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SAN FRANCISCO -- The Agent paclitaxel-coated balloon was better than conventional balloon angioplasty for in-stent restenosis (ISR), according to the AGENT IDE pivotal trial that will be used to support the device's case for FDA approval in coronary circulation.

The drug-coated balloon (DCB) managed to meet criteria for superiority over balloon angioplasty in terms of target lesion failure (TLF) rates at 1 year (17.9% vs 28.7%, P=0.006), reported Robert Yeh, MD, MSc, MBA, of Beth Israel Deaconess Medical Center in Boston, during the Transcatheter Cardiovascular Therapeutics (TCT) meeting hosted by the Cardiovascular Research Foundation.

After audience applause for this result, Yeh proceeded to highlight the DCB's halving of target lesion revascularization (12.4% vs 24.0%, HR 0.49, 95% CI 0.31-0.78) and target vessel myocardial infarction (6.4% vs 12.3%, HR 0.51, 95% CI 0.27-0.95) in particular.

"Given the marked superiority over conventional balloon angioplasty at reducing recurrent events, the Agent DCB is likely to become an important new treatment option for patients with coronary restenosis in the U.S.," Yeh said.

A DCB is an angioplasty balloon that delivers an antiproliferative drug without leaving permanent metal behind. No DCB is currently approved in the U.S. -- though that may change following this pivotal randomized trial.

Session discussant Roisin Colleran, MBBCh, of Cardiovascular Research Institute Dublin, said that the "implications are clear" from Agent IDE, and that the "long overdue" trial should provide the basis for regulatory approval stateside. Over a decade after DCBs became established in Europe, this would finally give U.S. clinicians their turn to offer this kind of therapy for ISR.

Operators are currently stuck either giving someone a peripheral balloon too big for the coronaries or telling them, "You can buy a ticket to London to get this treated," said study chairman Ajay Kirtane, MD, of NewYork-Presbyterian Hospital/Columbia University Irving Medical Center in New York City, during a press conference. "It's been embarrassing to get this treated."

The main limitation of the Agent IDE trial was the choice of comparator, Colleran said, noting the practice of repeated stenting for ISR in the real world. She also referenced the old in which balloon angioplasty was inferior to both paclitaxel-eluting balloons and drug-eluting stents (DES) for the management of ISR.

Yeh acknowledged that a DES could have been another comparator for Agent DCB in this trial. He said the investigators settled on balloon angioplasty for the control after multiple discussions with the FDA while designing the study. What's more, clinicians wouldn't be comfortable putting a third or fourth layer of stent in these patients, he said during a TCT press conference.

Similar results may be expected if the trial had been performed with a DES comparator, he speculated, as many patients went into the study already having failed DES in the first place.

In any case, Agent IDE is already a "real game-changer," commented Hadley Wilson, MD, of the Sanger Heart & Vascular Institute in Charlotte, North Carolina. "For 25 years we've been trying to peel back this restenosis problem. Now we can see a light at the end of the tunnel."

The pivotal trial for the Agent DCB was conducted at 40 sites and enrolled patients with coronary ISR. Excluded were people with complex presentations such as a recent large heart attack or complex coronary anatomy.

Study participants were randomized, after successful predilation of target lesion, to the Agent DCB (n=321) or balloon angioplasty (n=159).

Average patient age was 68, and 27% were women. Over half of patients had diabetes, and 43-44% already had multiple stent layers, for whom additional drug-eluting stent placement is usually avoided.

The index procedure was most commonly indicated by stable angina (approximately 54%) and acute coronary syndrome (38%). Lesions were relatively simple, measuring 12 mm on average, Yeh reported. Intravascular imaging, namely intravascular ultrasound, was used in 72.3% of Agent DCB and 76.7% of angioplasty procedures.

Diameter stenosis fell from 65% at baseline to 22% postprocedure in both study arms.

Agent IDE's primary endpoint of TLF was defined as a composite of recurrent blockage, heart attack within the treated vessel, and cardiac death at 1 year.

The 50% reductions in target lesion revascularization and target vessel myocardial infarction are "incredible" and suggest that patients may soon get "definitive therapy upfront ... reducing cost and improving care," commented John Messenger, MD, of the University of Colorado School of Medicine in Aurora.

There was no stent thrombosis after Agent DCB placement. The balloon angioplasty arm, on the other hand, had a 3.9% incidence of stent thrombosis (P=0.001). This may be related to differences in the restenotic benefits between groups, Yeh surmised.

He said a 600-patient full sample of AGENT IDE will be used for the final study manuscript. This analysis is still pending.

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