1

Introduction

It is now well established that assessment of patients presenting with cardiac-sounding chest pain based upon angiography alone is flawed . Specifically, the coronary anatomy at angiography does not inevitably reflect the presence and extent of myocardial ischemia, which is recognized as the best indicator of the cause of symptoms and near term prognosis, and thus represents the clearest target for revascularization . This is due to a discrepancy between the anatomical assessment of lesion severity and the presence or absence of lesion-level ischemia . Lesion-level ischemia is measured by pressure wire assessment using fractional flow reserve (FFR). The ability of FFR measurement to predict clinical outcome has been established in a variety of randomized clinical trials. In the deferral of percutaneous coronary intervention (DEFER) study, the practice of deferring percutaneous coronary intervention (PCI) in lesions that had been identified as requiring PCI based upon angiographic appearances, but were FFR negative, was shown to be safe and associated with a better clinical outcome than stenting them . Furthermore, in patients who had been listed for multi-vessel PCI, the Fractional Flow Reserve Versus Angiography for Multivessel Evaluation (FAME) trial demonstrated a reduced incidence of the combined clinical endpoint of death, non-fatal myocardial infarction, and repeat revascularization at 1 year, as well as lower cost, in an FFR-directed strategy compared to an angiogram-directed approach, despite fewer lesions being stented . Fractional Flow Reserve Guided Percutaneous Coronary Intervention Plus Optimal Medical Therapy Versus Optimal Medical Therapy (FAME 2) trial subsequently demonstrated a reduced rate of unplanned revascularization in patients with FFR positive lesions who were stented compared to a cohort treated with optimal medical therapy alone .

Despite these robust data, the uptake of FFR in routine clinical practice has been lower than expected in patients already being considered for PCI, with rates as low as 6.6% reported in large PCI registries . Furthermore, a series of predominantly observational studies has been published that demonstrate the ability of FFR to modify the management of patients who are undergoing diagnostic angiography for the investigation of chest pain (i.e., at an earlier stage in their management pathway .

The aim of this paper is to describe the degree to which some use of FFR affects the angiography-derived management strategy for patients in these studies.

2

Methods

2

Methods

3

Results

3.1

Description of studies included in analysis

Eight studies have been identified that fit our prespecified criteria. The studies were published between 2007 and 2016 and report data derived from between 200 and 3093 patients ( Fig. 1 ). Seven of the studies were observational and 1 was randomized . Seven were derived from invasive angiography and intracoronary FFR measurement and one study is based on CT coronary angiography and FFR _CT . In 4 studies the patients were elective only, in 1 study only acute coronary syndrome patients were included and in 3 there was a mixture. The angiographic lesion characteristics representing triggers for FFR measurement varied (range: ≥30% up to ≤90%) between studies, as did the number of vessels targeted (range: further assessment of at least one intermediate lesion to FFR of all vessels of a diameter that was suitable for PCI) ( Table 1 ).

PRISMA flow diagram of included publications.

Table 1

Clinical characteristics of the publications included in the systematic review.

Name	Country	Study type	Study period	Inclusion criteria	Exclusion criteria	Year
Sant’Anna et al.	Brazil	Prospective	October 2004 to April 2005	Elective PCI	Transmural acute myocardial infarction (AMI) in the last 7 days, chronic total occlusion, or angiographically significant left main disease	2007
Curzen et al. The RIPCORD Study	United Kingdom	Prospective	NA	Stable cardiac-sounding CP included the presence in any epicardial vessel of ≥2.25 mm diameter of a ≥30% stenosis	Failure to provide written informed consent, participation in other clinical studies, previous CABG, acute coronary syndrome at presentation, diagnostic angiography or PCI within the previous 12 months, contraindication to adenosine, severe valve disease, serum creatinine >180 μmol/L, and life-threatening comorbidity	2014
Nakamura et al. CVIT-DEFER Registry	Japan	Prospective	December 2012 and September 2013	Angiographically intermediate to moderate coronary stenosis and in whom FFR was clinically indicated	NA	2014
Layland et al. FAMOUS-NSTEMI trial	United Kingdom	Prospective	October 2011 to May 2013	NSTEMI and with at least one risk factor for coronary artery disease (e.g., diabetes mellitus) within 72 h of the index episode of myocardial ischemia or if there was a history of recurrent ischemic symptoms within 5 days. ≥1 coronary stenosis ≥30% of the lumen diameter assessed visually	Presence of ischemic symptoms that were not controlled by medical therapy, hemodynamic instability, MI with persistent ST elevation, intolerance to anti-platelet drugs, ineligible for coronary revascularization, a treatment plan for non-coronary heart surgery (e.g., valve surgery), a history of prior CABG, angiographic evidence of severe (e.g., diffuse calcification), a life expectancy, 1 year and an inability to give informed consent	2014
Van Belle et al. FFR-R3F study	France	Prospective	October 2008 to June 2010	NA	NA	2014
Baptista et al. POST-IT Multicenter Registry	Portugal	Prospective	March 2012 to November 2013	NA	Unwillingness to provide written informed consent and life expectancy <1 year because of known noncardiovascular comorbidity	2016
De Backer et al.	Denmark	Prospective	1 July 2010 and 30 June 2014	Stable angina pectoris (AP) and at least one 50%–89% coronary stenosis were selected.	NA	2016
Curzen et al. The FFRCT RIPCORD Study	United Kingdom	Prospective	NA	Stable cardiac-sounding CP included the presence in any epicardial vessel of ≥2.25 mm diameter of a ≥30% stenosis	Failure to provide written informed consent, participation in other clinical studies, previous CABG, acute coronary syndrome at presentation, diagnostic angiography or PCI within the previous 12 months, contraindication to adenosine, severe valve disease, serum creatinine >180 μmol/L, and life-threatening comorbidity	2016

Name	No. patients	% Female	Mean age, years	Follow up period	Setting	Diabetes mellitus	% Multivessel disease	Unstable angina pectoris	ACS%	FFR limit	Stenosis limit	Number of diameter stenosis >70%
Sant’Anna et al.	250	38%	61	NA	Elective	23%	70%	7%	0%	0.75	>50%	327
Curzen et al. The RIPCORD Study	200	25%	64	NA	Elective	NA	NA	NA	0	0.8	>30%	68
Nakamura et al. CVIT-DEFER Registry	3093	26.2	69.5	NA	Elective and ACS	37.7	34.8	7.2	1.4	0.8	50%–90%	NA
Layland et al. FAMOUS- NSTEMI trial	350	24.6	62.3	12 months	ACS	14.8	29	0	100	0.8	>30%	63.1
Van Belle et al. FFR-R3F study	1075	24.70%	64.7	12 months	Elective and ACS	35.8	47.6	NA	19.5	0.8	35%–65%	NA
Baptista et al. POST-IT Multicenter Registry	918	23.7	65.1	12 months	Elective and ACS	35	37.5	4.4	35.4	0.75–0.8	Intermediate	31.9
De Backer et al.	1716	28.8	64.5	23.2 months	Elective	23.8	32.5	0	0	0.8	50%–89%	74
Curzen et al. The FFRCT RIPCORD Study	200	NA	NA		Elective	NA	NA	NA	0	0.8	>70%	126

3.2

Quality assessment in included studies

Quality Assessment Tool for Case Series Studies was used to gauge the quality of evidence and all studies were of good quality. Their detailed evaluation has been tabulated in Table 2 .

Table 2

Quality assessment of the studies

Criteria	Sant’Anna et al.	Curzen et al. The RIPCORD Study	Nakamura et al. CVIT-DEFER Registry	Layland et al. FAMOUS-NSTEMI trial	Belle et al. FFR-R3F study	Baptista et al. POST-IT study	Backer et al.	Curzen et al. The FFRCT RIPCORD Study
1. Was the study question or objective clearly stated?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
2. Was the study population clearly and fully described, including a case definition?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
3. Were the cases consecutive?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
4. Were the subjects comparable?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
5. Was the intervention clearly described?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
6. Were the outcome measures clearly defined, valid, reliable, and implemented consistently across all study participants?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
7. Was the length of follow-up adequate?	NA	NA	NA	Yes	Yes	Yes	Yes	NA
8. Were the statistical methods well described?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
9. Were the results well described?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Quality rating	Good	Good	Good	Good	Good	Good	Good	Good

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