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Meta-analysis Confirms Benefits of FFR-Guided Revascularization

By Yael L. Maxwell

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A revascularization strategy guided by fractional flow reserve (FFR) compared with anatomy alone reduces adverse events and angina symptoms while lowering procedural rates, according to a comprehensive analysis of study- and patient-level data published in the October 21, 2014, issue of the Journal of the American College of Cardiology.

“We demonstrated that FFR provides a continuous and independent marker of subsequent MACE as modulated by treatment (medical therapy vs revascularization) in a broad range of clinical scenarios comprising thousands of patients from more than 12 countries and spanning more than 15 years of publications,” write Nils P. Johnson, MD, of the University of Texas Medical School at Houston (Houston, TX), and colleagues.

Methods
The researchers examined data on 9,173 lesions at the study level and 6,961 lesions at the patient level from various published FFR studies with median follow-up of 16 and 14 months, respectively. Although most patients (n = 6,061) had only a single lesion assessed by FFR, 589 had 2 lesions and 151 had at least 3 lesions evaluated.


Optimal FFR Thresholds Identified

Mean FFR values were 0.69 and 0.70 in patients undergoing revascularization (PCI or CABG) in the study- and patient-level analyses, respectively, and 0.87 in patients treated medically in both analyses. Two variables—quantitative percent diameter stenosis and minimal lumen diameter—showed not only statistically (P < .001 for both) but clinically significant associations with FFR.

Clinical events increased as FFR decreased, and revascularization showed a larger net benefit for lower baseline FFR values. The optimal FFR threshold for minimizing the composite of death, MI, and revascularization was 0.75 in the study-level analysis and 0.67 in the patient level-analysis (rising to 0.76 after adjustment for percent diameter stenosis).

FFR measured immediately after stenting was inversely related to subsequent events (HR 0.86; 95% CI 0.80-0.93; P < .001). Additionally, an FFR-assisted strategy reduced the PCI rate by half compared with an anatomy-based strategy. The former also lowered MACE by at least 20% and increased angina relief by at least 10%.

“FFR can be seen not only as a physiologic ‘biomarker,’ because of its continuous and independent relationship to outcomes, but also as a target for treatment because revascularization alters the outcome curve,” the authors write.

No Justification for FFR’s Underuse

These results are not news, observes John McB. Hodgson, MD, of the Case Western Reserve School of Medicine (Cleveland, OH), in an accompanying editorial, citing 3 prior studies—DEFER, a 2005 paper in European Heart Journal by Legalery et al., and FAME—showing clear patient benefit with an FFR-guided approach. “Unfortunately, these trials failed to alter the clinical practice of most cardiologists,” he adds.

Dr. Hodgson reports that though FFR use increased following the release of FAME data in 2009, “as of 2012 the percent of diagnostic catheterizations having FFR performed remained a paltry 4%.”

FFR guidance has proven its value in a myriad of lesion types and interventional and surgical procedures to the point that multisociety guidelines, scientific statements, and appropriate use criteria recommend its use, Dr. Hodgson observes. “So, one is left wondering what part of the FFR link don’t interventional cardiologists understand?” he says. “The data are clear; the cardiology community should not tolerate continuing to ignore it.”

FAME 2 Might Inform Guidelines

In an email with TCTMD, Herbert D. Aronow, MD, MPH, of St. Joseph Mercy Health System (Ann Arbor, MI), said, “Early, rapid diffusion of new diagnostic and therapeutic medical technologies may fail [because] practitioners may be skeptical in the absence of multiple randomized trials, may question whether the outcomes selected in published trials are relevant, may raise questions about a technology’s cost-effectiveness, and/or may not have access to these technologies due to restrictions on reimbursement.”

With regard to FFR, “few of these potential concerns are applicable,” he continued. “While I don’t believe the cardiology community is ‘ignoring’ the data, there is a clear opportunity to increase the use of FFR in evidence-based revascularization decisions.”

Given the recently released FAME 2 results, Dr. Aronow said, “a change to current multispecialty PCI guidelines that elevates FFR from a Class IIa to a Class I indication would further incentivize its use.”

Moreover, he added, “Additional trials using incident fatal or nonfatal ACS as a primary endpoint would be useful but wouldn’t negate currently available clinical trial data that already support more widespread use.”

Sources:

 1. Johnson NP, Tóth GG, Lai D, et al. Prognostic value of fractional flow reserve: linking physiologic severity to clinical outcomes. J Am Coll Cardiol. 2014;64:1641-1654.

2. Hodgson JM. What part of the FFR link don’t we understand [editorial]? J Am Coll Cardiol. 2014;64:1655-1657.

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Disclosures
  • Dr. Johnson reports receiving internal funding from the Weatherhead PET Center for Preventing and Reversing Atherosclerosis and institutional research support from St. Jude Medical and Volcano.
  • Dr. Hodgson reports receiving educational grants and consulting fees from Boston Scientific, St. Jude Medical, and Volcano and serving on the speaker’s bureau for InfraReDx, St. Jude Medical, and Volcano.
  • Dr. Aronow reports no relevant conflicts of interest.

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