Acute ST-elevation myocardial infarction (STEMI) is a severe form of coronary artery disease, with a mortality rate of 40% to 50% in patients with cardiogenic shock. In patients with STEMI and cardiogenic shock, the time from onset of symptoms to death in patients with progressive heart failure is usually < 24 hours. Because cardiogenic shock occurs when cardiac output is insufficient to meet the body's metabolic demands, restoring perfusion with mechanical circulatory support (MCS) is therapeutic. The percutaneous miniature axial flow pump (Impella CP) is an active MCS device capable of draining oxygenated blood from the left ventricle and pumping it directly into the ascending aorta, but it is uncertain whether there is a clinical benefit in using it in patients with STEMI and cardiogenic shock. The results of the Danger shock trial were recently presented at the 2024 ACC Annual Meeting and published in the New England Journal of Medicine.
Research Methods:
Danger shock is a prospective, randomized, multicenter, open-label trial conducted at 14 centers in Denmark, Germany, and the United Kingdom. The study included patients aged ≥18 years with STEMI and cardiogenic shock, who had persistent hypotension, end-organ hypoperfusion with arterial lactate > 2.5 mmol/L, and left ventricular ejection fraction (LVEF) <45%, except for patients who were comatose after out-of-hospital cardiac arrest and had right ventricular failure. According to the time of diagnosis of cardiogenic shock, the enrolled patients were randomized before, during, or within 12 hours after cardiac catheterization and assigned 1:1 to receive standard treatment alone or standard treatment combined with miniature axial flow pump therapy.
Fig.1 Study design
The primary endpoint of the study was all-cause mortality at 180 days of follow-up. Secondary endpoints included mean survival and days to hospital discharge and composite cardiac endpoint outcomes requiring additional mechanical support, heart transplantation, and death. Safety endpoints included the incidence of adverse events such as moderate to severe bleeding, vascular complications, stroke, and mechanical hemolysis.
Findings:
A total of 360 patients were included in the study between January 2013 and July 2023, of which 5 patients were excluded after randomization due to inability to obtain informed consent, and after randomization, 179 patients were in the mini-axial flow pump group and 176 patients were in the standard care group. The median age of the patients was 67 years, 79.2% were male, the median arterial blood lactate was 4.5 mmol/L, the median systolic blood pressure was 82 mmHg, and the median LVEF was 25%. Baseline characteristics were similar in both groups (Figure 2). Thirty-four patients (96.6%) were treated with percutaneous coronary intervention and 5 (1.4%) were treated with emergency coronary artery bypass grafting. Of the 179 patients assigned to the miniature axial flow pump set, 170 were successfully implanted.
Fig.2 Characteristics of enrolled patients
In terms of primary endpoints, 82 patients (45.8%) died in the miniature axial pump group and 103 patients (58.5%) in the standard care group at 180 days (HR=0.74; 95% CI: 0.55-0.99; p=0.04; Figure 3).
Fig.3 The primary endpoint of the study, all-cause mortality within 180
In terms of secondary endpoints, 94 patients (52.5%) in the miniature axial flow pump group and 112 patients (63.6%) in the standard care group had composite cardiac endpoint events (HR=0.72; 95% CI: 0.55-0.95; Figure 4). In addition, the mean number of days of survival and hospital discharge was 82 days in the mini-axial pump group and 73 days in the standard treatment group (mean difference between groups was 8).
Fig. 4 Incidence of composite cardiac endpoint events was studied as a secondary endpoint
In terms of safety endpoints, 43 patients (24.0%) in the miniature axial flow pump group and 11 patients (6.2%) in the standard treatment group had composite safety endpoint events (RR=4.74; 95% CI: 2.36-9.55). The mini-axial flow pump group was associated with a higher risk of moderate to severe bleeding, limb ischemia, and positive blood culture-positive sepsis compared with the standard management group, and more renal replacement therapy.
Conclusions and discussions
The Danger shock study was a prospective, randomized controlled trial conducted with strict exclusion criteria in a more homogeneous patient population. The results showed that patients with STEMI and cardiogenic shock had lower 180-day all-cause mortality and a lower rate of composite cardiac endpoint events compared with patients treated with a miniature axial flow pump in addition to standard care alone. However, patients treated with miniature axial flow pumps had a higher incidence of adverse events and more patients who received renal replacement therapy, which may be related to survival bias due to early death and mechanical hemolysis due to miniature axial pumps in the standard treatment group. Through this study, the effect of miniature axial flow pumps in reducing mortality in patients with STEMI and cardiogenic shock has been further confirmed, and it is believed that more studies will emerge in the future to help improve patient outcomes.
bibliography
1.Møller JE, Engstrøm T, Jensen LO, et al. Microaxial Flow Pump or Standard Care in Infarct-Related Cardiogenic Shock. N Engl J Med. Published online April 7, 2024.
2.J. E. Møller, et al. Percutaneous Transvalvular Micro-axial Flow Pump In Infarct Related Cardiogenic Shock. Results Of The Danger-shock Trial. 2024ACC. 6–8 April 2024.
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