Fractional Flow Reserve and Coronary Artery Revascularization
Executive Summary
Background
Deciding whether and when to revascularize atherosclerotic coronary arteries are subjects of controversy and some uncertainty. When revascularization is considered, evidence and guidelines recommend evaluating whether the lesion in question causes ischemia. Fractional flow reserve (FFR) is used to measure the functional or ischemic consequences of obstruction to predict benefit from revascularization—which lesions to treat. Compared to noninvasive functional tests, the advantage of FFR is its vessel specificity and spatial resolution.
Objective
To review and evaluate available evidence comparing outcomes following FFR-guided percutaneous coronary intervention (PCI) to PCI guided by angiography alone in patients with angina.
Search Strategy
Studies were identified by searching the MEDLINE® (via PubMed) database for articles indexed under the MeSH® heading “fractional flow reserve, myocardial” or the keyword “fractional flow reserve” through January 2011. Articles were limited to those published in English that reported on human subjects. The searches were supplemented by manual bibliography review of selected references and ClinicalTrials.gov.
Selection Criteria
Published randomized, controlled trials were included. Observational studies meeting the following criteria were also reviewed: enrolled more than 50 patients; ascertained at least one relevant outcome; performed an informative comparison; and the mean target vessel stenoses in compared groups were similar in magnitude.
Main Results
Two good-quality randomized controlled trials, DEFER and FAME (Fractional Flow Reserve Versus Angiography for Multivessel Evaluation), and 4 observational studies were identified. DEFER enrolled 325 patients without evidence of ischemia by noninvasive testing. The trial was designed to compare outcomes following immediate to deferred PCI in patients with a single target vessel stenosis and FFR 0.75 or greater. Outcomes following PCI in a group with FFR less than 0.75 were also assessed. In the subgroups with FFR 0.75 or greater, through 2 years, fewer patients in the deferral (n=91) than perform arm (n=90) experienced events (death, myocardial infarction, bypass graft, PCI, or procedural complication)—10 (11.1%) versus 15 (16.7%) (Risk Difference -5.6%; 95% CI: -15.7 to 4.6%); through 5 years 19 (21.1%) versus 24 (27.3%) (Risk Difference -6.2%; 95% CI: -18.8 to 6.5). In comparison, in the referent group with target vessel stenoses FFR less than 0.75 (n=144) all undergoing PCI through 2 years events occurred in 31 (22.6%); through 5 years 52 (38.8%). FAME randomized 1,005 patients with multivessel disease and anticipated PCI to angiography alone-guided PCI (n=496) or FFR-guided PCI (n=509), treating only lesions with FRR 0.80 or less. More stents were placed in the angiography alone (2.7±1.2) than FFR (1.9±1.3) arm. Through 1 year, event rates (death, MI, and repeat revascularization) in the FFR and angiography alone arms were 13.2% and 18.3%, respectively (Risk Difference -5.1%; 95% CI: -9.6 to -0.6); 2-year primary event rates were 17.9% and 22.4%, respectively (Risk Difference -4.5%; 95% CI; -9.5 to 0.5%). FFR prevented 1 adverse cardiac event over 2 years for every 22 treated patients. Results from 4 prospective observational studies meeting inclusion criteria were consistent with those of DEFER and FAME.
Author’s Conclusions and Comment
The evidence is consistent with prior physiologic data and long-held beliefs that identifying stenoses is insufficient to determine when revascularization is likely to have benefit. If revascularization is anticipated in patients with angina, evidence supports a conclusion that FFR-guided PCI results in better outcomes than an angiography alone-guided strategy.
Based on the available evidence, the Blue Cross and Blue Shield Association Medical Advisory Panel (MAP) made the following judgments about whether fractional flow reserve (FFR) measurement to guide PCI in patients with angina, single or multivessel disease, meets the Blue Cross and Blue Shield Association Technology Evaluation Center (TEC) criteria.
1. The technology must have final approval from the appropriate governmental regulatory bodies.
The pressure-sensing wire used in FFR has been cleared for marketing by the U.S. Food and Drug Administration (FDA) via the 510(k) process as a class 2 device (catheter guide wire as predicate). The PressureWire™ is the only FDA-cleared catheter.
2. The scientific evidence must permit conclusions concerning the effect of the technology on health outcomes.
In patients with angina, single or multivessel disease, available evidence permits conclusions regarding the use of FFR to guide PCI.
3. The technology must improve the net health outcome.
When revascularization is anticipated in patients with angina, available evidence supports a conclusion that FFR-guided PCI results in better outcomes than a non-FFR-guided strategy.
4. The technology must be as beneficial as any established alternatives.
Available evidence supports concluding that FFR-guided PCI is as, or more, beneficial than angiography alone to guide PCI in this setting.
5. The improvement must be attainable outside the investigational settings.
Observational data are consistent with a conclusion that improvements are attainable outside the investigational setting.
Based on the above, when revascularization is anticipated in patients with angina, single or multivessel disease, fractional flow reserve measurement meets the TEC criteria.
Full Study
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Fractional Flow Reserve Coronary Artery Revascularization
