Clinical Efficacy of ECMO in the Treatment of AMI Complicated with Refractory CS

doi:10.21203/rs.3.rs-2587032/v1

Objective: The aim of this single-centre retrospective study was to investigate the efficacy of extracorporeal membrane oxygenation (ECMO) in the treatment of acute myocardial infarction (AMI) complicated by refractory cardiogenic shock (CS).

Background: While mechanical circulatory support (MCS) devices are widely used in reperfusion therapy, no significant reduction in mortality has been observed. ECMO is a rescue tool for patients refractory CS, with a paucity of data evaluating its efficacy in the treatment of AMI complicated with refractory CS.

Methods: All consecutively enrolled patients with AMI and refractory CS admitted to the First Hospital of Lanzhou University from July 1, 2015, to October 31, 2021, were enrolled. According to the MCS device, the patients were divided into the ECMO and IABP groups. The primary outcome of our study was 30-day mortality. Secondary outcomes included perioperative mortality, 90-day mortality, renal failure requiring CRRT, life-threatening bleeding, moderate bleeding, ischaemic complications, and bacteremia.

Results: A total of 81 patients, with a mean age of 62 ± 10 years, were included, 79% of them were males. Forty-four patients (54.3%) were included in the IABP group, and 37 (45.7%) were included in the ECMO group. The average lactate level was 7.05 ± 3.56 mmol/L. A total of 72.0% of patients had multivessel coronary artery disease (CAD). Compared with IABP, ECMO led to lower 30-day mortality (68.2% vs. 43.2%, χ²=8.423, P=0.004) and perioperative mortality rates (20.0% vs. 0.00%, χ²=5.877, P=0.015) but prolonged the patient's CCU (10.0 vs. 3.5, p < 0.001) and total hospital stay (13 vs. 4, p < 0.001). In the subgroup analysis of multivessel CAD, the 30-day mortality rate in the ECMO group who underwent immediate multivessel PCI was significantly lower than that in those who initially underwent PCI of the culprit lesion only (21.4% vs. 61.5%, χ²=4.402, P=0.036).

Conclusion: ECMO can significantly reduce the risk of 30-day mortality and does not increase the risk of serious complications. In addition, immediate multivessel PCI with ECMO can significantly reduce 30-day mortality in patients with multivessel CAD.

acute myocardial infarction

cardiogenic shock

revascularization

intra-aortic balloon pumping

extracorporeal membrane oxygenation

Acute myocardial infarction (AMI) is a life-threatening disease in which the mortality rate of refractory cardiogenic shock (CS) is as high as 67%-78%.¹ Early revascularization is an effective treatment to improve the survival rate.² With the improvement of percutaneous coronary intervention (PCI) and the popularization of the concept of chest pain centres, the time window of revascularization has been significantly shortened, but the mortality of AMI complicated with CS has not significantly decreased.³

In recent years, various mechanical circulatory support (MCS) devices have been used in patients with AMI complicated with CS and include intra-aortic balloon pump (IABP), Impella and extracorporeal membrane oxygenation (ECMO) to improve the prognosis of the patients.^{4, 5} IABP is readily available and the process of its implantation is simple, thus it was first used in patients with AMI combined with CS.^{6, 7} However, IABP SHOCK II has proven that IABP cannot improve the prognosis of AMI patients with CS.⁸ The study by Dhruva et al.⁹ found that Impella increases the risk of death and bleeding when compared with IABP. ECMO is one of the most important adjuvant therapies at present,¹⁰ but Brunner et al.¹¹ did not find that ECMO can improve the prognosis, which may be related to the increase in left ventricular afterload associated with ECMO.^{5, 12, 13,14}

ECMO in specific groups with an appropriate CS risk classification may lead to improved outcomes. However, there is little evidence that ECMO can improve the prognosis of AMI complicated with refractory CS. The aim of this retrospective study was to investigate the efficacy of ECMO in the treatment of AMI complicated with refractory CS.

A retrospective analysis of all patients who were diagnosed with AMI and refractory CS at a single tertiary care centre (the First Hospital of Lanzhou University, China) from July 1, 2015, to October 31, 2021, was undertaken. This study design and protocol were approved by the Ethics Committee of the First Hospital of Lanzhou University (Ethics # LDYYLL-2022-295).

All consecutive patients were recorded in the MCS registry and presented with AMI complicated with refractory CS. The diagnosis of AMI was made by the treating physician. Refractory CS as defined by the Society for Cardiovascular Angiography and Interventions (SCAI) as having an intravenous administration of multiple vasoactive drugs or having haemodynamic instability on a single MCS, so it was necessary to add different types of vasoactive drugs or to add more MCS devices in these patients—“SCAI Stage D”. ECMO support could be given to patients whose MAP could not be maintained above 60 mmHg, despite the intravenous use of more than two vasoactive drugs and IABP support. With the exception of cardiac arrest, all patients received ECMO as a remedy for IABP. Inclusion criteria included those aged 18 to 90 years and AMI within 24 hours of onset. Exclusion criteria were patients with respiratory and cardiac arrest who underwent cardiopulmonary resuscitation (CPR) or extracorporeal cardiopulmonary resuscitation (e-CPR)- “SCAI Stage E”, ECMO alone, CS caused by mechanical complications after infarction, a previous history of tumour or chronic cardiopulmonary disease and patients with a previous history of bleeding, such as gastrointestinal bleeding. Patients treated from March 1, 2019 (our centre started an ECMO program on March 2019) to April 30, 2019, were also excluded because of the learning curve. 37 AMI patients with refractory CS who received ECMO for haemodynamic support from May 1, 2019, to October 31, 2021, were included in the study group. The control group included 44 patients with AMI complicated with CS who were supported by IABP alone from July 1, 2015, to February 28, 2019.

VA ECMO was started percutaneously by the interventional cardiologist. The femoral vein was typically cannulated with a 19–21 Fr (Medtronic, Bio-Medicus, USA) venous cannula, and the femoral artery was typically cannulated with a Medtronic 15–17 Fr arterial cannula. This circuit was connected to a centrifugal pump, membrane oxygenator and heparinization cannula (Maquet, PLS7050/2050, Germany or LivaNava, D905, Italy), air-oxygen mixer, variable temperature water tank, oxygen saturation monitor (Medtronic), primed with lactated Ringer’s solution and infused with intravenous unfractionated heparin (80–100 u/kg) for a target activated clotting time > 200 s. To avoid lower limb ischaemia, echocardiography was used to evaluate the conditions of the femoral arteriovenous before the operation. The diameter of arterial intubation was less than 80% of the diameter of blood vessels, and the distal perfusion cannula was not routinely placed.

If persistent elevated left atrial pressure was noted haemodynamically or by echocardiographic assessment, the flow was reduced and a positive inotropic drug was used. The protocol and indications for discontinuation of ECMO were in accordance with previous descriptions.¹⁵ The time of IABP discontinuation was determined according to the recovery of patients' cardiac function and changes in vital signs.

The patient’s demographic data and medical history were extracted from clinical records. Clinical course data, including in-hospital complications and survival, were collected from hospital records. The main outcome of the study was 30-day mortality. The secondary outcomes included perioperative mortality (during and 24 hours after PCI), 90-day all-cause mortality, renal failure requiring CRRT, life-threatening haemorrhage (cerebral haemorrhage or haemorrhagic stroke and active massive haemorrhage, as suggested by CT), moderate bleeding (bleeding that requires blood transfusion but does not cause haemodynamic damage), ischaemic complications (ischaemic stroke on CT, interventions due to ischaemia at the intubation site), and bacteremia (defined as the standard of systemic inflammatory response syndrome and ≥ 2 positive blood cultures).

Statistical Analysis

All values are presented as numbers with percentages for categorical variables and means ± standard deviations/medians with interquartile ranges for continuous variables. Comparisons between continuous variables were made using a t test or Mann–Whitney U test. Categorical data were analysed using the chi-square test or Fisher’s exact test, as appropriate. Event-free survival curves were estimated by the Kaplan‒Meier method and compared using the log-rank test. All tests were two-tailed, and p < 0.05 was considered statistically significant. SPSS version 26.2 was used for statistical analysis.

Between May 2015 and October 2021, the data of 179 patients who presented with AMI complicated with refractory CS were included in the MCS registry (Figure 1). After exclusion, 81 AMI complicated with refractory CS patients, with a mean age of 62 ± 10 years (79% male), were included in this study. Of the included patients, there were 37 patients in the study group and 44 patients in the control group. Sixty-six patients (81.5%) had ST segment elevation myocardial infarction (STEMI). All patients completed the 90-day follow-up. The baseline characteristics of the two groups were matched, thus indicating that the characteristics of the study population were inconsistent. The average lactate levels of the study group and the control group were 7.06 ± 3.90 mmol/L and 7.02 ± 2.90 mmol/L, respectively, and the proportions of patients with multivessel CAD were 77.1% and 67.5%, respectively (Table 1).

The 30-day mortality rate in the ECMO group was significantly lower than that in the IABP group (43.2% vs. 68.2%, P=0.004, Figure 2). None of the patients died during the perioperative period in the study group, thus indicating that the mortality rate during the perioperative period in the study group was significantly lower than that in the control group (8 cases, P < 0.05) (Table 2). At the 90-day follow-up, we found that 2 patients in the study group had died, including one who died of sudden cardiac death and the other who died of renal failure complicated with infection. No deaths were observed in the control group. The 90-day mortality rates of the two groups were 48.6% and 68.2%, respectively (Table 2). There was no significant difference in the incidence of acute renal failure requiring CRRT, life-threatening bleeding or ischaemic complications between the two groups. However, the CCU (10.0 vs. 3.5, P < 0.001) and total hospital stays (13 vs. 4, P < 0.001) in the study group were significantly longer than those in the control group. A total of 10 patients had moderate bleeding (9 patients in the study group and 1 patient in the control group, p=0.008). The incidence of bacteremia in the two groups was 35.1% and 4.5%, respectively (P < 0.001) (Table 2).

PCI was performed in 94.6% (35 cases) of patients the study group and 90.9% (40 cases) of patients in the control group. As shown in Table 3, 54 patients had multivessel CAD (27 in the study group and 27 in the control group). The proportion of patients in the two groups who underwent immediate multivessel PCI was 51.9% and 37%, and the percentage of patients who underwent thrombolysis for grade III myocardial infarction (TIMI) after PCI was 92.6% and 74.1%, respectively. There were no significant differences between the two groups (Table 3). We conducted a subgroup analysis of the PCI strategies for multivessel CAD in the ECMO group. The 30-day mortality rate in those who underwent immediate multivessel PCI was significantly lower than that in those who underwent PCI of the culprit vessel only (21.4% vs. 78.6%, χ²=4.402, P < 0.036, Figure 3).

The results of this study showed that compared with IABP, ECMO significantly reduced 30-day mortality. In terms of safety, ECMO did not increase the risk of serious cardiopulmonary, neurological, gastrointestinal or limb-related complications. However, with ECMO, the risk of moderate bleeding increased, more blood products were needed, the incidence of bacteremia was significantly increased, and the CCU and total hospital stays were longer than those in the control group. In addition, we found that the 30-day mortality rate in patients with multivessel CAD in the ECMO group was significantly lower than that in patients who underwent immediate multivessel PCI.

The mortality rate in patients with CS increased with increasing SCAI classification,¹⁶ so the 30-day mortality rate in the patients included in this study should be higher than that in previous studies that had not stratified the risk of CS.^{8, 17} VA-ECMO and IABP can be quickly applied, so they are often used to rescue patients with AMI complicated with CS.^{5, 18, 19} Although VA ECMO and IABP have shown survival advantages in previous studies,^{13, 20} their effectiveness in patients with refractory CS has been debated. Animal experiments have shown that the use of IABP with ECMO can improve the balance of myocardial oxygen supply and demand²¹. Lin et al.²² compared the 2-week difference in left ventricular systolic function, incidence of multiple-organ failure and mortality rate between patients with ECMO alone and those with ECMO + IABP and found no differences. Vallabhajosyula et al.¹³ conducted a meta-analysis that showed that the mortality rate in patients who received ECMO + IABP for AMI-induced CS was significantly lower than that in those who received only ECMO. ECMO combined with IABP can significantly reduce the 30-day mortality rate in patients with AMI complicated with refractory CS, reduce cardiac afterload, improve haemodynamics, and provide more pulsatile blood flow that better aligns with human physiology.

Better revascularization can improve cardiac function and haemodynamics.⁶ We found that more operators chose to perform immediate multivessel PCI in the study group and that the culprit vessels achieved better reperfusion after PCI. Therefore, we believe that the decision of operators who increasingly use ECMO will be affected in terms of PCI strategies for multivessel CAD and the recovery of blood flow. We observed some differences chosen PCI strategy between the two groups, although there was no significant difference. We performed a subgroup analysis of the patients with multivessel CAD in the ECMO group, and the results were significantly different from those obtained in the CULPRIT SHOCK trial²³. The CULPRIT SHOCK trial concluded that the 30-day risk of composite of death or severe renal failure leading to renal replacement therapy in patients with AMI complicated with CS with multivessel CAD was lower in those who underwent immediately culprit vessel-only PCI. Based on the results of this study, immediate revascularization of nonculprit vessels under routine conditions is no longer recommended for patients with AMI and CS in the current guidelines.⁷ However, a substudy of the CULPRIT SHOCK trial found that in patients with AMI-related CS with multivessel CAD, the residual SYNTAX score was independently related to mortality; in other words, better revascularization is the key factor in reducing mortality risk.²⁴ It was also found that the 30-day mortality rate in patients who underwent immediate multivessel PCI in the ECMO group was significantly lower than that in patients who underwent culprit vessel PCI. We speculate that this difference may be related to the fact that immediate multivessel PCI can achieve better revascularization in patients with stable haemodynamics and the increased risk of harmful complementary PCI treatment. Therefore, better revascularization under ECMO support may have been one of the reasons for a better prognosis in patients who underwent immediate multivessel PCI.

Excessive use of vasoactive drugs will increase myocardial oxygen consumption and lead to arrhythmias.^{25, 26} In this study, increasing the use of ECMO decreased the vasoactive drug score, suggesting that ECMO can significantly reduce the dosage of vasoactive drugs, thus reducing its adverse effects on organ microcirculation. The CCU and total hospital stays of the study group were significantly longer than those of the control group. The 5-day mortality rate in the two groups was 13.5% and 54.5%, respectively. This may be one of the reasons for the shorter hospital stay in the control group. In addition, the incidence of bacteremia in the ECMO group was higher, which may be another reason for the prolonged hospitalization time of the patients.

Although the study group had longer survival times, the incidence of bacteremia was much higher than that in the control group. Compared with IABP, ECMO is more invasive, thus increasing the risk of intubation-related complications, including bleeding, infection, and lower limb ischaemia.^{10, 14, 19} Significantly more blood products were transfused in the study group than in the control group, which was consistent with that reported in previous studies.^27–29 The incidence of bacteremia in this study was 35.1%, and most cases were intubation-related infections,^{30, 31} which was similar with guidelines.¹⁰ There was no significant difference in the incidence of ARF requiring CRRT between the two groups, suggesting that ECMO did not increase the incidence of renal failure. Renal failure is mainly caused by acute renal failure caused by systemic hypotension and low perfusion.

All patients who experienced cardiac arrest underwent rescue measures such as CPR/eCPR—“SCAI Stage E”. The mortality rate is extremely high and is affected by many factors. Such patients have severely diminished cardiac function, prolonged times to receiving medical treatment and from cardiac arrest to ECMO, underlying neurological system disorders and multiple-organ failure in addition to being affected by the presence or absence of witnesses. To avoid bias caused by the above factors, patients with cardiac arrest were excluded from this study.

This study was a single-centre retrospective cohort study, and the sample size was relatively small. Due to the lack of data for some of the patients, only a few items could be analysed. We followed the patients in this study for only 90 days. The value of ECMO cannot be determined by the current results. However, the results of this study have a certain value for the population who can benefit from the assistance of ECMO and the choice of PCI strategies. Obviously, large, multicentre randomized controlled trials are needed to further confirm the potential benefits of ECMO for refractory CS patients.

The combination of a CS risk stratification strategy and a more optimized MCS strategy can improve the prognosis of refractory CS patients. This study showed that compared with IABP, ECMO significantly reduced the 30-day mortality rate in AMI patients with refractory CS. However, after 30 days, ECMO no longer reduced the all-cause mortality rate. In addition, immediate multivessel PCI with ECMO combined with IABP significantly reduced the 30-day mortality rate in patients with multivessel CAD.

ECMO	extracorporeal membrane oxygenation
AMI	acute myocardial infarction
CS	cardiogenic shock
MCS	mechanical circulatory support
IABP	intra-aortic balloon pump
CRRT	continuous renal replacement treatment
CAD	coronary artery disease
PCI	percutaneous coronary intervention
CCU	coronary care unit
SCAI	the Society for Cardiovascular Angiography and Interventions
CPR	cardiopulmonary resuscitation
e-CPR	extracorporeal cardiopulmonary resuscitation
BMI	body mass index
HR	heart rate
MAP	mean arterial pressure
SAPS Ⅱ	simplified acute physiology score Ⅱ
VIS	vasoactive inotropic scores
MCS	mechanical circulatory support
MI	myocardial infarction
CKD	chronic kidney disease
STEMI	ST-segment elevation myocardial infarction
NSTEMI	non-ST-segment elevation myocardial infarction
BE	base excess
ARF	acute renal failure
RCA	Right coronary artery
LAD	Left anterior descending artery
LCX	Left circumflex artery
LM	Left main artery
TIMI	thrombolysis in myocardial infarction

Ethics approval and consent to participate: This study is a single-centre retrospective case analysis, approved by the Ethics Committee of the first Hospital of Lanzhou University (Ethics # LDYYLL-2022-295) and exempted from the informed consent of the patients. All methods were carried out in accordance with relevant guidelines and regulations.

Consent for publication: Not applicable.

Availability of data and materials: The data that support the findings of this study included in this manuscript and the original files are available from the corresponding author upon reasonable request.

Competing interests: The authors declare that they have no competing interests.

Funding: Key Research and Development projects of Science and Technology in Gansu Province (No: 21YF5FA118) and the Project of Youth Science and Technology Fund of Gansu Province (No: 21JR7RA385)

Authors' contributions: We confirm that the manuscript has been read and approved by the authors and that no other persons who satisfied the criteria for authorship are listed. We further confirm that the order of authors listed in the manuscript has been approved by all the authors. Wenjing Qu, Andong Lu, Chenliang Pan, Weiting Cai, Yongling Wa, Peng Lei, Sixiong Hu, Jing Zhao and Ming Bai performed the study. Wenjing Qu and Andong Lu drafted the manuscript. Ming Bai helped supervise the project.

Acknowledgements: The authors gratefully acknowledge the financial support provided by Key Research and Development projects of Science and Technology in Gansu Province (No: 21YF5FA118), as well as the Project of Youth Science and Technology Fund of Gansu Province (No: 21JR7RA385). The authors also acknowledge the useful suggestions provided by Dr. Ming Bai, a postgraduate supervisor of Lanzhou University.

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TABLE 1. Characteristics of the Patients at Baseline.

Characteristic	Study Group (N=37)	Control Group (N=44)	P
Sex, male (%)	32(86.5%)	32(72.7%)	0.130
Age (y)	59.49±9.80	63.80±10.41	0.060
BMI (kg/m2)	24.05±3.22	23.44±3.43	0.407
HR (bpm)	102.76±16.38	98.30±20.50	0.132
MAP (mmHg)	60.29±8.89	63.70±11.66	0.148
SAPS II	48.49±11.51	48.68±8.33	0.932
VIS	69.65±58.19	63.98±66.55	0.687
Medical history
Smoking	19(51.4%)	24(54.5%)	0.774
Hypertension	15(40.5%)	17(38.6%)	0.861
Hyperlipidaemia	7(18.9%)	9(20.5%)	0.863
Type 2 diabetes	16(43.2%)	13(29.5%)	0.200
Previous MI	6(16.2%)	6(13.6%)	0.745
Previous PCI	5(13.5%)	5(11.4%)	1.000
Type of MI			0.510
STEMI	29(78.4%)	37(84.1%)
NSTEMI	8(21.6%)	7(15.9%)
Laboratory examination
Hgb	139.68±27.44	148.34±20.58	0.148
WBC	15.21±7.91	13.04±5.92	0.207
N (%)	81.78±14.85	80.26±14.01	0.663
AST	137.0 (44.5, 637.0)	155.0 (67.0, 388.0)	0.995
ALT	65.0 (27.0, 161.0)	52.0 (26.0, 87.0)	0.352
Blood glucose	11.95±6.73	13.13±7.93	0.508
Serum creatinine(mg/dL)	1.45 ± 0.77	1.17 ± 0.58	0.107
BE	-8.02±6.65	-7.40±6.89	0.729
lac	7.06±3.90	7.02±2.90	0.965

Abbreviations: BMI: body mass index; HR: heart rate; MAP: mean arterial pressure; SAPS Ⅱ: simplified acute physiology score Ⅱ; VIS: vasoactive inotropic scores; MCS: mechanical circulatory support; MI: myocardial infarction; CKD: chronic kidney disease; STEMI: ST-segment elevation myocardial infarction; NSTEMI: non-ST-segment elevation myocardial infarction; BE: base excess

Table 2. Comparison of end point events of the two groups.

Outcome	Study Group (N=37)	Control Group (N=44)	P
End points
In-hospital mortality	17(45.9%)	30(68.2%)	0.043
30-day mortality	16(43.2%)	30(68.2%)	0.004
90-day mortality	18(48.6%)	30(68.2%)	0.01
Perioperative mortality	0(0.0%)	8(20.0%)	0.015
ECMO Running time (h)	111.91±49.47
ECMO Weaning rate	27(73.0%)
VIS after MCS running	33.18±37.95	58.83±69.24	0.048
Total hospitalization days	13.0 (7.0, 17.0)	4.0 (1.0, 10.75)	＜0.001
CCU hospitalization days	10.0 (7.0, 14.5)	3.5 (1.0, 3.5)	＜0.001
Complication
Cerebrovascular events	1(2.7%)	0(0.0%)	0.457
Life-threatening bleeding	1(2.7%)	0(0.0%)	0.457
Moderate bleeding	9(24.3%)	1(2.3%)	0.008
Bacteremia	13(35.1%)	2(4.5%)	＜0.001
ARF requiring CRRT	10(27.0%)	6(13.6%)	0.132
AV thrombosis of lower extremities	2(5.4%)	0(0.0%)	0.206

CCU: coronary care unit; ARF: acute renal failure; CRRT: continuous renal replacement therapy

Table 3. Comparison of the PCI characteristics of the two groups.

characteristics	Study Group (N=35)	Control Group (N=40)	P
Lesions
RCA	20(57.1%)	22(55.0%)	0.852
LAD	29(82.9%)	33(82.5%)	0.967
LCX	24(68.6%)	18(45.0%)	0.040
LM	4(11.4%)	8(20.0%)	0.353
Multivessel CAD	27 (77.1%)	27(67.5%)	0.353
PCI strategies			0.273
Culprit-PCI	13/27(48.1%)	17/27(63.0%)
Multi-PCI	14/27(51.9%)	10/27(37.0%)	0.457
Before PCI of culprit lesion			0.394
0	20/27(74.1%)	16/27(59.3%)
Ⅰ	5/27(18.5%)	6/27(22.2%)
Ⅱ	2/27(7.4%)	5/27(18.5%)
Ⅲ	0(0.0%)	0(0.0%)
After PCI of culprit lesion			0.154
0	1/27(3.7%)	4/27(14.8%)
Ⅰ	0/27(0.0%)	2/27(7.4%)
Ⅱ	1/27(3.7%)	1/27(3.7%)
Ⅲ	25/27(92.6%)	20/27(74.1%)

RCA: Right coronary artery; LAD: Left anterior descending artery; LCX: Left circumflex artery; LM: Left main artery TIMI: thrombolysis in myocardial infarction CAD: coronary artery disease

No competing interests reported.

supplement.docx

Clinical Efficacy of ECMO in the Treatment of AMI Complicated with Refractory CS

Status:

Version 1

Abstract

Figures

Introduction

Materials And Methods

Statistical Analysis

Results

Discussion

Limitations

Conclusion

Abbreviations

Declarations

References

Tables

Additional Declarations

Supplementary Files

Status:

Version 1