SAN DIEGO — Percutaneous coronary intervention (PCI) guided by coronary CT angiography (CCTA) was associated with similarly low rates of target-vessel failure but a 17-minute reduction in procedural time relative to intravascular ultrasound (IVUS), according to a large multicenter randomized trial.

CCTA planning before entry into the catheterization laboratory was also associated with significantly reduced exposure to contrast and a trend toward reduced radiation relative to IVUS, said Carlos Collet, MD, PhD, director of Cardiovascular Imaging, Physiology, and Translational Therapeutics at the Cardiovascular Research Foundation in New York City.

This investigator-initiated trial, called P4, enrolled 1105 patients with chronic coronary syndromes or stabilized acute coronary syndromes, coronary artery disease, and at least one lesion with more than 70% diameter stenosis associated with a fractional flow reserve ≤ 0.80. The patients were randomly assigned at 23 centers in eight countries to preprocedural CCTA evaluated with proprietary software called a cardiac package or IVUS guidance, performed before and after the procedure.

Noninferior Primary Endpoint Met

At 12 months, the primary efficacy endpoint of target lesion failure had occurred in 4.1% of study participants in the CCTA arm and 4.6% of those in the IVUS arm, Collet reported during a late-breaker session at Transcatheter Cardiovascular Therapeutics (TCT) 2026.

The study was published simultaneously in The New England Journal of Medicine.

The numerically lower risk in the CCTA arm produced a highly significant confirmation of noninferiority (P < .001), fulfilling the study hypothesis.

The median 17-minute shorter procedural time (46 vs 63 minutes) was accompanied by a statistically significant 20.0-mL reduction in median contrast volume (150 mL vs 170 mL; P < .001). A median 2.91 Gy·cm² reduction in radiation exposure (35.6 vs 38.5 Gy·cm²) narrowly missed statistical significance (P = .07).

Procedural preplanning is performed to variable degrees before every PCI, but the structured preplanning in the CCTA arm of this study involved AI analytics that could provide three-dimensional images and preview the physiologic impact of intervention. The package employed in this study provided guidance on such aspects of PCI as lesion preparation, proximal and distal landing zones, and the benefit expected from revascularization.

The time required to review the CCTA package before the procedure does not meaningfully dilute the savings in procedure time. Interventionalists can digest the preprocedural report “in 2 or 3 minutes,” whereas the time savings in the cath lab involve the entire clinical team, Collet said.

Although CCTA, unlike IVUS, imposes its own radiation burden, it is low, Collet said. He indicated the burden would not be expected to meaningfully mitigate the overall reduction in contrast exposure when performing CCTA-guided rather than IVUS-guided PCI.

“The advantage of the preplanning can be huge,” said R. Jay Widmer, MD, PhD, interventionalist and chief of cardiology at the Baylor Scott & White The Heart Hospital - McKinney, McKinney, Texas, who was not involved in this study. “You go into the cath lab with a plan in place, and everyone on the team already knows the challenges and potential solutions. It takes a lot of the cognitive load and anxiety out of the procedure.”

Preprocedural Planning Relieves Anxiety

Widmer, who is a member of the American College of Cardiology’s Interventional Section Leadership Council, believes these data are likely to produce a change in practice eventually, but the change will be slow. He identified several challenges to reproducing the advantages shown in the P4 trial among cardiologists without commensurate skill.

“The information provided by a CCTA package depends on very good scans, and this is likely to be a generalizability hurdle,” he added.

Widmer predicted that CCTA uptake might accelerate as state-of-the-art but expensive CCTA scanners, which make good-quality scans easier to obtain, are widely available. He also cautioned that not all practicing interventionalists have received detailed training in CCTA, which was a requirement for the investigators in this study.

Notably, the advantage of CCTA guidance over IVUS in this study was shown after poor-quality scans were excluded. Results should also be interpreted on the basis of other exclusions, which included more than two target lesions, BMI ≥ 35, and previous PCI in the target vessel or prior coronary artery bypass grafting.

The TCT-invited discussant, Emmanouil S. Brilakis, MD, PhD, noted some of the same limitations as Widmer, particularly the hurdle of achieving high-quality CT scans because they are not always readily available.

Even so, he called the P4 trial a “landmark” because of its support for preprocedural planning.

“The study does provide the clinical evidence we need in this new era,” Brilakis said, noting that the results will place more emphasis on planning procedures before entering the cath lab. He does not feel that the advantage of CCTA in this study precludes applications for IVUS, particularly in cases where it might provide complementary information.

There was some concern that CCTA packages might overload interventionalists with information. A panelist at the late-breaker session, Margaret B. McEntegart, MD, PhD, director of Complex PCI and CTO Programs at the Columbia University Irving Medical Center in New York City, cautioned that uptake might be slow if this approach is not readily intuitive, minimizing demands on time.

Collet, however, does consider the information provided by CCTA relatively simple to apply in the cath lab. By revealing challenging anatomy and explaining lesion characteristics, such as calcium burden, the CCTA package can expedite procedures by largely eliminating or greatly reducing surprises.

Collet reported potential financial relationships with Abbott Vascular, CathFlow, CathWorks, Coroventis Research, GE HealthCare, Insight Lifetech, Medyria, Powerful Medical, Siemens, and Shockwave. Widmer reported financial relationships with Abbott, Medtronic, and Philips. Brilakis reported financial relationships with Abbott Vascular, Boston Scientific, Biotronik, Cleerly Health, GE HealthCare, Hippocrates, IMDS, Recor, Shockwave, SIS Medical, Teleflex, Terumo, and TrueVue. McEntegart reported financial relationships with Abbott, Biosense Webster, Boston Scientific, Medtronic, Shockwave, and Teleflex.

Ted Bosworth, a career medical writer based in New York City, has been covering advances in clinical medicine, including cardiology, for several decades.