Usefulness of optical coherence tomography with angiographic coregistration in the guidance of coronary stent implantation.

Optical coherence tomography (OCT)-angiography coregistration during stent implantation may be useful to avoid geographical mismatch and incomplete lesion coverage. Untreated lipid-rich plaque at stent edge is associated with subsequent stent edge restenosis. The present study sought to compare the frequency of untreated lipid-rich plaque at the stent edge between OCT-guided percutaneous coronary intervention (PCI) with and without OCT-angiography coregistration. We investigated 398 patients who underwent OCT-guided stent implantation (n = 198 in the coregistration group, and n = 200 in the no coregistration group). In OCT after PCI, untreated lipid-lich plaque was identified by the maximum lipid arc > 180˚ in the 5-mm stent edge segment. The PCI-targeted lesion characteristics and stent length were not different between the coregistration group and the no coregistration group. The frequency of untreated lipid-rich plaque in either proximal or distal stent edge segment was significantly lower in the coregistration group than in the no coregistration group (16% vs. 26%, P = 0.015). The frequency of stent-edge dissection (5% vs. 6%, P = 0.516) and untreated stenosis (2% vs. 3%, P = 0.724) was low and without significant differences between the two groups. In OCT-guided PCI, the use of OCT-angiography coregistration was associated with a reduced frequency of untreated lipid-rich plaque at stent edges. OCT-angiography coregistration has a positive impact on PCI results.

Impact of Optical Coherence Tomography Imaging on Decision-Making During Percutaneous Coronary Intervention in Patients Presented With Acute Coronary Syndromes.

BACKGROUND: Optical coherence tomography (OCT) provides valuable information to guide percutaneous coronary intervention (PCI) in acute coronary syndrome (ACS) regarding lesion preparation, stent sizing, and optimization. The aim of the present study was to compare lumen expansion of stent-treated lesions immediately after the procedure for ACS between OCT-guided PCI and angiography-guided PCI.Methods and Results:This study investigated stent-treated lesions immediately after PCI for ACS by using quantitative coronary angiography in 390 patients; 260 patients with OCT-guided PCI and 130 patients with angiography-guided PCI. Before stenting, the frequency of pre-dilatation and thrombus aspiration were not different between the OCT-guided and angiography-guided PCI groups. Stent diameter was significantly larger as a result of OCT-guided PCI (3.11±0.44 mm vs. 2.99±0.45 mm, P=0.011). In post-dilatation, balloon pressure-up (48% vs. 31%, P=0.001) and balloon diameter-up (33% vs. 6%, P<0.001) were more frequently performed in the OCT-guided PCI group. Minimum lumen diameter (2.55±0.35 mm vs. 2.13±0.50 mm, P<0.001) and acute lumen gain (2.18±0.54 mm vs. 1.72±0.63 mm, P<0.001) were significantly larger in the OCT-guided PCI group. Percent diameter stenosis (14±4% vs. 24±10%, P<0.001) and percent area stenosis (15±5% vs. 35±17%, P<0.001) were significantly smaller in the OCT-guided PCI group. CONCLUSIONS: OCT-guided PCI potentially results in larger lumen expansion of stent-treated lesions immediately after PCI in the treatment of ACS compared with angiography-guided PCI.

Optical Coherence Tomography Comparison of Percutaneous Coronary Intervention Among Plaque Rupture, Erosion, and Calcified Nodule in Acute Myocardial Infarction.

BACKGROUND: Acute myocardial infarction (AMI) is caused by coronary plaque rupture (PR), plaque erosion (PE), or calcified nodule (CN). We used optical coherence tomography (OCT) to compare stent expansion immediately after primary percutaneous coronary intervention (PCI) in patients with AMI caused by PR, PE, or CN.Methods and Results:In all, 288 AMI patients were assessed by OCT before and immediately after PCI, performed with OCT guidance according to OPINION criteria for stent sizing and optimization. The frequency of OCT-identified PR (OCT-PR), OCT-PE, and OCT-CN was 172 (60%), 82 (28%), and 34 (12%), respectively. Minimum stent area was smallest in the OCT-CN group, followed by the OCT-PE and OCT-PR groups (mean [±SD] 5.20±1.77, 5.44±1.78, and 6.44±2.2 mm2, respectively; P<0.001), as was the stent expansion index (76±13%, 86±14%, and 87±16%, respectively; P=0.001). The frequency of stent malapposition was highest in the OCT-CN group, followed by the OCT-PR and OCT-PE groups (71%, 38%, and 27%, respectively; P<0.001), as was the frequency of stent edge dissection in the proximal reference (44%, 23%, and 10%, respectively; P<0.001). The frequency of tissue protrusion was highest in the OCT-PR group, followed by the OCT-PE and OCT-CN groups (95%, 88%, and 85%, respectively; P=0.036). CONCLUSIONS: Stent expansion was smallest in the OCT-CN group, followed by the OCT-PR and OCT-PE groups. Plaque morphology in AMI culprit lesions may affect stent expansion immediately after primary PCI.

Comparison of Optical Flow Ratio and Fractional Flow Ratio in Stent-Treated Arteries Immediately After Percutaneous Coronary Intervention.

BACKGROUND: Optical flow ratio (OFR) is a recently developed method for functional assessment of coronary artery disease based on computational fluid dynamics of vascular anatomical data from intravascular optical coherence tomography (OCT). The purpose of this study was to investigate the relationship between OFR and fractional flow reserve (FFR) in stent-treated arteries immediately after percutaneous coronary intervention (PCI).Methods and Results:The OFR and FFR were measured in 103 coronary arteries immediately after successful PCI with a stent. An increase in the OFR and FFR values within the stent was defined as in-stent ∆OFR and ∆FFR, respectively. The values of FFR and OFR were 0.89±0.06 and 0.90±0.06, respectively. OFR was highly correlated with FFR (r=0.84, P<0.001). OFR showed a good agreement with FFR, presenting small values of mean difference and root-mean-squared deviation (FFR-OFR: -0.01±0.04). In-stent ∆OFR showed a moderate correlation (r=0.69, P<0.001) and good agreement (in-stent ∆FFR - in-stent ∆OFR: 0.00±0.02) with in-stent ∆FFR. CONCLUSIONS: OFR showed a high correlation and good agreement with FFR in stent-treated arteries immediately after PCI.

Effect of Atherectomy on Lesion Preparation in Heavily Calcified Coronary Artery Disease.

Background: Percutaneous coronary intervention (PCI) of heavily calcified lesions remains challenging. This study examined whether calcified lesion preparation is better with an ablation-based than balloon-based technique. Methods and Results: Results of lesion preparations with and without atherectomy devices were compared in 121 patients undergoing optical coherence tomography (OCT)-guided PCI of heavily calcified lesions. Lesion preparation was performed with the ablation-based technique in 59 patients (atherectomy group) and with the balloon-based technique in 62 patients (balloon group). Lower grades of angiographic coronary dissections (National Heart, Lung, and Blood Institute [NHLBI] classification) occurred in the atherectomy than balloon group (atherectomy group: none, 33%; NHLBI A, 59%; B, 8%; C, 0%; D, 0%; balloon group: none, 1%; NHLBI A, 24%; B, 58%; C, 15%; D, 2%). On OCT, a large dissection was less common (49% vs. 90%; P<0.001) and calcium fractures were more frequent (75% vs. 18%; P<0.001) in the atherectomy than balloon group. In multivariable analyses, the ablation-based technique was associated with a lower grade of angiographic coronary dissection (adjusted odds ratio [aOR] 0.04; 95% confidence interval [CI] 0.01-0.12; P<0.001), a lower incidence of OCT-detected large dissection (aOR 0.09; 95% CI 0.03-0.30; P<0.001), and a higher incidence of OCT-detected calcium fracture (aOR 18.19; 95% CI 6.45-58.96; P<0.001). Conclusions: The ablation-based technique outperformed the balloon-based technique in the lesion preparation of heavily calcified lesions.

Serial changes of coronary flow reserve over one year after transcatheter aortic valve implantation in patients with severe aortic stenosis.

Background: Impaired coronary flow reserve (CFR) portends a poor prognosis in patients with aortic stenosis. The present study aims to investigate how CFR changes over one year after transcatheter aortic valve implantation (TAVI) in patients with severe aortic stenosis, and to explore factors related to the changes. Methods: Consecutive patients undergoing TAVI were registered. CFR in the left anterior descending artery was measured by transthoracic echocardiography on three occasions pre-TAVI, one-day post-TAVI, and one-year post-TAVI. Results: A total of 59 patients were enrolled, 46 of whom completed one-year follow-up. CFR was impaired in 35 (59.3%) patients pre-TAVI, but the impairment was only seen in 2 patients (4%) one-year post-TAVI. CFR value improved from 1.75 (1.50-2.10) cm/s pre-TAVI, to 2.00 (1.70-2.30) one-day post-TAVI, and further to 2.60 (2.30-3.10) one-year post-TAVI (P < 0.001). The median difference in CFR between pre-TAVI and one-year post-TAVI was 0.90 (0.53-1.20). Patients with significant improvement of CFR (more than the median value of 0.9) had larger aortic valve area (1.55 [1.38-1.92] vs. 1.36 cm2 [1.26-1.69], P = 0.042) and greater improvement in left ventricular ejection fraction (3.10 [-1.67-4.24] vs. -1.46 [-3.42-1.48] percentage points, P = 0.019) than those without. Conclusions: CFR is impaired in a considerable proportion of patients with severe aortic stenosis, but improvement is seen immediately after TAVI, and one year later. Patients with significant improvement of CFR had larger aortic valve area and greater increase in left ventricular ejection fraction after TAVI.

Prevalence of myocardial perfusion scintigraphy derived ischemia in coronary lesions with discordant fractional flow reserve and non-hyperemic pressure ratios.

BACKGROUND: Whether a coronary lesion with discordant fractional flow reserve (FFR) and non-hyperemic pressure ratios (NHPRs) causes myocardial ischemia remains unclear. This study investigates the prevalence of myocardial ischemia as assessed by myocardial perfusion scintigraphy (MPS) in coronary lesions with discordant FFR and instantaneous wave-free ratio (iFR), and, additionally, other NHPRs: resting full-cycle ratio (RFR), diastolic pressure ratio (dPR), and resting Pd/Pa. METHODS: A total of 484 coronary arteries in 295 patients with stable coronary artery disease that underwent MPS and invasive physiological pressure measurements were categorized into four groups (FFR+/NHPR+, FFR+/NHPR-, FFR-/NHPR+, and FFR-/NHPR-) using the respective cut-off values of FFR ≤ 0.80, iFR ≤ 0.89, RFR ≤ 0.89, dPR < 0.89, and Pd/Pa ≤ 0.92. The proportions of MPS-derived myocardial ischemia in a relevant myocardial territory were compared between the four groups. RESULTS: In total, 175 (36%), 61(13%), 35(7%) and 213(44%) vessels were classified into FFR+/iFR+, FFR+/iFR-, FFR-/iFR+ and FFR-/iFR- groups, respectively. The FFR+/iFR+ group had the highest proportion of MPS-derived ischemia (70%), followed by the FFR+/iFR- group (38%), the FFR-/iFR+ group (23%), and the FFR-/iFR- group (10%) (P < 0.001). Similar proportions of MPS-derived ischemia were found when RFR. (70%, 34%, 24%, and 10%, P < 0.001), dPR (70%, 38%, 26%, and 10%, P < 0.001), and Pd/Pa (70%, 31%, 22%, and 10%, P < 0.001) were used in place of iFR. CONCLUSIONS: The prevalence of MPS-derived myocardial ischemia in coronary lesions with discordance between FFR and NHPRs is lower than those with concordantly positive FFR and NHPRs, but higher than those with concordantly negative FFR and NHPRs.

Near-infrared spectroscopy to predict microvascular obstruction after primary percutaneous coronary intervention.

BACKGROUND: Successful restoration of epicardial coronary artery patency by primary percutaneous coronary intervention (PPCI) for ST-elevation myocardial infarction (STEMI) does not always lead to adequate reperfusion at the microvascular level. AIMS: This study sought to investigate the association between lipid-rich coronary plaque identified by near-infrared spectroscopy combined with intravascular ultrasound (NIRS-IVUS) and microvascular obstruction (MVO) detected by cardiac magnetic resonance imaging (MRI) after PPCI for STEMI. METHODS: We investigated 120 patients with STEMI undergoing PPCI. NIRS-IVUS was used to measure the maximum lipid core burden index in 4 mm (maxLCBI4 mm) in the infarct-related lesions before PPCI. Delayed contrast-enhanced cardiac MRI was performed to evaluate MVO one week after PPCI. RESULTS: MVO was identified in 40 (33%) patients. MaxLCBI4 mm in the infarct-related lesion was significantly larger in the MVO group compared with the no-MVO group (median [interquartile range]: 745 [522-853] vs 515 [349-698], p<0.001). A multivariable logistic regression model showed that maxLCBI4 mm was an independent predictor of MVO (odds ratio: 24.7 [95% confidence interval: 2.5-248.0], p=0.006). Receiver operating characteristic curve analysis demonstrated that maxLCBI4 mm >600 was the optimal cut-off value to predict MVO (Youden index=0.44 and area under the curve=0.71) with a sensitivity of 75% and a specificity of 69%. CONCLUSIONS: Lipid content measured by NIRS in the infarct-related lesions was associated with the occurrence of MVO after PPCI in STEMI.

Optical coherence tomography detection of vulnerable plaques at high risk of developing acute coronary syndrome.

AIMS: The ability of optical coherence tomography (OCT) to detect plaques at high risk of developing acute coronary syndrome (ACS) remains unclear. The aim of this study was to evaluate the association between non-culprit plaques characterized as both lipid-rich plaque (LRP) and thin-cap fibroatheroma (TCFA) by OCT and the risk of subsequent ACS events at the lesion level. METHODS AND RESULTS: In 1378 patients who underwent OCT, 3533 non-culprit plaques were analysed for the presence of LRP (maximum lipid arc > 180°) and TCFA (minimum fibrous cap thickness < 65 µm). The median follow-up period was 6 years [interquartile range (IQR): 5-9 years]. Seventy-two ACS arose from non-culprit plaques imaged by baseline OCT. ACS was more often associated with lipidic plaques that were characterized as both LRP and TCFA vs. lipidic plaques that did not have these characteristics [33% vs. 2%, hazard ratio 19.14 (95% confidence interval: 11.74-31.20), P < 0.001]. The sensitivity and specificity of the presence of both LRP and TCFA for predicting ACS was 38% and 97%, respectively. A larger maximum lipid arc [1.01° (IQR: 1.01-1.01°)], thinner minimum fibrous cap thickness [0.99 µm (IQR: 0.98-0.99 µm)], and smaller minimum lumen area [0.78 mm2 (IQR: 0.67-0.90 mm2), P < 0.001] were independently associated with ACS. CONCLUSION: Non-culprit plaques characterized by OCT as both LRP and TCFA were associated with an increased risk of subsequent ACS at the lesion level. Therefore, OCT might be able to detect vulnerable plaques.

NIRS-IVUS for Differentiating Coronary Plaque Rupture, Erosion, and Calcified Nodule in Acute Myocardial Infarction.

OBJECTIVES: This study sought to investigate the ability of combined near-infrared spectroscopy and intravascular ultrasound (NIRS-IVUS) to differentiate plaque rupture (PR), plaque erosion (PE), or calcified nodule (CN) in acute myocardial infarction (AMI). BACKGROUND: Most acute coronary syndromes occur from coronary thrombosis based on PR, PE, or CN. In vivo differentiation among PR, PE, and CN is a major challenge for intravascular imaging. METHODS: The study enrolled 244 patients with AMI who had a de novo culprit lesion in a native coronary artery. The culprit lesions were assessed by both NIRS-IVUS and optical coherence tomography (OCT). Maximum lipid core burden index in 4 mm (maxLCBI4mm) was measured by NIRS. Plaque cavity and convex calcium was detected by IVUS. The OCT diagnosis of PR (n = 175), PE (n = 44), and CN (n = 25) was used as a reference standard. RESULTS: In the development cohort, IVUS-detected plaque cavity showed a high specificity (100%) and intermediate sensitivity (62%) for identifying OCT-PR. IVUS-detected convex calcium showed a high sensitivity (93%) and specificity (100%) for identifying OCT-CN. NIRS-measured maxLCBI4mm was largest in OCT-PR (705 [interquartile range (IQR): 545 to 854]), followed by OCT-CN (355 [IQR: 303 to 478]) and OCT-PE (300 [IQR: 126 to 357]) (p < 0.001). The optimal cutoff value of maxLCBI4mm was 426 for differentiating between OCT-PR and -PE; 328 for differentiating between OCT-PE and -CN; and 579 for differentiating between OCT-PR and -CN. In the validation cohort, the NIRS-IVUS classification algorithm using plaque cavity, convex calcium, and maxLCBI4mm showed a sensitivity and specificity of 97% and 96% for identifying OCT-PR, 93% and 99% for OCT-PE, and 100% and 99% for OCT-CN, respectively. CONCLUSIONS: By evaluating plaque cavity, convex calcium, and maxLCBI4mm, NIRS-IVUS can accurately differentiate PR, PE, and CN.

The inter-study reproducibility of instantaneous wave-free ratio and angiography coregistration.

BACKGROUND: Coregistration system of instantaneous wave-free ratio (iFR) pullback and angiography has been developed to enhance benefits of physiology oriented percutaneous coronary intervention (PCI), but its reproducibility has not yet been fully assessed. METHODS AND RESULTS: In 51 coronary arteries from 39 patients with stable coronary artery disease, iFR angio-coregistrations were repeated twice. The mean iFR values were comparable between the first and second studies (0.85 ±â€¯0.12 vs. 0.84 ±â€¯0.13, p = 0.97). In terms of a coronary segment with predominant iFR gradients defined by the largest segmental iFR gradients, the repeated iFR angio-coregistrations matched in 47 of 51 (92%) studies and showed good agreement (κ = 0.75) in overall vessels. When assessed only in vessels with positive iFR (≤0.89), iFR angio-coregistrations matched in 31 of 32 (97%) studies and showed an excellent agreement (κ = 0.91). The predominant iFR gradients in the repeated iFR angio-coregistrations demonstrated strong correlation (r = 0.96, p < 0.0001) and an excellent agreement: mean difference was 0.0006, and the lower and upper limits (mean difference ±â€¯1.96 standard deviation) of agreement were -0.0312 and 0.0324. CONCLUSIONS: iFR angio-coregistration is highly reproducible and can precisely identify a suitable target for PCI.

Very late-phase vascular response after everolimus-eluting stent implantation assessed by optical coherence tomography.

Long-term safety of second generation drug-eluting stents (DES) has not yet been evaluated. We sought to evaluate the very late phase (> 3 years) vascular response after second generation everolimus-eluting stent (EES) as compared with first generation sirolimus-eluting stent (SES) by using optical coherence tomography (OCT). We examined the vascular response in 39 patients with a total of 55 DESs [31 EESs (mean 54 months after stenting) and 24 first generation SES (mean 66 months after stenting)] by OCT. The frequency of lesions with any malapposed stent struts (19% vs. 46%, p = 0.035) and evagination (6% vs. 42%, p = 0.002) was significantly lower. Segments with malapposed stent struts were significantly shorter (0.4 ± 0.9 mm vs. 1.9 ± 3.5 mm, p = 0.024), maximal malapposition area and malapposition volume were significantly smaller (0.26 ± 0.38 mm2 vs. 0.95 ± 1.54 mm2, p = 0.019, and 0.78 ± 1.35 mm3 vs. 6.22 ± 15.76 mm3, p = 0.016, respectively) in EES. Compared with first generation SES, second generation EES showed more favourable vascular responses at the very late phase.

Prevalence, Features, and Prognosis of Artery-to-Artery Embolic ST-Segment-Elevation Myocardial Infarction: An Optical Coherence Tomography Study.

Background The major underlying mechanisms contributing to acute coronary syndrome are plaque rupture, plaque erosion, and calcified nodule. Artery-to-artery embolic myocardial infarction (AAEMI) was defined as ST-segment-elevation myocardial infarction caused by migrating thrombus formed at the proximal ruptured plaque. The aim of this study was to investigate the prevalence and clinical features of AAEMI by using optical coherence tomography. Methods and Results This study retrospectively enrolled 297 patients with ST-segment-elevation myocardial infarction who underwent optical coherence tomography before percutaneous coronary intervention. Patients were divided into 4 groups consisting of plaque rupture, plaque erosion, calcified nodule, and AAEMI according to optical coherence tomography findings. The prevalence of AAEMI was 3.4%. The culprit vessel in 60% of patients with AAEMI was right coronary artery. Minimum lumen area at the culprit site was larger in AAEMI compared with plaque rupture, plaque erosion, and calcified nodule (4.0 mm2 [interquartile range (IQR), 2.2-4.9] versus 1.0 mm2 [IQR, 0.8-1.3] versus 1.0 mm2 [IQR, 0.8-1.2] versus 1.1 mm2 [IQR, 0.7-1.6], P<0.001). Lumen area at the rupture site was larger in patients with AAEMI compared with patients with plaque rupture (4.4 mm2 [IQR, 2.5-6.7] versus 1.5 mm2 [IQR, 1.0-2.4], P<0.001). In patients with AAEMI, the median minimum lumen area at the occlusion site was 1.2 mm2 (IQR, 1.0-2.1), 40% of them had nonstent strategy, and the 3-year major adverse cardiac event rate was 0%. Conclusions AAEMI is a rare cause for ST-segment-elevation myocardial infarction and has unique morphological features of plaque including larger lumen area at rupture site and smaller lumen area at the occlusion site.

Extent of the difference between microcatheter and pressure wire-derived fractional flow reserve and its relation to optical coherence tomography-derived parameters.

BACKGROUND: Although previous studies demonstrated that microcatheter-derived fractional flow reserve (mc-FFR) tends to overestimate lesion severity compared to pressure wire-derived FFR (pw-FFR), the clinical utility of mc-FFR remains obscure. The extent of differences between the two FFR systems and its relation to a lesion-specific parameter remain unknown. In this study, we sought to compare mc-FFR with pw-FFR and determine the lower and upper mc-FFR cut-offs predicting ischemic and non-ischemic stenosis, using an ischemic and a clinical FFR threshold of 0.75 and 0.80 as references, respectively. We further explored optical coherence tomography (OCT) parameters influencing the difference in FFR between the two systems. METHODS AND RESULTS: In this study, 44 target vessels with intermediate de novo coronary artery lesion in 36 patients with stable ischemic heart disease were evaluated with mc-FFR, pw-FFR and OCT. Bland-Altman plots for mc-FFR versus pw-FFR showed a bias of -0.04 for lower mc-FFR values compared to pw-FFR values. The mc-FFR cut-off values of 0.73 and 0.79 corresponded to the 0.75 ischemic pw-FFR and 0.80 clinical pw-FFR thresholds with high predictive values, respectively. The differences in the two FFR measurements (pw-FFR minus mc-FFR) were negatively correlated with OCT-derived minimum lumen area (MLA) (R = -0.359, p = 0.011). The OCT-derived MLA of 1.36 mm2 was a cut-off value for predicting the clinically significant difference between the two FFR measurements defined as >0.03. CONCLUSION: Mc-FFR is clinically useful when the specific cut-offs are applied. An OCT-derived MLA accounts for the clinically significant difference in FFR between the two systems.

Intracoronary pressure increase due to contrast injection for optical coherence tomography imaging.

BACKGROUND: Optical coherence tomography (OCT) requires intracoronary injection of contrast media to remove blood from the field of view during image acquisition. Contrast injection may cause a temporal increase in intracoronary pressure. The aim of this study was to compare the intracoronary pressure during contrast injection between OCT and coronary angiography. METHODS: We measured intracoronary pressure by using a pressure guidewire during contrast injection for OCT and angiography in 30 coronary arteries (mean fractional flow reserve = 0.90 ±â€¯0.03). Contrast media was injected into coronary artery through the guiding catheter by using a mechanical injector pump. RESULTS: Intracoronary pressure before contrast injection was similar between OCT and angiography (systolic pressure: 123 ±â€¯18 mmHg vs. 122 ±â€¯19 mmHg, p = 0.863). Intracoronary pressure was increased due to contrast injection in both OCT (systolic pressure: 123 ±â€¯18 mmHg to 132 ±â€¯18 mmHg, p < 0.001) and angiography (systolic pressure: 122 ±â€¯19 mmHg to 128 ±â€¯19 mmHg, p < 0.001). The increase in intracoronary pressure was slightly greater in OCT compared with angiography (absolute increase of systolic pressure: 9 ±â€¯2 mmHg vs. 6 ±â€¯1 mmHg, p < 0.001; and relative increase of systolic pressure: 8 ±â€¯2% vs. 5 ±â€¯1%, p < 0.001). Intracoronary pressure during contrast injection was not significantly different between OCT and angiography (systolic pressure: 132 ±â€¯18 mmHg vs. 128 ±â€¯19 mmHg, p = 0.831). CONCLUSIONS: Contrast injection for OCT induced significant but small increase in intracoronary pressure compared with that for angiography.