Comparison between two- and three-dimensional quantitative coronary angiography bifurcation analyses for the assessment of bifurcation lesions: A subanalysis of the TRYTON pivotal IDE coronary bifurcation trial.

BACKGROUND: Three-dimensional (3D) quantitative coronary angiography (QCA) provides more accurate measurements by minimizing inherent limitations of two-dimensional (2D) QCA. The aim of this study was to compare the measurements between 2D and 3D QCA analyses in bifurcation lesions. METHODS AND RESULTS: A total of 114 cases with non-left main bifurcation lesions in the TRYTON pivotal IDE Coronary Bifurcation Trial (ClinicalTrials.gov: NCT01258972) were analyzed using a validated bifurcation QCA software (CAAS 5.10, Pie Medical Imaging, Maastricht, the Netherlands). All cases were analyzed in matched projections between pre- and post-procedure. The 2D analysis was performed using one of two angiographic images used for 3D reconstruction showing a larger distal bifurcation angle. In the treated segments (stent and balloon), there were no differences in minimal luminal diameter (MLD) between 2D and 3D, while diameter stenosis (DS) was significantly higher in 2D compared to 3D both pre-procedure and post-procedure (53.9% for 2D vs. 52.1% for 3D pre-procedure, P < 0.01; 23.2% for 2D vs. 20.9% for 3D post-procedure, P = 0.01). In the sub-segment level analysis, lengths of proximal main branch, distal main branch, and side branch were consistently shorter in 2D compared to 3D both pre-procedure and post-procedure. Using 3D QCA, the anatomic location of the smallest MLD or the highest DS was relocated to a different bifurcation sub-segment in a considerable proportion of the patients compared to when 2D-QCA was used (kappa values: 0.50 for MLD, 0.55 for DS). CONCLUSIONS: Our data showed differences in addressing anatomical severity and location of coronary bifurcation lesions between in vivo 2D and 3D QCA analyses. More studies are needed to investigate potential clinical benefits in using 3D approach over 2D QCA for the assessment of bifurcation lesions.

A CT-based Medina classification in coronary bifurcations: does the lumen assessment provide sufficient information?

AIMS: To evaluate the distribution of atherosclerosis at bifurcations with computed tomography coronary angiography (CTCA) and propose a novel CT-Medina classification for bifurcation lesions. METHODS: In 26 patients (age 55 ± 10 years, 81% male) imaged with CTCA, 39 bifurcations were studied. The bifurcations analysis included the proximal main vessel, the distal main vessel and the side branch (SB). Plaque contours were manually traced on CTCA; the lumen, vessel and plaque area were measured, as well as plaque burden (%). The carina cross-sections were divided into four equal parts according to the expected wall shear stress (WSS) to assess circumferential plaque distribution. All the bifurcation lesions were classified using the Medina classification and a novel CT-Medina classification combining lumen narrowing and plaque burden ≥70%. RESULTS: Presence of severe plaque (plaque burden ≥70%) by CTCA was demonstrated in 12.8% (5/39) of the proximal segments, 15.4% (6/39) of the distal segments and 7.7% (3/39) of the SB segments. The thickest plaque was located more often in low WSS parts of the carina cross-sections, whereas the flow divider was rarely affected. Although in the majority of bifurcations plaque was present, based on the Medina classification 92% of the assessed bifurcations were identified as 0,0,0. Characterization of bifurcation lesions using the new CT-Medina classification provided additional information in seven cases (18%) compared to the Medina classification CONCLUSION: Atherosclerotic plaque is widely present in all bifurcation segments, even in the absence of coronary lumen stenosis. A CT-Medina classification combining lumen and plaque parameters is more informative than angiographic classification of bifurcation lesions and could potentially facilitate the decision-making on the treatment of these lesions.

Advanced three-dimensional quantitative coronary angiographic assessment of bifurcation lesions: methodology and phantom validation.

AIMS: Validation of new three-dimensional (3-D) bifurcation quantitative coronary angiography (QCA) software. METHODS AND RESULTS: Cardiovascular Angiography Analysis System (CAAS 5v10) allows 3-D angiographic reconstructions based on two or more 2-D projection images. Measurements for minimal lumen diameter (MLD), reference vessel diameter (RVD), percent diameter stenosis (DS) and bifurcation angle (BA) were validated against precision manufactured phantom bifurcations. Length measurements were validated against angiographic measurement catheters inserted into a plexiglas bifurcation phantom. In 3-D reconstructions based on two 2-D images, acquired at variable rotation and angulation, accuracy and precision (mean difference ± SD) of the 11-segment model for MLD, RVD and DS were 0.013±0.131 mm, -0.052±0.039 mm and -1.08±5.13%, respectively; inter-observer variability was 0.141 mm, 0.058 mm and 5.42%, respectively. Adding the antero-posterior (optimal) projection to these basic reconstructions resulted in reduced variability (0.101 mm, 0.041 mm and 3.93% for MLD, RVD and DS, p<0.01 for all) and showed a trend towards improved precision (0.109 mm, 0.031 mm and 4.26%, respectively, p>0.05 for all). In basic reconstructions, accuracy and precision for BA was -1.3±5.0°, whereas inter-observer variability was 7.5°; respective measures for length were 0.15±0.26 mm and 0.54 mm. Adding the antero-posterior projection resulted in decreased precision (0.47 mm, p<0.01) and increased variability (1.03 mm, p<0.01) for length measurements; precision (5.4°) and variability (7.9°) for BA did not change significantly (p>0.30). CONCLUSIONS: Advances in the methodology of 3-D reconstruction and quantitative analysis for bifurcation lesions translated into highly accurate, precise and reproducible measures of diameter, length and BA.

Assessment of atherosclerotic plaques at coronary bifurcations with multidetector computed tomography angiography and intravascular ultrasound-virtual histology.

AIMS: We evaluated the distribution and composition of atherosclerotic plaques at bifurcations with intravascular ultrasound-virtual histology (IVUS-VH) and multidetector computed tomography (MDCT) in relation to the bifurcation angle (BA). METHODS AND RESULTS: In 33 patients (age 63±11 years, 79% male) imaged with IVUS-VH and MDCT, 33 bifurcations were matched and studied. The analysed main vessel was divided into a 5 mm proximal segment, the in-bifurcation segment, and a 5 mm distal segment. Plaque contours were manually traced on MDCT and IVUS-VH. Plaques with >10% confluent necrotic core and <10% dense calcium on IVUS-VH were considered high risk, whereas plaque composition by MDCT was graded as non-calcified, calcified, or mixed. The maximum BA between the main vessel and the side branch was measured on diastolic MDCT data sets. Overall the mean plaque area decreased from the proximal to the distal segment [8.5±2.8 vs. 6.0±3.0 mm2 (P<0.001) by IVUS-VH and 9.0±2.6 vs. 6.5±2.5 mm2 (P<0.001) by MDCT]. Similarly, the necrotic core area was higher in the proximal compared with the distal segment (1.12±0.7 vs. 0.71±0.7 mm2, P=0.001). The proximal segment had the higher percentage of high-risk plaques (13/25, 52%), followed by the in-bifurcation (6/25, 24%), and the distal segment (6/25, 24%); these plaques were characterized by MDCT as non-calcified (72%) or mixed (28%). The presence of high-risk and non-calcified plaques in the proximal segment was associated with higher BA values (71±19° vs. 55±19°, P=0.028 and 74±20° vs. 50±14°, P=0.001, respectively). CONCLUSION: The proximal segment of bifurcations is more likely to contain high-risk plaques, especially when the branching angle is wide.

Advances in two-dimensional quantitative coronary angiographic assessment of bifurcation lesions: improved small lumen diameter detection and automatic reference vessel diameter derivation.

AIMS: To validate a new two dimensional (2-D) bifurcation quantitative coronary angiography (QCA) software. METHODS AND RESULTS: In the latest edition of the Cardiovascular Angiography Analysis System (CAAS 5.9; Pie Medical Imaging, Maastricht, The Netherlands) video-densitometric information is dynamically integrated into the edge-detection algorithm of 11- and 6-segment models to reduce overestimation of small diameters. Furthermore, automatic reference obstruction analysis was optimised. Values of the minimal lumen diameter (MLD), reference vessel diameter (RVD), percent diameter stenosis (DS) and bifurcation angle (BA) for the different bifurcation segment models were validated against precision manufactured plexiglass phantoms. In anteroposterior views, accuracy and precision (mean difference±SD) of 11- and 6-segment models for MLD were 0.013±0.082 mm vs. 0.003±0.100 mm, for RVD -0.030±0.047 mm vs. -0.029±0.045 mm and for DS -0.48±3.66% vs. -0.11±3.97%. In smaller vessel segments (true MLD <0.7 mm), MLD overestimation was reduced. Inter-observer variability for MLD, RVD and DS for either model was ≤0.052 mm, ≤0.043 mm and ≤2.24%, respectively. Agreement between models for MLD, RVD and DS was ±0.076 mm, ±0.021 mm and ±2.53%, respectively. Accuracy and precision for BA were -2.6±3.5°, and variability was ≤1.2°. Accuracy and precision for diameter-derived parameters were slightly decreased in projections with 30° rotation; BA precision dropped to 6.2°. CONCLUSIONS: MLD quantification is improved for true MLD <0.7 mm, resulting in highly accurate and precise diameter measurements over the entire range of phantom diameters. Automatic reference obstruction analysis provides highly accurate, precise and reproducible RVD and DS measurements.

Validity and variability in visual assessment of stenosis severity in phantom bifurcation lesions: a survey in experts during the fifth meeting of the European Bifurcation Club.

OBJECTIVES: To investigate the adequacy of visual estimate regarding the percent diameter stenosis (DS) in bifurcation lesions. BACKGROUND: Quantitative coronary angiography (QCA) is more accurate and precise compared to visual estimate in assessing stenosis severity in single-vessel lesions. METHODS: Thirty-six experts in the field of bifurcation PCI visually assessed the DS in cine images of five precision manufactured phantom bifurcation lesions, experts being blinded to the true values. Expert DS estimates were compared with the true values and they were also used to define the Medina class of each individual bifurcation. Results were pooled together both for proximal main vessel (PMV), distal main vessel (DMV) and side-branch (SB) segments and for vessel segments with similar DS values. RESULTS: Individual performance was highly variable among observers; pooled values and range of accuracy and precision were 2.79% (-6.67% to 17.33%) and 8.69% (4.31-16.25%), respectively. On average, DS was underestimated in the PMV (-1.08%, P = 0.10) and overestimated in the DMV (3.86% P < 0.01) and SB segments (5.58%, P < 0.01). Variability in visual estimates was significantly larger in lesions of medium severity compared to the clearly obstructive ones (P < 0.01); the latter were consistently overestimated. Inter-observer agreement was moderate (κ = 0.55) over the entire number of estimates. However, if the segments with true DS = 0% were excluded, agreement was diminished (κ = 0.27). Inter-observer agreement in Medina class was rather low (κ = 0.21). True bifurcation lesions were misclassified as non-true ones in 14/180 estimates. CONCLUSIONS: Visual assessment by experts is more variable and less precise in the analysis of bifurcation lesions compared to bifurcation QCA software.

Value of the SYNTAX score for risk assessment in the all-comers population of the randomized multicenter LEADERS (Limus Eluted from A Durable versus ERodable Stent coating) trial.

OBJECTIVES: We aimed to assess the predictive value of the SYNTAX score (SXscore) for major adverse cardiac events in the all-comers population of the LEADERS (Limus Eluted from A Durable versus ERodable Stent coating) trial. BACKGROUND: The SXscore has been shown to be an effective predictor of clinical outcomes in patients with multivessel disease undergoing percutaneous coronary intervention. METHODS: The SXscore was prospectively collected in 1,397 of the 1,707 patients enrolled in the LEADERS trial (patients after surgical revascularization were excluded). Post hoc analysis was performed by stratifying clinical outcomes at 1-year follow-up, according to 1 of 3 SXscore tertiles. RESULTS: The 1,397 patients were divided into tertiles based on the SXscore in the following fashion: SXscore8 and 16 (SXhigh) (n=461). At 1-year follow-up, there was a significantly lower number of patients with major cardiac event-free survival in the highest tertile of SXscore (SXlow=92.2%, SXmid=91.1%, and SXhigh=84.6%; p<0.001). Death occurred in 1.5% of SXlow patients, 2.1% of SXmid patients, and 5.6% of SXhigh patients (hazard ratio [HR]: 1.97, 95% confidence interval [CI]: 1.29 to 3.01; p=0.002). The myocardial infarction rate tended to be higher in the SXhigh group. Target vessel revascularization was 11.3% in the SXhigh group compared with 6.3% and 7.8% in the SXlow and SXmid groups, respectively (HR: 1.38, 95% CI: 1.1 to 1.75; p=0.006). Composite of cardiac death, myocardial infarction, and clinically indicated target vessel revascularization was 7.8%, 8.9%, and 15.4% in the SXlow, SXmid, and SXhigh groups, respectively (HR: 1.47, 95% CI: 1.19 to 1.81; p<0.001). CONCLUSIONS: The SXscore, when applied to an all-comers patient population treated with drug-eluting stents, may allow prospective risk stratification of patients undergoing percutaneous coronary intervention. (LEADERS Trial Limus Eluted From A Durable Versus ERodable Stent Coating; NCT00389220).

Bifurcation lesions: Functional assessment by fractional flow reserve vs. anatomical assessment using conventional and dedicated bifurcation quantitative coronary angiogram.

BACKGROUND: The purpose of this study was to compare the performance of both conventional quantitative coronary angiography (QCA) and the dedicated three branch QCA model for bifurcations in the prediction of a functionally significant lesion according to fractional flow reserve (FFR) in patients with bifurcation lesions. METHODS: Twenty patients with bifurcation lesions underwent coronary angiography together with a functional evaluation of both the main branch and side-branch using FFR. QCA was performed off-line with both conventional QCA software (CAASII, Pie Medical Imaging, Maastricht, The Netherlands) and three branch QCA software (CAAS5, Pie Medical Imaging, Maastricht, The Netherlands). A stenosis was considered hemodynamically significant when the FFR value was ≤ 0.80 and anatomically significant when the diameter stenosis was >50%. The QCA and FFR data were correlated by means of the Pearson correlation. RESULTS: Eighteen bifurcation lesions were suitable for the QCA analysis. In the main vessel, a significant inverse correlation with FFR was seen with both conventional QCA (Pearson r = 0.52 for the MV, P = 0.02), and the three branch QCA model (Pearson r = 0.67 for the MV, P = 0.002). Conversely, in the side-branch, the correlation between QCA and FFR was only significant with the three branch QCA model (Pearson r = 0.57, P = 0.02 for the SB). CONCLUSIONS: In bifurcation lesions the correlation between the anatomic severity of a coronary stenosis and its functional significance appears to be somewhat higher when QCA is performed using the three branch model. This is most notable for side-branch stenoses which can be overestimated when using conventional QCA.