Acute myocardial infarction (AMI) complicated by cardiogenic shock (CS) presents a formidable challenge in clinical practice, possessing a mortality rate of approximately 40–50% [1]. Notably, AMI patients with cardiac arrest (CA) are more prone to developing CS. In the subset of AMI complicated by CS (AMI-CS), the incidence of CA ranges from 28.5 to 51% [2, 3, 4, 5], and CA is frequently inferred as the primary cause of death in cases of AMI complicated by CS [6].

While previous studies have established CA as a significant risk factor for mortality in patients with acute coronary syndrome (ACS) [7, 8, 9, 10], this association exhibits inconsistency within AMI-CS patients [2, 3, 11]. Some studies suggest that CA may not independently influence all-cause in-hospital or long-term mortality among patients hospitalized with AMI-CS [2, 3]. Notably, these studies reported low proportions of coronary angiography (61.3%) and revascularization (53.3%), potentially compromising the survival probability of CA patients [2, 3]. In contrast, a comprehensive registry study demonstrated higher rates of coronary angiography (88.8%) and revascularization (77.2%) in AMI-CS patients [12].

Recent advancements in acute percutaneous coronary intervention (PCI) and circulatory support devices have significantly improved the short-term prognosis of AMI patients, particularly through early revascularization [1]. Consequently, in the context of active revascularization, the association between CA and the prognosis of patients with AMI-CS has become a subject of debate. In this study, we aimed to assess the impact of CA on AMI-CS outcomes by analyzing data collected from September 2018 to November 2021. Notably, the study cohort exhibited high proportions of coronary angiography (89.5%) and revascularization (80.2%), providing valuable insights into the contemporary landscape of AMI-CS management.

The primary finding of this study was that CA did not emerge as an independent risk factor for either short- or long-term mortality in AMI-CS patients. Despite this, it is noteworthy that CA showed a significant association with the occurrence of brain injury in this patient population. While CA is acknowledged as a crucial element in the GRACE scoring system, our results indicate that the GRACE risk score provides only a moderate predictive value for individuals with AMI-CS. Furthermore, including CA as a risk factor in the IABP-SHOCK II scoring system did not improve its predictive accuracy for either the short- or long-term mortality assessment among AMI-CS patients. This suggests that the predictive value of CA within established risk models may not be as impactful as initially anticipated in shaping the prognosis of individuals with AMI-CS.

Cardiogenic shock after AMI poses a significant threat to life, with an overall 30-day mortality rate of approximately 40–50% [17]. Our study aligns with existing literature, revealing a comparable 30-day mortality rate of 40.7% in patients with AMI-CS. Historically, CA has been identified as a substantial risk factor for mortality in patients with ACS [3, 4, 5, 6]. While the GRACE score, a widely utilized tool for assessing death risk in ACS patients, includes CA as an important predictive factor [18], limited data exists on the correlation between CA and mortality, specifically in AMI-CS patients [11]. Current risk prediction models for CS, such as the IABP-SHOCK Ⅱ score, CARD-SHOCK risk score, SAVE, and ENCOURAGE score, notably omit CA as a risk factor [17]. Our study underscores that CA is not a significant prognostic factor for short- and long-term mortality in AMI-CS patients. Instead, age, lactate level, creatinine level, a TIMI grade 3 after PCI, and ventilation were identified as risk factors for mortality, consistent with previous research [4, 19, 20, 21]. Notably, the GRACE score exhibited moderate predictive performance for mortality in AMI-CS patients, although the addition of CA did not enhance the predictive value of the IABP-SHOCK II score. These observations align with prior studies [2, 3, 5], suggesting that CA may not influence the 7-day, in-hospital, and long-term mortality of AMI-CS patients [2, 3, 5]. The age and comorbidity profile of CA survivors and the simplicity of coronary lesions were proposed to explain these outcomes [4, 19, 20, 21, 22, 23]. Our study also highlighted that effective resuscitation, improved post-resuscitation care, and lower rates of hypoxic brain damage might contribute to the observed low proportion of non-cardiac deaths in the CA group [4, 15, 24]. Contrary to previous reports where hypoxic brain damage and cardiac failure were leading causes of in-hospital death in AMI-CS patients with CA [25], our population predominantly succumbed to cardiac causes. This discrepancy may stem from the impact of effective resuscitation on influencing outcomes, consistent with prior research [26].

This study holds significant clinical implications on multiple fronts. Firstly, it contributes valuable data to the ongoing exploration of whether CA is a prognostic factor for mortality in patients with AMI-CS. This finding emphasizes the importance of proactive rescue efforts for such patients, urging the public to engage in life-saving interventions actively. In China, where awareness regarding cardiac arrest and CPR remains limited [27, 28], our study underscores the critical need for heightened public education on CA and CPR. Importantly, our results suggest that surviving CA does not independently jeopardize the prognosis of AMI-CS patients. Thus, advocating for effective CPR becomes even more imperative, particularly in regions where a substantial number of patients grapple with AMI and cardiogenic shock. Secondly, our study poses a challenge to the GRACE score in predicting outcomes in AMI-CS patients, revealing its limited predictive capability. This observation prompts a reassessment of the GRACE score’s applicability, suggesting that it may not be universally suitable for all patients with ACS. This insight calls for a critical examination of existing risk assessment tools and the potential development of more tailored predictive models for specific subsets of ACS patients, particularly those confronting the complexities of AMI-CS.

While providing valuable insights, this study has limitations. Firstly, the observed rate of CA in our study was 15.8%, lower than previously reported rates [2, 3, 4, 5, 29]. This discrepancy might be attributed to excluding patients who did not survive until hospital admission, potentially leading to an underestimation of the true incidence of CA. The exclusion criteria, particularly limiting CPR time to 30 minutes, aimed to ensure a focus on genuine cases of AMI-CS. Secondly, despite not reaching statistical significance, the 30-day and 1-year mortality rates appeared higher in the CA group (53.9% vs. 38.5% and 59% vs. 44.7%, respectively). While not statistically conclusive, these findings may still bear clinical significance. Previous studies noted comparable outcomes, with one reporting a 62.7% mortality rate at 7 days for the cardiogenic shock population with CA, surpassing that of the non-CA group [3]. Another study, encompassing 1573 patients, identified a relatively higher short-term mortality risk in the CA group, though long-term mortality risk did not reach statistical significance (HR = 1.19, p = 0.055) [30]. Indeed, it is essential to acknowledge these trends, even without statistical significance. Thirdly, our study is limited by its retrospective, single-center design, which may limit the generalizability of findings to the broader Chinese population. However, the study population adhered to the criteria established by large prospective randomized controlled trials of AMI-CS [26, 29], and patients spanned various SCAI stages. Fourthly, the lack of exact timing and detailed information on the cardiac arrest events constitutes another limitation. Nevertheless, the meticulous selection of comprehensive clinical data and a robust sample size, pre-determined through careful sample size estimation, mitigate the likelihood of results occurring by chance. Despite these limitations, the study’s findings contribute valuable insights into the complex interplay of cardiac arrest and mortality in the context of AMI-CS.

In the context of AMI-CS in China, cardiac arrest has emerged as a non-contributory factor in predicting both short- and long-term mortality. Contrary to its significant impact on other cardiac conditions, CA does not independently pose an elevated risk in AMI-CS patients. This finding underscores the importance of active CPR efforts for patients facing AMI-CS, as survival from CA does not inherently compromise their overall prognosis. These results advocate for a proactive and vigorous approach to CPR in this specific patient cohort, emphasizing the need for continued efforts to enhance public awareness and responses to cardiac emergencies in the Chinese population.

AMI, acute myocardial infarction; CS, cardiogenic shock; AMI-CS, AMI complicated by CS; CA, cardiac arrest; GRACE, Global Registry of Acute Coronary Event; IABP-SHOCK, Intra-aortic Balloon Pump in Cardiogenic Shock; ACS, acute coronary syndrome; PCI, percutaneous coronary intervention; SCAI, cardiovascular angiography, and intervention; VT, ventricular tachycardia; CPR, cardiopulmonary resuscitation; ROSC, return of spontaneous circulation; BMI, body mass index; LVEF, left ventricular ejection fraction; TIMI, thrombolysis in myocardial infarction; CPC, cerebral performance categories; HR, hazard ratio; SBP, systolic blood pressure; MAP, mean arterial pressure; CAD, coronary artery disease; PAD, peripheral artery disease; CKD, chronic kidney disease; STEMI, ST-segment elevation myocardial infarction; IABP, intra-aortic balloon pump; AUC, area under the curve.

The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.

QFX: Conceptualization, Methodology, Software, Writing-Original draft preparation. XW: Conceptualization, revise-original draft preparation. SW: Data collection, Writing-Original draft preparation, Funding acquisition. YX and YY: Data collection, Writing-Original draft preparation. FYH: Conceptualization, Software, Writing-Reviewing, Funding acquisition. MC: Conceptualization, Supervision, Funding acquisition, Writing-Reviewing and Editing critically. All authors read and approved the final manuscript. All authors have participated sufficiently in the work and agreed to be accountable for all aspects of the work.

We declare that the study protocol received approval from the Ethics Committee of West China Hospital, Sichuan University (Chengdu, China; approval number: 2021–1770). All participants provided written informed consent.

Not applicable.

This work was supported by the National Natural Science Foundation of China (81970325, and 82170375); Key Research and Development Project of Science & Technology Department of Sichuan Province (2022ZDZX0020); Chinese Medical Association Cardiovascular Branch (CSC) Clinical Research Special Fund Project (CSCF2020B04); “1$\cdot$ 3$\cdot$ 5 project for disciplines of excellence–Clinical Research Fund, West China Hospital, Sichuan University”; the Sichuan Science and Technology Program (Grant Numbers: 2023YFS0296 and 2023NSFSC0581).

The authors declare no conflict of interest.