Lithotripsy Advantage in Calcified Peripheral Vessels Holds Up at 1 Year

ATLANTA -- Intravascular lithotripsy (IVL) beat percutaneous transluminal angioplasty (PTA) for keeping calcified peripheral artery lesions open at 1 year, the Disrupt PAD III trial showed.

Primary patency at 1 year was 80.5% for the IVL arm compared with 68.0% for the PTA arm (P=0.017), reported William Gray, MD, co-director of the Lankenau Heart Institute in Wynnewood, Pennsylvania, in the Journal of the Society for Cardiovascular Angiography & Interventions and at the Society's annual meeting here.

Superiority on this prespecified secondary endpoint was driven by freedom from provisional stenting at the index procedure (95.4% vs 81.7%, P<0.0001), without a difference in the other components of restenosis or clinically driven target lesion revascularization.

And less stenting is an important difference, Gray argued at the featured clinical research session.

"The need not to put in a stent and all the things that come with that, especially in calcified lesions, I think tips the scale in favor of IVL over PTA because you have less of a complicating feature later down the road," he said.

Historical data on stents, especially in calcified lesions and in longer lesions with overlapping stents, show that stent fracture starts to occur and patients' long-term management becomes very difficult. "In-stent stenosis in SFA [superficial femoral artery] is just a nidus for more restenosis," Gray noted.

The 30-day outcomes from the trial -- IVL increased procedural success (65.8% vs 50.4%, P=0.01) and reduced the proportion of lesions with residual stenosis ≤30% (66.4% vs 51.9%, P=0.02) -- have already had an effect on the field.

"This is already consolidating the mainstream effect of IVL," said session panelist Subhash Banerjee, MD, of UT Southwestern Medical Center and Dallas VA Medical Center. "We've always complained about reimbursement in the endovascular space, but when something really works, we don't really care about that."

The new findings, he predicted, "will help penetration and adoption greatly."

Disrupt PAD III included 306 patients at 45 sites around the world who had moderately-to-severely calcified, previously untreated femoropopliteal arteries (Rutherford category 2, 3, or 4), but no critical limb ischemia or unsuccessfully treated multilevel disease. They were randomized to IVL or PTA prior to drug-coated balloon treatment or stenting. Bailout stenting followed a treatment algorithm.

The trial was powered for primary patency as a secondary efficacy endpoint at 1 year, defined as:

• Freedom from clinically driven target lesion revascularization and from restenosis of at least 50% as determined by duplex ultrasound or an angiogram
• No acute failure requiring a stent at any point during the index procedure

For the 1-year outcome analysis, 123 of the 153 IVL patients (80%) had data available, as did 128 of the 153 PTA patients (84%). Other than treatment group, predictors of primary patency at this point were age and chronic total occlusion.

At 2 years, 111 IVL and 113 PTA patients were available for analysis, showing that the difference between groups was maintained (74.4% vs 57.7% primary patency, P=0.005).

Still, the PTA group did better than expected in such heavily calcified lesions, noted session co-moderator Alexandra J. Lansky, MD, of Yale University in New Haven, Connecticut.

Gray agreed that it was "surprising," given that no drug-coated balloon trial has shown this level of patency at 1 year in femoropopliteal lesions. But, he noted, no such study has been done in such a heavily calcified population. "From a strictly scientific point, [these are] new data that we don't really have a comparator for."

"We said to some of the best investigators in the world, 'Make this lesion the best you can make it.' So there was a lot of vessel prep going on here. And, I suspect, as has been seen in other trials with other devices, vessel prep does make a difference in long-term patency," he added.

A much larger single-arm observational study of IVL in 1,373 patients, dubbed Disrupt PAD III OS, has completed enrollment but not yet reported results.

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