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PARIS -- A device providing pressure-controlled intermittent coronary sinus occlusion (PICSO) therapy may be tied to reduced infarct size and better microvascular function when used in certain ST-segment elevation myocardial infarction (STEMI) patients, researchers reported.

As described by Giovanni Luigi De Maria, MD, of England's Oxford Heart Centre, at a late-breaking trial session here at the annual , the index of microcirculatory resistance (IMR) was used to predict which individuals with anterior STEMI would be at risk of poor myocardial reperfusion after primary percutaneous coronary intervention (PCI). These patients then had the PICSO balloon-tipped catheter placed temporarily in the coronary sinus -- where it was alternately inflated and deflated to achieve cyclical occlusion -- before moving onto stent placement.

Within 24-48 hours of PCI, PICSO recipients had the advantage of a median 24.8 IMR, compared with the 45.0 observed in a historical control cohort from the OxAMI study that also had abnormal IMR values before stenting (P<0.001).

Between these groups, however, there was no observable difference in infarct size on cardiac magnetic resonance imaging (MRI) in that time (both around 40%, P=0.42). It was only at 6 months that the PICSO group showed smaller infarcts (26.0% versus 33.0%, P=0.006) that were no different from those of patients who could had stenting alone because of their normal IMR (~20%, P=0.11).

The results of OxAMI-PICSO were also published online ahead of print in .

"The study shows that IMR-guided and targeted application of PICSO is associated with an early improvement of coronary microvascular function. While IMR was reported to improve over time in all patients, confirming previous evidence about progressive microvascular function recovery over time, PICSO appeared to accelerate such recovery, with significantly lower IMR at 24-48 hours in PICSO patients," De Maria and colleagues said.

The study participants were divided into three groups:

• PICSO recipients with pre-stenting IMR values above 40 (n=25)
• Those whose pre-stenting IMR stayed in the normal range (n=30)
• Peers with pre-stenting IMRs above 40 who got PCI but not PICSO (n=50)

The authors noted that a limitation of the research was the non-randomized nature of the single-center study, which suffered from imbalances in ischemic time and periprocedural bivalirudin administration among groups. Another caveat was the fact that the 6-month MRI was performed in just over half of the patients.

The practicality of introducing more complexity and cost to STEMI treatment was questioned by a member of the panel where the study was presented, James Nolan, MD, of University Hospitals of North Midlands in England.

De Maria responded that it's important to keep in mind that the device doesn't stay in for 24 hours. "We need to deliver a PICSO dose of 800 mmHg, and usually that might take 20-25 minutes. That's the actual time the device was in place. In terms of cost-effectiveness, it's still a [relatively small] non-randomized trial. What it's doing is pointing us toward a possible direction of investigation."

"We do need a large randomized trial to prove clinical efficacy and cost-effectiveness of this device," he and his colleagues said.

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