Percutaneous coronary intervention (PCI) guided by quantitative flow ratio (QFR), a wire‑free angiography analysis tool, may better target lesions that impair blood flow, according to a new study.

While PCI is one of the most common minimally invasive procedures in cardiology, the new data show QFR-guided interventions may improve long‑term outcomes, such as myocardial infarction and repeat revascularization, while reducing unnecessary procedures, study authors said.

The study was published in the Journal of the American College of Cardiology and was based on 5‑year data from the FAVOR III China trial to determine whether QFR could provide a more precise physiologic assessment of blood flow than angiography alone.

QFR May Offer a Clearer Picture

FAVOR III China was a multicenter, randomized, sham-controlled trial conducted at 26 hospitals across China. Between December 2018 and January 2020, researchers enrolled 3825 adults with stable or unstable angina or a recent myocardial infarction.

Participants had at least one intermediate coronary lesion (50%-90% stenosis) considered for PCI. About 70% were men, with a mean age of 62.7 years, and about one third had diabetes.

Patients were assigned to either a QFR-guided strategy, in which PCI was performed only when QFR was ≤ 0.80 (the number at which blood flow is considered significantly impaired), or a conventional angiography-guided strategy. More than 94% of patients completed long-term follow-up.

At the 5-year mark, 17.5% of patients randomly assigned to QFR-guided PCI had major adverse cardiac events (MACE) compared with 21.1% treated with angiography-guided PCI. The researchers noted reductions in myocardial infarction (5.8% vs 9.0%) and ischemia-driven repeat revascularization (9.6% vs 12.0%). There was no significant difference in all-cause mortality.

Better Decision Options

One of the most compelling findings from FAVOR III China is that QFR appears to help cardiologists make better treatment decisions, study authors said.

By distinguishing lesions that impair blood flow from those that do not, QFR may help physicians avoid unnecessary stenting while ensuring clinically significant blockages receive treatment.

The impact of those decisions was substantial: MACE rates were 16.2% in patients whose treatment plans changed after QFR assessment compared with 33.5% in patients whose treatment plan changed in the angiography-guided group.

Barriers Ahead?

Despite the encouraging evidence, adoption remains limited in routine care. One major reason is that conventional physiologic assessment typically requires the use of a pressure wire threaded across a coronary blockage to determine whether blood flow is significantly impaired. The added equipment, time, cost, and complexity create real barriers to routine use.

Gregg W. Stone, MD, of the Mount Sinai Health System in New York City and a coauthor of the study, believes this limitation helps explain the promise of quantitative flow ratio, which derives physiologic information from routine angiographic images rather than a pressure wire.

“The greatest limitation to the widespread use of physiology-guided PCI, in my opinion, is the need to use a pressure wire,” Stone said. The ready availability of an angiography-based estimate of fractional flow reserve (FFR) that is quick and simple “should markedly increase adoption of real-time physiology for lesion assessment,” he said.

“I believe the biggest barrier to greater adoption of coronary physiology to guide PCI is workflow, as the need to use a special wire, recording system, and additional medications adds time and complexity,” said William F. Fearon, MD, of Stanford Health Care in California. “Other factors like reimbursement, training, and/or lack of belief in the data may also play a role in some circumstances.”

Unlike conventional FFR requiring a pressure wire to measure pressure gradients across a coronary lesion, QFR estimates lesion-specific ischemia directly from angiographic images, eliminating the need for wire-based physiologic assessment.

The authors wrote that using QFR as the initial guidance modality offers several important clinical advantages as a pragmatic, wire‑free tool that lowers logistical and financial barriers to physiology‑guided PCI, especially where pressure‑wire use is limited by cost, time, side effects, or expertise.

Fearon reported receiving institutional research support from Abbott Vascular, Medtronic, and CathWorks and serving as a consultant for Edwards Lifesciences.

Stone reported receiving speaker honoraria from Medtronic, Amgen, and Boehringer Ingelheim; serving as a consultant to Robocath, Daiichi Sankyo, Vectorious, Miracor, Apollo Therapeutics, Cardiac Success, Occlutech, Millennia Biopharma, Ablative Solutions, Oxitope, Impulse Dynamics, Remote Cardiac Enablement, Valfix, Zoll, HeartFlow, Shockwave, Adona Medical, Abbott, HighLife, Elixir, Elucid Bio, Aria, Alleviant, FBR Medical, Myochron, Colibri, Bioventrix, MedHub, and Asceneuron; and has equity/options from Cardiac Success, Ancora, Cagent, Applied Therapeutics, Biostar family of funds, SpectraWave, Orchestra Biomed, Aria, Valfix, and Xenter. Stone’s employer, Mount Sinai Hospital, receives research grants from Shockwave, Biosense-Webster, Bioventrix, Abbott, Abiomed, Cardiovascular Systems, Philips, Vascular Dynamics, Pulnovo, V-wave, and PCORI (via Weill Cornell Medical Center).

The study was funded by research grants from the National High-Level Hospital Clinical Research Funding, the CAMS Innovation Fund for Medical Sciences, and the Noncommunicable Chronic Diseases-National Science and Technology Major Project.

Lois Anzelowitz Levine is a lifestyle and medical writer who lives in Dallas.