3

Results

3.1

Search results

The initial database search retrieved 475 potentially relevant publications. The selection of studies was conducted according to the PRISMA statements. After removing 197 duplicates, 278 studies were screened by title and abstract. Of these, 54 full-text articles remained to assess for eligibility. Finally, a total of 16 studies met the inclusion criteria and were included in the meta-analysis. A flowchart of the search and selection process of the studies is shown in Fig. 1 . 

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Flow diagram of search and study selection. FFR: fractional flow reserve.

 

3.2

Description of the included trials

Baseline characteristics of these studies and the subjects are shown in Tables 1-3 . Briefly, this meta-analysis was based on 16 nonrandomized, observational, prospective, diagnostic performance studies (nine multicenter, seven single center) that included 5756 lesions (range per trial 123 to 1593). Mean age ranged from 62 to 70 years old; male sex: 64% to 83%; diabetes: 17% to 41%; smoking: 22% to 69%; hypertension: 56% to 81%; stable angina: 35% to 96%; unstable angina: 4% to 65%; single vessel disease: 36% to 100%; multivessel disease: 0% to 63%; left anterior descending artery: 0% to 100%; left circumflex artery: 0% to 27%; right coronary artery: 0% to 29%; intravenous adenosine: 0% to 100%; and intracoronary adenosine: 0% to 100%. 

Table 1

Summary characteristics of included studies.

Study	Published year	# of lesions	Design	Inclusion criteria	Exclusion criteria	Ffr acutoff	Ifr bcutoff
ADVISE[10]	2011	157	Multicenter, nonrandomized, observational, prospective	Patients with coronary stenosis	Valvular diseases, previous CABG c , contraindication to adenosine, increased troponin, and overweight	0.8	0.83
VERIFY[37]	2013	206	Multicenter, nonrandomized, observational, prospective	Patients with coronary stenosis required functional intracoronary assessment	Prior CABG, extremely tortuous, calcified lesions, coronary artery occlusion, acute MI d within 5 days	0.8	0.83
Park et al.[27]	2013	238	Multicenter, nonrandomized, observational, prospective	Patients with coronary stenosis required functional intracoronary assessment	In-stent restenosis, acute ST-segment elevation myocardial infarction, chronic total occlusion lesions, vessels with collateral feeders, regional wall motion abnormalities of a target vessel segment, left ventricular ejection fraction < 40%, primary myocardial or valvular disease, contraindication to adenosine, or angiographically visible thrombus of a target lesion	0.8	0.9
ADVISE In PRACTICE[12]	2014	392	Multicenter, nonrandomized, observational, prospective	Patients with coronary stenosis required functional intracoronary assessment	Previous CABG, contraindication to adenosine administration	0.8	0.9
Indolfi et al.[33]	2014	123	Single center, nonrandomized, observational, prospective	Patients referred for coronary angiography who had multivessel disease with at least one intermediate stenosis in setting of ACS e	Noncardiac life-threatening disease, requiring valvular surgery, cardiologist decided not to perform FFR to guide the treatment, hemodynamic instability, ongoing arrhythmias, valve disease, contraindication to adenosine administration	0.8	0.92
ADVISE 2 2015 [34]	2015	690	Multicenter, nonrandomized, observational, prospective, double blind	Patients with coronary stenosis required functional intracoronary assessment	Previous CABG, contraindication to adenosine administration, increased troponin, and overweight	0.8	0.89
Harle et al.[35]	2015	151	Single center, nonrandomized, observational, prospective	Patients with coronary stenosis required functional intracoronary assessment	Contraindications to adenosine administration	0.8	0.896
Shiode et al. [14]	2016	123	Single center, nonrandomized, observational, prospective	Mild or moderate stenosis who were undergoing coronary angiography	–	0.8	0.89
Kobayashi et al. (LM f/pLAD g )[15]	2016	201	Multicenter, nonrandomized, observational, prospective	18 years or older who underwent invasive physiological assessment of coronary artery lesions for standard clinical indications	Previous CABG, an extremely tortuous or calcified coronary artery, known severe LVH h , left ventricular ejection fraction < 30%, inability to receive adenosine, renal insufficiency such that additional contrast would pose unwarranted risk, or recent (within 3 weeks before cardiac catheterization) ST-segment elevation myocardial infarction	0.8	0.9
Kobayashi et al. (other lesions)[15]	2016	559	Multicenter, nonrandomized, observational, prospective	18 years or older who underwent invasive physiological assessment of coronary artery lesions for standard clinical indications	Previous CABG, an extremely tortuous or calcified coronary artery, known severe LVH, left ventricular ejection fraction < 30%, inability to receive adenosine, renal insufficiency such that additional contrast would pose unwarranted risk, or recent (within 3 weeks before cardiac catheterization) ST-segment elevation myocardial infarction	0.8	0.9
VERIFY 2[16]	2016	257	Single center, nonrandomized, observational, prospective	18–90 years old with angiographically intermediate coronary stenoses in which FFR measurement was clinically indicated	Severe calcific coronary disease, severe tortuosity rendering pressure wire studies difficult or impossible, recent myocardial infarction within 72 h, ongoing unstable chest pain, known intolerance of adenosine, or severe asthma	0.8	0.9
Meimoun et al. [17]	2016	94	Single center, nonrandomized, observational, prospective	Stable CAD i with 50–70% intermediate LAD jstenosis	Hemodynamic instability, acute coronary syndrome involving the LAD as a culprit vessel, contra indication to adenosine, a stenosis in the distal part of the LAD, and two or more stenoses in the LAD	0.8	0.88
Johnson et al. [18]	2016	763	Multicenter, nonrandomized, observational, prospective	Undergoing routine FFR assessment for standard indications	Previous coronary bypass surgery, known severe cardiomyopathy (left ventricular ejection fraction < 30%) or left ventricular hypertrophy (septal wall thickness > 13 mm), contraindication to adenosine, or renal insufficiency such that an additional 12 to 20 mL of contrast would pose an unwarranted risk	0.8	0.9
Kanaji et al. [19]	2016	120	Single center, nonrandomized, observational, prospective	Undergoing coronary angiography for suspected coronary artery disease with lesions in at least one epicardial proximal coronary artery that were angiographically intermediate (30–80% by visual estimation)	History of CABG, tortuous coronary arteries, severely calcified arteries, acute coronary syndrome, history of myocardial infarction, occluded coronary arteries, left main disease, coronary ostial stenosis, congestive heart failure, significant arrhythmias, renal insufficiency (creatinine 1.5 mg/dL), or absolute contraindication to adenosine	0.8	0.89
Fede et al.[20]	2015	89	Single center, nonrandomized, observational, prospective	Undergoing coronary angiography for stable or unstable angina, or for non ST elevation myocardial infarction found to have intermediate stenosis of 50–70% by visual estimation	ST-segment elevation myocardial infarction or hemodynamic unstable conditions	0.8	0.89
RESOLVE[21]	2014	1593	Multicenter, nonrandomized, observational, retrospective	Patients with stable angina, unstable angina, or non ST-segment myocardial infarction undergoing coronary angiography with or without percutaneous coronary intervention in whom FFR of a single stenosis in a major epicardial coronary artery was performed during the procedure	Left main disease, heart failure as defined by New York Heart Association class III or IV, respiratory failure requiring intubation or supplementary oxygen, cardiogenic shock, significant arrhythmia precluding waveform analysis (examples include premature ventricular contractions or atrial fibrillation), and tachycardia with heart rate > 120 beats/min	0.8	0.9

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a FFR: fractional flow reserve.

b IFR: instantaneous wave-free ratio.

c CABG: Coronary artery bypass grafting.

d MI: myocardial infarction.

e ACS: acute coronary syndrome.

f LM: left main artery.

g pLAD: proximal left anterior descending artery.

h LVH: left ventricular hypertrophy.

i CAD: coronary artery disease.

j LAD: left anterior descending.

Table 2

Baseline data and cardiovascular risk factors of study population.

Study	Age	Male (%)	Smoking (%)	Diabetes (%)	Hypertension (%)	Stable angina (%)	Unstable angina (%)
ADVISE [10]	62.6 ± 10.2	131 (83)	34 (22)	54 (34)	88 (56)	151 (96)	6 (4)
VERIFY [37]	65.2 ± 10.2	146 (71)	64 (31)	50 (24)	137 (67)	140 (68)	46 (22)
Park et al. [27]	62.8 ± 0.6	161 (68)	64 (27)	66 (28)	133 (56)	151 (63)	84 (36)
ADVISE In PRACTICE [12]	67 ± 11	247 (79)	160 (51)	94 (30)	232 (74)	228 (73)	85 (27)
Indolfi et al. [33]	64 ± 9	67 (82)	49 (60)	14 (17)	61 (74)	29 (35)	53 (65)
ADVISE 2 [34]	63.6 ± 10.8	412 (69)	135 (23)	209 (35)	471 (78.8)	320 (54)	151 (25)
Harle et al. [35]	67 ± 11	69 (64)	–	–	–	–	–
Shiode et al. [14]	70.4 ± 8.7	77 (74.8)	28 (27.1)	40 (39)	82 (80)	92 (89.3)	–
Kobayashi et al. (LM a/pLAD b ) [15]	66 (58–72)	141 (70.1)	87 (43.3)	47 (23.4)	138 (68.7)	160 (79.6)	–
Kobayashi et al. (other lesions) [15]	67 (58–73)	406 (72.6)	276 (49.4)	131 (23.4)	406 (72.6)	435 (77.8)	–
VERIFY 2 [16]	–	136 (69)	48 (24.4)	31 (15.7)	123 (62.4)	129 (50.1)	18 (7)
Meimoun et al. [17]	68 ± 10	75 (80)	36 (38)	29 (31)	53 (56)	71 (76)	–
Johnson et al. [18]	66 ± 10	547 (72)	363 (48)	219 (29)	545 (71)	598 (78)	84 (11)
Kanaji et al. [19]	66.6 ± 10.3	94 (79.3)	83 (69.2)	49 (40.8)	80 (63.8)	–	–
Fede et al. [20]	67 ± 11	41 (76)	–	14 (26)	44 (81)	36 (66)	9 (17)
RESOLVE [21]	63.4 ± 10.3	1193 (74.9)	468 (29.4)	448 (28.1)	–	1093 (68.6)	229 (14.4)

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a LM: left main artery.

b pLAD: proximal left anterior descending artery.

Table 3

Baseline angiographic and procedural characteristics.

Study	Single vessel (%)	Multi-vessel (%)	Lad a(%)	Lcx b(%)	Rca c(%)	Iv d adenosine (%) €	Ic e adenosine (%) €
ADVISE [10]	108 (69)	49 (31)	69 (44)	43 (27)	45 (29)	63 (40)	94 (60)
VERIFY [31]	85 (41)	105 (51)	133 (64)	28 (14)	45 (22)	206 (100)	0 (0)
Park et al. [32]	–	–	173 (73)	–	–	238 (100)	238 (100)
ADVISE In PRACTICE [12]	141 (36)	247 (63)	259 (66)	39 (10)	55 (14)	153 (39)	239 (61)
Indolfi et al. [33]	–	18 (15)	–	–	–	123 (100)	0 (0)
ADVISE 2 [34]	–	–	380 (55)	179 (26)	138 (20)	690 (100)	0 (0)
Harle et al. [35]	75 (69)	33 (31)	66 (44)	20 (13)	42 (28)	138 (91)	13 (9)
Shiode et al. [36]	–	–	90 (73)	4 (3)	29 (24)	0 (0)	123 (100)
Kobayashi et al. (LM f/pLAD g ) [15]	–	–	201 (100)	0 (0)	0 (0)	201 (100)	201 (100)
Kobayashi et al. (other lesions) [15]	–	–	0 (0)	–	–	559 (100)	559 (100)
VERIFY 2 [16]	–	–	148 (58)	37 (14)	45 (18)	257 (100)	0 (0)
Meimoun et al. [17]	94 (100)	0 (0)	94 (100)	0 (0)	0 (0)	0 (0)	94 (100)
Johnson et al. [18]	–	–	460 (60)	138 (18)	140 (18)	315 (72)	124 (28)
Kanaji et al. [19]	89 (74)	31 (26)	77 (64)	16 (13)	27 (23)	120 (100)	0 (0)
Fede et al. [20]	–	–	52 (58)	20 (23)	17 (19)	0 (0)	89 (100)
RESOLVE [21]	736 (46)	857 (54)	1004 (63)	271 (17)	319 (20)	1276 (80)	317 (20)

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a LAD: left anterior descending artery.

b LCx: left circumflex artery.

c RCA: right coronary artery.

d IV: intravenous.

e IC: intracoronary.

f LM: left main artery.

g pLAD: proximal left anterior descending artery.

€ Multiple studies used both intravenous and intracoronary adenosine in same lesion.

 

3.3

Quality assessment and publication bias

The overall methodological quality of the included studies, according to the QUADAS-2 assessment, varied from moderate to high in our study. Deeks' asymmetry test did not show association between the sample size and sensitivity values ( p > 0.05 for all), which suggest absence of publication bias.

3.4

Diagnostic accuracy of iFR

As depicted in Table 4 and Fig. 2 , the pooled diagnostic accuracy estimates of iFR versus FFR ≤ 0.80 were: sensitivity, 0.78 (95% CI, 0.76–0.79); specificity, 0.83 (0.81–0.84); positive likelihood ratio, 4.54 (3.85–5.35); negative likelihood ratio, 0.28 (0.24–0.32); diagnostic odds ratio, 17.38 (14.16–21.34), and an overall diagnostic accuracy of 0.81 (0.78–0.84). The AUC for iFR was 0.87 ( Fig. 3 ). However, significant heterogeneity existed between the studies for sensitivity (I ² = 70%), specificity (74.8%), DOR (41.7%), LR + (70%), and LR − (73.1%). 

Table 4

Pooled diagnostic accuracy measures of iFR ^a referenced to FFR ^b .

Measure	Value (95% CI c )
Diagnostic accuracy	0.81 (0.78–0.84)
Sensitivity	0.78 (0.76–0.79)
Specificity	0.83 (0.81–0.84)
Positive likelihood ratio	4.54 (3.85–5.35)
Negative likelihood ratio	0.28 (0.24–0.32)
Diagnostic odds ratio	17.38 (14.16–21.34)

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a iFR: instantaneous wave-free ratio.

b FFR: fractional flow reserve.

c CI: confidence interval.

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Forest plots for sensitivity, specificity, LR +, LR-, and DOR of iFR referenced to FFR ≤ 0.80. CI: confidence interval. LR: likelihood ratio. OR: odds ratio.

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Summary receiver-operating characteristic curve for iFR using random-effects model. sROC: summary receiver-operating characteristic curve. SE: standard error. AUC: area under sROC. Q: result of Cochran's Q test.

 

3.5

Diagnostic threshold effect

A Spearman's rank correlation was performed to evaluate for the presence of a threshold effect. The Spearman's correlation coefficient was 0.678 ( p = 0.08) indicating the possibility of a threshold effect. The positive value indicates that the thresholds increase sensitivity at the expense of specificity. This could be explained by the different cutoff values used in the various studies. Therefore, a symmetrical sROC curve was drawn.

3.6

Meta-regression analysis

The meta-regression analysis, using the predefined potential sources of heterogeneity as covariates in the Moses–Shapiro–Littenberg model, indicated that the iFR cut-off value ( p < 0.05) might be a significant predictor. Other factors did not influence the diagnostic accuracy, including age ( p = 0.72), sex ( p = 0.48), the prevalence of diabetes ( p = 0.57), hypertension ( p = 0.48), and smoking habit ( p = 0.18). A meta-regression on DOR with percent stable angina (B = 0.15, CI = − 1.1 to 1.4, p = 0.82) and unstable angina (B = − 0.09, CI − 1.03 to − 0.86) cases as covariates demonstrated no significant association with diagnostic outcome.

Author bio

Source:

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