What happened
LV unloading before PCI fails to reduce infarct size vs PCI alone in anterior STEMI.
“Our findings do not support the routine use of a left-ventricular transaxial flow pump followed by a 30-minute waiting period before performing PCI, as opposed to performing immediate PCI without the heart pump.”
Conference Coverage ↗
“We're excited because this opens up a new chapter of investigation. There's much more work to do, but you can see a number of different study designs coming out – for the first time, we can say that putting in an LV support device, even if you had to delay up to 30 minutes, is not going to increase the infarct size. That's where the investigative opportunities open up.”
News Coverage ↗From published coverage, not an answer posted here.
David Kandzari
Practice takeInterventional cardiologist, Piedmont Heart Institute, Atlanta, GA“There has been truly a graveyard of pharmaceutical and device therapies, all of which were intended to reduce infarct size as an adjunct to revascularization in acute MI.”
He places the strategy in a graveyard of drug and device therapies meant to shrink infarcts alongside revascularization in acute MI. The sixfold rise in major bleeding or vascular complications matches other studies of this technology, and here no net clinical benefit offsets it, judged by infarct size as a surrogate.
“As a clinician, I'm going to continue using Impella in cardiogenic shock. In anterior STEMIs, I don't think we'll be using this technology.”
As a clinician he will continue Impella in cardiogenic shock. He does not expect the technology to be used in anterior STEMIs.
“During the period between Impella CP insertion and PCI, operators could bail out and perform PCI at their discretion based on patient stability. However, there was never a clinical need to begin PCI during this waiting period. We had 100% compliance. Many of my patients began to snore, suggesting that they were clinically stable enough to fall asleep. This suggests that pre-PCI LV unloading rested the heart without worsening the infarction.”
News Coverage ↗William O'Neill
Henry Ford Health System“STEMI DTU is the first clinical trial to test this novel and disruptive hypothesis and demonstrate the ability to stop the ischemic clock during infarct. More research is needed in older age, abnormal lactate subsets and the impact of concomitant beta blockade. We will continue to explore LV unloading impact without PCI in STEMI patients in future studies.”
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Answers are grounded in this paper and cite their sources.
Why the trial, key points, tables, limitations, PICO, abstract, media & sources
Why the trial?
The STEMI-DTU trial was conducted to address whether mechanical left ventricular unloading combined with a 30-minute delay before PCI reduces infarct size compared to immediate PCI alone in patients with anterior STEMI without cardiogenic shock, based on preclinical evidence suggesting LV unloading may limit infarct size.
Does left ventricular unloading with a transvalvular microaxial flow pump for 30 minutes before PCI reduce infarct size in patients with anterior STEMI without cardiogenic shock?
RCT (n=527)
Open-label
1:1
Yes
Does left ventricular unloading with a transvalvular microaxial flow pump for 30 minutes before PCI reduce infarct size in patients with anterior STEMI without cardiogenic shock?
In patients with anterior STEMI without cardiogenic shock, left ventricular unloading with a transvalvular microaxial flow pump and a 30-minute delay before PCI did not reduce infarct size compared with immediate PCI alone, but increased bleeding and vascular complications.
Experts agree the heart pump should not be used routinely before stenting in anterior heart attacks without shock, but they split on whether the neutral result closes the door or opens new research.
Trial leaders and outside interventionalists alike say the results do not support routine pump support before opening the artery. Skeptics point to the added bleeding and vascular harm with no benefit to offset it. Investigators argue that the pump-first delay did not enlarge the infarct and may hint at a protective effect, so the live question is whether unloading the heart deserves further trials.
Several clinicians state directly that the pump-first strategy should not become routine care for anterior heart attacks without shock. That includes the trial's own lead voice.
Dead end with excess harm, or a safe signal worth more trials.
Investigators raise but do not test whether a delay-adjusted effect on infarct size is real. They also leave open whether combining mechanical support with drug therapy could help. Kandzari notes that infarct size is only a surrogate for clinical benefit.
Avoid routine LV unloading with delayed PCI in anterior STEMI; reinforces immediate reperfusion priority and limited mechanical support role in non-shock MI.
BACKGROUND: Despite rapid percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI), large infarcts contribute to heart failure and mortality. Left ventricular (LV) wall tension and load are major determinants of infarct size. Preclinical studies identified that delaying reperfusion to permit LV unloading with a transvalvular microaxial flow pump (TV-mAFP) reduces infarct size. We tested whether this combination reduces infarct size compared with reperfusion alone in patients with anterior STEMI without cardiogenic shock. OBJECTIVES: The STEMI-Door to Unload (DTU) pivotal trial tested the central hypothesis that the combination of mechanical LV unloading plus a 30-minute delay before PCI reduces infarct size compared with immediate PCI alone in patients with anterior STEMI without cardiogenic shock. METHODS: We conducted an open-label, randomized controlled trial at 55 hospitals in the United States, Germany, Italy, United Kingdom, Switzerland, and Canada. Adults aged 18 to 85 years with no prior myocardial infarction and presenting with acute anterior STEMI within 1 to 6 hours of symptom onset before hospital arrival were eligible for inclusion. Patients were randomly assigned (1:1) by study site personnel to either LV unloading with a TV-mAFP for 30 minutes before PCI (treatment group) or PCI alone (control group). The primary outcome was infarct size normalized to LV mass (IS/LVM) evaluated by cardiac magnetic resonance imaging 3 to 5 days after PCI and was evaluated in all randomized patients. The trial is closed to new participants. RESULTS: Between December 12, 2019 and September 3, 2024, 527 patients were randomized; 262 patients were assigned to the treatment group and 265 to the control group. Mean patient age was 61 ± 11 years, and 417 patients (79.1%) were men. Total ischemic time was longer in the treatment arm. IS/LVM was 30.8% ± 16.2% in the treatment group and 31.9% ± 16.9% in the control group (mean difference: -1.1%; 95% CI: -4.2 to 2.0; P = 0.50). Major bleeding or vascular complications at 30-day follow-up occurred more frequently in the treatment group when compared with either a prespecified performance goal or the control group. CONCLUSIONS: Combination of a TV-mAFP plus delayed PCI did not reduce infarct size in patients with anterior STEMI without cardiogenic shock compared with PCI alone. (Primary Unloading and Delayed Reperfusion in ST-Elevation Myocardial Infarction: The STEMI-DTU Trial [DTU-STEMI]; NCT03947619).
Kapur et al. (2026) conducted an RCT in Anterior STEMI without cardiogenic shock (n=527). LV unloading with a transvalvular microaxial flow pump (TV-mAFP) for 30 minutes before PCI vs. Immediate PCI alone was evaluated on Infarct size normalized to LV mass (IS/LVM) evaluated by cardiac magnetic resonance imaging 3 to 5 days after PCI (MD -1.1%, 95% CI -4.2 to 2.0, p=0.50). LV unloading with a transvalvular microaxial flow pump for 30 minutes before PCI did not reduce infarct size compared with PCI alone in anterior STEMI without shock (mean difference -1.1%; P=0.50).
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