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ACC 2026: Door to Unload Randomized Clinical Trial

Published: 28 Mar 2026

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ACC 2026 — Drs Karim Al-Azizi (Baylor Scott & White The Heart Hospital, Plano) and Babar Basir (Henry Ford Hospital, US) deliver a short, front-line interventional view of the STEMI Door-to-Unload (STEMI-DTU) trial (NCT03000270), making this an efficient 5-minute update for cardiologists and cath lab teams. 

STEMI-DTU randomised haemodynamically stable patients aged 18–85 years with a first acute anterior STEMI, presenting 1–6 hours after symptom onset, without cardiogenic shock and with an LAD culprit suitable for primary PCI. Patients were allocated either to femoral Impella CP with at least 30 minutes of left ventricular unloading before PCI (followed by 4–24 hours of continued support), or to standard immediate coronary angiography and primary PCI without Impella. 

The primary endpoint was infarct size at 3–5 days on cardiac MRI (percentage of LV mass), supported by a powered hierarchical composite of clinical outcomes and a key safety endpoint of major bleeding or major vascular complications at 30 days.

The trial found no statistically significant reduction in infarct size with Impella-supported unloading and delayed PCI; mean infarct size remained around one-third of LV mass in both groups, despite longer total ischaemic and door-to-balloon times in the unloading arm. Twelve-month clinical outcomes, including mortality and heart failure events, were similarly neutral, while major bleeding and vascular complications were notably higher with large-bore femoral access and Impella use. 

Drs Al-Azizi and Basir conclude that, for anterior STEMI without cardiogenic shock, these data do not justify altering current practice: radial-first, rapid reperfusion remains the standard of care, and routine Impella unloading with a planned delay to PCI should, for now, be confined to the research setting.

Recorded at ACC 2026, New Orleans.

For more expert insights and late-breaking science from ACC 2026, visit the Late-breaking Science Video Collection.


Editors: Jordan Rance, Mirjam Boros
Videographer: David Ben-Harosh, Tom Green


Support: This is an independent video produced by Radcliffe Cardiology.

 

Transcript

Dr. Karim Al-Azizi: Hello everyone. Welcome to ACC 2026. I’m Karim Al-Azizi, an interventional cardiologist at Baylor Scott & White The Heart Hospital – Plano. Here with me today is Dr. Babar Basir from Henry Ford Hospital in Detroit, Michigan. We’re going to discuss a very interesting study that was presented today: the STEMI Door-to-Unload trial. Babar, welcome.

Dr. Babar Basir: Thank you, Karim. Thanks for having me.
Dr. Karim Al-Azizi: So, just a little bit of high-level information and conclusions—what is the Door to Unload study, just so everyone is well-informed on it?

Dr. Babar Basir: The Door to Unload study was a disruptive trial built on over two decades of work regarding myocardial protection with unloading. Dr. Navin Kapur and Dr. William O’Neill were the principal investigators for this pivotal trial. They randomized patients presenting with an anterior STEMI within one to six hours of symptom onset to either Impella-supported unloading with delayed reperfusion or standard-of-care primary PCI.
The Impella arm included a 30-minute delay prior to reperfusion, which was the disruptive part of the study. Animal modeling had suggested that this 30-minute window maximized infarct size reduction. It is important to note these patients were not in cardiogenic shock.

Ultimately, the trial showed a small numerical reduction in infarct size with the use of Impella, but there was no statistically significant difference between the treatment arm and standard of care. Additionally, there was more bleeding in the Impella arm, reflecting the higher bleeding and vascular complication risk we generally see with large-bore access.

Dr. Karim Al-Azizi: Thank you, Babar. Impella has served many patients, but this was a unique study picking a specific group of patients with the concept of unloading while not in cardiogenic shock. Based on this study, how do you see this informing practice and care for anterior STEMI patients?

Dr. Babar Basir: Practically speaking, our practice is going to stay the same. Our routine for STEMI is to go radial and open the artery as quickly as we can. This trial really focused on the future burden of heart failure by looking at infarct size, which remains a problem in anterior infarcts.
While we may evaluate how to unload in a safer way or enhance treatment with medications, that remains in the research space. Clinically, we have a good protocol already. We know from the DANGER-SHOCK trial that Impella is very beneficial for mortality in patients with STEMI and cardiogenic shock. It will be interesting to see, in sub-analyses, whether higher-risk anterior MI patients who are starting to “creep” toward shock might derive more benefit.

Dr. Karim Al-Azizi: I think the biggest thing is clarifying that while a study like this might make people pause, these patients were completely stable and not in cardiogenic shock, whereas the device signal is different for those teetering into or in actual shock.

Dr. Babar Basir: Yes, it is very important to note that our standard of care for anterior MI has not changed.

Dr. Karim Al-Azizi: All right. Well, thank you, Babar. Thank you all for your attention, and welcome to ACC 2026.

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