The Effect of IABP in the Early Stage of Acute Myocardial Infarction With Cardiogenic Shock (SCAI-B): a Multicenter, Prospective, Randomized Controlled Study

(A).Background AMICS is the most common cause of death in patients with coronary heart disease. Even with modern treatment, including early reperfusion combined with mechanical assistive devices, the 30-day mortality of AMICS is still close to 50%. At present, mechanical assistive devices mainly include IABP, ECMO, and impalla.

As far as China's national conditions are concerned, IABP is still the most easily available mechanical assistive device for clinical operation and management. IABP can reduce cardiac afterload, decrease myocardial oxygen consumption and increase cardiac output in patients with AMICS, which is helpful to protect the myocardium and improve end-organ perfusion. In previous registration studies or retrospective analyses on IABP, the mortality of CS patients using IABP was significantly lower than that of the control group. Therefore, the use of IABP in patients with AMICS are class I recommendations in the early (before 2012) American and European guidelines. Until 2012, the results of IABP-SHOCK II study were released, the effect of IABP on patients with AMICS began to be questioned. IABP-SHOCK II study is the largest randomized controlled study so far. Compared with traditional treatment, IABP did not improve AMICS mortality in 30 days, 1 year, and 6 years. Subsequently, European guidelines did not recommend routine use of IABP (level III recommendation) in AMICS, while American guidelines changed from level I recommendation to level IIb recommendation . However, the IABP-SHOCK II study has some limitations: (1) the severity of CS in the patients included in this study varies greatly; (2) IABP was used relatively late (most patients received IABP treatment after revascularization and severe tissue hypoperfusion).

CS patients are a heterogeneous population, and the prognosis may vary greatly with the severity of shock. In order to guide treatment and predict clinical outcomes more accurately, the consensus statement of clinical experts on classification of cardiogenic shock SCAI was issued at the 42nd Annual Meeting of angiocardiography and intervention (SCAI) in 2019, which divided CS into five stages: a (risk stage), B (initial stage), C (typical stage), D (deterioration stage) and E (end stage). In the IABP-SHOCK II study, the inclusion criteria of CS patients were (1) systolic blood pressure < 90mmHg for more than 30min or the need for catecholamine drugs to maintain systolic blood pressure > 90mmHg with signs of pulmonary congestion; (2) The symptoms of organ hypoperfusion (at least in accordance with the following 1 item): (a) change of mental state; (b) The limbs and skin are cold and wet; (c) The decrease of urine volume was less than 30ml / h; (d) Lactic acid > 2.0mmol/l. Therefore, patients with CS of stage C (typical stage) or more severity were included in IABP-SHOCK II study. According to the "Chinese expert consensus on diagnosis and treatment of cardiogenic shock (2018)", it is emphasized that IABP should be implanted as soon as possible and maintained for enough time in patients with AMICS. In addition, in a recent retrospective study, the project team investigated the use of IABP and the outcomes of more than 300 AMI cases in three provincial capitals of Northeast China in 2016. It was found that the 28-day survival rate of patients in the early use of IABP group was significantly higher than that in the late use group.

The investigators speculated that IABP could significantly improve the clinical outcomes of patients with AMICS if it could be used in the earlier stage of CS (stage B). At present, there is no clinical study on the use of IABP in AMICS (stage B). It is worth carrying out the corresponding clinical research, in order to study the real role of IABP in patients with AMICS and explore the treatment strategy of AMICS in line with China's national conditions.

(B).Preliminary Data The clinical data of all patients receiving IABP treatment in 8 top three hospitals in three provincial capitals of Northeast China. The reasons for receiving IABP treatment, the duration of treatment and the clinical outcomes of patients were recorded. At the same time, the high-risk PCI patients were analyzed according to early IABP implantation (before PCI or at the same time) and late implantation (after PCI).