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PARIS -- Intra-aortic balloon pumps (IABP) didn't significantly improve outcomes for patients with ischemia persisting well after percutaneous coronary intervention (PCI) for a large acute ST-segment elevation MI (STEMI), a pilot study suggested.

But there was a trend toward lower rates of mortality, need for mechanical circulatory support, and hospital readmission for congestive heart failure at 6 months in patients randomized to IABP therapy (2% versus 8% of peers who didn't receive it, P=0.16).

On the other hand, the impact of IABP therapy trended the wrong way in infarct size estimated by CK-MB (338 U/L for IABP versus 311 U/L for control, P=0.532), according to Lokien van Nunen, MD, PhD, of Catharina Hospital Eindhoven in the Netherlands, during his late-breaking trial presentation at the EuroPCR meeting here.

"Use of IABP in patients presenting with persistent ischemia after primary PCI is a plausible concept," he maintained, adding that his pilot study of 100 patients is the first to show a trend towards better prognosis for these patients, who received IABP support for 15 hours on average.

A fully-powered trial of around 400 might show a real benefit of IABP therapy in these patients in the future, van Nunen said.

His study included adults with large STEMIs -- ST deviations adding up to 15 mm or more -- who had persistent ischemia after primary PCI. This group arrived at the cath lab just over 3 hours after chest pain onset on average.

Patients who were randomized to go without the IABP started out with numerically higher rates of hypertension, dyslipidemia, diabetes, and smokers, and also tended to have higher blood pressure.

Session co-moderator Farrel Hellig, MBBCh, of Sunninghill and Sundward Park Hospitals in Johannesburg, South Africa, emphasized to the audience that the IABP strategy in question was aimed at reducing infarct size rather than just providing hemodynamic support.

That was important after panelist Volker Schächinger remarked that IABP-SHOCK II, reported in 2012, was "full-on negative for balloon pumping" for MI complicated by cardiogenic shock.

Now the thinking is that IABP's effects on coronary flow can reduce infarcts by providing afterload reduction (with a subsequent drop in myocardial workload and oxygen demand) and improved coronary blood flow (leading to more myocardial oxygen supply).

"In the presence of persistent ischemia, coronary autoregulation is exhausted and myocardial blood flow is directly and proportionally dependent upon perfusion pressure, which is augmented by diastolic inflation of the IABP," according to van Nunen.

Debabrata Mukherjee, MD, of Texas Tech University Health Sciences Center El Paso, agreed that it's a plausible mechanism with the benefit potentially applicable to all patients undergoing any type of revascularization.

The data aren't there yet, however: "The study itself is small, underpowered, with some soft endpoints such as need for mechanical circulatory support and readmission for heart failure," he told 番茄社区app. "The study should at best be considered exploratory."

Mortality should be the focus, he said, adding that he would also like to see safety endpoints such as bleeding and hematomas.

"There has been no prospectively specifiable group of patients with acute MI whose mortality is reduced by the insertion of an IABP," Mukherjee emphasized.

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