Impact of Right Ventricular Performance in Patients Undergoing Extracorporeal Membrane Oxygenation Following Cardiac Surgery

Association Between Three-Dimensional Right Ventricular Ejection Fraction and In-Hospital Outcomes in Patients Undergoing Cardiac Surgery: A Multicenter Study

AIMS

Cardiac surgery is the cornerstone of treatment of several heart conditions, but accurate risk stratification is critical. Commonly used scores do not include right ventricular (RV) function. We aimed to evaluate whether three-dimensional (3D) RV ejection fraction (RVEF) predicts outcomes in patients undergoing cardiac surgery after adjusting for the EuroSCORE II.

METHODS AND RESULTS

This is a prospective multicenter study of adult patients undergoing cardiac surgery at 3 centers. Right ventricular function parameters were analyzed with transesophageal echocardiogram before the surgery. We evaluated the association of 3D RVEF with the primary outcome (composite of in-hospital mortality or need of temporary ventricular assist device) after adjusting for the EuroSCORE II. Exploratory end points were time on mechanical ventilation and time on inotropes. We included 248 patients (median age, 69 years; 43% female). Sixty-nine percent had normal RVEF (≥45%). Right ventricular function parameters (tricuspid annular plane systolic excursion, fractional area change, and RV free-wall longitudinal strain) were lower in the group of decreased RVEF (P < .001 for all). The primary outcome occurred in 28 patients (11%). After adjusting for the EuroSCORE II, decreased RVEF was independently associated with the primary outcome (hazard ratio = 2.46; 95% CI, 1.10, 5.50; P = .028). Importantly, 3D RVEF was superior to all other parameters of RV systolic function to predict the primary outcome (P = .006). At 30 days, survival free of the primary end point was 72% ± 8% versus 93% ± 3% (P < .001) in decreased versus normal RVEF, respectively. Right ventricular ejection fraction was associated with shorter time on mechanical ventilation (r = -0.27, P < .001) and shorter time on inotropes (r = -0.20, P = .01).

CONCLUSIONS

Among the RV function parameters, 3D RVEF is the strongest predictor of in-hospital mortality or need of temporary ventricular assist device in patients undergoing cardiac surgery. This multicenter study suggests that 3D RVEF should be included in the evaluation of patients undergoing surgery because it might improve stratification.

Impact of prognostic nutritional index on mortality among patients receiving coronary artery bypass grafting surgery: a retrospective cohort study

BACKGROUND

The Prognostic Nutritional Index (PNI), calculated from serum albumin levels and lymphocyte counts, is a simple and objective measure of nutritional status. While PNI has been shown to be a significant prognostic tool in gastrointestinal surgery and heart failure, its role in patients undergoing coronary artery bypass grafting (CABG) remains unclear. This study aims to evaluate whether PNI can serve as a meaningful risk factor for patients undergoing CABG.

METHODS

This observational retrospective analysis involved a substantial sample of 2889 patients who underwent isolated CABG at one of four medical centres. The primary outcomes included short- and long-term mortality. Perioperative serum albumin levels and total lymphocyte counts used to calculate PNIs were collected 48 hours before the operation, 24 hours after the operation and at discharge. Univariate and multivariate logistic regression analyses were conducted to identify the risk factors of short-term mortality. Survival and relative risks were assessed using Cox regression analysis and the Kaplan-Meier test.

RESULTS

Among the 2889 patients, 64 (2.2%) died within 30 days following CABG. Multivariate logistic regression revealed that higher preoperative PNI was independently associated with reduced short-term mortality (OR=0.852 per unit increase, 95% CI 0.802 to 0.904, p<0.001). Regarding long-term outcomes, among the 2825 patients who were discharged alive, 199 deaths occurred over a median follow-up period of 54.9 months. Patients with a normal PNI at discharge (>40) exhibited significantly higher long-term survival rates compared with those with a lower PNI (≤40) (log-rank p=0.003). Multivariate Cox regression analysis confirmed that a normal PNI at discharge(>40) independently predicted a lower risk of long-term all-cause mortality (HR=0.718, 95% CI 0.529 to 0.974, p=0.033).

CONCLUSIONS

PNI at various time points may play a crucial predictive role in mortality among CABG-treated patients, and a low PNI serves as a risk factor for both short- and long-term survival.

Tricuspid Regurgitation After Heart Transplantation: The Cause or the Result of Graft Dysfunction?

BACKGROUND

Tricuspid regurgitation (TR) is common following heart transplantation and has been shown to adversely influence patient outcomes. The aim of this study was to identify causes of progression to moderate-severe TR in the first 2 y after transplantation.

METHODS

This was a retrospective, single-center study of all patients who underwent heart transplantation over a 6-y period. Transthoracic echocardiogram (TTE) was performed at month 0, between 6 and 12 mo, and 1-2 y postoperatively to determine the presence and severity of TR.

RESULTS

A total of 163 patients were included, of whom 142 underwent TTE before first endomyocardial biopsy. At month 0, 127 (78%) patients had nil-mild TR before first biopsy, whereas 36 (22%) had moderate-severe TR. In patients with nil-mild TR, 9 (7%) progressed to moderate-severe TR by 6 mo and 1 underwent tricuspid valve (TV) surgery. Of patients with moderate-severe TR before first biopsy, by 2 y, 3 had undergone TV surgery. The use of postoperative extracorporeal membrane oxygenation (ECMO) in the latter group was significant (78%; P < 0.05) as was rejection profile ( P = 0.02). Patients with late progressive moderate-severe TR had a significantly higher 2-y mortality than those who had moderate-severe TR immediately.

CONCLUSIONS

Overall, our study has shown that in the 2 main groups of interest (early moderate-severe TR and progression from nil-mild to moderate-severe TR), TR is more likely to be the result of significant underling graft dysfunction rather than the cause of it.

Effect of venoarterial extracorporeal membrane oxygenation initiation timing on tricuspid valve surgery outcomes

Objectives

Tricuspid valve surgery is associated with high rates of shock and in-hospital mortality. Early initiation of venoarterial extracorporeal membrane oxygenation after surgery may provide right ventricular support and improve survival. We evaluated mortality in patients undergoing tricuspid valve surgery based on the timing of venoarterial extracorporeal membrane oxygenation.

Methods

All consecutive adult patients undergoing isolated or combined surgical tricuspid valve repair or replacement from 2010 to 2022 requiring venoarterial extracorporeal membrane oxygenation use were stratified by initiation in the operating room (Early) versus outside of the operating room (Late). Variables associated with in-hospital mortality were explored using logistic regression.

Results

There were 47 patients who required venoarterial extracorporeal membrane oxygenation: 31 Early and 16 Late. Mean age was 55.6 years (standard deviation, 16.8), 25 (54.3%) were in New York Heart Association class III/IV, 30 (60.8%) had left-sided valve disease, and 11 (23.4%) had undergone prior cardiac surgery. Median left ventricular ejection fraction was 60.0% (interquartile range, 45-65), right ventricular size was moderately to severely increased in 26 patients (60.5%), and right ventricular function was moderately to severely reduced in 24 patients (51.1%). Concomitant left-sided valve surgery was performed in 25 patients (53.2%). There were no differences in baseline characteristics or invasive measurements immediately before surgery between the Early and Late groups. Venoarterial extracorporeal membrane oxygenation was initiated 194 (23.0-840.0) minutes after cardiopulmonary bypass in the Late venoarterial extracorporeal membrane oxygenation group. In-hospital mortality was 35.5% (n = 11) in the Early group versus 68.8% (n = 11) in the Late group (P = .037). Late venoarterial extracorporeal membrane oxygenation was associated with in-hospital mortality (odds ratio, 4.00; 1.10-14.50; P = .035).

Conclusions

Early postoperative initiation of venoarterial extracorporeal membrane oxygenation after tricuspid valve surgery in high-risk patients may be associated with improvement in postoperative hemodynamics and in-hospital mortality.

Prognostic models for mortality risk in patients requiring ECMO

PURPOSE

To provide an overview and evaluate the performance of mortality prediction models for patients requiring extracorporeal membrane oxygenation (ECMO) support for refractory cardiocirculatory or respiratory failure.

METHODS

A systematic literature search was undertaken to identify studies developing and/or validating multivariable prediction models for all-cause mortality in adults requiring or receiving veno-arterial (V-A) or veno-venous (V-V) ECMO. Estimates of model performance (observed versus expected (O:E) ratio and c-statistic) were summarized using random effects models and sources of heterogeneity were explored by means of meta-regression. Risk of bias was assessed using the Prediction model Risk Of BiAS Tool (PROBAST).

RESULTS

Among 4905 articles screened, 96 studies described a total of 58 models and 225 external validations. Out of all 58 models which were specifically developed for ECMO patients, 14 (24%) were ever externally validated. Discriminatory ability of frequently validated models developed for ECMO patients (i.e., SAVE and RESP score) was moderate on average (pooled c-statistics between 0.66 and 0.70), and comparable to general intensive care population-based models (pooled c-statistics varying between 0.66 and 0.69 for the Simplified Acute Physiology Score II (SAPS II), Acute Physiology and Chronic Health Evaluation II (APACHE II) score and Sequential Organ Failure Assessment (SOFA) score). Nearly all models tended to underestimate mortality with a pooled O:E > 1. There was a wide variability in reported performance measures of external validations, reflecting a large between-study heterogeneity. Only 1 of the 58 models met the generally accepted Prediction model Risk Of BiAS Tool criteria of good quality. Importantly, all predicted outcomes were conditional on the fact that ECMO support had already been initiated, thereby reducing their applicability for patient selection in clinical practice.

CONCLUSIONS

A large number of mortality prediction models have been developed for ECMO patients, yet only a minority has been externally validated. Furthermore, we observed only moderate predictive performance, large heterogeneity between-study populations and model performance, and poor methodological quality overall. Most importantly, current models are unsuitable to provide decision support for selecting individuals in whom initiation of ECMO would be most beneficial, as all models were developed in ECMO patients only and the decision to start ECMO had, therefore, already been made.

Impact of Extracorporeal Membrane Oxygenation on Right Ventricular Function After Heart Transplantation

Aims

Acute right ventricular failure remains a common challenging clinical syndrome in heart transplant (HTx) recipients. While extracorporeal membrane oxygenation (ECMO) is a proven strategy for the treatment of this condition, the outcomes after weaning and during follow up remain understudied. We aimed to evaluate the right-sided heart function in ECMO survivors following HTx.

Methods

Between September 2005 and December 2019, 205 patients with end-stage heart failure who underwent standard orthotopic HTx were enrolled. In total, 68 (33.2%) patients were included in the ECMO group and 137 (66.8%) patients were included in the non-ECMO group.

Results

Of the 68 patients in the ECMO group, 42 (61.8%) were successfully weaned from ECMO. After a median follow-up period of 53 months, there were 25 (59.5%) and 27 (23.7%) deaths in the ECMO and non-ECMO groups (P = 0.023), respectively. Systolic pulmonary artery pressure (SPAP) before discharge (P = 0.003) was the unique predictor of all-cause mortality during follow up. Meanwhile, patients in the ECMO group with more than moderate SPAP increase before discharge had higher mortality than patients in the non-ECMO group without such increase (P = 0.005).

Conclusions

Recipient right-sided heart characteristics were strong predictors of ECMO need after HTx. ECMO patients had high mortality in the perioperative and follow-up periods, and the changes in right ventricular function in ECMO patients may be associated with pulmonary vessel injury before and after HTx.

Exploration of the Utility of Speckle-Tracking Echocardiography During Mechanical Ventilation and Mechanical Circulatory Support

This narrative review aims to discuss the potential applicability of speckle-tracking echocardiography (STE) in patients under mechanical ventilation (MV) and mechanical circulatory support (MCS). Both its benefits and limitations were considered through critical analyses of the current available evidence.

Utility of echocardiographic right ventricular subcostal strain in critical care

AIMS

Right ventricular (RV) strain is a known predictor of outcomes in various heart and lung pathologies but has been considered too technically challenging for routine use in critical care. We examined whether RV strain acquired from the subcostal view, frequently more accessible in the critically ill, is an alternative to conventionally derived RV strain in intensive care.

METHODS AND RESULTS

RV strain data were acquired from apical and subcostal views on transthoracic echocardiography (TTE) in 94 patients (35% female), mean age 50.5 ± 15.2 years, venovenous extracorporeal membrane oxygenation (VVECMO) (44%). RV strain values from the apical (mean ± standard deviation; -20.4 ± 6.7) and subcostal views (-21.1 ± 7) were highly correlated (Pearson's r -0.89, P < 0.001). RV subcostal strain correlated moderately well with other echocardiography parameters including tricuspid annular plane systolic excursion (r -0.44, P < 0.001), RV systolic velocity (rho = -0.51, P < 0.001), fractional area change (r -0.66, P < 0.01), and RV outflow tract velocity time integral (r -0.49, P < 0.001). VVECMO was associated with higher RV subcostal strain (non-VVECMO -19.6 ± 6.7 vs. VVECMO -23.2 ± 7, P = 0.01) but not apical RV strain. On univariate analysis, RV subcostal strain was weakly associated with survival at 30 days (R2 = 0.04, P = 0.05, odds ratio =1.08) while apical RV was not (P = 0.16).

CONCLUSION 

RV subcostal deformation imaging is a reliable surrogate for conventionally derived strain in critical care and may in time prove to be a useful diagnostic marker in this cohort.

ECMO and Right Ventricular Failure: Review of the Literature

Right ventricular (RV) failure is the inability of the RV to maintain sufficient cardiac output in the setting of adequate preload, due to either intrinsic injury to the RV or increased afterload. Medical treatment of RV failure should include optimizing preload, augmenting contractility with vasopressors and inotropes, and considering inhaled pulmonary vasodilators. However, when medical therapies are insufficient, mechanical circulatory support (MCS) is needed to maintain systemic and RV perfusion. The data on MCS for isolated RV failure are limited, but extracorporeal membrane oxygenation (ECMO) appears to be the most efficient and effective modality. For patients with isolated RV failure from acute hypoxemic respiratory failure, veno-venous (VV) ECMO is an appropriate initial configuration, even if the patient is in shock. With primary RV injury or RV failure with concomitant left ventricle (LV) failure, however, venoarterial (VA) ECMO is indicated. Both modalities provide indirect support to the RV by reducing preload, reducing RV wall tension, and delivering oxygenated blood to the coronary circulation. Peripheral cannulation is required in VV-ECMO and is most commonly used in VA-ECMO, allowing for rapid cannulation even in emergencies. Changes in pulsatility on an arterial catheter waveform can indicate changes in clinical status including changes in myocardial function, inadequate preload, worsening RV failure, and excessive VA-ECMO support leading to an elevated LV afterload. Myocardial function may be improved by titration of inotropes or vasodilators, utilization of an Impella or an intra-aortic balloon counterpulsation support devices, or by changes in VA-ECMO support.

Risk factors of in-hospital mortality in adult postcardiotomy cardiogenic shock patients successfully weaned from venoarterial extracorporeal membrane oxygenation

OBJECTIVE

Mortality of adult postcardiotomy cardiogenic shock patients after successfully weaned from venoarterial extracorporeal membrane oxygenation remains high. The objective of this study is to identify the risk factors associated with mortality after successfully weaning from venoarterial extracorporeal membrane oxygenation in adult postcardiotomy cardiogenic shock patients.

METHODS

All consecutive patients who were successfully weaned from venoarterial extracorporeal membrane oxygenation between January 2011 and December 2016 at the Beijing Anzhen Hospital were analyzed retrospectively. Multivariate logistic regression was performed to identify risk factors associated with in-hospital mortality after successfully weaning from venoarterial extracorporeal membrane oxygenation.

RESULTS

In total, 212 (58.4%) of 363 postcardiotomy cardiogenic shock patients were successfully weaned from venoarterial extracorporeal membrane oxygenation. The non-survivors had a longer duration of extracorporeal membrane oxygenation than the survivors (120.0 (98.0, 160.50) vs. 100.0 (77.0, 126.0), p = 0.000). Variables associated with mortality of patients successfully weaned from extracorporeal membrane oxygenation by univariable analysis were age, diabetes, vasoactive inotropic score pre-extracorporeal membrane oxygenation, vasoactive inotropic score at weaning, left ventricular ejection fraction at weaning, central venous pressure at weaning, sequential organ failure assessment score pre-extracorporeal membrane oxygenation, sequential organ failure assessment at weaning, survival after venoarterial ECMO pre-extracorporeal membrane oxygenation, and survival after venoarterial ECMO at weaning. In the multivariate analysis, sequential organ failure assessment score at weaning (odds ratio = 1.889, 95% confidence interval = 1.460-2.455, p < 0.001) was an independent risk factor for in-hospital mortality of patients successfully weaned from venoarterial extracorporeal membrane oxygenation. The cumulative 30-day survival rate in patients with a sequential organ failure assessment score < 7 was significantly (p < 0.001) higher than in patients with a sequential organ failure assessment score ⩾ 7 (87% vs. 56.7%, p < 0.001).

CONCLUSION

Vasoactive inotropic score, left ventricular ejection fraction, central venous pressure, and sequential organ failure assessment score at weaning were associated with in-hospital mortality for postcardiotomy cardiogenic shock patients successfully weaned from venoarterial extracorporeal membrane oxygenation. Sequential organ failure assessment score might help clinicians to predict in-hospital mortality for patients successfully weaned from venoarterial extracorporeal membrane oxygenation.

Extracorporeal organ support (ECOS) in critical illness and acute kidney injury: from native to artificial organ crosstalk

The complex nature of single organ failure potentially leading to multiple organ dysfunction syndrome (MODS) in critically ill patients necessitates integrated supportive therapy. Rather than a primary disease, acute kidney injury (AKI) is considered a window to a potentially serious underlying systemic disease, which may partially explain the high morbidity and mortality rates associated with the condition. Renal replacement therapy (RRT) has been routinely used for more than a decade in various intensive care settings and there has also been an increase in the use of extracorporeal membrane oxygenation and extracorporeal carbon dioxide removal. When these renal and cardiopulmonary modalities are used together, a multidisciplinary approach is necessary to minimize negative interactions and unwanted adverse effects. In this review, we describe the patterns of organ crosstalk between the native and artificial organs, the incidence of AKI and need for RRT and associated mortality after extracorporeal organ support (ECOS) therapy, including the potential short- and long-term advantages and disadvantages of organ support in terms of renal function. We also review potential indications of RRT outside its conventional indications in patients with MODS, as well as technical considerations when RRT is used alongside other organ support therapies. Overall, available literature has not definitely established the ideal timing of these interventions, and whether early implementation impacts organ recovery and optimizes resource utilization is still a matter of open debate: it is possible that future research will be devoted to identify patient groups that may benefit from short- and long-term multiple organ support.