Abstract
Objective
To examine the potential yield of three-dimensional (3D) reconstruction of left main coronary lesions.
Methods
A novel, previously validated, system for 3D reconstruction of the coronary vessels was used to evaluate 302 angiographic images, before and after stenting, from 62 consecutive patients (age 73.5±11.3 years) with unprotected left main lesions.
Results
Three-dimensional reconstructions significantly improved morphological analysis, especially for ostial and bifurcation lesions. In cases of bifurcation involvement, lesion length was significantly longer in the 3D reconstructions than in the 2D images (12.3±4.1 vs. 10.6±4.9 mm, P =.003). The 3D analysis showed that procedures performed in distal left main were associated with a decrease in the bifurcation angle after intervention (from 82±27° to 72±28°, P =.01). The mortality rate was 18% at 6 months. Elective intervention was associated with significantly lower mortality (5% vs. 39% at 6 months).
Conclusions
Three-dimensional reconstruction adds insights on the morphology and lesion length of unprotected left main artery lesions, especially those involving the bifurcation, which may make it an important tool in planning interventional procedures and evaluating their results.
1
Introduction
Significant left main coronary artery disease places a large area of myocardium in jeopardy, thereby putting the patient at high risk. Although bypass surgery is considered the treatment of choice, percutaneous coronary interventions (PCI) are being increasingly performed in “unprotected” left main segments in selected clinical settings and have been associated with high feasibility and a high procedural success rate . However, some reports have noted an unacceptably high incidence of long-term adverse events . Moreover, the optimal stenting technique and stent size in left main bifurcation lesions are still unclear. These problems may be partly attributable to the failure of conventional two-dimensional (2D) angiography to properly represent vessel morphology and plaque distribution . A system for three-dimensional (3D) reconstruction of the coronary segments in real-time has recently been evaluated and validated , but there are as yet no clinical studies assessing the use and value of 3D reconstructions of left main lesions in PCI.
The objective of this study was to examine the potential yield of 3D reconstruction of unprotected left main coronary lesions before and after stenting.
2
Methods
2.1
Patients
The study sample included all patients with de novo unprotected left main stenosis who were treated with a catheter-based approach at our medical center from January 2003 to May 2007. Data on baseline characteristics, clinical events, and angiographic details were prospectively collected into a special database at the center. Left main disease was defined as ≥50% left main stenosis in the absence of a patent coronary graft to one of the major branches of the left coronary arteries. Procedures were performed on either an emergent or planned basis, according to clinical indications. The decision to perform coronary artery bypass grafting or PCI was left to the discretion of the physician, taking the clinical findings, age of the patient, comorbidities, and surgical risk score into consideration. All patients received a detailed explanation of the options and provided informed consent.
2.2
Procedural characteristics
PCI was performed conventionally with or without dilatation before stenting, or with rotational atherectomy before stenting in cases of heavy calcification; the method used was left to the discretion of the operator, with consideration of lesion location and morphology. The technique for treating bifurcation or trifurcation lesions included stenting of the left main segment into a major branch of the left coronary artery with or without stenting of the other branch, depending on the degree of residual stenosis of the left anterior descending or left circumflex vessels. All stents were implanted with a moderate to high deployment pressure of 12–16 atm followed by a systematic high pressure of 16–20 atm after dilatation with a noncompliant balloon. Kissing balloon inflation was used as the final step in cases of bifurcation or trifurcation lesions. The selection of a drug-eluting or a bare-metal stent was left to the operator, as was the use of intracoronary ultrasonic imaging during the procedure.
2.3
Image acquisition
A single-plane digital angiography system (Philips Medical System, Netherlands) was used to obtain 3–5 cineangiograms for each patient at 25 frames/s. The gantry angle of the projections and the diameter of the catheters were determined by the individual operator. Analyses were performed off-line, after completion of the angiographic study, using end-diastolic images selected from each of the different projections and transferred to a computer workstation. The 3D reconstructions were not used to guide the procedures.
2.4
Two-dimensional analysis
All images were analyzed by an independent and experienced investigator using quantitative coronary analysis software (McKesson, Medcon Telemedicine Technology, Tel-Aviv, Israel). The following variables were measured: proximal and distal reference diameter; minimal lesion diameter (including the percentage of diameter stenosis); proximal and distal reference area; and minimal lesion cross-sectional area (including the percentage of area stenosis).
2.5
Three-dimensional reconstruction and analysis
For 3D reconstruction, we used the CardiOp-B system (Paieon, Inc., Rosh Haain, Israel), which has been described in previous studies . The system integrates information from at least two single-plane angiographic images taken from different angles. The projection of the images must differ by at least 30°. The initial steps in the 3D-reconstruction protocol are catheter calibration, which is performed manually, and demarcation of the region of interest. The rest of the reconstruction is performed automatically by the system, although fine adjustments are possible with manual edge detection, according to the judgment of the operator. For quantitative analysis, the operator marks the proximal and distal reference points in addition to a third point within the area of stenosis. The placement of the third point is used as an anchor between different images. The severity of the stenosis is represented graphically by different colors. In the present study, the reconstructions were analyzed for the same quantitative parameters analyzed in the 2D system, and the bifurcation angle was evaluated as well. After stenting, it was possible to analyze only those cases in which at least two different projections were available.
2.6
Statistical analysis
Means and standard deviations of sets of data are presented. Differences between continuous variables were analyzed by t test (one-sided or two-sided, as appropriate). The significance threshold was set at P <.05. BMDP statistical software was used for all analyses.
2
Methods
2.1
Patients
The study sample included all patients with de novo unprotected left main stenosis who were treated with a catheter-based approach at our medical center from January 2003 to May 2007. Data on baseline characteristics, clinical events, and angiographic details were prospectively collected into a special database at the center. Left main disease was defined as ≥50% left main stenosis in the absence of a patent coronary graft to one of the major branches of the left coronary arteries. Procedures were performed on either an emergent or planned basis, according to clinical indications. The decision to perform coronary artery bypass grafting or PCI was left to the discretion of the physician, taking the clinical findings, age of the patient, comorbidities, and surgical risk score into consideration. All patients received a detailed explanation of the options and provided informed consent.
2.2
Procedural characteristics
PCI was performed conventionally with or without dilatation before stenting, or with rotational atherectomy before stenting in cases of heavy calcification; the method used was left to the discretion of the operator, with consideration of lesion location and morphology. The technique for treating bifurcation or trifurcation lesions included stenting of the left main segment into a major branch of the left coronary artery with or without stenting of the other branch, depending on the degree of residual stenosis of the left anterior descending or left circumflex vessels. All stents were implanted with a moderate to high deployment pressure of 12–16 atm followed by a systematic high pressure of 16–20 atm after dilatation with a noncompliant balloon. Kissing balloon inflation was used as the final step in cases of bifurcation or trifurcation lesions. The selection of a drug-eluting or a bare-metal stent was left to the operator, as was the use of intracoronary ultrasonic imaging during the procedure.
2.3
Image acquisition
A single-plane digital angiography system (Philips Medical System, Netherlands) was used to obtain 3–5 cineangiograms for each patient at 25 frames/s. The gantry angle of the projections and the diameter of the catheters were determined by the individual operator. Analyses were performed off-line, after completion of the angiographic study, using end-diastolic images selected from each of the different projections and transferred to a computer workstation. The 3D reconstructions were not used to guide the procedures.
2.4
Two-dimensional analysis
All images were analyzed by an independent and experienced investigator using quantitative coronary analysis software (McKesson, Medcon Telemedicine Technology, Tel-Aviv, Israel). The following variables were measured: proximal and distal reference diameter; minimal lesion diameter (including the percentage of diameter stenosis); proximal and distal reference area; and minimal lesion cross-sectional area (including the percentage of area stenosis).
2.5
Three-dimensional reconstruction and analysis
For 3D reconstruction, we used the CardiOp-B system (Paieon, Inc., Rosh Haain, Israel), which has been described in previous studies . The system integrates information from at least two single-plane angiographic images taken from different angles. The projection of the images must differ by at least 30°. The initial steps in the 3D-reconstruction protocol are catheter calibration, which is performed manually, and demarcation of the region of interest. The rest of the reconstruction is performed automatically by the system, although fine adjustments are possible with manual edge detection, according to the judgment of the operator. For quantitative analysis, the operator marks the proximal and distal reference points in addition to a third point within the area of stenosis. The placement of the third point is used as an anchor between different images. The severity of the stenosis is represented graphically by different colors. In the present study, the reconstructions were analyzed for the same quantitative parameters analyzed in the 2D system, and the bifurcation angle was evaluated as well. After stenting, it was possible to analyze only those cases in which at least two different projections were available.
2.6
Statistical analysis
Means and standard deviations of sets of data are presented. Differences between continuous variables were analyzed by t test (one-sided or two-sided, as appropriate). The significance threshold was set at P <.05. BMDP statistical software was used for all analyses.
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