for left ventricular assist devices have resulted in the HeartMate 3 (HM3) being the only commercially-available device. This study evaluates the outcomes of patients with a HM3 waitlisted for and undergoing orthotopic heart transplantation (OHT).

METHODS

Patients waitlisted for isolated OHT with a HM3 or undergoing OHT after bridge-to-transplant (BTT) with a HM3 between 2015 and 2021 were identified from the UNOS registry and included in this study. Propensity matching was used to compare outcomes of BTT-HM3 versus primary OHT.

RESULTS

A total of 1321 patients supported with a HM3 underwent OHT during our study period. Unadjusted 30-day, 90-day, and 1-year survival following OHT in the BTT-HM3 cohort was 96.5%, 94.4%, and 90.7%, respectively. In propensity-matched analysis, 1103 BTT-HM3 patients were compared with 1103 primary OHT patients. Rates of post-OHT stroke were higher in the BTT-HM3 group (4.4% vs. 2.0%, p = .001). The BTT-HM3 group had lower 30-day survival (96.2% vs. 97.4%, p = .033) although 90-day (94.2% vs. 95.3%, p = .103) and 1-year survival (90.4% vs. 91.7%, p = .216) were comparable. A total of 1251 patients were supported with a HM3 at the time of OHT listing during the study period. At the time of this analysis, 60 (4.5%) remained on the waitlist, 991 (75.0%) underwent OHT, and 119 (9.0%) died or clinically deteriorated with waitlist removal.

CONCLUSIONS

The HM3 is a viable method for BTT with acceptable waitlist outcomes. Although 1-year survival is comparable to primary OHT, early outcomes are worse, suggesting that refinement of patient selection and perioperative management is prudent to optimizing outcomes.

Early Outcomes of Heart Transplantation Using Donation After Circulatory Death Donors in the United States

BACKGROUND

Limited donor availability and evolution in procurement techniques have renewed interest in heart transplantation (HT) with donation after circulatory death (DCD). The aim of this study is to evaluate outcomes of HT using DCD in the United States.

METHODS

The United Network for Organ Sharing registry was used to identify adult HT recipients from 2019 to 2021. Recipients were stratified between DCD and donation after brain death. Propensity-score matching was performed. Cox proportional hazards was used to identify independent predictors of 1-year mortality. Kaplan-Meier analysis was used to estimate 1-year survival.

RESULTS

Of 7496 HTs, 229 DCD and 7267 donation after brain death recipients were analyzed. The frequency of DCD HT increased from 0.2% of all HT in 2019 to 6.4% in 2021 (P<0.001), and the number of centers performing DCD HT increased from 3 of 120 centers to 20 of 121 centers (P<0.001). DCD donors were more likely to be younger, male, and White. After propensity matching, 1-year survival was 92.5% for DCD versus 90.3% for donation after brain death (hazard ratio, 0.80 [95% CI, 0.44-1.43]; P=0.44). Among DCD HTs, increasing recipient age and waitlist time predicted 1-year mortality on univariable analysis.

CONCLUSIONS

Rates of DCD HT in the United States are increasing. This practice appears safe and feasible as mortality outcomes are comparable to donation after brain death. Although this study represents early adopting centers, outcomes of the experience for DCD HT in the United States is consistent with existing international data and encourages broader utilization of this practice.

Comparison of Accuracy of Estimation of Cardiac Output by Thermodilution Versus the Fick Method Using Measured Oxygen Uptake

The thermodilution (TD) method is routinely used for the estimation of cardiac output (Q̇_C). However, its accuracy, compared with the gold-standard Fick method, where systemic oxygen uptake (V̇O₂) is directly measured, and Q̇_C calculated from V̇O₂ and the arterio-venous oxygen difference ("direct" Fick), has not been well validated. The present study determined the agreement between TD and Fick methods in consecutive patients who underwent pulmonary artery catheterization for a broad range of clinical conditions. This is a subanalysis of a previous study comparing the indirect versus Fick method based on a prospective, consecutive patient registry of 253 patients who underwent pulmonary artery catheterization for clinical indications at a single center between 1999 and 2005. We included patients that had an estimation of Q̇_C both by the Fick method using measured V̇O₂ by exhaled gas analyses from timed Douglas bag collections and by TD. Cardiac index was classified as low when ≤2.2 L/min/m² or normal when >2.2 L/min/m². The median (25th, 75th percentile) age of the cohort was 59 (50,67) years, and 50% were female. A total of 43.5% had normal left ventricular function by ventriculography, and 25.7% had ischemic heart disease. Median overall Fick and TD Q̇_C were 4.4 (3.5, 5.5) and 4.3 (3.7, 5.2) L/min, respectively (p = 0.04). The median absolute percent error between Fick and TD Q̇_C was 17.5 (7.7, 28.4)%, with a typical error of 0.88 L/min (95% confidence interval [CI] 0.82 to 0.95). Median absolute percent error was comparable in the low (n = 118) and normal Q̇_CI (n = 135) groups (16.9% vs 18.9%, respectively, p = 0.88). typical error was 0.3 (95% CI 0.27 to 0.33) and 0.49 (95% CI 0.45 to 0.55) L/min/m² in that comparison. Percent error >25% between Fick and TD Q̇_C was observed in over 30% of patients. Overall, Fick and TD Q̇_C modestly correlated (R_s = 0.64, p <0.001), with a nondirectional error introduced by TD Q̇_C [mean bias of 0.21 (-2.2, 2.7) L/min]. There was poor agreement between TD and the gold-standard Fick method, highlighting the limitations of making clinical decisions based on TD.

Diagnosis of Heart Failure With Preserved Ejection Fraction Among Patients With Unexplained Dyspnea

Importance

Diagnosis of heart failure with preserved ejection fraction (HFpEF) among dyspneic patients without overt congestion is challenging. Multiple diagnostic approaches have been proposed but are not well validated against the independent gold standard for HFpEF diagnosis of an elevated pulmonary capillary wedge pressure (PCWP) during exercise.

Objective

To evaluate H2FPEF and HFA-PEFF scores and a PCWP/cardiac output (CO) slope of more than 2 mm Hg/L/min to diagnose HFpEF.

Design, Setting, and Participants

This retrospective case-control study included patients with unexplained dyspnea from 6 centers in the US, the Netherlands, Denmark, and Australia from March 2016 to October 2020. Diagnosis of HFpEF (cases) was definitively ascertained by the presence of elevated PCWP during exertion; control individuals were those with normal rest and exercise hemodynamics.

Main Outcomes and Measures

Logistic regression was used to evaluate the accuracy of HFA-PEFF and H2FPEF scores to discriminate patients with HFpEF from controls.

Results

Among 736 patients, 563 (76%) were diagnosed with HFpEF (mean [SD] age, 69 [11] years; 334 [59%] female) and 173 (24%) represented controls (mean [SD] age, 60 [15] years; 109 [63%] female). H2FPEF and HFA-PEFF scores discriminated patients with HFpEF from controls, but the H2FPEF score had greater area under the curve (0.845; 95% CI, 0.810-0.875) compared with the HFA-PEFF score (0.710; 95% CI, 0.659-0.756) (difference, -0.134; 95% CI, -0.177 to -0.094; P < .001). Specificity was robust for both scores, but sensitivity was poorer for HFA-PEFF, with a false-negative rate of 55% for low-probability scores compared with 25% using the H2FPEF score. Use of the PCWP/CO slope to redefine HFpEF rather than exercise PCWP reclassified 20% (117 of 583) of patients, but patients reclassified from HFpEF to control by this metric had clinical, echocardiographic, and hemodynamic features typical of HFpEF, including elevated resting PCWP in 66% (46 of 70) of reclassified patients.

Conclusions and Relevance

In this case-control study, despite requiring fewer data, the H2FPEF score had superior diagnostic performance compared with the HFA-PEFF score and PCWP/CO slope in the evaluation of unexplained dyspnea and HFpEF in the outpatient setting.

Hemodynamic and Clinical Determinants of Left Atrial Enlargement in Liver Transplant Candidates

New-onset heart failure is a frequent complication after orthotopic liver transplantation (OLT). Left atrial enlargement (LAE) may be a sign of occult left heart disease. Our primary objective was to determine invasive hemodynamic and clinical predictors of LAE and then investigate its effect on post-transplant outcomes. Of 609 subjects who received OLT between January 1, 2010, and October 1, 2018, 145 who underwent preoperative right-sided cardiac catheterization and transthoracic echocardiography were included. Seventy-eight subjects (54%) had pretransplant LAE. Those with LAE had significantly lower systemic vascular resistance with higher cardiac and stroke volume index (61.0 vs 51.7 ml/m²; p <0.001), but there was no difference in pulmonary artery wedge pressure. There was a linear relation between left atrial volume index and stroke volume index (R² = 0.490, p<0.001), but not pulmonary artery wedge pressure. The presence of severe LAE was associated with a reduced likelihood (hazard ratio = 0.26, p = 0.033) of reaching the composite end point of new-onset systolic heart failure, heart failure hospitalization, or heart failure death within 12 months post-transplant. There was also a significant reduction in LAE after transplantation (p = 0.013). In conclusion, LAE was common in OLT recipients and was more closely associated with stroke volume than left heart filling pressures. The presence of LAE was associated with a reduced likelihood of reaching composite outcomes and tended to regress after transplant.

Outcomes in LVAD Patients Undergoing Simultaneous Heart-Kidney Transplantation

BACKGROUND

Multiple studies have shown better outcomes for simultaneous heart kidney transplant (sHKT) compared with isolated orthotopic heart transplant (iOHT) in recipients with chronic kidney disease (CKD). However, outcomes in patients supported by durable LVAD have not been well studied.

METHODS

Patients with durable LVADs and stage 3 or greater CKD (eGFR <60ml/min/1.73m2) undergoing iOHT or sHKT between 2008-2020 were identified from the United Network for Organ Sharing (UNOS) registry. Kaplan Meier survival analysis with associated log-rank test was conducted to compare post-transplant survival. Multivariable modeling was used in order to identify risk adjusted predictors of one-year posttransplant mortality.

RESULTS

4375 patients were identified, 366 underwent sHKT and 4009 iOHT. The frequency of sHKT increased over the study period. One-year post-transplant survival was worse in sHKT compared with iOHT (80.3% vs 88.3%, p<0.001), and persisted up to 5 years post-transplant (p=0.001). sHKT recipients were more likely to require dialysis after transplant and had longer hospital length of stay (p<0.001). Multivariable analysis showed sHKT remained an independent risk factor for mortality at 1 year (OR 1.58, p=0.002).

CONCLUSIONS

HKT is becoming more common in patients with durable LVADs. Compared with iOHT, sHKT have worse short and long-term survival are more likely to require posttransplant dialysis.

Angiotensin-converting enzyme inhibitor therapy after heart transplant: from molecular basis to clinical effects

The use of angiotensin-converting enzyme inhibitors is an important therapy for various cardiovascular diseases, such as hypertension, ischemic heart disease and heart failure. In heart transplant recipients, angiotensin-converting enzyme inhibitors have been demonstrated to be a keystone for the treatment of hypertension with a wide spectrum of pleiotropic molecular effects ranging from improvement of the peripheral vascular system to regulation of the fluid and sodium balance. In addition, angiotensin-converting enzyme inhibitors may be also useful in the prevention of graft failure, cardiac allograft vasculopathy and chronic kidney disease progression. Further tailored multi-center and randomized studies are warranted to confirm the pleiotropic clinical effects of ACEi therapy in HTRs and to support more extended use in daily clinical practice. Finally in the near future, the use of novel pharmacological agents that inhibit the renin-angiotensin-aldosterone system such as the neprylisin inhibitor sacubitril should be investigated in heart transplant recipients. This article is protected by copyright. All rights reserved.

Association of soluble Flt-1 with heart failure and cardiac morphology: The MESA angiogenesis study

BACKGROUND

Soluble Fms-like tyrosine kinase 1 (sFlt-1) may inhibit angiogenesis. Higher levels of sFlt-1 are associated with worse prognosis in prevalent heart failure patients. The aim of this study was to better understand the role of sFlt-1 in heart failure pathogenesis by characterizing relationships between sFlt-1, cardiac morphology, and the composite outcome of incident heart failure or cardiovascular (CV) death in in a multiethnic cohort free of CV disease at baseline.

METHODS

sFlt-1 was measured in 1,381 participants in the Multi-Ethnic Study of Atherosclerosis Angiogenesis sub-study. Linear regression was used to estimate the association between sFlt-1 and cardiac morphology and Cox proportional hazard regression was used to estimate associations with incident heart failure or CV mortality.

RESULTS

Over a median follow-up of 13.1 years, higher sFlt-1 levels were associated with incident heart failure or CV mortality independent from CV risk factors or NT-proBNP levels (HR 1.17, 95% CI 1.10-1.26, p < 0.001). Higher sFlt-1 levels were also associated with greater baseline left ventricular (LV) mass by cardiac MRI and increased loss of LV mass over the 10 years following the baseline exam (p-value 0.02 for each), but this association was no longer statistically significant after adjustment for baseline NT-proBNP (p = 0.11 and 0.10 respectively).

CONCLUSIONS

Baseline sFlt-1 levels are associated with incident heart failure and cardiovascular mortality independent of traditional CV risk factors or NT-proBNP. An association was also found with cardiac mass but was no longer significant after adjustment for NT-proBNP.