Patients still present with drug-eluting stent (DES) failure despite an angiographically successful implantation. The aim of the present study was to investigate the relation between the fractional flow reserve (FFR) measured after DES implantation and the clinical outcomes at 1 year. A total of 80 patients (mean age 62 years, 74% men, 99 DESs) underwent coronary pressure measurement at maximum hyperemia after successful DES implantation. The composite of major adverse cardiac events (MACE), including death, myocardial infarction, and ischemia-driven target vessel revascularization was evaluated at 1 year. The patients were divided into 2 groups (low-FFR group, FFR ≤0.90 and high-FFR group, FFR >0.90) according to the median FFR. The mean poststent percent diameter stenosis was 11 ± 5% in the low-FFR group and 12 ± 3% in the high-FFR group (p = 0.31). Left anterior descending coronary artery lesions were more frequent in the low-FFR group than in the high-FFR group (82% vs 55%, p = 0.02). The mean stent length was greater in the low-FFR group than in the high-FFR group (38 ± 18 vs 28 ± 13 mm, p = 0.01). Six cases (7.5%) of MACE occurred during the 1-year follow-up. The rate of MACE was 12.5% in the low-FFR group and 2.5% in the high-FFR group (p <0.01). Receiver operating characteristic curves revealed 0.90 as the best cutoff of FFR after DES implantation for the prediction of 1-year MACE. In conclusion, a poststent FFR of ≤0.90 correlated with a greater adverse event rate at 1 year.
The limitations in the diagnostic accuracy of coronary angiography and in the clinical efficacy of drug-eluting stents (DESs) underscore the relevance of adjunctive techniques to more accurately evaluate the success of percutaneous coronary intervention (PCI) with DESs. Several studies have demonstrated that coronary pressure measurement has a good correlation with intravascular ultrasound findings in the evaluation of the success of PCI, thereby informing optimal stent deployment. The fractional flow reserve (FFR) can identify a residual hyperemic pressure gradient that results in abnormal resistance across both the stented and the adjacent segments. Although the FFR measured after bare metal stent implantation correlated with the 6-month clinical outcomes in a previous study, it is unknown whether the same applies to DES implantation. The aim of the present study was to investigate the relation between optimal physiologic DES implantation assessed by the poststent FFR and the outcomes at 1 year.
Methods
The study population consisted of 80 patients who underwent FFR measurement immediately after angiographically successful PCI with DES implantation in de novo coronary lesions. The angiographic success of PCI was defined as residual stenosis <20% by visual assessment with Thrombolysis In Myocardial Infarction grade 3 coronary flow and FFR ≥0.80. The patients were not eligible for enrollment if they had undergone intervention in the setting of primary or emergent PCI for acute coronary syndrome, had undergone previous coronary artery bypass graft surgery, or had multiple significant lesions in the same epicardial artery, left main disease, primary myocardial disease, contraindications to adenosine, aspirin, or clopidogrel, or a major life-threatening illness. Implanted stents were commercially available DESs in all cases.
PCI was performed using standard interventional techniques. Antiplatelet and antithrombotic agents were prescribed according to the current PCI guidelines. All coronary angiograms were analyzed using standard definitions and measurements, which were determined according to the American Heart Association classification, using the guiding catheter for calibration and an edge detection quantitative coronary angiography system (Digital Cardiac Imaging System, Philips Medical Systems, Best, The Netherlands). Quantitative coronary angiography was performed by a single experienced observer who was unaware of the FFR value. FFR was defined as the ratio between the mean distal coronary pressure and the mean aortic pressure, both measured simultaneously at maximum hyperemia. Coronary pressure was measured using a 0.014-in. sensor-tipped PCI guidewire (Pressure Wire, Radi Medical Systems, Uppsala, Sweden). The wire was introduced through a 6Fr or 7Fr guiding catheter, equalized, and advanced distal to the stented segment ≥10 mm. The FFR was measured after intracoronary administration of adenosine (40 μg in the right and 80 to 120 μg in the left coronary artery) to induce maximum hyperemia, as previously described. The lowest FFR value was selected after ≥2 measurements.
The primary outcome was defined as a composite of major adverse cardiac events (MACE), defined as death, myocardial infarction, and target vessel revascularization at 12 months after the index procedure. Death was defined as all-cause mortality. Myocardial infarction was defined as threefold or greater elevation of creatine kinase-MB level or new Q waves in ≥2 contiguous leads on the electrocardiogram. Target vessel revascularization included target vessel PCI and bypass surgery of the target vessel performed in the presence of symptoms and/or signs of ischemia. Stent thrombosis was defined according to the Academic Research Consortium guidelines. In-stent restenosis was defined as ≥50% diameter stenosis on the follow-up angiogram.
Data are expressed as the mean ± SD for continuous variables and percentages for discrete variables. Continuous variables were compared using Student’s t test or analysis of variance. Categorical variables were compared using chi-square tests, nonparametric chi-square tests, or Fisher exact tests, as appropriate. Multivariate logistic regression analysis was used to assess the independent predictors of MACE. The parameters analyzed in multivariate regression analysis were selected when p <0.10 on univariate analysis. Receiver operating characteristic curve analysis was used to determine the cutoff FFR after DES implantation for the prediction of 1-year MACE. All calculated p values were 2-sided, and differences were considered statistically significant at p <0.05. All statistical analyses were performed using the Statistical Package for Social Sciences, version 15.0, for Windows (SPSS, Chicago, Illinois).
Results
The baseline clinical characteristics, angiographic characteristics, and quantitative coronary angiographic results are summarized in Tables 1 and 2 . The average number of DESs deployed per target lesion was 1.2 ± 0.4. Three types of DESs were implanted (sirolimus-eluting stent, 51%; paclitaxel-eluting stent, 39%; and zotarolimus-eluting stent, 10%). No complications attributable to FFR measurement occurred in any of the studied patients. The patients were divided into 2 groups according to the median FFR: the low-FFR (≤0.90) group and the high-FFR (>0.90) group, with 40 patients in each group. The DES type and mean poststent percent diameter stenosis were similar between the 2 groups. The left anterior descending coronary artery (LAD) was more often stented in the low-FFR group (82%) than in the high-FFR group (55%, p = 0.02). The mean lesion length was greater in the low-FFR group (34 ± 17 mm) than in the high-FFR group (26 ± 13 mm, p = 0.02). The implanted stent length was also significantly greater in the low-FFR group than in the high-FFR group (38 ± 18 vs 28 ± 13 mm, respectively, p = 0.01). On multivariate linear regression analysis for predicting the value of FFR after DES implantation, only the target coronary artery (LAD vs non-LAD) affected the poststent FFR significantly (β = 0.33, 95% confidence interval 0.01 to 0.07, p = 0.003), and complex lesion type showed a trend (β = 0.19, 95% confidence interval −0.01 to 0.06, p = 0.099; Table 3 ).
| Variable | FFR ≤0.90 Group (n = 40) | FFR >0.90 Group (n = 40) | p Value |
|---|---|---|---|
| Age (years) | 62 ± 10 | 63 ± 8 | 0.48 |
| Men | 31 (78%) | 28 (70%) | 0.31 |
| Diabetes | 8 (20%) | 3 (7.5%) | 0.19 |
| Hypertension ⁎ | 23 (58%) | 17 (43%) | 0.26 |
| Hypercholesterolemia † | 4 (10%) | 6 (15%) | 0.37 |
| Current smoking | 11 (28%) | 19 (48%) | 0.11 |
| Previous percutaneous coronary intervention | 6 (15%) | 6 (15%) | 1.00 |
| Previous myocardial infarction | 4 (10%) | 5 (13%) | 1.00 |
| Clinical presentation | 1.00 | ||
| Stable angina | 12 (30%) | 13 (33%) | |
| Acute coronary syndrome | 28 (70%) | 27 (67%) | |
| Left ventricular ejection fraction (%) | 61 ± 9 | 60 ± 9 | 0.54 |
⁎ Defined as history of hypertension diagnosed and treated with medication, diet, and/or exercise, blood pressure >140 mm Hg systolic or >90 mm Hg diastolic on ≥2 occasions, or currently receiving antihypertensive pharmacologic therapy.
† Defined as total cholesterol >200 mg/dl, low-density lipoprotein cholesterol ≥130 mg/dl, or receiving statin therapy.
| Variable | FFR ≤0.90 Group (n = 40) | FFR >0.90 Group (n = 40) | p Value |
|---|---|---|---|
| Lesion related | |||
| Multivessel coronary artery disease | 25 (62%) | 60 (24) | 1.00 |
| Complex lesion type ⁎ | 36 (90%) | 77 (31) | 0.23 |
| Left anterior descending artery lesion | 33 (82%) | 55 (22) | 0.02 |
| Ostial lesion | 2 (3.9%) | 3.9 (2) | 1.00 |
| Bifurcation involvement | 9 (17.3%) | 13.5 (7) | 0.77 |
| Quantitative coronary angiography | |||
| Lesion length (mm) | 34 ± 17 | 26 ± 13 | 0.02 |
| Reference vessel diameter (mm) | 3.1 ± 0.3 | 3.2 ± 0.4 | 0.07 |
| Preintervention minimum lumen diameter (mm) | 0.7 ± 0.3 | 0.7 ± 0.2 | 0.56 |
| Preintervention diameter stenosis (%) | 76 ± 8 | 76 ± 8 | 0.97 |
| Stent length (mm) | 38 ± 18 | 28 ± 13 | 0.01 |
| Postintervention minimum lumen diameter (mm) | 2.8 ± 0.3 | 3.0 ± 0.4 | 0.12 |
| Postintervention diameter stenosis (%) | 11 ± 5 | 12 ± 3 | 0.31 |
| Postintervention fractional flow reserve | 0.86 ± 0.04 | 0.94 ± 0.03 | <0.001 |
⁎ According to American College of Cardiology/American Heart Association classification, type A and B1 lesions are simple, and type B2 and C lesions are complex.
| Variable | Univariate | Multivariate | ||||
|---|---|---|---|---|---|---|
| β | 95% CI | p Value | β | 95% CI | p Value | |
| Left anterior descending coronary artery lesion | 0.39 | 0.02–0.07 | <0.001 | 0.33 | 0.01–0.07 | 0.003 |
| Complex lesion ⁎ | 0.26 | 0.01–0.07 | 0.02 | 0.19 | −0.01–0.06 | 0.10 |
| Reference vessel diameter | 0.21 | 0.01–0.06 | 0.07 | 0.02 | −0.06–0.07 | 0.92 |
| Stent diameter | 0.20 | −0.01–0.06 | 0.07 | 0.10 | −0.05–0.09 | 0.69 |
| Total stented length | −0.19 | −0.01–0.00 | 0.09 | −0.05 | 0.00–0.01 | 0.66 |
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