By Jeffrey Zimmet, MD, PhD
Synopsis: In this post-hoc analysis of the DanGer Shock trial, patients in the highest quartile of age appeared to have higher mortality compared with younger patients, suggesting less benefit from routine application of the microaxial flow pump in older patients with acute myocardial infarction-related cardiogenic shock.
Source: Klein A, Beske RP, Hassager C, et al; DanGer Shock Investigators. Treating older patients in cardiogenic shock with a microaxial flow pump: Is it DANGERous? J Am Coll Cardiol. 2025;85(6):595-603.
In 2024, the DanGer Shock trial made headlines by reporting a significant reduction in all-cause mortality with the use of the Impella microaxial flow pump in treating patients with cardiogenic shock resulting from acute ST elevation myocardial infarction (AMI-CS). The number needed to treat (NNT) of eight to prevent one mortality was tempered by a high rate of adverse events in the treatment group, including significant bleeding, limb ischemia, and the need for renal replacement therapy. In addition, despite the reported beneficial effect of device therapy on the primary outcome, mortality at six months remained high despite the use of the pump device. Analysis of the trial shows that enrolled participants represent a highly selected subpopulation of all patients with AMI-CS. Much of the subsequent discussion has focused on determining which patients are most likely to obtain benefit from this invasive therapy.
This secondary analysis of the DanGer Shock data sought to assess the interaction of age with clinical outcomes among patients enrolled in the trial. The 355 patients included in the analysis were divided into quartiles by age, with mean ages of 54 years (range 31-59), 65 years (range 60-69), 73 years (range 70-76), and 81 years (range 77-92). Resuscitation prior to randomization was more common in the youngest quartile, while the proportion of women was higher in the oldest quartile (41%) compared with the others (12% to 18%). Other variables were not significantly different across quartiles of age, including essential measures such as lactate level, ejection fraction, blood pressure, or Society for Cardiovascular Angiography and Interventions shock class.
The overall mortality in the trial at six months was 52%. This analysis demonstrated a stepwise increase in mortality with each increased quartile of age — mortality in the lowest age quartile was 31%, with subsequent quartiles showing mortality of 47%, 61%, and 73%, respectively. When the effect of age was examined as a continuous variable, the authors found that mortality was significantly lower in the microaxial flow pump group (compared with standard care) until approximately age 77 years. At ages older than 77 years, there was no significant difference in mortality between the two care groups. Importantly, procedural complications, including limb ischemia and major bleeding, were similar across all quartiles of age.
The authors reported that older patients with cardiogenic shock caused by acute myocardial infarction may not have the same benefit from routine use of the microaxial flow pump compared to younger patients. They propose that incorporating age into the decision-making process for adults with AMI-CS may improve the benefit of this device therapy.
Commentary
This analysis by Klein and others represents a superb example of the use of existing trial data to answer important practical questions about how a therapy may best be targeted to patients who are most likely to benefit.
For every case of AMI-CS, decision-making about when to apply this therapy — with potentially large rewards but also significant costs in terms of both complications and economics — needs to happen quickly and preferentially involves multidisciplinary shock teams. Simple analyses such as this one cannot, of course, substitute for the judgment of these clinicians, and yet this information may better inform those decisions for selected patients. In the absence of more expected trial data, this analysis provides some very helpful perspective.
It also is important to realize that in this arena, no additional randomized trials are immediately forthcoming or even expected in the next several years. In the wake of the publication of the DanGer Shock trial in mid-2024, for example, the RECOVER IV randomized trial of the Impella mechanical circulatory device in patients with AMI complicated by cardiogenic shock was halted because of concerns that investigators no longer would have clinical equipoise about randomizing patients. For now, analyses such as this one will be important for refining clinical decision-making in AMI-CS.
Jeffrey Zimmet, MD, PhD, is Associate Professor of Medicine, University of California, San Francisco; Director, Cardiac Catheterization Laboratory, San Francisco VA Medical Center.
In this post-hoc analysis of the DanGer Shock trial, patients in the highest quartile of age appeared to have higher mortality compared with younger patients, suggesting less benefit from routine application of the microaxial flow pump in older patients with acute myocardial infarction-related cardiogenic shock.
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