
==== Front
Interdiscip Cardiovasc Thorac Surg
Interdiscip Cardiovasc Thorac Surg
icvts
Interdisciplinary Cardiovascular and Thoracic Surgery
2753-670X
Oxford University Press

39208291
10.1093/icvts/ivae147
ivae147
Heart Failure
Original Article
Eacts/118
Eacts/119
Eacts/125
AcademicSubjects/MED00920
Outcomes of 576 patients with extracorporeal life support for the treatment of perioperative cardiogenic shock
Aboud Anas Department of Cardiac and Thoracic Vascular Surgery, University of Schleswig-Holstein, Luebeck Campus, Lübeck, Germany

Hüting Felix Department of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr-University Bochum, Bad Oeynhausen, Germany

Fujita Buntaro Department of Cardiac and Thoracic Vascular Surgery, University of Schleswig-Holstein, Luebeck Campus, Lübeck, Germany

https://orcid.org/0000-0001-6085-6554
Zittermann Armin Department of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr-University Bochum, Bad Oeynhausen, Germany

Al-Khalil Riad Department of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr-University Bochum, Bad Oeynhausen, Germany

https://orcid.org/0000-0002-4990-1892
Puehler Thomas Department of Cardiac and Thoracic Vascular Surgery, University of Schleswig-Holstein, Luebeck Campus, Lübeck, Germany
German Center for Cardiovascular Research (DZHK), Partner Site Hamburg-Kiel-Luebeck, Luebeck, Germany

https://orcid.org/0000-0002-9508-3261
Ensminger Stephan Department of Cardiac and Thoracic Vascular Surgery, University of Schleswig-Holstein, Luebeck Campus, Lübeck, Germany
German Center for Cardiovascular Research (DZHK), Partner Site Hamburg-Kiel-Luebeck, Luebeck, Germany

Gummert Jan Department of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr-University Bochum, Bad Oeynhausen, Germany

Corresponding author. Department of Cardiac and Thoracic Vascular Surgery, University of Schleswig-Holstein, Lübeck Campus, Ratzeburger Allee 160, 23562 Lübeck, Germany. Tel: +49-17620517365; e-mail: anas.aboud76@gmail.com (A. Aboud).
9 2024
29 8 2024
29 8 2024
39 3 ivae14714 3 2024
17 7 2024
04 9 2024
© The Author(s) 2024. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery.
2024
https://creativecommons.org/licenses/by-nc/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (https://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com

Abstract

OBJECTIVES

This study aims to analyse the short- and long-term outcomes in patients who received extracorporeal life support for the treatment of perioperative low-output syndrome and identify risk factors for mortality.

METHODS

All consecutive patients who received extracorporeal life-support system during or after cardiac surgery at a high-volume German cardiac centre between 2008 and 2017 were identified retrospectively and followed up to December 2023. This cohort was characterized, and long-term survival (>10 years) was analysed. Univariate and multivariable regression analyses were performed to identify risk factors for mortality.

RESULTS

Five-hundred and seventy-six patients were included; 21.7% underwent isolated coronary bypass, 16.5% single valve surgery, 34.3% combined cardiac surgery and 13.2% heart transplantation. The system was implanted peripherally in 60.8% of patients. In-hospital and 1-year mortality for all patients was 66.0% and 77.7%, respectively. In the multivariable Cox adjustment, severe aortic valve stenosis, previous cardiac surgery and intra-aortic balloon pump were independent risk factors for in-hospital mortality (P < 0.05). Older age, severe mitral regurgitation and patients on insulin were predictors for long-term mortality (P < 0.05). However, peripheral cannulation significantly reduced mortality. There was no time-dependent interaction of perioperative stroke with mortality. For patients who were discharged alive, the estimated 10-year survival was 32.4%.

CONCLUSIONS

Treatment of perioperative low-output syndrome with extracorporeal life-support systems is associated with poor outcome and only 34% of patients could be discharged successfully. Peripheral cannulation is prognostically favourable. Special attention should be paid to these patients because age, insulin therapy and severe mitral regurgitation are strong predictors for mortality after 10 years.

The complexity of cardiac surgery has increased recently due to the treatment of more elderly and comorbid patients [1].

Graphical Abstract

Extracorporeal life support
Low-output syndrome
Post cardiotomy
==== Body
pmcINTRODUCTION

The complexity of cardiac surgery has increased recently due to the treatment of more elderly and comorbid patients [1]. In many instances, patients have challenging valvular or coronary pathologies alongside comorbid conditions that result in a high-risk procedure [2]. Cardiac surgery sometimes has to be performed during life-threatening cardiogenic shock following myocardial infarction [3] or cardiac decompensation as a consequence of a valvular heart defect [4]. In addition, the occurrence of acute complications during or after cardiac surgery may lead to the development of post-cardiotomy cardiogenic shock (PCCS) [5].

PCCS is a devastating complication after heart surgery that is associated with significant morbidity and mortality [6]. First-line treatment strategies include high-dose inotropic and vasopressor support and the use of an intra-aortic balloon pump (IABP) to maintain tissue perfusion and oxygen supply [2, 7]. In certain cases, treatment of the resulting cardiac decompensation is refractory to the above-mentioned therapy [8]. In such cases, extracorporeal life support (ECLS) is used as an ultima ratio therapy, trying to reach a stable circulation and stabilize the patient’s metabolic situation [9]. Depending on the patient’s clinical course, ECLS can be weaned during the postoperative course or used as a bridge to transplant or to a ventricular-assist device [9]. This highly complex group of patients also exhibits increased morbidity and mortality [10].

In this single-centre study, we retrospectively analysed short- and long-term outcomes of patients who were treated with ECLS after PCCS and identified predictors for mortality in a high-volume centre.

MATERIALS AND METHODS

Ethics statement

The study was approved by the ethics committee of HDZ-NRW on 15 January 2018, under the approval code 7/2016.

Study design

The present study is a retrospective single-centre study. All consecutive adult patients who were treated with ECLS during and after cardiac surgery at the HDZ-NRW in Bad Oeynhausen (Germany) from 2008 to 2017 were identified. The observation period lasted until December 2023. Baseline and perioperative data were prospectively entered into a database and retrospectively obtained from medical records. Due to a very rigorous prospective data collection, there were no missing preoperative and perioperative data of listed parameters. With respect to long-term survival, we assessed the completeness of follow-up data as percentage of potential follow-up. The study was performed in accordance with the STrengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement (www.strobe-statement.org).

Patient population

All patients who received ECLS while experiencing PCCS were included in this analysis. The study population was characterized according to baseline demographic and surgical data. Peripheral ECLS was defined for patients in which the cannulation was performed through a peripheral vein and artery. Central ECLS was defined as the arterial cannulation of the aorta and/or central venous cannulation over right atrium or over vena cava.

Inclusion and exclusion criteria

All types of cardiac operations were included, except patients who had primary surgery for left ventricular assist device (LVAD) implantation. This patient group was excluded because in these patients, ECLS was used to postoperatively support the right ventricular function and therefore differed significantly from the patient group analysed in this study.

Follow-up

Long-term survival follow-up was ensured by phone interviews with the respective patients or their relatives, or acquired from local state registration offices. The clinical data were collected in consultation with the family doctor, the cardiologist or directly from the patients or their relatives.

Endpoints

The primary end point was overall mortality up to 15 years after treatment with ECLS. Secondary end point was in-hospital mortality. Risk factors of short- and long-term mortality have been analysed.

We also assessed perioperative stroke to analyse the potential interaction of stroke with mortality. A stroke was considered present when a clinically manifest motoric, sensory or cognitive neurological deficit was recorded due to a cerebrovascular event. Clinical assessment was performed using the modified Rankin score. All patients with suspected neurological symptoms underwent a cranial CT scan. Additional outcomes were rethoracotomy for bleeding, perioperative myocardial infarction, laparotomy and arterial vascular complication.

Statistical analysis

Numerical data are expressed as mean with standard deviation or median with 25th to 75th percentile, according to the distribution of the variable. Categorical data were summarized as absolute and relative frequencies.

To identify possible risk factors for in-hospital mortality and long-term mortality, binary logistic regression analysis and Cox regression analysis, respectively, were used. First, a univariate analysis was performed, with baseline demographic and procedural variables, characteristics of the ECLS systems, and clinically relevant variables. Second, a multivariable analysis was run on all clinically relevant variables and also on those that were associated with in-hospital or long-term mortality in the univariate analysis with a P < 0.1. The following parameters were used as potential predictor variables: age, sex, body mass index, New York Heart Association (NYHA) functional class, left ventricular ejection fraction (3 classes: <30%, 30–50% and >50%), any chronic obstructive pulmonary disease, chronic obstructive pulmonary disease with medication, smoking, previous stroke, peripheral vascular disease, carotid disease, coronary artery disease, previous myocardial infarction <48 h, previous percutaneous coronary intervention, severe aortic stenosis (AS), severe mitral regurgitation, severe tricuspid insufficiency, arterial hypertension, pulmonary hypertension, diabetes mellitus, diabetes mellitus on insulin, hyperlipidaemia, atrial fibrillation, previous pacemaker/defibrillator implant, dialysis, IABP support, non-elective cardiac surgery, mechanical ventilation dependence, type of oxygenator, previous cardiac surgery and peripheral cannulation. Results are presented as odds ratio (OR; in-hospital mortality) or hazard ratio (HR; long-term mortality) with 95% confidence interval (CI). Survival rates were estimated using the Kaplan–Meier method. We also tested in a time-dependent Cox regression analysis, whether there was a significant interaction of perioperative stroke with mortality. All statistical analyses were performed using IBM SPSS Statistics for Windows, Version 25.0 (Armonk, NY).

RESULTS

Patient population: baseline characteristics and surgical data

During the analysed time period, 1943 patients were treated with ECLS at our institution. Of those, 576 patients received ECLS due to PCCS and therefore comprised the study population. Baseline demographic characteristics are summarized in Table 1.

Table 1: Baseline characteristics, procedural data and ECLS characteristics of the study population

Baseline characteristics (N = 576)	Mean/median (n); % (n)	
Age (years)	65 (SD: 12)	
Female	37.3 (215)	
BMI (kg/m²)	27.6 (SD: 6)	
NYHA		
 I	2.8 (16)	
 II	17.0 (98)	
 III	46.0 (265)	
 IV	34.2 (197)	
LVEF, % (IQR)	45 (30–57)	
LVEF < 30%	29.0 (167)	
COPD		
 Any	12.8 (74)	
 With medication	9.5 (55)	
Smoker	14.4 (83)	
Previous stroke	9.0 (52)	
Peripheral vascular disease	13.0 (75)	
Carotid disease	7.1 (41)	
Coronary artery disease		
Any	68.1 (392)	
 1-VD	12.0 (69)	
 2-VD	12.5 (72)	
 3-VD	43.6 (251)	
 Left main disease	24.1 (139)	
Previous myocardial infarction		
 Any	38.5 (222)	
 <24 h	12.2 (70)	
 <48 h	16.8 (97)	
Previous PCI	30.6 (176)	
Previous cardiac surgery	34.7 (200)	
Severe AS	20.8 (120)	
Severe AR	6.9 (40)	
Severe MI	24.1 (139)	
Severe TI	15.3 (88)	
Acute endocarditis	7.3 (42)	
Type A aortic dissection	3.3 (19)	
Arterial hypertension		
 Any	85.6 (493)	
 Untreated	1.4 (8)	
Pulmonary artery pressure >60 mmHg	14.8 (85)	
Diabetes mellitus		
 Any	30.7 (177)	
 On insulin	17.5 (101)	
Hyperlipidaemia		
 Any	63.2 (364)	
 Untreated	4.3 (25)	
Atrial fibrillation	24.5 (141)	
Previous pacemaker/ICD	25.2 (145)	
Dialysis		
 Any	12.3 (71)	
 Acute	5.6 (32)	
 Chronic	6.8 (39)	
On ventilator	9.2 (53)	
log EuroSCORE	24.0 (10.3–46.4)	
EuroSCORE II	14.4 (5.0–31.8)	
Procedural data	
 Procedural variables (N = 576)	% (n)	
 Procedure urgency		
  Elective	46.4 (267)	
  Non-elective	53.6 (309)	
 Procedures		
  Isolated CABG	21.7 (125)	
  On pump	64.0 (80)	
  Off pump	25.6 (32)	
  Conversion to on pump	10.4 (13)	
  Single valve surgery	16.5 (95)	
  Isolated aortic valve surgery	53.7 (51)	
  Isolated mitral valve surgery	30.5 (29)	
  Multi-valve surgery	13.5 (78)	
  CABG + valve surgery	20.8 (120)	
  Aortic surgery	9.0 (52)	
  Heart transplantation	13.2 (76)	
  Others	5.2 (30)	
 Procedure times		
  Procedure time (min)	295 (219–382)	
  CPB time (min)	163 (106–227)	
  Cross-clamp time (min)	80 (35–120)	
 Serum lactatea		
  First lactate in operation room >4 mmol/l	12.5 (72)	
  Last lactate in operation room >4 mmol/l	52.3 (301)	
ECLS characteristics	
 ECLS variables (N = 576)	% (n)	
 Device		
  Levitronex	56.6 (326)	
  Rotaflow	22.4 (129)	
  Deltastream	21.0 (121)	
 Inflow cannula		
  RA/VCS/VCI	36.8 (212)	
  Femoral vein	63.0 (363)	
  Other	0.2 (1)	
 Outflow cannula		
  Aorta	38.7 (223)	
  Femoral artery	59.9 (354)	
  Subclavian artery	1.2 (7)	
  Other	0.2 (1)	
 Cannulation		
  Central	39.2 (226)	
  Peripheral	60.8 (350)	
 ECLS support		
  Duration (days)	7.44 (3.72–14.09)	
  Duration > 5 days	65.8 (379)	
 Oxygenator		
  Hilite LT 7000	36.6 (211)	
  Paragon	24.7 (142)	
  HLS	17.4 (100)	
  Quadrox	5.6 (32)	
  Other	15.8 (91)	
 IABP support	44.6 (257)	
a A threshold of 4 mmol/l was considered because values above this threshold are associated with increased in-hospital mortality [13].

AR: aortic regurgitation; AS: aortic stenosis; BMI: body mass index; CABG: coronary artery bypass graft surgery; COPD: chronic obstructive pulmonary disease; CPB: cardiopulmonary bypass; ECLS: extracorporeal life support; IABP: intra-aortic balloon pump; ICD: implantable cardioverter defibrillator; HLS: Heart-Lung-Support, LVEF: left ventricular ejection fraction; MI: myocardial infarction; NYHA: New York Heart Association; PCI: percutaneous coronary intervention; RA: right atrium; SD: standard deviation; TI: tricuspid insufficiency; VCI: inferior vena cava; VCS: superior vena cava; VD: vascular disease.

Procedural data

Procedural data are summarized in Table 1.

ECLS data

The median duration on ECLS was 7.44 days (3.72–14.09) (Table 1). A peripheral ECLS implantation was done in 350 cases (60.8%). In 36 patients (6.25%), an IABP was implanted prior to surgery.

Outcomes

In our study cohort, 272 patients (47.2%) could be weaned from ECLS (Table 2). In 274 cases (47.6%), the therapy was unsuccessful and was terminated. Twenty-seven patients were bridged to ventricular-assist device and 3 patients received a heart transplant.

Table 2: Reasons for ECLS termination and in-hospital outcomes

ECLS termination from (N = 576)	% (n)	
 Weaning	47.2 (272)	
 End of therapy	47.6 (274)	
 Switch to VAD	4.7 (27)	
 Heart transplant	0.5 (3)	
In-hospital outcomes	
 In-hospital outcomes (N = 576)	% (n)	
 Mortality	66.0 (380)	
 Stroke	18.8 (108)	
 Re-thoracotomy for bleeding	60.2 (347)	
 Myocardial infarction	6.3 (36)	
 Laparotomy	6.8 (39)	
 Arterial vascular complication	18.6 (107)	
 Cardiac arrest	26.0 (150)	
 Dialysis	83.9 (483)	
 Low output syndrome	82.1 (473)	
ECLS: extracorporeal life support; VAD: ventricular assist device.

The in-hospital mortality was 66.0% (n = 380) (Table 2). The remaining 196 patients were discharged to intensive rehabilitation facilities (n = 157) and home (n = 39). One-hundred and eight patients (18.8%) had a stroke postoperatively. The postoperative incidence of re-thoracotomy for bleeding, myocardial infarction, laparotomy and arterial vascular complication was 60.2%, 6.3%, 6.8% and 18.6%, respectively.

The completeness of long-term follow-up was 98.6%. Actuarial cumulative overall survival was 22.3% (95% CI 19.1–26.1%) at 1 year, 20.1% (95% CI 16.9–23.8) at 2 years, 15.7% (95% CI 12.5–19.8%) at 5 years and 11.0% (95% CI 3.6–18.4%) at 10 years (Fig. 1). Patients who survived the in-hospital period presented with a 10-year survival rate of 32.4% (95% CI 12.3–52.5%; Fig. 2). Exclusion of patients receiving a ventricular-assist device (n = 27) implant or a heart transplantation (n = 3) resulted in 1-year, 5-year and 10-year survival rates of 21.7% (95% CI 18.2–24.2%), 15.4% (95% CI 12.3–18.5%) and 10.6% (95% CI 7.9–13.4%), respectively.

Figure 1: Kaplan–Meier curve of actuarial cumulative overall survival for postcardiotomy ECLS in all study patients. ECLS: extracorporeal life support system.

Figure 2: Kaplan–Meier curve of actuarial cumulative overall survival for postcardiotomy ECLS in discharged patients. ECLS: extracorporeal life support system.

Predictors of in-hospital mortality

The predictors of in-hospital mortality are summarized in Table 3. The multivariable analysis suggests that severe AS, previous cardiac surgery and IABP support were risk factors for in-hospital mortality (OR 1.77, 95% CI 1.09–2.88, P = 0.040; OR 2.46, 95% CI 1.05–5.87, P = 0.043, respectively). There was also a tendency for a higher mortality risk in older patients and patients (OR 1.02, 95% CI 1.01–1.03, P = 0.05). The in-hospital risk of mortality was lower in patients with peripheral cannulation (OR 0.63, 95% CI 0.43–0.92, P = 0.016) and tended to be lower in active smokers (OR 0.64, 95% CI 0.38–1.06, P = 0.09).

Table 3: Predictors of in-hospital mortality

Variables	Univariate	Multivariable	
OR (95% CI)	P-value	OR (95% CI)	P-value	
Age (years)	1.02 (1.01–1.04)	0.002	1.02 (1.01–1.03)	0.05	
BMI (kg/m²)	1.03 (1.00–1.07)	0.04	1.02 (0.99–1.06)	0.22	
COPD with med	1.75 (0.92–3.34)	0.09	1.59 (0.81–3.10)	0.18	
Smoker	0.53 (0.33–0.84)	0.01	0.64 (0.38–1.06)	0.09	
Severe AS	1.77 (1.09–2.88)	0.02	1.71 (1.04–2.83)	0.040	
DM on insulin	1.61 (0.99–2.61)	0.05	1.48 (0.89–2.47)	0.13	
Previous cardiac surgery	1.37 (0.95–1.98)	0.095	1.62 (1.08–2.42)	0.018	
Non-elective surgery	1.07 (0.76–1.51)	0.71			
Mechanical ventilation	1.10 (0.60–2.02)	0.75			
IABP support	2.07 (0.88–4.83)	0.094	2.46 (1.05–5.87)	0.043	
Peripheral cannulation	0.63 (0.44–0.91)	0.01	0.63 (0.43–0.92)	0.016	
LVEF (3 classes): class 1: <30%; class 2: 30–50%; class 3 >50%.

AS: aortic stenosis; BMI: body mass index; CI: confidence interval; COPD: chronic obstructive pulmonary disease; DM: diabetes mellitus; IABP: intra-aortic balloon pump; OR: odds ratio. Statistically relevant values (P < 0.1) are marked bold.

Predictors of long-term mortality

With respect to the primary end point, predictors are summarized in Table 4. The multivariable analysis revealed that age (HR 1.02, 95% CI 1.02–1.03, P < 0.001), insulin-dependent diabetes (HR 1.48, 95% CI 1.08–2.03, P = 0.015) and severe mitral regurgitation (HR 1.28, 95% CI 1.04–1.57, P = 0.019) were independent predictors of long-term mortality. Long-term mortality was lower in patients with peripheral cannulation (HR 0.72, 95% CI 0.60–0.87, P = 0.001).

Table 4: Predictors of long-term mortality (patients alive at discharge)

Variables	Univariate	Multivariable	
HR (95% CI)	P-value	HR (95% CI)	P-value	
Age	1.03 (1.02–1.03)	<0.001	1.02 (1.02–1.03)	<0.001	
BMI	1.01 (1.–1.03)	0.10	1.01 (0.99–1.02)	0.33	
COPD any	1.24 (0.97–1.60)	0.09	0.78 (0.48–1.26)	0.31	
COPD with medication	1.42 (1.07–1.89)	0.017	1.51 (0.87–2.61)	0.14	
Smoker	0.64 (0.49–0.84)	0.001	0.81 (0.61–1.07)	0.14	
PVD	1.31 (1.02–1.68)	0.038	1.25 (0.96–1.62)	0.10	
Diabetes on insulin	1.49 (1.19–1.86)	<0.001	1.48 (1.08–1.03)	0.015	
Diabetes any	1.31 (1.09–1.58)	0.005	0.96 (0.73–1.25)	0.74	
Severe AS	1.39 (1.12–1.71)	0.003	1.20 (0.96–1.51)	0.12	
Severe MR	1.26 (1.03–1.54)	0.024	1.28 (1.04–1.57)	0.019	
Peripheral cannulation	0.75 (0.61–0.87)	<0.001	0.72 (0.60–0.87)	0.001	
Oxygenator	0.98 (0.95–1.00)	<0.09	0.98 (0.95–1.01)	0.08	
Previous cardiac surgery	1.17 (0.97–1.40)	0.10	1.22 (0.99–1.51)	0.06	
Pacemaker/defibrillator	1.28 (1.05–1.56)	0.014	1.19 (0.95–1.50)	0.14	
LVEF (3 classes): class 1: <30%; class 2: 30–50%; class 3 > 50%.

AS: aortic stenosis; BMI: body mass index; CI: confidence interval; COPD: chronic obstructive pulmonary disease; HR: hazard ratio; MR: mitral regurgitation; PVD: peripheral vascular disease. Statistically relevant values (P < 0.1) in the mutivariable anlysis are marked bold.

Patients with stroke

Stroke was present in 108 patients (18.8%) of our study group. The modified Rankin score was 5 in 29 stroke patients and 8 patients had severe stroke symptoms (modified Rankin score 4). Moderate and slight disability were seen in 15 patients each (modified Rankin score 2 and 3). One patient had no significant disability. There was no time-dependent interaction of perioperative stroke with mortality (HR 1.03, 95% CI 0.92–1.17, P = 0.60).

DISCUSSION

The present study reports long-term survival in a relatively large set of patients with cardiogenic shock after cardiac surgery with the need for ECLS intra- or postoperatively. Outcomes of 576 patients with a mean age of 65 years were investigated. The obtained results represent predictors for better survival after ECLS, which are of great importance for the management of this therapy, especially with the increasing number of ECLS implantations worldwide. The main findings of our study can be summarized as follows:

Thirty-four percent of all patients could be discharged from the hospital and 32.4% of them were alive after 10 years. Increased age, diabetes on insulin and severe mitral regurgitation were negative predictors for long-term survival, whereas was lower in patients with peripheral cannulation.

Severe AS, previous cardiac surgery and IABP support were risk factors for in-hospital mortality, whereas in-hospital risk of mortality was lower in patients with peripheral cannulation and tended to be lower in active smokers.

Neurological complications did not influence long-term survival of discharged patients.

Survival

In this study, we found an in-hospital mortality rate of 66.0% in a high comorbidity study group [log EuroSCORE = 24.0% (10.3–46.4) and EuroSCORE II = 14.4% (5.0–31.8)] who received ECLS for treatment for PCCS. This mortality rate may seem rather high; however, one has to take into account that ECLS therapy provides the last option to stabilize the cardiopulmonary situation and in this regard our results seem acceptable. It has to be noted that 34.0% of patients were discharged alive, which is an encouraging result. This rate is in accordance with the ones published in the literature [11, 12]. However, other single-centre studies with patient cohorts of over 350 subjects showed even lower in-hospital survival (<30%) compared to our patient cohort [13, 14]. Despite a relatively good weaning rate of 47.2% in our study, more than 13.0% of these patients died before being discharged from the hospital. This finding is similar to the results from other studies [11, 13]. The survival was very poor in the 1st year after discharge. The vast majority of the patients were transferred to the intensive rehabilitation facility in poor general condition. The prognosis for these patients is poor and mortality is high.

To our knowledge, the present study is one of the largest patient cohorts (N = 576) ever published, with a follow-up time of up to 15 years. Estimated long-term survival after 10 years was 11.0%, whereas 32.4% of the successfully discharged patients were alive after 10 years. This is still an acceptable rate for this critically ill group of patients. Unosawa et al. [6] showed in a group of 47 patients, a 10-year survival rate of 17.6%. Rastan et al. [13] and Papadopoulos et al. [14] in a shorter follow-up time of 5 years published cumulative survival rates of 13.7% and 22.0%, respectively.

Predictors of mortality

In order to analyse the factors that could have an influence on the short- and long-term survival of this high-risk set of patients, uni- and multivariable analyses of peri-, intraoperative and device-dependent parameters were performed. Patients with severe AS constituted 20.8% of the study group and showed a significantly higher risk of mortality. Guihaire et al. [15] also reported poor survival rates in patients after valvular surgery. These findings could be due to the vulnerability of hypertrophic ventricles to ischaemic insults after intraoperative cardiac arrest [16]. There is a plausible increase in mortality in patients with previous heart surgery. According to our data, previous cardiac operations also increase the risk of mortality. This could plausibly be explained by the increased surgical complications and perioperative risk of this patient population.

Additionally, based on our results, which indicate the use of IABP as a predictor for in-hospital mortality, its role should be discussed intensively in this patient group. Despite many studies in the past suggesting the use of an IABP as protective factor for shock patients [2], other studies doubted its function [17]. However, the negative results from the use of IABP in our study could be explained by its use in high-risk patients, especially when the LV function is extremely depressed. These patients are expected to have worse results.

Surprisingly, patients who smoked showed a tendency for risk reduction of in-hospital mortality compared to patients who did not. Rastan et al. [13] found a similar risk reduction in the smoking population, but did not offer an explanation for this finding. However, this predictor could not be found in other studies [10, 14]. A theoretical possible reason could be derived from the anti-inflammatory advantages of nicotine [18, 19]. which may reduce the systemic inflammatory response that results from the use of ECLS. These unusual findings require more investigation, especially in patients with cardiogenic shock.

Predictors of long-term mortality

Our data are in line with other studies pointing out that age is a key variable in predicting patients’ survival rate [13, 20]. Advanced age was a predictor of higher risk of mortality in our investigated patients, especially in the analysis of the patients’ long-term survival (P < 0.001). Better organ function and more reserves in younger patients may explain their increased survival after an acute cardiac failure.

Many past studies presented diabetes as an independent predictor of mortality [13, 14]. Following our analysis, we can confirm that patients on insulin therapy clearly showed a worse outcome in their long-term survival and a strong tendency in the short-term survival data (P = 0.01, P = 0.09, respectively). A plausible explanation may be the potentially increased risk of end organ hypoperfusion as a result of the lack of pulsatility and previous dysfunction, and damage leading to an impairment of the clinical outcome, as also mentioned by Papadopoulos et al. [14]. Interesting in our analysis was that not the AS but the mitral valve regurgitation has an influence on the long-term prognosis. Presumably, the stabilizing effect of the ECLS on the cardiopulmonary situation of mitral valve patients in the acute phase get lost in the long-term follow-up due to residual organ damage happening after removal of the ECLS, which leads to an increase the long-term mortality. Guihaire et al. [15] have shown in their analysis of post-cardiotomy ECLS patients higher mortality in patients after valvular surgery, but the isolated effect of mitral disease on long-term survival has not yet been described.

Peripheral cannulation of the ECLS reduced the risk of mortality both in hospital and in the long follow-up. Although the patient with peripheral cannulation has higher complications on the femoral vessels, central cannulation, especially with open thorax, has a higher periprocedural mortality due to the higher risk of mediastinitis and perioperative bleeding. Unosawa et al. [6] described increased mortality in patients with incomplete sternum closure seen in patients with central cannulation. According to our results, this type of cannulation should be avoided if possible. Switching to peripheral ECLS should be done as early as possible.

Stroke and outcome

Despite the relatively high incidence of stroke in patients with cardiogenic shock needing ECLS—18.8% in our study—comparable with findings from other research groups [21, 22], no time-dependent interaction of perioperative stroke with mortality has been found. However, this finding differs from other studies demonstrating higher mortality in patients with neurological complications after the use of extracorporeal circulatory systems or assist devices [23, 24]. Nevertheless, in the study of Le Guennec et al. [23], patients with intracranial bleeding but not ischaemic stroke were associated with higher mortality. Derived from our own data, patients with stroke after ECLS can also have a good long-term survival and should be treated with maximum effort.

Limitations

The retrospective nature of this study carries inherent, well-known limitations such as selection bias and unexplained confounding. The statements made in this study concern patients post cardiac surgery and could not be generalized to the full extent to patients treated with ECLS because of other events such as out of hospital re-animation. The missing data regarding quality of life of the surviving patients is a limitation of our investigation.

CONCLUSION

ECLS is a powerful tool for severe cardiogenic shock after cardiac surgery. Despite a relatively high in-hospital mortality, long-term survival up to 10 years in this multimorbid group of patients was acceptable. Severe aortic valve stenosis, previous cardiac surgery and IABP support were associated with higher in-hospital mortality. Age, patients on insulin therapy and severe mitral valve regurgitation were strong negative predictors for long-term mortality. On the contrary, periphery ECLS cannulation was protective. Neurologic complications after ECLS are relatively frequent; nevertheless, in our cohort, stroke did not influence the long-term survival.

FUNDING

No external funding body was required for the study.

Conflict of interest: none declared.

DATA AVAILABILITY

The data underlying this article are available in the article.

Author contributions

Anas Aboud: Conceptualization; Data curation; Formal analysis; Investigation; Project administration; Supervision; Writing—original draft; Writing—review & editing. Felix Hüting: Data curation; Formal analysis; Resources; Software; Writing—review & editing. Buntaro Fujita: Formal analysis; Investigation; Methodology; Resources; Software; Validation; Visualization. Armin Zittermann: Formal analysis; Methodology; Software; Writing—review & editing. Riad Al-Khalil: Data curation; Investigation; Resources. Thomas Puehler: Investigation; Methodology; Writing—review & editing. Stephan Ensminger: Conceptualization; Methodology; Writing—review & editing. Jan Gummert: Conceptualization; Data curation; Methodology; Resources; Supervision; Validation; Writing—review & editing.

Reviewer information

Interactive CardioVascular and Thoracic Surgery thanks Matthias Thielmann, Praveen K. Varma and Andrea Agostinelli for their contribution to the peer review process of this article.

ABBREVIATIONS

AS Aortic stenosis

CI Confidence interval

ECLS Extracorporeal life support

HR Hazard ratio

IABP Intra-aortic balloon pump

NYHA New York Heart Association

OR Odds ratio

PCCS Post-cardiotomy cardiogenic shock

STROBE STrengthening the Reporting of Observational Studies in Epidemiology
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