Achieving a post-percutaneous coronary intervention (PCI) instantaneous wave-free ratio (iFR) of 0.95 or higher is associated with improved 1-year event-free survival, according to new analysis from the DEFINE PCI trial.
The study, published online Monday and in the Jan. 10 issue of JACC: Cardiovascular Interventions, noted that while the most established index used to determine the hemodynamic significance of a coronary stenosis is fractional flow reserve (FFR), over the past decade, iFR, has been shown to be noninferior to FFR in large, randomized trials.
Led by Manesh R. Patel, MD, from Duke University, Durham, North Carolina, the new study used data from the DEFINE PCI (Physiologic Assessment of Coronary Stenosis Following PCI) study to identify the post-PCI target value for iFR that best discriminated clinical events at 1-year follow-up.
“At one-year follow-up in DEFINE PCI, post-PCI iFR ≥0.95 compared with <0.95 was associated with diminished anginal symptoms at 12 months, particularly in patients with significant angina (SAQ-AF score ≤60; ie, daily or weekly angina) at baseline,” said the authors.
“Furthermore, achieving post-PCI iFR ≥0.95 was associated with a lower composite rate of cardiac death, spontaneous (myocardial infarction), or clinically driven (target vessel revascularization) during one year of follow-up.”
Patel and colleagues noted that while the findings should be considered hypothesis-generating, they suggest that the use of intracoronary physiology during PCI may improve clinical outcomes, “not only by assisting in the selection of appropriate lesions for intervention but also by potentially guiding the achievement of an optimal postprocedural result.”
As part of the DEFINE PCI study, blinded iFR pull back was performed after successful stent implantation in 500 patients, noted the authors. The primary endpoint was the rate of residual ischemia, defined as iFR ≤0.89, after operator-assessed angiographically successful PCI, while secondary endpoints included clinical events at 1 year and change in Seattle Angina Questionnaire angina frequency (SAQ-AF) score during follow-up.
“As reported, 24.0% of patients had residual ischemia (iFR ≤0.89) after successful PCI, with 81.6% of cases attributable to angiographically inapparent focal lesions,” they said.
However, the team found that a post-PCI iFR target value of ≥0.95 was present in 182 cases (39%), and was associated with a significant reduction in the composite of cardiac death, spontaneous myocardial infarction (MI), or clinically driven target vessel revascularization compared with post-PCI iFR <0.95 (1.8% vs 5.7%; P = 0.04).
“For highly symptomatic patients (baseline SAQ-AF score ≤60), SAQ-AF score increased by ≥10 points more frequently in patients with versus without post-PCI iFR ≥0.95 (100.0% vs 88.5%; P = 0.01),” revealed the authors.
“As this was a relatively short-term … pilot study (one-year follow-up), longer term prospectively driven studies are needed to demonstrate the value of post-revascularization physiology,” they added.
Writing in an accompanying editorial Nick, Curzen, BM, PhD, from the University Hospital Southampton NHS Trust, England, noted that although there are, as yet, no randomized trials that specifically address the question, a number of studies have suggested that there is a relationship between post-PCI physiology and the risk of future adverse events including revascularization and spontaneous MI.
“The notion that measurement of post-PCI physiology could be of value in order to direct interventional therapy, and thereby improve clinical outcome, is a plausible extrapolation,” he said.
“However, it remains unclear as to whether there is a threshold target for post-PCI physiology above which an excellent vessel-related clinical outcome can be virtually assured.”
The editorialist noted that such an observation “would potentially justify routine post-PCI pressure wire assessment if it was supported by randomized trial data,” noting that the results of the study “provide a tantalizing insight into this gap in our current knowledge base.”
He added that, importantly, a post-PCI threshold of ≥0.95, which was present in 39% of cases, was associated with a significantly lower composite event rate when compared with those with a post-PCI iFR below this threshold (1.8% vs 5.7%; P=0.04).
Curzen added that the results are “thought-provoking” and should intensify interest in the idea that post-PCI physiological assessment could offer a means of improving clinical outcomes for patients.
“The observation that we fail to render vessels “nonischemic” (according to our binary definition of iFR ≥0.89) in nearly one quarter of cases should surely raise alarm bells for routine angiographic guidance alone,” he said.
Patel MR, Jeremias A, Maehara A, et al. 1-Year Outcomes of Blinded Physiological Assessment of Residual Ischemia After Successful PCI: DEFINE PCI Trial. JACC Cardiovasc Interv 2022;15:52-61.
Curzen N. Defining Successful PCI: Edging Closer to Meaningful Targets? JACC Cardiovasc Interv 2022;15:62-64.
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