Predictors of low cardiac output syndrome after isolated coronary artery bypass surgery: trends over 20 years

Time-Varying Clearance in Milrinone Pharmacokinetics from Premature Neonates to Adolescents

BACKGROUND AND OBJECTIVES

Milrinone is an inotrope and vasodilator used for prophylaxis or treatment of low cardiac output syndrome after weaning from cardiopulmonary bypass (CPB). It is renally eliminated and has an acceptable therapeutic range of 100-300 μg/L, but weight-based dosing alone is associated with poor target attainment. We aimed to develop a population pharmacokinetic model for milrinone from premature neonates to adolescents, and to evaluate how age, renal function and recovery from CPB may impact dose selection.

METHODS

Fifty paediatric patients (aged 4 days to 16 years) were studied after undergoing cardiac surgery supported by CPB. Data from 29 premature neonates (23-28 weeks' postmenstrual age) treated for prophylaxis of low systemic blood flow were available for a pooled pharmacokinetic analysis. Population parameters were estimated using non-linear mixed effects modelling (NONMEM 7.5.1).

RESULTS

There were 369 milrinone measurements available for analysis. A one-compartment model with zero-order input and first-order elimination was used to describe milrinone disposition. Population parameters were clearance 17.8 L/70 kg [95% CI 15.8-19.9] and volume 20.4 L/h/70 kg [95% CI 17.8-22.1]. Covariates included size, postmenstrual age and renal function for clearance, and size and postnatal age for volume. Milrinone clearance is reduced by 39.5% [95% CI 24.0-53.7] immediately after bypass, and recovers to baseline clearance with a half-time of 12.0 h [95% CI 9.7-15.2]. Milrinone volume was 2.07 [95% CI 1.87-2.27] times greater at birth than the population standard and decreased over the first days of life with a half-time of 0.977 days [95% CI 0.833-1.12].

CONCLUSION

Milrinone is predominately renally eliminated and so renal function is an important covariate describing variability in clearance. Increasing clearance over time likely reflects increasing cardiac output and renal perfusion due to milrinone and return to baseline following CPB.

Identifying and mitigating risk of postcardiotomy cardiogenic shock in patients with ischemic and nonischemic cardiomyopathy

OBJECTIVES

To identify preoperative predictors of postcardiotomy cardiogenic shock in patients with ischemic and nonischemic cardiomyopathy and evaluate trajectory of postoperative ventricular function.

METHODS

From January 2017 to January 2020, 238 patients with ejection fraction <30% (206/238) or 30% to 34% with at least moderately severe mitral regurgitation (32/238) underwent conventional cardiac surgery at Cleveland Clinic, 125 with ischemic and 113 with nonischemic cardiomyopathy. Preoperative ejection fraction was 25 ± 4.5%. The primary outcome was postcardiotomy cardiogenic shock, defined as need for microaxial temporary left ventricular assist device, extracorporeal membrane oxygenation, or vasoactive-inotropic score >25. RandomForestSRC was used to identify its predictors.

RESULTS

Postcardiotomy cardiogenic shock occurred in 27% (65/238). Pulmonary artery pulsatility index <3.5 and pulmonary capillary wedge pressure >19 mm Hg were the most important factors predictive of postcardiotomy cardiogenic shock in ischemic cardiomyopathy. Cardiac index <2.2 L·min-1 m-2 and pulmonary capillary wedge pressure >21 mm Hg were the most important predictive factors in nonischemic cardiomyopathy. Operative mortality was 1.7%. Ejection fraction at 12 months after surgery increased to 39% (confidence interval, 35-40%) in the ischemic group and 37% (confidence interval, 35-38%) in the nonischemic cardiomyopathy group.

CONCLUSIONS

Predictors of postcardiotomy cardiogenic shock were different in ischemic and nonischemic cardiomyopathy. Right heart dysfunction, indicated by low pulmonary artery pulsatility index, was the most important predictor in ischemic cardiomyopathy, whereas greater degree of cardiac decompensation was the most important in nonischemic cardiomyopathy. Therefore, preoperative right heart catheterization will help identify patients with low ejection fraction who are at greater risk of postcardiotomy cardiogenic shock.

Anisocytosis as a possible predictor of low cardiac output syndrome in children undergoing mitral valve surgery

PURPOSE

Mitral valve surgery in children involves correcting congenital and acquired pathologies, with a reported mortality rate of 0.9%. Low cardiac output syndrome (LCOS) is a serious complication with the incidence of 20-25%. The aim of the study was to estimate possible prognostic factors of LCOS in children undergoing mitral valve procedure.

MATERIAL AND METHOD

This single-center retrospective analysis enrolled children aged <18 years who underwent mitral valve surgery during 24 year period. Preoperative clinical and laboratory parameters, and operative factors were analyzed.

RESULTS

Thirty consecutive pediatric patients (11 (37%) males and 19 (63%) females) in median (Q1 - Q3) age of 57 (25-115) months, who underwent mitral valve replacement, were included. The 30-day mortality was 7% (2 patients) and was related to postoperative multiorgan failure. LCOS occurred in 8 (27%) children. The receiver operator curve (ROC) analysis established parameters that have predictive value for LCOS occurrence: cardiopulmonary bypass (CPB) time, with 89 ​min as optimal cut-off point (AUC ​= ​0.744, p ​= ​0.011) yielding sensitivity of 100% and specificity of 42.9%; left ventricular ejection fraction (LVEF) ​< ​60 % (AUC ​= ​0.824, okp ​= ​0.001) with sensitivity of 62.5% and specificity of 93.75%; and red blood cell distribution width (RDW) above 14.5 % (AUC ​= ​0.840, p ​< ​0.001; sensitivity of 87.5% and specificity of 75%).

CONCLUSIONS

In mitral valve replacement in pediatric patients, CPBtime above 89 ​min, preoperative LVEF below 60% and preoperative RDW above 14.5% can be regarded as the potential predictors of LCOS.

Effects of multimodal low-opioid anesthesia protocol during on-pump coronary artery bypass grafting: a prospective cohort study

BACKGROUND

The most favorable anesthesia protocol during on-pump coronary artery bypass grafting (CABG) in patients with coronary heart disease remains unclear, despite previous publications regarding the interaction between anesthesia protocol and postoperative complications. The aim of the study was to compare the effect of a multimodal low-opioid anesthesia protocol (MLOP) on early postoperative complications during on-pump CABG.

METHODS

A single-center prospective cohort study including 120 patients undergoing on-pump CABG aged 18 to 65 years, divided into two groups according to undergoing MLOP or routine-opioid anesthesia protocol (ROP). The analyzed parameters were plasma IL-6 levels, complications, duration of mechanical ventilation, length of intensive care unit stay, and hospitalization.

RESULTS

In the MLOP group, the levels of IL-6 at the end of the surgery were 25.6% significantly lower compared to the ROP group (33.4 ± 9.4 vs. 44.9 ± 15.9, p < 0.0001), the duration of mechanical ventilation was significantly shorter (2.0 (2.0; 3.0) h vs. 4.0 (3.0; 5.0) h, p < 0.001), the incidence of low cardiac output syndrome was almost two and half times lower (7 (11.7%) vs. 16 (26.7%), p = 0.037), and also the incidence of postoperative atrial fibrillation was significantly lower (9 (15.0%) vs. 19 (31.7%), p = 0.031).

CONCLUSION

Our study confirms that using MLOP was characterized by significantly lower levels of IL-6 at the end of surgery and a lower incidence of low cardiac output syndrome and postoperative atrial fibrillation than ROP.

TRIAL REGISTRATION

The study is registered in clinicaltrials.gov №NCT05514652.

Development and Validation of a Prediction Score for Low-Cardiac-Output Syndrome After Adult Cardiac Surgery

OBJECTIVES

The authors aimed to develop a simple prediction score to help identify patients at high risk of low-cardiac-output syndrome after adult cardiac surgery.

DESIGN

A single-center, retrospective, observational study.

SETTING

At a tertiary hospital.

PARTICIPANTS

Adult patients who underwent on-pump cardiac surgery between April 2016 and March 2021.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Among the 2,806 patients retained for final analyses, 355 (12.7%) developed low-cardiac-output syndrome. Using a stepwise backward variable selection procedure applied to a multivariate logistic regression, a prediction model, including 8 risk factors, could be identified-preoperative left ventricular ejection fraction, glomerular filtration rate <60 mL/min according to the Cockcroft formula or preoperative dialysis, combined surgery, nonelective surgery, mitral valve surgery for mitral valve regurgitation, history of extracardiac arteriopathy, preoperative hemoglobin <13 g/dL, and New York Heart Association functional class III or IV. A clinical prediction score was derived from the regression coefficients. The model had a good discriminative ability, with an area under the receiver operating characteristics curve of 0.8 (95% CI: 077-0.84). Using a threshold value of 5, the score had a 68% sensitivity, 79% specificity, a positive-predictive value of 33%, and a negative-predictive value of 94%. These results were validated on a validation sample using the bootstrap resampling technique.

CONCLUSIONS

The authors developed a clinical score to facilitate the prediction of low- cardiac-output syndrome after adult cardiac surgery. This could help tailor patient management by contributing to the early identification of those at high risk of postoperative low cardiac output.

Analysis of P(v-a)CO2/C(a-v)O2 Ratio and Other Perfusion Markers in a Population of 98 Pediatric Patients Undergoing Cardiac Surgery

BACKGROUND

The so-called Low Cardiac Output Syndrome (LCOS) is one of the most common complications in pediatric patients with congenital heart disease undergoing corrective surgery. LCOS requires high concentrations of inotropes to support cardiac contractility and improve cardiac output, allowing for better systemic perfusion. To date, serum lactate concentrations and central venous oxygen saturation (ScVO2) are the most commonly used perfusion markers, but they are not completely reliable in identifying a state of global tissue hypoxia. The study aims to evaluate whether the venoarterial carbon dioxide difference/arterial-venous oxygen difference ratio [P(v-a)CO2/C(a-v)O2] can be a good index to predict the development of LCOS in the aforementioned patients, so as to treat it promptly.

METHODS

This study followed a population of 98 children undergoing corrective cardiac surgery from June 2018 to October 2020 at the Department of Cardiac Surgery of University Hospital Integrated Trust and their subsequent admission at the Postoperative Cardiothoracic Surgery Intensive Care Unit. During the study, central arterial and venous blood gas analyses were carried out before and after cardiopulmonary bypass (CPB) (pre-CPB and post-CPB), at admission to the intensive care unit, before and after extubation, and at any time of instability or modification of the patient's clinical and therapeutic conditions.

RESULTS

The data analysis shows that 46.9% of the children developed LCOS (in line with the current literature) but that there is no statistically significant association between the P(v-a)CO2/C(a-v)O2 ratio and LCOS onset. Despite the limits of statistical significance, however, a 31% increase in the ratio emerged from the pre-CPB phase to the post-CPB phase when LCOS is present.

CONCLUSIONS

This study confirms a statistically significant association between the most used markers in adult patients (serum lactate concentration, ScVO2, and oxygen extraction ratio-ERO2) measured in the pre-CPB phase and the incidence of LCOS onset, especially in patients with hemodynamic instability before surgery.

The Value of Stress-Gated Blood Pool SPECT in Predicting Early Postoperative Period Complications in Ischemic Cardiomyopathy Patients: Focus on Mechanical Dyssynchrony

(1) Objective: The objective of this study was to assess the prognostic value of stress-gated blood pool SPECT (GBPS) estimates in patients with ischemic cardiomyopathy (ICM) in the early postoperative period. (2) Methods: A total of 57 patients (age 59.7 ± 6.6, 47 men) with ICM and LV ejection fraction (30 [27.5; 35]%) were enrolled in the study. Before surgical treatment, all patients underwent GBPS (rest-stress, dobutamine doses of 5/10/15 µg/kg/min). Stress-induced changes in left ventricular (LV) ejection fraction, peak ejection rate, volumes, and mechanical dyssynchrony (phase histogram standard deviation, phase entropy (PE), and phase histogram bandwidth) were estimated. Two-dimensional transthoracic echocardiography was performed baseline. Serum levels of NT-proBNP were analyzed with enzyme-linked immunoassay. (3) Results: After surgical treatment, patients were divided into two groups, one, with death, the need for an intra-aortic balloon pump (IABP) or/and inotropic support with a stay in the intensive care unit for more than two days and two, without complications in the early postoperative period (EPOP). Complicated EPOP (CEPOP) was observed in 17 (30%) patients (death-2, IABP-4, extra inotropic support in intensive care unit-11), and 40 patients had no complications (NCEPOP). GBPS showed differences in LV EDV (mL) (321 [268; 358] vs. 268 [242; 313], p = 0.02), LV ESV (mL) (242 [201; 282] vs. 196 [170; 230], p = 0.005), and stress-induced changes in PE (1 (-2; 3) vs. -2 (-4; 0), p = 0.02). Aortic cross-clamp time and stress-induced changes in PE between rest and dobutamine dose of 10 µg/kg/min were the only independent predictors of CEPOP. An increase in LV entropy ≥ 1 on the dobutamine dose of 10µg/kg/min in comparison to rest investigation showed AUC = 0.853 (sensitivity = 62%, specificity = 90%, PPV = 71%; NPV = 85%; p < 0.0001). Conclusion: Stress-induced changes in PE obtained during low-dose dobutamine GBPS are associated with a complicated course of the early postoperative period after surgical treatment for ICM.

Assessing the Patient Outcomes and Performance of a Cardiothoracic and Vascular Surgery (CTVS) Unit During Its First Two Years in a Tier-2 City in India: A Comprehensive Audit and Analysis

This detailed article presents a comprehensive overview of the initial two-year experience in establishing a new cardiothoracic vascular surgery (CTVS) facility in a tier-2 city in India. The article discusses various aspects of setting up and operating a specialized healthcare facility. The first two years of developing the CTVS facility were included in the study period. The manpower included one cardiothoracic vascular surgeon, one cardiac anesthesiologist, two perfusionists, and two physician assistants, along with four other ancillary staff to assist in the smooth functioning of the operation theater. The CTVS recovery staff included 15 nursing officers. There was only one modular operation theater reserved for cardiothoracic vascular surgeries, along with a five-bed recovery room (CTVS intensive care unit). One-hundred-seventy-two procedures were done, including 122 open heart surgeries, 36 vascular procedures, and 14 thoracic procedures. The majority of patients were discharged by the seventh day postoperatively. Overall complication and mortality rates were 8% and 4.6%, respectively. This article also discusses relevant hospital policy, challenges faced, and future recommendations for similar endeavors. The findings highlight the successful implementation of the facility and its impact on providing specialized cardiac care to the local population.

Patient-, Clinician-, and Institution-level Variation in Inotrope Use for Cardiac Surgery: A Multicenter Observational Analysis

BACKGROUND

Conflicting evidence exists regarding the risks and benefits of inotropic therapies during cardiac surgery, and the extent of variation in clinical practice remains understudied. Therefore, the authors sought to quantify patient-, anesthesiologist-, and hospital-related contributions to variation in inotrope use.

METHODS

In this observational study, nonemergent adult cardiac surgeries using cardiopulmonary bypass were reviewed across a multicenter cohort of academic and community hospitals from 2014 to 2019. Patients who were moribund, receiving mechanical circulatory support, or receiving preoperative or home inotropes were excluded. The primary outcome was an inotrope infusion (epinephrine, dobutamine, milrinone, dopamine) administered for greater than 60 consecutive min intraoperatively or ongoing upon transport from the operating room. Institution-, clinician-, and patient-level variance components were studied.

RESULTS

Among 51,085 cases across 611 attending anesthesiologists and 29 hospitals, 27,033 (52.9%) cases received at least one intraoperative inotrope, including 21,796 (42.7%) epinephrine, 6,360 (12.4%) milrinone, 2,000 (3.9%) dobutamine, and 602 (1.2%) dopamine (non-mutually exclusive). Variation in inotrope use was 22.6% attributable to the institution, 6.8% attributable to the primary attending anesthesiologist, and 70.6% attributable to the patient. The adjusted median odds ratio for the same patient receiving inotropes was 1.73 between 2 randomly selected clinicians and 3.55 between 2 randomly selected institutions. Factors most strongly associated with increased likelihood of inotrope use were institutional medical school affiliation (adjusted odds ratio, 6.2; 95% CI, 1.39 to 27.8), heart failure (adjusted odds ratio, 2.60; 95% CI, 2.46 to 2.76), pulmonary circulation disorder (adjusted odds ratio, 1.72; 95% CI, 1.58 to 1.87), loop diuretic home medication (adjusted odds ratio, 1.55; 95% CI, 1.42 to 1.69), Black race (adjusted odds ratio, 1.49; 95% CI, 1.32 to 1.68), and digoxin home medication (adjusted odds ratio, 1.48; 95% CI, 1.18 to 1.86).

CONCLUSIONS

Variation in inotrope use during cardiac surgery is attributable to the institution and to the clinician, in addition to the patient. Variation across institutions and clinicians suggests a need for future quantitative and qualitative research to understand variation in inotrope use affecting outcomes and develop evidence-based, patient-centered inotrope therapies.

EDITOR’S PERSPECTIVE

Comparison of vasoactive-inotropic score, vasoactive-ventilation-renal score, and modified vasoactive-ventilation-renal score for predicting the poor prognosis after coronary artery bypass grafting

BACKGROUND

Exploring reliable prediction scoring systems is valuable for the poor prognosis of patients after coronary artery bypass grafting (CABG). Herein, we explored and compared the predictive performance of vasoactive-inotropic score (VIS), vasoactive-ventilation-renal (VVR) score, and modified VVR (M-VVR) score in the poor prognosis of patients undergoing CABG.

METHODS

A retrospective cohort study was performed in Affiliated Hospital of Jining Medical University, and data of 537 patients were collected from January 2019 to May 2021. The independent variables were VIS, VVR, and M-VVR. Study endpoint of interest was the poor prognosis. Association between VIS, VVR, M-VVR and poor prognosis was assessed using logistic regression analysis, and odds ratios (OR) and 95% confidence intervals (CIs) were reported. The performance of VIS, VVR, and M-VVR to predict the poor prognosis was assessed by calculating the area under the curve (AUC), and differences of the AUC of the three scoring systems were compared using DeLong test.

RESULTS

After adjusting gender, BMI, hypertension, diabetes, surgery methods, and left ventricular ejection fraction (LVEF), VIS (OR: 1.09, 95%CI: 1.05-1.13) and M-VVR (OR: 1.09, 95%CI: 1.06-1.12) were associated with the increased odds of poor prognosis. The AUC of M-VVR, VVR, and VIS was 0.720 (95%CI: 0.668-0.771), 0.621 (95%CI: 0.566-0.677), and 0.685 (95%CI: 0.631-0.739), respectively. DeLong test displayed that the performance of M-VVR was better than VVR (P = 0.004) and VIS (P = 0.003).

CONCLUSIONS

Our study found the good prediction performance of M-VVR for the poor prognosis of patients undergoing CABG, indicating that M-VVR may be a useful prediction index in the clinic.

A new machine learning algorithm to predict veno-arterial ECMO implantation after post-cardiotomy low cardiac output syndrome

BACKGROUND

Post-cardiotomy low cardiac output syndrome (PC-LCOS) is a life-threatening complication after cardiac surgery involving a cardiopulmonary bypass (CPB). Mechanical circulatory support with veno-arterial membrane oxygenation (VA-ECMO) may be necessary in the case of refractory shock. The objective of the study was to develop a machine-learning algorithm to predict the need for VA-ECMO implantation in patients with PC-LCOS.

PATIENTS AND METHODS

Patients were included in the study with moderate to severe PC-LCOS (defined by a vasoactive inotropic score (VIS) > 10 with clinical or biological markers of impaired organ perfusion or need for mechanical circulatory support after cardiac surgery) from two university hospitals in Paris, France. The Deep Super Learner, an ensemble machine learning algorithm, was trained to predict VA-ECMO implantation using features readily available at the end of a CPB. Feature importance was estimated using Shapley values.

RESULTS

Between January 2016 and December 2019, 285 patients were included in the development dataset and 190 patients in the external validation dataset. The primary outcome, the need for VA-ECMO implantation, occurred respectively, in 16% (n = 46) and 10% (n = 19) in the development and the external validation datasets. The Deep Super Learner algorithm achieved a 0.863 (0.793-0.928) ROC AUC to predict the primary outcome in the external validation dataset. The most important features were the first postoperative arterial lactate value, intraoperative VIS, the absence of angiotensin-converting enzyme treatment, body mass index, and EuroSCORE II.

CONCLUSIONS

We developed an explainable ensemble machine learning algorithm that could help clinicians predict the risk of deterioration and the need for VA-ECMO implantation in moderate to severe PC-LCOS patients.

The relationship between pre-operative right ventricular longitudinal strain and low-cardiac-output syndrome after surgical aortic valve replacement

Objectives

This study was performed to investigate the relationship between right ventricular free wall longitudinal strain (RVFWSL) and low cardiac output syndrome (LCOS) after surgical aortic valve replacement (SAVR) and to further explore its association with readmission within 2 years in patients who developed LCOS after SAVR.

Methods

This single-center retrospective observational study involved consecutive patients who underwent SAVR at our hospital from May 2018 to June 2020. Preoperative echocardiography was obtained within 3 days before SAVR. The longitudinal strain of the right ventricle was analyzed using the right ventricle as the main section, and the RVFWSL and right ventricular four-chamber longitudinal strain (RV4CSL) were obtained. The primary observation was the occurrence of LCOS. The secondary prognostic indicators were mainly the readmission rates within 2 years.

Results

In total, 146 patients were finally included in this study. The RVFWSL was significantly lower in the LCOS group than in the No-LCOS group (16.63 ± 2.10) vs. (23.95 ± 6.33), respectively; P < 0.001). The multivariate regression analysis showed that the RVFWSL was associated with LCOS (odds ratio, 1.676; 95% confidence interval, 1.258-2.232; P < 0.001). The receiver operating characteristic curve showed that the cut-off value for RVFWSL to predict LCOS was less than -18.3, with an area under the curve of 0.879, sensitivity of 100%, and specificity of 80.47%. The multivariate regression analysis showed that LCOS was an independent risk factor for readmission within 2 years in patients undergoing SAVR.

Conclusion

Patients with RVFWSL (<-18.3%) may be an increased risker for LCOS after SAVR. The occurrence of LCOS after SAVR is Yong-jian Zhang a risk factor for readmission within 2 years. Right ventricular function monitoring may have some predictive value for the postoperative prognosis in patients undergoing SAVR.

Predictors and associated clinical outcomes of low cardiac output syndrome following cardiac surgery: insights from the LEVO-CTS trial

AIMS

High-risk cardiac surgery is commonly complicated by low cardiac output syndrome (LCOS), which is associated with high mortality. There are limited data derived from multi-centre studies with adjudicated endpoints describing factors associated with LCOS and its downstream clinical outcomes.

METHODS AND RESULTS

The Levosimendan in Patients with Left Ventricular Systolic Dysfunction Undergoing Cardiac Surgery Requiring Cardiopulmonary Bypass (LEVO-CTS) trial evaluated prophylactic levosimendan vs. placebo in patients with a reduced ejection fraction undergoing coronary artery bypass grafting (CABG) and/or valve surgery. We conducted a pre-specified analysis on LCOS, which was characterized by a four-part definition. We constructed a multivariable logistical regression model to evaluate risk factors associated with LCOS and performed Cox proportional hazards modelling to determine the association of LCOS with 90-day mortality. A total of 186 (22%) of 849 patients in the LEVO-CTS trial developed LCOS. The factors most associated with a higher adjusted risk of LCOS were pre-operative ejection fraction [odds ratio (OR) 1.26; 95% confidence interval (CI): 1.08-1.46 per 5% decrease] and age (OR 1.13; 95% CI: 1.04-1.24 per 5-year increase), whereas isolated CABG surgery (OR 0.44, 95% CI: 0.31-0.64) and levosimendan use (OR 0.65; 95% CI: 0.46-0.92) were associated with a lower risk of LCOS. Patients with LCOS had worse outcomes, including renal replacement therapy at 30-day (10 vs. 1%) and 90-day mortality (16 vs. 3%, adjusted hazard ratio of 5.04, 95% CI: 2.66-9.55).

CONCLUSION

Low cardiac output syndrome is associated with a high risk of post-operative mortality in high-risk cardiac surgery.

Predictors and clinical outcomes of post-coronary artery bypass grafting cerebrovascular strokes

Background

Despite the improved medical and surgical managements, still there is a significant risk of developing acute cerebrovascular strokes after coronary artery bypass grafting (CABG). Our objectives were to study the immediate and long-term outcomes after CABG and to identify the possible predictors of post-CABG strokes.

Results

Between January 2016 and August 2020, 410 adult patients, mostly males (82.2%), were retrospectively enrolled after CABG. Acute postoperative strokes occurred in 31 (7.5%) patients; of them, 30 (96.8%) patients had ischemic stroke, while 1 (3.2%) had hemorrhagic stroke. Mechanical thrombectomy was done in two cases. The patients who developed acute cerebral stroke had significantly higher admission (p = 0.02) and follow-up (p < 0.001) SOFA scores, higher arterial blood lactate level (p < 0.001), longer hospitalization (p < 0.001) and more hospital mortality (p < 0.001) compared with the patients who did not develop stroke. Kaplan–Meier curves for 5-year mortality showed increased risk in those patients with postoperative stroke (HR: 23.03; 95% CI: 6.10–86.92, p < 0.001). After multivariate regression, the predictors of early postoperative stroke were carotid artery stenosis (CAS), postoperative atrial fibrillation, cardiopulmonary bypass time, prior cerebral stroke, admission SOFA score and chronic kidney disease (CKD). The predictors of late cerebrovascular stroke were CAS, combined CABG and valve surgery, CKD, atrial fibrillation, prior stroke and HbA1c.

Conclusions

The development of post-CABG acute cerebrovascular stroke is associated with longer hospitalization, multiple morbidities and increased mortality. Careful assessment and management of risk factors especially atrial fibrillation and carotid artery stenosis should be implemented to decrease this substantial complication after CABG.

Definitions of low cardiac output syndrome after cardiac surgery and their effect on the incidence of intraoperative LCOS: A literature review and cohort study

Objectives

Low cardiac output syndrome (LCOS) is a serious complication after cardiac surgery. Despite scientific interest in LCOS, there is no uniform definition used in current research and clinicians cannot properly compare different study findings. We aimed to collect the LCOS definitions used in literature and subsequently applied the definitions obtained to existing data to estimate their effect on the intraoperative LCOS incidences in adults, children and infants.

Design

This is a literature review, followed by a retrospective cohort study.

Setting

This is a single-institutional study from a university hospital in the Netherlands.

Participants

Patients from all ages undergoing cardiac surgery with cardiopulmonary bypass between June 2011 and August 2018.

Interventions

We obtained different definitions of LCOS used in the literature and applied these to data obtained from an anesthesia information management system to estimate intraoperative incidences of LCOS. We compared intraoperative incidences of LCOS in different populations based on age (infants, children and adults).

Measurements and main results

The literature search identified 262 LCOS definitions, that were applied to intraoperative data from 7,366 patients. Using the 10 most frequently published LCOS definitions, the obtained incidence estimates ranged from 0.4 to 82% in infants, from 0.6 to 56% in children and from 1.5 to 91% in adults.

Conclusion

There is an important variety in definitions used to describe LCOS. When applied to data obtained from clinical care, these different definitions resulted in large distribution of intraoperative LCOS incidence rates. We therefore advocate for standardization of the LCOS definition to improve clinical understanding and enable adequate comparison of outcomes and treatment effects both in daily care and in research.

Prediction of low cardiac output syndrome in patients following cardiac surgery using machine learning

Background

This study aimed to develop machine learning models to predict Low Cardiac Output Syndrome (LCOS) in patients following cardiac surgery using machine learning algorithms.

Methods

The clinical data of cardiac surgery patients in Nanjing First Hospital between June 2019 and November 2020 were retrospectively extracted from the electronic medical records. Six conventional machine learning algorithms, including logistic regression, support vector machine, decision tree, random forest, extreme gradient boosting and light gradient boosting machine, were employed to construct the LCOS predictive models with all predictive features (full models) and selected predictive features (reduced models). The discrimination of these models was evaluated by the area under the receiver operating characteristic curve (AUC) and the calibration of the models was assessed by the calibration curve. Shapley Additive explanation (SHAP) and Local Interpretable Model-Agnostic Explanations (LIME) were used to interpret the predictive models.

Results

Data from 1,585 patients [982 (62.0%) were male, aged 18 to 88, 212 (13.4%) with LCOS] were employed to train and validate the LCOS models. Among the full models, the RF model (AUC: 0.909, 95% CI: 0.875–0.943; Sensitivity: 0.849, 95% CI: 0.724–0.933; Specificity: 0.835, 95% CI: 0.796–0.869) and the XGB model (AUC: 0.897, 95% CI: 0.859–0.935; Sensitivity: 0.830, 95% CI: 0.702–0.919; Specificity: 0.809, 95% CI: 0.768–0.845) exhibited well predictive power for LCOS. Eleven predictive features including left ventricular ejection fraction (LVEF), first post-operative blood lactate (Lac), left ventricular diastolic diameter (LVDd), cumulative time of mean artery blood pressure (MABP) lower than 65 mmHg (MABP &lt; 65 time), hypertension history, platelets level (PLT), age, blood creatinine (Cr), total area under curve above threshold central venous pressure (CVP) 12 mmHg and 16 mmHg, and blood loss during operation were used to build the reduced models. Among the reduced models, RF model (AUC: 0.895, 95% CI: 0.857–0.933; Sensitivity: 0.830, 95% CI: 0.702–0.919; Specificity: 0.806, 95% CI: 0.765–0.843) revealed the best performance. SHAP and LIME plot showed that LVEF, Lac, LVDd and MABP &lt; 65 time significantly contributed to the prediction model.

Conclusion

In this study, we successfully developed several machine learning models to predict LCOS after surgery, which may avail to risk stratification, early detection and management of LCOS after cardiac surgery.

Comparison of different metrics of cerebral autoregulation in association with major morbidity and mortality after cardiac surgery

BACKGROUND

Cardiac surgery studies have established the clinical relevance of personalised arterial blood pressure management based on cerebral autoregulation. However, variabilities exist in autoregulation evaluation. We compared the association of several cerebral autoregulation metrics, calculated using different methods, with outcomes after cardiac surgery.

METHODS

Autoregulation was measured during cardiac surgery in 240 patients. Mean flow index and cerebral oximetry index were calculated as Pearson's correlations between mean arterial pressure (MAP) and transcranial Doppler blood flow velocity or near-infrared spectroscopy signals. The lower limit of autoregulation and optimal mean arterial pressure were identified using mean flow index and cerebral oximetry index. Regression models were used to examine associations of area under curve and duration of mean arterial pressure below thresholds with stroke, acute kidney injury (AKI), and major morbidity and mortality.

RESULTS

Both mean flow index and cerebral oximetry index identified the cerebral lower limit of autoregulation below which MAP was associated with a higher incidence of AKI and major morbidity and mortality. Based on magnitude and significance of the estimates in adjusted models, the area under curve of MAP < lower limit of autoregulation had the strongest association with AKI and major morbidity and mortality. The odds ratio for area under the curve of MAP < lower limit of autoregulation was 1.05 (95% confidence interval, 1.01-1.09), meaning every 1 mm Hg h increase of area under the curve was associated with an average increase in the odds of AKI by 5%.

CONCLUSIONS

For cardiac surgery patients, area under curve of MAP < lower limit of autoregulation using mean flow index or cerebral oximetry index had the strongest association with AKI and major morbidity and mortality. Trials are necessary to evaluate this target for MAP management.

Serum FGF21 Levels Predict the MACE in Patients With Myocardial Infarction After Coronary Artery Bypass Graft Surgery

Objectives

Prognosis evaluation in myocardial infarction (MI) patients with major adverse clinical events (MACE) who have undergone coronary artery bypass graft (CABG) is greatly important to identify high-risk patients. Elevated metabolic hormone fibroblast growth factor 21 (FGF21) is associated with the risk of MI. The aim of this study is to assess the relationship between FGF21 and the incidence of MACE in patients with MI after CABG surgery.

Methods

Patients with three-vessel disease who were scheduled for first-time isolated CABG were enrolled in this project and underwent to evaluate the incidence of MACE during 48 h after CABG surgery, as well as to collect serum samples for FGF21 levels in both preoperative- and postoperative-CABG (pre-CABG and post-CABG).

Results

A total of 265 patients with MI undergoing CABG were enrolled in this study, 21 patients experienced MACE during the 48 h after CAGB surgery. Serum FGF21 levels of patients with MACE at post-CABG were significantly higher than that in patients without MACE [553.7 (433.6) vs. 291.7 (334.4), p &lt; 0.001]. Furthermore, among 81 individuals of these 265 patients, a lower level of FGF21 in preoperative-CABG (pre-CABG) and a higher level of FGF21 at postoperative-CABG (post-CABG) were observed in MI patients with MACE as compared to those without MACE respectively [ (275.0 (260.4) vs. 410.3 (420.7), p = 0.049; 550.7 (519.9) vs. 370.6 (441.2), p = 0.031]. In addition, serum FGF21 levels of MI patients with MACE at post-CABG were significantly increased compared with the baseline levels in pre-CABG [550.7 (519.9) vs.275.0 (260.4) p &lt; 0.001]. However, these profiles were not observed in patients without MACE [410.3 (420.7) vs. 370.6 (441.2), p=0.2137]. Logistic regression analysis demonstrated that both serum FGF21 and CK-MB levels at post-CABG were independently associated with the incidence of MACE in patients with MI after CABG surgery. Finally, ROC analysis for FGF21 levels of 265 MI patients at post-CABG identified 455.4 pg/ml as an optimal cut-off value to predict MACE, with a sensitivity and specificity of 91.7 and 68.4% respectively.

Conclusion

Serum FGF21 levels at post-CABG are independently associated with the incidence of MACE in patients with MI who have undergone CABG. Measurement of FGF21 may help distinguish patients with MI at a high risk of MACE after CABG surgery.

Risk factors of postoperative low cardiac output syndrome in children with congenital heart disease: A systematic review and meta-analysis

BACKGROUND

Low cardiac output syndrome (LCOS) is the most common complication after cardiac surgery, which is associated with the extension of postoperative hospital stay and postoperative death in children with congenital heart disease (CHD). Although there are some studies on the risk factors of LCOS in children with CHD, an unified conclusion is lack at present.

PURPOSES

To synthesize the risk factors of LCOS after CHD in children, and to provide evidence-based insights into the early identification and early intervention of LCOS.

METHODS

The databases of the China National Knowledge Infrastructure (CNKI), Wanfang Database, China Science and Technology Journal Database (VIP), PubMed, Cochrane Library, Embase and Web of Science were searched for relevant articles that were published between the establishing time of each database and January 2022. Based on retrospective records or cohort studies, the influencing factors of postoperative low cardiac output in children with congenital heart disease were included in Meta analysis.This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The risk of bias was evaluated according to the Newcastle-Ottawa Scale (NOS). RevMan 5.4 software was used to conduct the meta-analysis.

RESULTS

A total of 1,886 records were screened, of which 18 were included in the final review. In total, 37 risk factors were identified in the systematic review. Meta- analysis showed that age, type of CHD, cardiac reoperation, biventricular shunt before operation, CPB duration, ACC duration, postoperative residual shunt, cTn-1 level 2 h after CPB > 14 ng/ml and postoperative 24 h MR-ProADM level > 1.5 nmol/l were independent risk factors of LCOS. Additionally, the level of blood oxygen saturation before the operation was found to have no statistically significant relationship with LOCS.

CONCLUSION

The risk factors of postoperative LCOS in children with CHD are related to disease condition, intraoperative time and postoperative related indexes, so early prevention should be aimed at high-risk children.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/, identifier: CRD42022323043.

Prediction of Short-Term Mortality With Renal Replacement Therapy in Patients With Cardiac Surgery-Associated Acute Kidney Injury

Objective: We aimed to: (1) explore the risk factors that affect the prognosis of cardiac surgery-associated acute kidney injury (CS-AKI) in patients undergoing renal replacement therapy (RRT) and (2) investigate the predictive value of the Acute Physiology and Chronic Health Evaluation (APACHE) III score, Sequential Organ Failure Assessment (SOFA) score, and Vasoactive-Inotropic Score (VIS) for mortality risk in patients undergoing RRT. Methods: Data from patients who underwent cardiac surgery from January 2015 through February 2021 were retrospectively reviewed to calculate the APACHE III score, SOFA score, and VIS on the first postoperative day and at the start of RRT. Various risk factors influencing the prognosis of the patients during treatment were evaluated; the area under the receiver operating characteristics curve (AUCROC) was used to measure the predictive ability of the three scores. Independent risk factors influencing mortality were analyzed using multivariable binary logistic regression. Results: A total of 90 patients were included in the study, using 90-day survival as the end point. Of those patients, 36 patients survived, and 54 patients died; the mortality rate reached 60%. At the start of RRT, the AUCROC of the APACHE III score was 0.866 (95% CI: 0.795-0.937), the VIS was 0.796 (95% CI: 0.700-0.892), and the SOFA score was 0.732 (95% CI: 0.623-0.842). The AUCROC-value of the APACHE III score on the first postoperative day was 0.790 (95% CI: 0.694-0.885). After analyzing multiple factors, we obtained the final logistic regression model with five independent risk factors at the start of RRT: a high APACHE III score (OR: 1.228, 95% CI: 1.079-1.397), high VIS (OR: 1.147, 95% CI: 1.021-1.290), low mean arterial pressure (MAP) (OR: 1.170, 95% CI: 1.050-1.303), high lactate value (OR: 1.552, 95% CI: 1.032-2.333), and long time from AKI to initiation of RRT (OR: 1.014, 95% CI: 1.002-1.027). Conclusion: In this study, we showed that at the start of RRT, the APACHE III score and the VIS can accurately predict the risk of death in patients undergoing continuous RRT for CS-AKI. The APACHE III score on the first postoperative day allows early prediction of patient mortality risk. Predictors influencing patient mortality at the initiation of RRT were high APACHE III score, high VIS, low MAP, high lactate value, and long time from AKI to the start of RRT.

The multivariable prognostic models for severe complications after heart valve surgery

Background

To provide multivariable prognostic models for severe complications prediction after heart valve surgery, including low cardiac output syndrome (LCOS), acute kidney injury requiring hemodialysis (AKI-rH) and multiple organ dysfunction syndrome (MODS).

Methods

We developed multivariate logistic regression models to predict severe complications after heart valve surgery using 930 patients collected retrospectively from the first affiliated hospital of Sun Yat-Sen University from January 2014 to December 2015. The validation was conducted using a retrospective dataset of 713 patients from the same hospital from January 2016 to March 2017. We considered two kinds of prognostic models: the PRF models which were built by using the preoperative risk factors only, and the PIRF models which were built by using both of the preoperative and intraoperative risk factors. The least absolute shrinkage selector operator was used for developing the models. We assessed and compared the discriminative abilities for both of the PRF and PIRF models via the receiver operating characteristic (ROC) curve.

Results

Compared with the PRF models, the PIRF modes selected additional intraoperative factors, such as auxiliary cardiopulmonary bypass time and combined tricuspid valve replacement. Area under the ROC curves (AUCs) of PRF models for predicting LCOS, AKI-rH and MODS are 0.565 (0.466, 0.664), 0.688 (0.62, 0.757) and 0.657 (0.563, 0.751), respectively. As a comparison, the AUCs of the PIRF models for predicting LOCS, AKI-rH and MODS are 0.821 (0.747, 0.896), 0.78 (0.717, 0.843) and 0.774 (0.7, 0.847), respectively.

Conclusions

Adding the intraoperative factors can increase the predictive power of the prognostic models for severe complications prediction after heart valve surgery.

Cardioplegia between Evolution and Revolution: From Depolarized to Polarized Cardiac Arrest in Adult Cardiac Surgery

Despite current advances in perioperative care, intraoperative myocardial protection during cardiac surgery has not kept the same pace. High potassium cardioplegic solutions were introduced in the 1950s, and in the early 1960s they were soon recognized as harmful. Since that time, surgeons have minimized many of the adverse effects by lowering the temperature of the heart, lowering K⁺ concentration, reducing contact K⁺ time, changing the vehicle from a crystalloid solution to whole-blood, adding many pharmacological protectants and modifying reperfusion conditions. Despite these attempts, high potassium remains a suboptimalway to arrest the heart. We briefly review the historical advances and failures of finding alternatives to high potassium, the drawbacks of a prolonged depolarized membrane, altered Ca²⁺ intracellular circuits and heterogeneity in atrial-ventricular K⁺ repolarization during reanimation. Many of these untoward effects may be alleviated by a polarized membrane, and we will discuss the basic science and clinical experience from a number of institutions trialling different alternatives, and our institution with a non-depolarizing adenosine, lidocaine and magnesium (ALM) cardioplegia. The future of polarized arrest is an exciting one and may play an important role in treating the next generation of patients who are older, and sicker with multiple comorbidities and require more complex operations with prolonged cross-clamping times.

Cardiac Safety of Clonidine and Quetiapine in Post-Cardiac Surgery Intensive Care Unit Patients

Background: Clonidine and quetiapine are frequently used medications in the cardiac surgery intensive care unit (ICU). Objective: The purpose of this study is to assess the impact of clonidine compared to quetiapine on cardiac safety outcomes in adult cardiac surgery ICU patients. Methods: This was a single-center, retrospective observational analysis at a tertiary care, academic medical center. Results: One hundred and sixty-one cardiac surgery patients who were administered clonidine or quetiapine during their ICU stay were included between June 2015 and May 2017. The major endpoint of this study was a cardiac safety composite of bradycardia, hypotension, and QTc prolongation. Minor endpoints included ICU and hospital length of stay, and in-hospital mortality. There were 115 patients included in the clonidine arm and 46 patients in the quetiapine arm. There was no difference between groups with regard to the major endpoint (30.43% vs 33.15%; P < .8). There was a shorter ICU and hospital length of stay in the clonidine arm compared to quetiapine P < .0001. All other endpoints were not statistically significant. Conclusion: Patients who received clonidine tended to have undergone less complex procedures, be younger, and have a lower APACHE II score than patients who received quetiapine. The incidence of composite cardiac safety outcomes was not different in clonidine compared to quetiapine in cardiac surgery ICU patients.

Low Microcirculatory Perfused Vessel Density and High Heterogeneity are Associated With Increased Intensity and Duration of Lactic Acidosis After Cardiac Surgery with Cardiopulmonary Bypass

INTRODUCTION

Lactic acidosis after cardiac surgery with cardiopulmonary bypass is common and associated with an increase in postoperative morbidity and mortality. A number of potential causes for an elevated lactate after cardiopulmonary bypass include cellular hypoxia, impaired tissue perfusion, ischemic-reperfusion injury, aerobic glycolysis, catecholamine infusions, and systemic inflammatory response after exposure to the artificial cardiopulmonary bypass circuit. Our goal was to examine the relationship between early abnormalities in microcirculatory convective blood flow and diffusive capacity and lactate kinetics during early resuscitation in the intensive care unit. We hypothesized that patients with impaired microcirculation after cardiac surgery would have a more severe postoperative hyperlactatemia, represented by the lactate time-integral of an arterial blood lactate concentration greater than 2.0 mmol/L.

METHODS

We measured sublingual microcirculation using incident darkfield video microscopy in 50 subjects on intensive care unit admission after cardiac surgery. Serial measurements of systemic hemodynamics, blood gas, lactate, and catecholamine infusions were recorded each hour for the first 6 h after surgery. Lactate area under the curve (AUC) was calculated over the first 6 h. The lactate AUC was compared between subjects with normal and low perfused vessel density (PVD < 18 mm/mm2), high microcirculatory heterogeneity index (MHI > 0.4), and low vessel-by-vessel microvascular flow index (MFIv < 2.6).

RESULTS

Thirteen (26%) patients had a low postoperative PVD, 20 patients (40%) had a high MHI, and 26 (52%) patients had a low MFIv. Patients with low perfused vessel density had higher lactate AUC compared with subjects with a normal PVD (22.3 [9.4-31.0] vs. 2.6 [0-8.8]; P < 0.0001). Patients with high microcirculatory heterogeneity had a higher lactate AUC compared with those with a normal MHI (2.5 [0.1-8.2] vs. 13.1 [3.7-31.1]; P < 0.001). We did not find a difference in lactate AUC when comparing high and low MFIv.

CONCLUSION

Low perfused vessel density and high microcirculatory heterogeneity are associated with an increased intensity and duration of lactic acidosis after cardiac surgery with cardiopulmonary bypass.

Utility of NT-proBNP as an objective marker of postoperative heart failure after coronary artery bypass surgery: a prospective observational study

Background

Postoperative heart failure (PHF) is the main cause for mortality after cardiac surgery but unbiased evaluation of PHF is difficult. We investigated the utility of postoperative NT-proBNP as an objective marker of PHF after coronary artery bypass surgery (CABG).

Methods

Prospective study on 382 patients undergoing isolated CABG for acute coronary syndrome. NT-proBNP was measured preoperatively, the first (POD1) and third postoperative morning (POD3). A blinded Endpoints Committee used prespecified criteria for PHF. Use of circulatory support was scrutinized.

Results

After adjusting for confounders PHF was associated with 1.46 times higher NT-proBNP on POD1 (p = 0.002), 1.54 times higher on POD3 (p < 0.0001). In severe PHF, NT-proBNP was 2.18 times higher on POD1 (p = 0.001) and 1.81 times higher on POD3 (p = 0.019). Postoperative change of NT-proBNP was independently associated with PHF (OR 5.12, 95% CI 1.86–14.10, p = 0.002). The use of inotropes and ICU resources increased with incremental quartiles of postoperative NT-proBNP.

Conclusions

Postoperative NT-proBNP can serve as an objective marker of the severity of postoperative myocardial dysfunction. Due to overlap in individuals, NT-proBNP is useful mainly for comparisons at cohort level. As such, it provides a tool for study purposes when an unbiased assessment of prevention or treatment of PHF is desirable.

Trial registration

ClinicalTrials.gov Identifier: NCT00489827https://clinicaltrials.gov/ct2/show/NCT00489827?term=glutamics&draw=2&rank=1.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13741-021-00194-4.

Effect of levosimendan on renal function in background of left ventricular dysfunction: a meta-analysis of randomized trials

OBJECTIVE

Levosimendan, an inotrope, is widely used in the management of heart failure (HF) and cardiac surgery, but it remains uncertain whether levosimendan can improve renal function in patients with left ventricular dysfunction (LVD).

METHODS

PubMed, Embase, and Cochrane CENTRAL from the inception to June 2020 were systematically screened for randomized controlled trials (RCTs) to investigate whether levosimendan offers kidney-related advantages in cardiovascular patients with LVD. We pooled the effects using a random-effect model.

RESULTS

Twenty-eight studies enrolling 5069 patients were included. Levosimendan reduced the sCr (SMD -0.28, 95% CI (-0.48, -0.09), P = 0.005, I² = 52.5%, high quality) and the risk of ARF (relative risk 0.75, 95%CI (0.60, 0.95), P = 0.017, I² = 11.3%, moderate-quality) in patients with LVD compared with control group. The reduction of sCr was more pronounced in patients with a relatively higher baseline sCr level. For secondary outcomes, levosimendan therapy was associated with the improvement of GFR (SMD 0.32, 95%CI (-0.05, 0.68), P = 0.092, I² = 55.1%, low-quality) and urine output (SMD 0.42, 95%CI (0.06, 0.79), P = 0.024, I² = 50.0%, very low-quality), but there was no significant reduction in BUN (SMD -0.14, 95%CI (-0.97, 0.70), P = 0.774, I² = 77.9%, very low-quality).

CONCLUSIONS

Levosimendan might improve renal function of patients with LVD.

Association between In-hospital Mortality and Low Cardiac Output Syndrome with Morning versus Afternoon Cardiac Surgery

BACKGROUND

Recent work suggests that having aortic valve surgery in the morning increases risk for cardiac-related complications. This study therefore explored whether mortality and cardiac complications, specifically low cardiac output syndrome, differ for morning and afternoon cardiac surgeries.

METHODS

The study included adults who had aortic and/or mitral valve repair/replacement and/or coronary artery bypass grafting from 2011 to 2018. The components of the in-hospital composite outcome were in-hospital mortality and low cardiac output syndrome, defined by requirement for at least two inotropic agents at 24 to 48 h postoperatively or need for mechanical circulatory support. Patients who had aortic cross-clamping between 8 and 11 am (morning surgery) versus between 2 and 5 pm (afternoon surgery) were compared on the incidence of the composite outcome.

RESULTS

Among 9,734 qualifying operations, 0.4% (29 of 6,859) died after morning, and 0.7% (20 of 2,875) died after afternoon surgery. The composite of in-hospital mortality and low cardiac output syndrome occurred in 2.8% (195 of 6,859) of morning patients and 3.4% (97 of 2,875) of afternoon patients: morning versus afternoon confounder-adjusted odds ratio, 0.96 (95% CI, 0.75 to 1.24; P = 0.770). There was no evidence of interaction between morning versus afternoon and surgery type (P = 0.965), and operation time was statistically nonsignificant for surgery subgroups.

CONCLUSIONS

Patients having aortic valve surgery, mitral valve surgery, and/or coronary artery bypass grafting with aortic cross-clamping in the morning and afternoon did not have significantly different outcomes. No evidence was found to suggest that morning or afternoon surgical timing alters postoperative risk.

EDITOR’S PERSPECTIVE

Temporary mechanical circulatory support prevents the occurrence of a low-output state in high-risk coronary artery bypass grafting: A case series

BACKGROUND

Coronary artery bypass grafting (CABG) is a durable treatment for coronary artery disease. Left ventricular dysfunction (LVD) (a division of cardiothoracic surgery) (ejection fraction < 35%) significantly elevates perioperative risk for patients pursuing surgical revascularization. Periprocedural support with temporary mechanical circulatory support (tMCS) has shown benefit in this patient population.

METHODS

Four patients with ischemic cardiomyopathy and LVD underwent CABG at our institution between 2017 and 2018. Each patient received perioperative ventricular support using a microaxial tMCS device (Impella 5.0®). The occurrence of a postoperative low-output state (LOS) was assessed for as well as postoperative morbidity and mortality, device-specific complications, and tMCS support duration.

RESULTS

All patients survived to device explant without device-related complications. Two patients required reoperation for nondevice-related bleeding. All patients were without an LOS at 24 h postoperatively with cardiac indices of 2.9-3.6 L/min/m² , normalized serum lactate, and vasoactive-inotrope scores of 0-12.0. There was a notably high incidence of acute renal failure (50%), which was observed in patients with preoperative cardiogenic shock. One patient died 10 days after the device explant. Of the three patients that survived to discharge, two were alive at the most recent follow-up. Postoperative device support varied widely (0-500 h).

CONCLUSION

Perioperative tMCS may be a viable strategy for preventing postoperative LOS in high-risk CABG patients with a low complication rate and acceptable morbidity. The application of microaxial tMCS devices in CABG is an area that warrants further investigation to delineate its impact on perioperative outcomes and potentially expand the indications for such devices.

Right Ventricular Longitudinal Strain Predicts Low-Cardiac- Output Syndrome After Surgical Aortic Valve Replacement in Patients With Preserved and Mid-range Ejection Fraction

OBJECTIVES

The aim of this study was to analyze whether right ventricular free wall longitudinal strain (RVFWSL) could be a predictor of low-cardiac-output syndrome (LCOS) after surgical aortic valve replacement (SAVR) in patients with left ventricular ejection fraction ≥40%.

DESIGN

Prospective, observational study.

SETTING

The study was conducted at a third level university hospital.

PARTICIPANTS

The study comprised 75 patients with severe aortic stenosis and LVEF ≥40% who underwent SAVR. The primary outcome was the occurrence of LCOS, and secondary outcomes were in-hospital mortality, hospital stay, or vasoplegic syndrome.

INTERVENTIONS

Patients were divided into two groups (LCOS and no LCOS), and RVFWSL was analyzed to determine whether it is a predictor for LCOS. In addition, a receiver operating characteristic curve also was constructed, and the best cutoff value to predict LCOS was found. Furthermore, the reproducibility of RVFWSL measurements was evaluated.

MEASUREMENT AND MAIN RESULTS

The incidence of LCOS was 20% in the present study's cohort. After multivariate analysis, cross-clamp time (odds ratio 1.06, 95% confidence interval 1.02-1.11; p = 0.002) and RVFWSL (odds ratio 1.41, 95% confidence interval 1.07-1.87; p = 0.015) were the only predictors of LCOS. However, RVFWSL did not show association with secondary outcomes (p > 0.05 for all). The area under the curve of RVFWSL to predict LCOS was 0.75, and the best cutoff value was -17.3%, with a sensitivity of 86.7% and specificity of 61.7%.

CONCLUSIONS

RVFWSL seems to be a predictor of LCOS in patients with severe aortic stenosis and LVEF ≥40% undergoing SAVR. RVFWSL less than -17.3% may identify patients at increased risk for LCOS.

[Individualized use of levosimendan in cardiac surgery]

BACKGROUND

Levosimendan is a cardiac inotrope that augments myocardial contractility without increasing myocyte oxygen consumption. Additionally, levosimendan has been shown to exhibit anti-inflammatory, antioxidative, and other cardioprotective properties and is approved for treatment of heart failure. Recent studies indicated that these beneficial effects can be achieved with doses lower than the standard dose of 12.5 mg. Patients with preoperatively diagnosed left ventricular ejection fraction (LVEF) ≤40% received 1.25 mg levosimendan after induction of anesthesia. After surgery, administration of low-dose levosimendan was repeated until cardiovascular stability was achieved.

OBJECTIVE

This study aimed to evaluate if pharmacological preconditioning with 1.25 mg levosimendan in patients with LVEF ≤40% altered the postoperative need for inotropic agents, the incidence of newly occurring atrial fibrillation, renal replacement therapy, mechanical circulatory support and 30-day mortality. The cumulative dosage of levosimendan was recorded to assess the required dosage in the context of individualized treatment.

MATERIAL AND METHODS

This retrospective study included patients with preoperatively diagnosed LVEF ≤40% who underwent cardiac surgery at this institution between January 2015 and December 2018 and who received 1.25 mg levosimendan after induction of anesthesia to prevent postoperative low cardiac output syndrome. Based on echocardiography results, invasive hemodynamic monitoring, and central venous or mixed venous oxygen saturation and lactate clearance, repetitive doses of levosimendan in 1.25 mg increments could be postoperatively administered until cardiovascular stability was achieved. The results were compared to the current literature.

RESULTS

We identified 183 patients with LVEF <40% who received pharmacological preconditioning with 1.25 mg levosimendan. Maximum doses of epinephrine, incidence of atrial fibrillation, need for renal replacement therapy and 30-day mortality were found to be below the published rates of comparable patient collectives. In 73.2% of patients, a cumulative dosage of 5 mg levosimendan or less was considered sufficient.

CONCLUSION

The presented concept of pharmacological preconditioning with 1.25 mg levosimendan followed by individualized additional dosing in cardiac surgery patients with preoperative LVEF ≤40% suggests that this concept is safe, with possible advantages regarding the need of inotropic agents, renal replacement therapy, and 30-day mortality, compared to the current literature. Individualized treatment with levosimendan to support hemodynamics and a timely reduction of inotropic agents needs further confirmation in randomized trials.

High Central Venous-to-Arterial CO2 Difference is Associated With Poor Outcomes in Patients After Cardiac Surgery: A Propensity Score Analysis

PURPOSE

In contrast to arterial lactate, previous studies have proposed central venous-to-arterial CO2 difference (P (v-a)CO2) as a more useful guide for categorizing patients at risk of developing septic shock. It is worthwhile studying P (v-a)CO2 in determining whether it could serve as a useful predictor for poor postoperative outcomes in patients undergoing cardiac surgery. We investigated the ability of P(v-a)CO2 to predict poor outcomes of patients with postoperative cardiogenic shock.

METHODS

In total, 1,672 patients were enrolled in this study from January 1, 2014 to June 1, 2017. Of these patients, 143 exhibited complicated and poor outcomes. To address any bias, we derived a propensity score predicting the functions of P(v-a)CO2 on poor outcomes and matched 114 cases to 114 controls with a similar risk profile. In this cohort study, poor outcomes were defined as the occurrence of any adverse complications, including sudden death, cardiac arrest, extracorporeal membrane oxygenation, oliguria, and the administration of a large amount of vasoactive-inotropic drugs.

RESULTS

In propensity-matched patients, significant differences in P(v-a)CO2 (6.11 ± 2.94 mm Hg vs. 11.21 ± 5.22 mm Hg, P < 0.001) were noted between the control group and poor outcome group. The area under the receiver operating characteristic curve of P(v-a)CO2 (AUC: 0.837, 95% CI: 0.782-0.892) for the detection of poor outcomes was significantly better compared to that of the central venous oxygen saturation and arterial lactate. Additionally, there was a negative correlation between cardiac index and P(v-a)CO2 (R= -0.68, P < 0.001).

CONCLUSION

We have shown a correlation between P(v-a)CO2 to cardiac output which may be used as an alternative metric to predict the poor outcomes of patients with postoperative cardiogenic shock.

Characteristics, morbidity and mortality factors associated with Intra-Aortic Balloon Pump in Coronary Artery Bypass Graft Surgery patients

Objective:

The aim of our study is to analyze the characteristics, morbidity and mortality of patients requiring an Intra-Aortic Balloon Pump (IABP) in Coronary Artery Bypass Grafting (CABG).

Methods:

An analysis was done on the prospectively collected data of 1216 patients who had CABG in our center between July, 2017 and May, 2019 at our hospital. We categorized patients in to an IABP and non-IABP group on the basis of IABP use. We then compared the pre-operative, per-operative and post-operative characteristics of the two groups. We further stratified the patients according to pre-op ejection fraction (EF).

Results:

Out of 1216 patients, 135(11.10%) patients required an IABP. 70(51.9%) patients of IABP group and 699(64.7%) patients of non-IABP group had hypertension (p-value 0.0036). 23.0% had previous myocardial infarction (MI) in the IABP group and 13.8% had prior myocardial infarction (MI) in non-IABP group (p-value 0.0463). Among the patients requiring an IABP, 21(15.5%) of patients had normal EF (>50%) (P-value<0.0001), 72 (53.3%) had EF 35-50%, and 41(30.3%) patients had EF<35% (p-value <0.0001). Mortality of IABP group (19.3%) was greater than non-IABP group (2.4%) (P-value 0.00001).

Conclusions:

Use of IABP increased as the EF decreased. Rate of post-operative stroke, prolonged ICU stay, prolonged ventilation, re-opening due to bleeding and mortality was seen to be significantly higher in the IABP group.

Risk factors, resource use, and cost of postoperative low cardiac output syndrome

OBJECTIVE

Low cardiac output syndrome complicates recovery after cardiac surgery. We examined the incidence and risk factors for low cardiac output syndrome and its association with postoperative mortality, morbidity, resource use, and cost.

METHODS

This cross-sectional retrospective observational study examined patients having cardiac surgery captured in the Premier Healthcare Database. Low cardiac output syndrome was defined as the requirement for postoperative mechanical circulatory support and/or hemodynamic instability requiring prolonged inotropic support. Incidence, risk factors, and association of low cardiac output syndrome with postoperative outcomes, including mortality, hospital and intensive care unit length of stay, hospital readmission, and cost at 30 days, 90 days, and 6 months, were examined.

RESULTS

Among 59,810 patients from 164 hospitals having cardiac surgery between July 1, 2012, and June 30, 2014, low cardiac output syndrome developed in 6067 (10.1%) patients. Patients presenting in cardiogenic shock or systolic (± diastolic) heart failure were at greatest risk. Risk-adjusted in-hospital mortality was 12-fold greater with low cardiac output syndrome (odds ratio, 12.0; 95% confidence interval, 10.6-13.5). Risk-adjusted hospital costs (2019$; median [Q1, Q3]) were $64,041 [21,439] in patients who developed low cardiac output syndrome versus $48,086 [16,098] without; P < .001. Increased costs were driven by longer risk-adjusted hospital stay (10.1 [4.5] vs 8.5 [3.8] days); P < .001, intensive care unit (5.5 [2.5] vs 3.3 [1.5] days; P < .001) stay, and all-cause 30-day adjusted hospital readmission rates (mean [SD] 16.6 [8.2]% vs 13.9 [7.2]%; P < .001).

CONCLUSIONS

Cardiac surgical patients who develop postoperative low cardiac output syndrome suffer greater mortality and have greater resource use, health care costs, and all-cause readmission, which informs perioperative decision making, and impacts hospital performance metrics and federal priority to reduce health care costs.

The Impact of Anesthetic Regimen on Outcomes in Adult Cardiac Surgery: A Narrative Review

Despite improvements in surgical techniques and perioperative care, cardiac surgery still is burdened by relatively high mortality and frequent major postoperative complications, including myocardial dysfunction, pulmonary complications, neurologic injury, and acute kidney injury. Although the surgeon's skills and volume and patient- and procedure-related risk factors play a major role in the success of cardiac surgery, there is growing evidence that also optimizing perioperative care may improve outcomes significantly. The present review focuses on the aspects of perioperative care that are strictly related to the anesthesia regimen, with special reference to volatile anesthetics and neuraxial anesthesia, whose effect on outcome in adult cardiac surgery has been investigated extensively.

Long-term outcome of perioperative low cardiac output syndrome in cardiac surgery: 1-year results of a multicenter randomized trial

PURPOSE

Perioperative myocardial dysfunction occurs frequently in cardiac surgery, and is a risk factor for morbidity and mortality. Levosimendan has been suggested to reduce mortality of patients with perioperative myocardial dysfunction. However, long-term outcome data on its efficacy in cardiac surgery are lacking.

MATERIALS AND METHODS

Cardiac surgery patients with perioperative myocardial dysfunction were randomized to levosimendan or placebo, in addition to standard inotropic care. One-year mortality data were collected.

RESULTS

We randomized 506 patients (248 to levosimendan 258 to placebo). At 1-year follow-up, 41 patients (16.5%) died in the levosimendan group, while 47 (18.3%) died in the placebo group (absolute risk difference -1.8; 95% CI -8.4 to 4.9; P = .60). Female sex, history of chronic obstructive pulmonary disease, previous myocardial infarction, serum creatinine, hematocrit, mean arterial pressure, and duration of cardiopulmonary bypass were independently associated with 1-year mortality.

CONCLUSIONS

Levosimendan administration does not improve 1-year survival in cardiac surgery patients with perioperative myocardial dysfunction. One-year mortality in these patients is 17%. Six predictive factors for long-term mortality were identified.

STUDY REGISTRATION NUMBER

NCT00994825 (ClinicalTrials.gov).

Is Peripheral Artery Disease an Independent Predictor of Isolated Coronary Artery Bypass Outcome?

AIM

The aim was to use a propensity score-based analysis to determine the impact of peripheral artery disease (PAD) on early outcomes after coronary artery bypass surgery grafting (CABG) in patients with PAD.

METHOD

We conducted a multicentre retrospective analysis of 11,311 consecutive patients who underwent CABG between 1997 and 2017. Patients with previous or concomitant vascular surgery were excluded. The main endpoints were death, stroke, and limb ischaemia requiring percutaneous or surgical revascularisation. Subgroup analyses were performed to test the interaction of PAD with concomitant factors.

RESULTS

There was no difference in mortality in patients with and without PAD (p=0.06 and p=0.179, respectively). Patients with PAD had a greater incidence of stroke (p=0.04), acute kidney disease (p=0.003), and limb ischaemia requiring interventions (p<0.001) than those without PAD. The use of off-pump or no-touch aortic techniques did not influence the effect of PAD on the outcomes. Early mortality rate increased in patients with PAD when associated with long cardiopulmonary bypass, cross-clamp times (both p<0.001), and postoperative low cardiac output (p=0.01).

CONCLUSIONS

The presence of PAD is associated, independently of other factors, with greater incidence of stroke, acute kidney disease, and limb ischaemia following CABG, irrespective of the technique employed. Operative mortality was greater in patients with PAD only when associated with long cardiopulmonary bypass and aortic cross-clamp times, and low cardiac output.

Risk factors for low cardiac output syndrome in children with congenital heart disease undergoing cardiac surgery: a retrospective cohort study

Background

Low cardiac output syndrome (LCOS) is an important complication of cardiac surgery. It is associated with increased morbidity and mortality. The incidence of LCOS after surgery is high in patients with congenital heart disease (CHD). Therefore, determining the risk factors of LCOS has clinical significance for the management of CHD. This study aimed to analyze the risk factors of LCOS.

Methods

We conducted a retrospective analysis of children with CHD who underwent cardiac surgery at Shanghai Children’s Medical Center between January 1, 2014, and December 31, 2017. Demographic characteristics and baseline data were extracted from the health data resource center of the hospital, which integrates clinical routine data including medical records, diagnoses, orders, surgeries, laboratory tests, imaging, nursing, and other subsystems. Logistic regressions were performed to analyze the risk factors of LCOS.

Results

Overall, 8660 infants with CHD were included, and 864 (9.98%) had LCOS after surgery. The multivariate regression analysis identified that age (OR 0.992, 95% CI: 0.988–0.997, p = 0.001), tricuspid regurgitation (1.192, 1.072–1.326, p = 0.001), Risk Adjustment in Congenital Heart Surgery-1 risk grade (1.166, 1.011–1.345, p = 0.035), aortic shunt (left-to-right: 1.37, 1.005–1.867, p = 0.046; bi-directional: 1.716, 1.138–2.587, p = 0.01), atrial shunt (left-to-right: 1.407, 1.097–1.805, p = 0.007; right-to-left: 3.168, 1.944–5.163, p < 0.001; bi-directional: 1.87, 1.389–2.519, p < 0.001), ventricular level shunt (left-to-right: 0.676, 0.486–0.94, p = 0.02; bi-directional: 2.09, 1.611–2.712, p < 0.001), residual shunt (3.489, 1.502–8.105, p = 0.004), left ventricular outflow tract obstruction (3.934, 1.673–9.254, p = 0.002), right ventricular outflow tract obstruction (3.638, 1.225–10.798, p = 0.02), circulating temperature (mild hypothermia: 1.526, 95% CI: 1.205–1.934, p < 0.001; middle and low temperature: 1.738, 1.236–2.443, p = 0.001), duration of cardiopulmonary bypass (1.009, 1.006–1.012, p < 0.001), myocardial preservation using histidine-tryptophan-ketoglutarate (1.677, 1.298–2.167, p < 0.001), and mitral insufficiency (1.714, 1.239–2.37, p < 0.001) were independent risk predictors of LCOS.

Conclusions

The incidence of postoperative LCOS in CHD children remains high. Circulation temperature, myocardial preservation using histidine-tryptophan-ketoglutarate, and usage of residual shunt after surgery were independent risk predictors for LCOS.

Preservation of renal function in cardiac surgery patients with low cardiac output syndrome: levosimendan vs beta agonists

BACKGROUND

Some studies have been performed to assess the effects of levosimendan on cardiac function when administered to cardiac surgery patients with low cardiac output syndrome (LCOS) in the immediate postoperative period. Levosimendan is an inotropic agent for the treatment of low cardiac output syndrome that seems to have a protective effect on renal function.

METHODS

It is a quasi-experimental study. A total of 100 patients with LCOS received either beta-agonists or levosimendan. We assessed the incidence of postoperative kidney failure in cardiac surgery patients. In patients who had kidney failure at diagnosis of LCOS, we examined whether differences existed in the evolution of kidney failure based on the treatment administered for LCOS. The parameters measured included haemodynamics, oxygen supply, and renal function as assessed by the AKI scale. ANOVA, Student's t-test and Wilcoxon or Friedman tests were used.

RESULTS

Up to 30% of cardiac surgery patients had kidney failure at diagnosis of LCOS. Kidney failure at discharge from the ICU was more frequent in patients who received beta-agonist drugs as compared to those who received levosimendan (p < 0.05).

CONCLUSION

The incidence of kidney failure decreased with the postoperative administration of levosimendan to cardiac surgery patients with LCOS, as compared to beta-agonists.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN 46058317. Date of registration: 7/10/2019. Retrospectively registered.

[Critical illness - related corticosteroid insufficiency in patients after cardiac surgery and cardiologic emergencies]

Critical illness - related corticosteroid insufficiency (CIRCI) is associated with elevated level of circulating biomarkers of inflammation, pro - coagulant effects, deterioration of systemic inflammatory response syndrome (SIRS) and, consequently, prolonged in - hospital stay and increased mortality of intensive care patients. Incidence of CIRCI widely varies depending on specific patient's population and applied diagnostic thresholds being as high as 30% among postoperative patients on inotropes. CIRCI is a complex clinical and pathophysiological condition with substantial influence on immediate survival and prognosis. Clinical impact of CIRCI as well as pathogenetically based therapy arouse keen interest of intensive care specialists and clinical pathologists. The specific issues of CIRCI in patients after cardiac surgery and cardiology emergencies remain largely under - recognized, so further scrutinization is needed.

Using Soluble ST2 to Predict Adverse Postoperative Outcomes in Patients with Impaired Left Ventricular Function Undergoing Coronary Bypass Surgery

Background and Objectives: The aim of this study was to investigate the prognostic value of soluble ST2 (sST2) in predicting postoperative adverse events in patients with impaired left ventricular (LV) function undergoing coronary artery bypass graft (CABG) surgery. Materials and Methods: This study included 80 consecutive patients with stable coronary artery disease (CAD) and impaired LV function (ejection fraction ≤ 45%) undergoing on-pump coronary artery bypass graft surgery. The patients were divided into the “high” or “low” group according to their ST2 levels (≥35 or <35 ng/mL). Results: Postoperative adverse events were more common in patients with high sST2 levels than in patients with low sST2 levels (100% vs 26%, p < 0.0001). Multivariate analysis showed that sST2 level was an independent predictor of the presence of postoperative adverse events (OR: 1.117 (95% CI: 1.016–1.228), p = 0.022). The receiver operating characteristic curve (ROC) analysis of sST2 revealed an area under the curve (AUC) of 0.812 (95% CI: 0.710–0.913, p < 0.001) in predicting postoperative adverse events. An sST2 level of 26.50 ng/ml was identified as the optimal cut-off value, with a sensitivity and specificity of 74.1% and 75.3%, respectively. Conclusion: Higher sST2 levels were associated with adverse outcomes after CABG in patients with impaired LV and stable CAD.

Short-term multiscale complexity analysis of cardiovascular variability improves low cardiac output syndrome risk stratification after coronary artery bypass grafting

BACKGROUND

Low cardiac output syndrome (LCOS) is a myocardial dysfunction leading to systemic hypoperfusion, favored by particular conditions of the autonomic nervous system. LCOS is one of the adverse events that might occur after cardiac surgery.

OBJECTIVE

The aim is to test the hypothesis that short-term multiscale complexity (MSC) analysis of heart period (HP) and systolic arterial pressure (SAP) variability series in the frequency bands typical of cardiovascular control could be fruitfully exploited in identifying subjects at risk of developing LCOS after coronary artery bypass graft (CABG).

APPROACH

HP and SAP beat-to-beat series were derived from electrocardiogram (ECG) and invasive arterial pressure (AP) signal acquired in 128 patients scheduled for CABG before (PRE) and after (POST) the induction of general anesthesia with propofol and remifentanil. Subjects were labeled as LCOS (n  =  14) and noLCOS (n  =  114) according to the LCOS development. MSC markers were calculated as the complement to 1 of the modulus of the average position of the poles dropping in the low-frequency (LF, 0.04-0.15 Hz) and high-frequency (HF, 0.15-0.5 Hz) bands as derived from the autoregressive model of HP and SAP series. Traditional time and frequency domain indexes were also calculated.

MAIN RESULTS

Traditional parameters were able to assess the depression of the cardiovascular regulation induced by general anesthesia, but showed weak performances in differentiating LCOS and noLCOS groups. Conversely, HP complexity in LF band and SAP complexity in HF band assessed during POST remained associated with LCOS even after entering a multivariate logistic regression model adjusted for clinical and demographic factors.

SIGNIFICANCE

The MSC approach can be fruitfully applied to improve risk stratification for LCOS after CABG likely because MSC markers describe the dysfunction of the sympathetic control and the impairment of the mechanical properties of the heart in the LCOS group.

The efficacy and safety of prophylactic use of levosimendan on patients undergoing coronary artery bypass graft: a systematic review and meta-analysis

Prophylactic use of levosimendan in cardiac surgery remains controversial and no meta-analysis has been done exclusively about that in patients undergoing coronary artery bypass graft (CABG) surgery. We conducted this systematic review and meta-analysis of levosimendan in CABG using PubMed, Embase, Scopus, and Cochrane Library (till April 20, 2018). Two-hundred and forty manuscripts were identified and 21 randomized trials (1727 patients in total) investigating the effect of levosimendan on the patients undergoing CABG surgery were finally included in this analysis. We found that levosimendan was an effective, well-tolerated inotropic agent in CABG, which was associated with a significantly reduced mortality rate [odds ratio (OR) 0.43, 95% confidence interval (CI) (0.26, 0.71), p = 0.001, I² = 0%] and postoperative atrial fibrillation [OR 0.50, 95% CI (0.26, 0.97), p = 0.04, I² = 76%], but a higher incidence of hypotension [OR 2.26, 95% CI (1.05, 4.85), p = 0.04, I² = 79%]. Subgroup analyses revealed that such a benefit was mainly observed in the isolated CABG, the preoperative administration, with-bolus and on-pump subgroups. More high-quality and well-designed prospective studies are needed to confirm or disprove our findings in future.