Quantitative coronary angiography (QCA) in interventional cardiology: clinical application of QCA measurements

The mechanisms of arterial signal intensity profile in non-contrast coronary MRA (NC-MRCA): a 3D printed phantom investigation and clinical translations

Signal intensity (SI) drop has been proposed as an indirect stenosis assessment in non-contrast coronary MRA (NC-MRCA) but it uses unproven assumptions. We aimed to clarify the mechanisms that govern the SI in vitro and develop a stenosis detection method in vivo. Flow phantom tubes with/without stenosis were scanned under two spatial resolutions (0.5/1.0 mm³) on a 3.0 T MRI. Thirty-two coronary arteries from 11 volunteers were prospectively scanned with an EKG- and respiratory-gated 3D NC-MRCA with a resolution of 1.0 mm³, with coronary computed tomography angiography (CTA) as reference. The normalized SI along the centerline of the tubes or the coronary arteries was assessed against the distance from the orifice using a linear regression model. Its coefficient (SI decay slope) and goodness-of-fit (R2) were extracted to assess the effect of flow velocity and stenosis on the SI profile curve. The R2 was utilized for the stenosis detection. Phantom study: A slow flow velocity caused a steep SI decay slope. The SI drop revealed only at the inlet and outlet of stenosis due to the flow turbulence/vortex and yielded low R2, in which shape changed by the resolution. Clinical study: The R2 cutoff to detect ≥ 50% stenosis for the left and right coronary arteries were 0.64 and 0.20 with a sensitivity/specificity of 71.5/71.5 and 66.7/100 (%), respectively. The SI drop did not reflect the actual stenosis position and not suitable for the stenosis localization. The R2 cutoff represents an alternative method to detect stenoses on NC-MRCA at vessel level.Trial registration: ClinicalTrials.gov; NCT03768999, registered on December 7, 2018.

Accuracy of Artificial Intelligence-Based Automated Quantitative Coronary Angiography Compared to Intravascular Ultrasound: Retrospective Cohort Study. (Preprint)

BACKGROUND

An accurate quantitative analysis of coronary artery stenotic lesions is essential to make optimal clinical decisions. Recent advances in computer vision and machine learning technology have enabled the automated analysis of coronary angiography.

OBJECTIVE

The aim of this paper is to validate the performance of artificial intelligence-based quantitative coronary angiography (AI-QCA) in comparison with that of intravascular ultrasound (IVUS).

METHODS

This retrospective study included patients who underwent IVUS-guided coronary intervention at a single tertiary center in Korea. Proximal and distal reference areas, minimal luminal area, percent plaque burden, and lesion length were measured by AI-QCA and human experts using IVUS. First, fully automated QCA analysis was compared with IVUS analysis. Next, we adjusted the proximal and distal margins of AI-QCA to avoid geographic mismatch. Scatter plots, Pearson correlation coefficients, and Bland-Altman were used to analyze the data.

RESULTS

A total of 54 significant lesions were analyzed in 47 patients. The proximal and distal reference areas, as well as the minimal luminal area, showed moderate to strong correlation between the 2 modalities (correlation coefficients of 0.57, 0.80, and 0.52, respectively; P<.001). The correlation was weaker for percent area stenosis and lesion length, although statistically significant (correlation coefficients of 0.29 and 0.33, respectively). AI-QCA tended to measure reference vessel areas smaller and lesion lengths shorter than IVUS did. Systemic proportional bias was not observed in Bland-Altman plots. The biggest cause of bias originated from the geographic mismatch of AI-QCA with IVUS. Discrepancies in the proximal or distal lesion margins were observed between the 2 modalities, which were more frequent at the distal margins. After the adjustment of proximal or distal margins, there was a stronger correlation of proximal and distal reference areas between AI-QCA and IVUS (correlation coefficients of 0.70 and 0.83, respectively).

CONCLUSIONS

AI-QCA showed a moderate to strong correlation compared with IVUS in analyzing coronary lesions with significant stenosis. The main discrepancy was in the perception of the distal margins by AI-QCA, and the correction of margins improved the correlation coefficients. We believe that this novel tool could provide confidence to treating physicians and help in making optimal clinical decisions.

Thinner Strut Sirolimus-Eluting BRS Versus EES in Patients With Coronary Artery Disease: FUTURE-II Trial

OBJECTIVES

The aim of the present study was to evaluate the safety and efficacy of thinner strut Firesorb (100/125 μm) sirolimus-eluting bioresorbable scaffolds (BRS) versus cobalt-chromium everolimus-eluting stents (CoCr-EES) in patients with coronary artery disease.

BACKGROUND

First-generation thicker strut BRS were associated with unexpected device-related adverse outcomes at long-term follow-up.

METHODS

Eligible patients with 1 or 2 de novo noncomplex coronary lesions were randomized to the Firesorb BRS group or CoCr-EES group in a 1:1 ratio. The primary endpoint was 1-year angiographic in-segment late loss (LL), powered for noninferiority testing. The key secondary endpoint was the 1-year proportion of covered struts assessed on optical coherence tomography, powered for noninferiority and subsequent superiority testing.

RESULTS

A total of 433 participants from 28 Chinese centers were randomized to the Firesorb BRS group (n = 215) or CoCr-EES group (n = 218). Patient-level 1-year in-segment LL was 0.17 ± 0.27 mm in the Firesorb BRS group and 0.18 ± 0.37 mm in the CoCr-EES group (difference -0.01 mm; 95% confidence interval [CI]: -0.07 to 0.06; p_{noninferiority} < 0.0001) in the intention-to-treat population and was 0.17 ± 0.27 mm in the Firesorb BRS group and 0.19 ± 0.37 mm in the CoCr-EES group (difference -0.005 mm; 95% CI: -0.07 to 0.06; p_{noninferiority} < 0.0001) in the per-protocol set. The proportion of covered struts was 99.3% in the Firesorb BRS group and 98.8% in the CoCr-EES group (difference 0.8%; 95% CI: -0.5% to 2.1%; p_{noninferiority} < 0.0001; p_superiority = 0.21). One-year clinical outcomes were similar between groups.

CONCLUSIONS

The thinner strut Firesorb BRS was noninferior to the CoCr-EES for the primary endpoint of 1-year angiographic in-segment LL and the key secondary endpoint of 1-year proportion of covered struts by optical coherence tomography. (A Trial of Firesorb in Patients With Coronary Artery Disease: FUTURE-II [FUTURE-II]; NCT02890160).

Use of Optical Coherence Tomography in Coronary Artery Disease: Review Article

Optical coherence tomography is a catheter-based imaging modality in heart catheterizations, which provides a significantly higher resolution of intravascular pathology by means of using light as opposed to ultrasound. The applications of this modality may include a detailed assessment of atherosclerotic plaques, stent evaluation including coverage and restenosis and percutaneous coronary intervention optimization. In this article, we provide a review of current literature highlighting the advantages and disadvantages of the use of optical coherence tomography in the catheterization lab.

Risk factors for silent myocardial ischemia in patients with well-controlled essential hypertension

Silent myocardial ischemia (SMI) is frequently observed in patients with essential hypertension (EH). The major risk factor for SMI is uncontrolled blood pressure (BP), but SMI is also observed in patients with well-controlled BP. To evaluate the prevalence of SMI and the factors associated with SMI in EH patients with well-controlled BP. The medical records of 859 EH patients who underwent simultaneous 24-h ambulatory blood pressure monitoring (ABPM) and 24-h ambulatory electrocardiogram recording (AECG) were retrospectively evaluated. Each SMI episode was characterized by: (a) ST segment depression ≥0.5 mm; (b) duration of ST segment depression >60 s; and (c) reversibility of the ST segment depression. Overall 126 EH patients (14.7 %) had at least one episode of SMI. The SMI events were more frequent among patients with poorly controlled compared to those with well-controlled BP [86/479 (17.95 %) vs. 40/380 (10.52 %), p < 0.01]. Among EH patients with well-controlled BP, current and past smoking as well as the presence of an additional metabolic syndrome (MetS) constitutive element (obesity, impaired fasting glucose level or dyslipidemia) were significantly associated with the occurrence of SMI. In all EH patients with well-controlled BP and AECG evidence of SMI, there were one or more coronary artery stenotic lesions greater than 50 % found at coronary angiography. In EH patients who are current smokers, or have one or more additional components of a MetS there is markedly reduced benefit associated with good BP control with regard to the occurrence of myocardial ischemia: in this patient category, an AECG may help detect this condition.

Association between Proliferative Scars and In-Stent Restenosis

Background:

Keloid and hypertrophic scars are two types of proliferative scars at sites of cutaneous injury that form as a result of an abnormal wound-healing process. Proliferative scar formation after skin injury and restenosis after coronary stenting have common features. The aim of this study was to investigate the association of proliferative scars with coronary stent restenosis.

Methods:

Patients with previous open heart surgery with median sternotomy who had coronary stenting after the surgery and were admitted for control angiography were included in the study. The patients were divided into two groups according to the presence or absence of proliferative scars. The primary end point was the incidence of angiographic restenosis in patient groups.

Results:

The study group consisted of 80 patients (64 men; mean age 64 ± 9 years). Twenty-three patients (29%) have a proliferative scar. In general, two groups were comparable with regard to baseline lipid profiles, demographics, and cardiovascular risk factors. Restenosis was significantly more prevalent in patients with proliferative scars than with controls ( p = .04). By multivariate logistic regression analysis, stent length (odds ratio [OR] 1.12, p = .005), diabetes (OR 3.3, p = .03), and proliferative scar (OR 4.2, p = .02) independently predicted in-stent restenosis.

Conclusion:

The findings of this study suggest that patients with proliferative scars may have a higher risk of in-stent restenosis.

Fluoroscopy Assisted Scoring of Myocardial Hypoperfusion (FLASH) ratio as a novel predictor of mortality after primary PCI in STEMI patients

BACKGROUND

The aim of this study was to investigate whether Fluoroscopy Assisted Scoring of Myocardial Hypoperfusion (FLASH) enabled a more accurate assessment of coronary blood flow and prediction of cardiac mortality after primary PCI (pPCI), than the presently used angiographic scores of reperfusion.

METHODS

We included 453 STEMI patients who received pPCI at our hospital. Using the novel FLASH algorithm, based on contrast passage time and quantitative coronary analysis, FLASH flow was measured after pPCI and was used to calculate FLASH ratio of culprit and reference artery. In 28 of the 453 patients, FLASH flow was compared to Doppler-derived-flow.

RESULTS

FLASH flow had a good correlation with Doppler derived flow (Pearson's R=0.65, p<0.001) and had a high inter-observer agreement (ICC=0.83). FLASH flow was significantly lower in patients that died of cardiac death within six months (25.9±17.7 ml/min vs. 38.2±18.8 ml/min, p=0.004). FLASH ratio had a high accuracy of predicting cardiac mortality with a significant higher area under the curve as compared with CTFC and QuBe (p=0.041 and p=0.008). FLASH ratio was an independent predictor of mortality at 6 months (HR=0.98 per 1% increase, p=0.014).

CONCLUSION

FLASH is a simple non-invasive method to estimate coronary blood flow and predict mortality directly following pPCI in STEMI patients, with a higher accuracy compared to the presently used angiographic scores.

Incidence and short-term clinical outcomes of small side branch occlusion after implantation of an everolimus-eluting bioresorbable vascular scaffold: an interim report of 435 patients in the ABSORB-EXTEND single-arm trial in comparison with an everolimus-eluting metallic stent in the SPIRIT first and II trials

OBJECTIVES

The aim of this study was to investigate the incidence and clinical sequelae of small side branch occlusion (SBO) after Absorb (Abbott Vascular, Santa Clara, California) bioresorbable vascular scaffold (BVS) implantation.

BACKGROUND

The thicker strut of metallic stents potentially contributes to a higher incidence of SBO.

METHODS

We performed a post-hoc angiographic assessment of 1,209 side branches in 435 patients enrolled in the ABSORB-EXTEND single-arm trial (ABSORB EXTEND Clinical Investigation: A Continuation in the Clinical Evaluation of the ABSORB Bioresorbable Vascular Scaffold [BVS] System in the Treatment of Subjects With de Novo Native Coronary Artery Lesions), in comparison with 682 side branches in 237 patients treated with the everolimus-eluting metallic stent (EES) in the SPIRIT (A Clinical Evaluation of an Investigational Device. The Abbott XIENCE V Everolimus Eluting Coronary Stent System in the Treatment of Patients With de Novo Native Coronary Artery Lesions) first and II trials. Any visible side branches originating within the device implantation site or the 5-mm proximal and distal margins were included in the angiographic assessment. The SBO was defined as a reduction in Thrombolysis In Myocardial Infarction flow grade 0 or 1.

RESULTS

Post-procedural SBO was observed in 73 side branches (6.0%) in BVS group and 28 side branches (4.1%) in EES group (p = 0.09). Patients with post-procedural SBO were significantly associated with an increased incidence of in-hospital myocardial infarction (6.5% in SBO group vs. 0.5% in non-SBO group, p < 0.01). Multivariable analysis revealed that BVS was an independent predictor of post-procedural SBO (odds ratio: 2.09; 95% confidence interval: 1.18 to 3.68). By stratified analysis, BVS demonstrated a higher incidence of post-procedural SBO compared with EES only in small side branches with a reference vessel diameter ≤0.5 mm (10.5% vs. 3.9%, p = 0.03 between the groups, p for interaction = 0.08).

CONCLUSIONS

Bioresorbable vascular scaffold was associated with a higher incidence of post-procedural SBO compared with EES. This effect was more pronounced with small side branches with a reference vessel diameter ≤0.5 mm. (ABSORB EXTEND Clinical Investigation: A Continuation in the Clinical Evaluation of the ABSORB Bioresorbable Vascular Scaffold [BVS] System in the Treatment of Subjects With de Novo Native Coronary Artery Lesions: NCT01023789).

A novel 3-d reconstruction system for the assessment of bifurcation lesions treated by the mini-crush technique

BACKGROUND

Conventional two-dimensional angiography lacks the ability to properly image the true bifurcation geometry, and its percutaneous coronary intervention-induced changes in the clinical setting.

METHODS AND RESULTS

A novel three-dimensional reconstruction system was investigated by retrospectively analyzing 39 lesions in 35 consecutive patients with coronary bifurcation disease treated with the mini-crush technique. At baseline, significant correlations were proved between two- and three-dimensional systems in terms of either reference vessel diameter (R(2)= 0.68 and 0.29 for main and side branches, respectively), minimum lumen diameter (R(2)= 0.73 and 0.36), stenosis diameter (R(2)= 0.69 and 0.29), and lesion length (R(2)= 0.48 and 0.58). These results were consistent with those observed after the procedure and at 8-month follow-up. Lesion length was significantly longer with the three-dimensional compared to the two-dimensional system for both main and side branches (P < 0.001, and P = 0.007, respectively).

CONCLUSIONS

The three-dimensional quantitative reconstruction system may provide accurate evaluation of the complex curvilinear structure of bifurcation lesions when using a double stent technique.

A bioabsorbable everolimus-eluting coronary stent system (ABSORB): 2-year outcomes and results from multiple imaging methods

BACKGROUND

Drug-eluting metallic coronary stents predispose to late stent thrombosis, prevent late lumen vessel enlargement, hinder surgical revascularisation, and impair imaging with multislice CT. We assessed the safety of the bioabsorbable everolimus-eluting stent (BVS).

METHODS

30 patients with a single de-novo coronary artery lesion were followed up for 2 years clinically and with multiple imaging methods: multislice CT, angiography, intravascular ultrasound, derived morphology parameters (virtual histology, palpography, and echogenicity), and optical coherence tomography (OCT).

FINDINGS

Clinical data were obtained from 29 of 30 patients. At 2 years, the device was safe with no cardiac deaths, ischaemia-driven target lesion revascularisations, or stent thromboses recorded, and only one myocardial infarction (non-Q wave). 18-month multislice CT (assessed in 25 patients) showed a mean diameter stenosis of 19% (SD 9). At 2-year angiography, the in-stent late loss of 0.48 mm (SD 0.28) and the diameter stenosis of 27% (11) did not differ from the findings at 6 months. The luminal area enlargement on OCT and intravascular ultrasound between 6 months and 2 years was due to a decrease in plaque size without change in vessel size. At 2 years, 34.5% of strut locations presented no discernible features by OCT, confirming decreases in echogenicity and in radiofrequency backscattering; the remaining apparent struts were fully apposed. Additionally, vasomotion occurred at the stented site and adjacent coronary artery in response to vasoactive agents.

INTERPRETATION

At 2 years after implantation the stent was bioabsorbed, had vasomotion restored and restenosis prevented, and was clinically safe, suggesting freedom from late thrombosis. Late luminal enlargement due to plaque reduction without vessel remodelling needs confirmation.

Naproxen treatment prevents periprocedural inflammatory response but not myocardial injury after percutaneous coronary intervention

BACKGROUND AND AIM

Recent studies have documented that elevation of C-reactive protein (CRP) levels after percutaneous coronary intervention (PCI) have been predictive of adverse outcome. This study was performed to test the hypothesis that preprocedural use of naproxen sodium is associated with a reduction in the extent of inflammatory response and myocardial injury after PCI.

METHODS

Ninety-seven patients who were scheduled for elective PCI were randomized either for naproxen sodium (500 mg bid) (n:39, 75% male, 59+/-10 years) or control (n:58, 76% male, 60+/-10 years). All patients were troponin negative before the procedure. Blood samples for CRP, Troponin I and CK-MB were collected at baseline and after the procedure.

RESULTS

The characteristics were similar between the two groups. After coronary stenting, the rise in CRP levels was significantly higher in controls than those treated with naproxen (DeltaCRP=6.4 mg/L in the controls and 0.43 mg/L in the naproxen group, p<0.0001). The incidence of any troponin I elevation or CK-MB elevation above upper limit of normal was not statistically different between groups. During follow up (12+/-2 months), major cardiac adverse events (death, myocardial infarction, and revascularization of target lesion) was similar between groups.

CONCLUSION

Our data show that naproxen pretreatment leads to significant suppression in PCI related CRP elevation. However this improvement in CRP levels was not associated with any significant reduction in post-PCI myonecrosis.

Clinical assessment of a new real time 3D quantitative coronary angiography system: Evaluation in stented vessel segments

BACKGROUND

Foreshortening is a recognized problem that is present in angiography and results from views that are not perpendicular to coronary lesions. This limits visual coronary analysis as well as 2D quantitative coronary angiography systems (QCA). The CardiOp-B System is a 3D image acquisition and processing software system designed as an add-on to conventional X-ray angiography system. CardiOp-B's features include real time and off line analysis with comprehensive 3D reconstruction integrating all of the available information of two 2D vessel angiographies into one 3D image. It was the aim of the study to analyze the accuracy of this new 3D QCA system.

METHODS

3D QCA was performed in 50 patients (age 64 +/- 10.9; 84% male; LV-EF 63 +/- 16%) measuring 61 stents during high-pressure inflation (diameter: 2.25-4 mm; length: 8-32 mm). The obtained values (proximal and distal stent diameter, stent length) were correlated with the predefined size of the stents at the used inflation pressure.

RESULTS

The linear correlation for the proximal stent diameter was Stent(prox)= 0.03 + 0.93 x real stent size (r(2) = 0.85). The linear correlation for the distal stent diameter was Stent(distal)= -0.03 + 0.89 x real stent size (r(2) = 0.81). The linear correlation for the stent length was Stent(length)= -0.61 + 1.02 x real stent length (r(2) = 0.98).

CONCLUSIONS

The CardiOp-B System(R) is a new 3D QCA system with a high linear correlation between the real vessel size and the obtained vessel dimension. It provides real time or off line accurate and comprehensive diagnostic information to the interventional cardiologist without changing the basic coronary angiography procedure.

Thr325Ile polymorphism of the TAFI gene is related to TAFI antigen plasma levels and angiographic restenosis after percutaneous coronary interventions

BACKGROUND

The fibrinolytic system is closely related to several processes that are involved in restenosis. We have previously shown that high pre-procedural plasma levels of thrombin-activatable fibrinolysis inhibitor (TAFI) antigen predicted angiographic restenosis. The aims of this study were to evaluate the relationship between Thr325Ile polymorphisms, plasma levels of TAFI antigen, and late angiographic restenosis after percutaneous coronary intervention (PCI).

METHODS

We prospectively studied 159 patients with stable angina who underwent successful elective angioplasty or stenting of de novo native coronary artery lesions. Blood samples were drawn before the procedure. TAFI antigen levels were measured, as well as the presence of TAFI Ile325Thr genetic variation. Follow-up coronary angiography was performed in 90% of patients.

RESULTS

The genotypes based on Ile325Thr substitution had significantly different TAFI antigen levels: genotype C/C>C/T>T/T (111+/-29%, 87+/-24%, and 59+/-22%, respectively, p<0.006). T/T genotype was associated with lower rates of restenosis compared to C/T and C/C genotypes (25% versus 37% and 33%, respectively, p<0.05).

CONCLUSIONS

These data suggest that plasma TAFI antigen levels are genetically controlled. The T/T Thr325Ile polymorphism of the TAFI gene is associated with lower plasma levels of TAFI antigen and lower restenosis rates after PCI.

Clinical and quantitative angiographic outcomes following elective implantation of the self-expanding Wallstent for longer coronary artery lesions--final results of the Wellstent native study

BACKGROUND: Implantation of short balloon-expandable stents provides superior clinical and angiographic outcome compared with balloon angioplasty in selected patients. The purpose of the Wellstent study was to evaluate the safety and efficacy of the self-expanding Wallstent combined with aspirin and ticlopidine in patients with stable or unstable angina related to a native coronary lesion up to 45 mm in length. METHODS: 105 patients (111 lesions) with stable (57%) or unstable (43%) angina were included in this prospective multicentre evaluation. Angiography before and after Wallstent implantation and at 6-month follow-up was analysed at the core lab using the CAAS 2 system. The primary end-point was incidence of major adverse cardiac events (MACE) at 30 days. Secondary end-points were angiographic outcome at 6 months and MACE at 6 months and 1 year. RESULTS: Acute procedural success (successful stent implantation with residual stenosis <20%) was achieved in 99%. Mean reference diameter was 3.18 +/- 0.66 mm, minimal luminal diameter was 1.00 +/- 0.50 mm pre- and 2.84 +/- 0.47 mm poststent (diameter stenosis 16 +/- 6%). The mean hospital stay was 2.2 days. At 30 days, 95% of patients were free of MACE. At 6 month and 1 year clinical follow-up, 75% and 71% of patients, respectively, remained free of MACE, the majority of which (19 of 30) were re-interventions at re-angiography. In 90% of eligible patients, MLD at follow-up was 1.65 +/- 0.75 mm (late loss 1.20 +/- 0.66 mm, loss index 0.66), diameter stenosis 42 +/- 15%, with a restenosis rate of 32%. Longer stents were associated with greater luminal loss (P = 0.001) and less-favourable clinical outcome. CONCLUSIONS: Wallstent implantation, combined with aspirin and ticlopidine, achieved excellent acute and 30 day clinical results in a heterogenous high-risk patient group. Clinical outcome at 6 months and 1 year remained good, and most adverse events were re-PTCA during follow-up angiography. The loss index of 0.66 and restenosis rate of 32%, related in part to the use of longer stents, emphasizes the continuing need for effective anti-proliferative therapy.

Effects of gold coating of coronary stents on neointimal proliferation following stent implantation

Experimental studies suggest a reduced neointimal tissue proliferation in vascular stainless steel stents coated with gold. This prospective multicenter trial evaluated the impact of gold coating on neointimal tissue proliferation in patients undergoing elective stent implantation. The primary end point was the in-stent tissue proliferation measured by intravascular ultrasound at 6 months comparing stents of identical design with or without gold coating (Inflow). Two hundred four patients were randomized to receive uncoated (group A, n = 101) or coated (group B, n = 103) stents. Baseline parameters did not differ between the groups. Stent length and balloon size were comparable, whereas inflation pressure was slightly higher in group A (14 +/- 3 vs 13 +/- 3 atm, p = 0.013). Procedural success was similar (A, 97%; B, 96%). The acute angiographic result was better for group B (remaining stenosis 4 +/- 12% vs 10 +/- 11%, p = 0.002). Six-month examinations revealed more neointimal proliferation in group B. By ultrasound, the neointimal volume within the stent was 47 +/- 25 versus 41 +/- 23 mm(3) (p = 0.04), with a ratio of neointimal volume-to-stent volume of 0.45 +/- 0.12 versus 0.40 +/- 0.12 (p = 0.003). The angiographic minimal luminal diameter was smaller in group B (1.47 +/- 0.57 vs 1.69 +/- 0.70 mm, p = 0.04), with a higher late luminal loss of 1.17 +/- 0.51 versus 0.82 +/- 0.56 mm (p = 0.001). Thus, gold coating of the tested stent type resulted in more neointimal tissue proliferation.

Mechanisms of ventricular fibrillation during coronary angioplasty: increased incidence for the small orifice caliber of the right coronary artery

BACKGROUND

Ventricular fibrillation (VF) is not an infrequent complication of percutaneous transluminal coronary angioplasty (PTCA). However, it is not clear why there is a marked discrepancy in the higher incidence of VF during right coronary artery (RCA) approach.

METHODS AND RESULTS

We analyzed in detail every case of VF occurring in 905 consecutive PTCA procedures to investigate possible mechanisms. Sixteen patients (M/F=15/1, mean age: 71 +/- 8 years) with VF during PTCA for the RCA as Group I. Those 51 patients (M/F=48/3, mean age: 70 +/- 9 years) without VF during PTCA for the RCA engagement were designated as Group II. Patients were equipped with cardiac event recorder (CardioCall, Reynolds Medical, UK) before the PTCA, and we set the time period 1 min before and after the event. The lead II was selected to check the QRS width, QTc interval, ST segment change and RR interval before and after event. A total of 905 PTCA procedures were included. There were 561 procedures for the left coronary artery and three events (0.5%) with spontaneous VF. However, there were 16 events (4.6%) of VF during 344 PTCA procedures for the right coronary artery. The incidence of VF for the right side PTCA was significantly higher than for the left side. The orifice of RCA in Group I was smaller than Group II (orifice of RCA in Group I vs. Group II - 2.7+/-0.8 vs. 4.1+/-1.2 mm, P<0.001). Most cases (68.7%) presented with ST segment depression before the onset of VF.

CONCLUSION

A small caliber of RCA and associated ST segment changes played important roles in the patients with VF during the PTCA.

Monocyte integrin expression and monocyte-platelet complex formation in humans with coronary restenosis

1. In the present study, we sought to determine whether patients with restenosis after coronary stenting possess increased monocyte reactivity, as manifested by a higher level of adhesion molecule expression and an enhanced propensity to form monocyte-platelet aggregates after activation in vitro. 2. Anti-coagulated peripheral venous blood from 24 patients, 10 with and 14 without angiographically verified restenosis, was obtained. Leucocyte antigen expression and the number of leucocyte-platelet complexes were measured by flow cytometry after activation in whole blood. 3. Surface integrin Mac-1 (CD11b/CD18) and VLA-4 (CD49d/ CD29) expression on monocytes and the relative number of monocyte-platelet complexes after in vitro activation were significantly elevated in patients with restenosis compared with patients without restenosis (fluorescence intensities of 1425 +/- 76 vs 1195 +/- 71, 87 +/- 7 vs 65 +/- 6 and 47 +/- 4 vs 29 +/- 3% for for Mac-1, VLA-4 and monocyte-platelet complexes, respectively; P < 0.05 for each parameter). 4. The results suggest that restenosis is associated with increased monocyte VLA-4 and Mac-1 integrin expression and monocyte-platelet complex formation, which can be revealed after activation in vitro.

Acute and 6-month clinical and angiographic outcome after implantation of the ACS Duet stent for single-vessel coronary artery disease: final results of the European and US ACS Multi-link Duet Registry

The aim of the study was to determine the safety and efficacy of the second-generation ACS Multi-Link Duet coronary stent system for the treatment of single, symptomatic, de novo, native coronary artery lesions. Between February and June 1998, 427 patients (69.3% male, 51.5% class 3 or 4 angina, 20.1% diabetic, 43.6% hyperlipidemia) were included at 38 centers in this prospective observational study. All patients received ticlopidine 500 mg/day for 1 month and aspirin > or =100 mg/day. The Duet stent was available in 8, 18, and 28 mm length and 3.0, 3.5, and 4.0 mm diameter. After adequate predilatation, stents were successfully implanted, at up to 16 atm, in 99.3% of patients. Mean vessel diameter by core laboratory quantitative coronary angiography was 3.0 +/- 0.53 mm and postprocedural minimum luminal diameter was 2.79 +/- 0.43 mm (12% +/- 9.3% diameter stenosis). At 30 days, 96.7% of patients were event-free and at 6 months 88.1% remained free of major adverse cardiac events. The restenosis rate was 18.1%. The ACS Duet stent was safely implanted in >99% of target lesions by a diverse group of international investigators. With late outcomes at least comparable to the best published results, this stent platform provides safe and effective percutaneous treatment of obstructive coronary artery disease. Cathet Cardiovasc Intervent 2001;54:25-33.

Three dimensional reconstruction of coronary arteries from two views

Geometric representation and measurements of localized lumen stenosis of coronary arteries are important considerations in the diagnosis of cardiovascular diseases. This discrete narrowing of the arteries typically impairs blood flow in regions of the heart, and can be present along the entire length of the artery. Three-dimensional (3-D) reconstruction of coronary arterial tree allows clinician to visualize vascular geometry. Three-dimensional representation of tree topology facilitates calculation of hemodynamic measurements to study myocardial infarction and stenosis. The 3-D arterial tree, computed from two views, can provide more information about the tree geometry than individual views. In this paper, a 3-step algorithm for 3-D reconstruction of arterial tree using two standard views is presented. The first step is a multi-resolution segmentation of the coronary vessels followed by medial-axis detection along the entire arterial tree for both views. In the second step, arterial trees from the two views are registered using medial-axis representation at the coarsest resolution level to obtain an initial 3-D reconstruction. This initial reconstruction at the coarsest level is then modified using 3-D geometrical a priori information. In the third step, the modified reconstruction is projected on the next higher-resolution segmented medial-axis representation and an updated reconstruction is obtained at the higher resolution. The process is iterated until the final 3-D reconstruction is obtained at the finest resolution level. Linear programming based constrained optimization method is used for registering two views at the coarse resolution. This is followed by a Tree-Search method for registering detailed branches at higher resolutions. The automated 3-D reconstruction method was evaluated on computer-simulated as well as human angiogram data. Results show that the automated 3-D reconstruction method provided good registration of computer-simulated data. On human angiogram data, the computed 3-D reconstruction matched well with manual registration.

Methodological and clinical implications of the relocation of the minimal luminal diameter after intracoronary radiation therapy. Dose Finding Study Group

OBJECTIVES

The aims of the study were to determine the incidence of relocation of the minimal luminal diameter (MLD) after beta-radiation therapy following balloon angioplasty (BA) and to describe a new methodological approach to define the effect of brachytherapy on treated coronary stenoses.

BACKGROUND

Luminal diameter of coronary lesions may increase over time following angioplasty and irradiation. As a result, the MLD at follow-up may be relocated from its location preintervention, which may induce misleading results when a restricted definition of the target segment by quantitative coronary angiography (QCA) is performed.

METHODS

Patients treated with BA followed by intracoronary brachytherapy according to the Dose-Finding Study constituted the study population. A historical cohort of patients treated with BA was used as control group. To be included in the analysis, an accurate angiographic documentation of all instrumentations during the procedure was mandatory. In the irradiated patients, four regions were defined by QCA: vessel segment (VS), target segment (TS), injured segment (INS), and irradiated segment (IRS).

RESULTS

Sixty-five patients from the Dose-Finding Study and 179 control patients were included. At follow-up, MLD was relocated more often in the radiation group (78.5% vs. 26.3%; p < 0.0001). The rate of >50% diameter stenosis differed among the four predefined regions: 3.1% in the TS; 7.7% in the INS; 9.2% in the IRS and 13.8% in the VS.

CONCLUSIONS

Relocation of the MLD is commonly demonstrated after BA and brachytherapy, and it should be taken into account during the analysis of the results of radiation clinical trials.

Homocysteine, lipoprotein(a), and restenosis after percutaneous transluminal coronary angioplasty: a prospective study

BACKGROUND

Restenosis complicates 30% to 40% of angioplasty procedures and may be unrelated to traditional coronary risk factors. Homocysteine, lipoprotein(a), and methylenetetrahydrofolate reductase (MTHFR 677T) (a genetic determinant of plasma homocysteine concentrations) are novel risk factors for coronary artery disease. Their roles in restenosis are unclear, and the potential synergism between homocysteine and lipoprotein(a) has not previously been studied. The objective of this study was to determine the relations among homocysteine, lipoprotein (a), MTHFR 677T, and restenosis after percutaneous transluminal coronary angioplasty.

METHODS

This prospective study enrolled patients with successful elective percutaneous transluminal coronary angioplasty or stenting of a single, de novo, native coronary lesion. Fasting blood was drawn the morning of the procedure for homocysteine, lipoprotein(a), and MTHFR 677T. Follow-up angiography was performed 6 months after the procedure or earlier if clinically indicated. All cineangiograms were analyzed quantitatively.

RESULTS

A total of 144 (92%) of 156 eligible patients underwent follow-up coronary angiography. The overall angiographic restenosis rate (residual stenosis >50%) was 31%. Mean homocysteine concentration was 10.1 +/- 3.7 micromol/L. Plasma homocysteine concentrations were not significantly different in patients with or without angiographic restenosis (9.6 +/- 3.3 vs 10.3 +/- 3.8 micromol/L; P =.31). Mean lipoprotein(a) concentration was 21.2 +/- 20.1 mg/dL. Plasma lipoprotein(a) concentrations were not significantly different in patients with or without restenosis (21.9 +/- 21.8 vs 20.9 +/- 19.5 mg/dL). Homozygosity for MTHFR 677T was present in 6.5% and was not associated with increased restenosis. No interaction between homocysteine and lipoprotein(a) was detected.

CONCLUSIONS

Homocysteine, lipoprotein(a), and MTHFR 677T are not associated with restenosis after percutaneous transluminal coronary angioplasty.

A comparison of systematic stenting and conventional balloon angioplasty during primary percutaneous transluminal coronary angioplasty for acute myocardial infarction. STENTIM-2 Investigators

OBJECTIVES

In a multicenter, randomized trial, systematic stenting using the Wiktor stent was compared to conventional balloon angioplasty with provisional stenting for the treatment of acute myocardial infarction (AMI).

BACKGROUND

Primary angioplasty in AMI is limited by in-hospital recurrent ischemia and a high restenosis rate.

METHODS

A total of 211 patients with AMI <12 h from symptom onset, with an occluded native coronary artery, were randomly assigned to systematic stenting (n = 101) or balloon angioplasty (n = 110). The primary end point was the binary six-month restenosis rate determined by core laboratory quantitative angiographic analysis.

RESULTS

Angiographic success (Thrombolysis in Myocardial Infarction [TIMI] flow grade 3 and residual diameter stenosis <50%) was achieved in 86% of the patients in the stent group and in 82.7% of those in the balloon angioplasty group (p = 0.5). Compared with the 3% cross-over in the stent group, cross-over to stenting was required in 36.4% of patients in the balloon angioplasty group (p = 0.0001). Six-month binary restenosis (> or = 50% residual stenosis) rates were 25.3% in the stent group and 39.6% in the balloon angioplasty group (p = 0.04). At six months, the event-free survival rates were 81.2% in the stent group and 72.7% in the balloon angioplasty group (p = 0.14), and the repeat revascularization rates were 16.8% and 26.4%, respectively (p = 0.1). At one year, the event-free survival rates were 80.2% in the stent group and 71.8% in the balloon angioplasty group (p = 0.16), and the repeat revascularization rates were 17.8% and 28.2%, respectively (p = 0.1).

CONCLUSIONS

In the setting of primary angioplasty for AMI, as compared with a strategy of conventional balloon angioplasty, systematic stenting using the Wiktor stent results in lower rates of angiographic restenosis.

Risk predictors in patients scheduled for percutaneous coronary revascularization

Traditionally, procedural risks associated with conventional balloon coronary angioplasty have been largely attributed to unfavorable lesion morphology. However, factors predicting adverse events in the current practice of percutaneous coronary revascularization are unclear. The present study was undertaken to determine factors predicting major adverse events (death or Q-wave myocardial infarction or emergency bypass surgery) in 3,335 consecutive patients undergoing percutaneous coronary revascularization in the current practice of percutaneous coronary revascularization. During the period of observation, the rate of lesions treated successfully increased from 91% to 95% (P < 0.0001), whereas the rate of major adverse events (MACE) decreased from 3.6% to 1.6% (odds ratio [OR], 0.70 per year). Using multiple stepwise logistic regression analysis, cardiogenic shock (OR, 8.59; confidence interval [CI], 4.27-17.27), renal disease (OR, 3.33; CI, 1.95-5.69), evolving myocardial infarction (OR, 2.80; CI, 1.47-5.31), congestive heart failure (OR, 2.18; CI, 1.23-3.86), total number of lesions treated (OR, 1.28; CI, 1.03-1.59), age (OR, 1.03; CI, 1.01-1.06), and history of prior coronary intervention (OR, 0.51; CI 0.26-0.99) were identified as independent predictors of MACE. In addition, vascular disease (OR, 2. 48; CI 1.37-4.50) and unstable angina pectoris (OR, 0.44; CI 0.25-0. 79) were related to adverse events when patients in cardiogenic shock were excluded from the model. With the exception of most unfavorable lesion morphology (AHA/ACC lesion type C; OR, 2.05; CI, 1.19-3.52), anatomic parameters added no further information. In the present era of device technology, success rates of percutaneous coronary revascularization procedures have increased and remain to be determined by lesion morphology. In contrast, the rate of MACE is declining and best predicted by easily identified patient characteristics.

Plasma urokinase antigen and plasminogen activator inhibitor-1 antigen levels predict angiographic coronary restenosis

BACKGROUND

The fibrinolytic system is intimately involved in several processes that contribute to restenosis, including clot dissolution, cell migration, and tissue remodeling. However, the role of the individual activators (urokinase [uPA] and tissue plasminogen [tPA] activators) and inhibitors (plasminogen activator inhibitor [PAI-1]) of the fibrinolytic system in maintaining patency after coronary artery angioplasty and stenting is unclear.

METHODS AND RESULTS

We prospectively studied 159 patients with stable angina who underwent successful elective angioplasty (n=110) or stenting (n=49) of de novo native coronary artery lesions. Plasma samples were drawn at baseline (before angioplasty) and serially after angioplasty (immediately afterward and 6 hours, 24 hours, 3 days, 7 days, 1 month, 3 months, and 6 months afterward). Antigen and activity assays were performed for uPA, tPA, and PAI-1. Follow-up quantitative coronary angiography was performed in 92% of eligible patients. The overall angiographic restenosis rate (diameter stenosis >50%) was 31% (37% in PTCA patients, 17% in stented patients). At all time periods, including baseline, uPA antigen levels were significantly higher and PAI-1 antigen levels were significantly lower in patients with restenosis. Restenosis rates for patients in the upper tertile of baseline uPA antigen levels were 2-fold higher than for those in the lower 2 tertiles (46% versus 24% and 22%, respectively; P<0.004). In a stepwise regression multivariate analysis, obstruction diameter after the procedure and uPA antigen were significant predictors of follow-up diameter stenosis.

CONCLUSIONS

Plasma uPA antigen levels and PAI-1 antigen levels identify patients at increased risk for restenosis after percutaneous coronary revascularization.

Quantitative measurements of in-stent restenosis: A comparison between quantitative coronary ultrasound and quantitative coronary angiography

While quantitative coronary angiography (QCA) remains the standard used to assess new interventional therapies, intracoronary ultrasound (ICUS) is gaining interest. The aim of the study was to determine the relationship between QCA and quantitative coronary ultrasound (QCU) measurements after stenting. Sixty-two consecutive patients with both QCA and QCU analysis after stent implantation were included in the study. The mean luminal diameter (QCU vs. QCA) were 2.74 +/- 0.46 mm and 2.41 +/- 0.49 mm (P < 0.0001), the minimal luminal diameter (MLD) 2.08 +/- 0.44 mm and 1.62 +/- 0.42 mm (P < 0. 0001), and the projected QCU MLD 1.90 +/- 0.42 mm (P < 0.0001 with respect to QCA). Percentage obstruction diameter (QCU vs. QCA) were 41.53% +/- 10.78% and 43.15% +/- 12.72% (P = NS). The stent diameter (QCU vs. QCA) were 3.54 +/- 0.65 mm and 3.80 +/- 0.37 mm (P = 0. 0004). Stent length measured by QCU were longer at 31.11 +/- 13.54 mm against 28.63 +/- 12.75 mm, P < 0.0001 with respect to QCA. In conclusion, while QCA and QCU appear to be comparable tools for measuring corrected stent diameters and stent lengths, smaller luminal diameters were found using QCA. This is of particular relevance to quantitative studies addressing absolute changes in vascular or luminal diameters. Cathet. Cardiovasc. Intervent. 48:133-142, 1999.

Integrated evaluation of relation between coronary lesion features and stress echocardiography results: the importance of coronary lesion morphology

OBJECTIVES

The aim of this study was to analyze, in the same group of patients, the relationship between multiple variables of coronary lesion and results of exercise, dobutamine and dipyridamole stress echocardiography tests.

BACKGROUND

Integrated evaluation of the relation between stress echocardiography results and angiographic variables should include not only the assessment of stenosis severity but also evaluation of other quantitative and qualitative features of coronary stenosis.

METHODS

Study population consisted of 168 (138 male, 30 female, mean age 51+/-9 years) patients, on whom exercise (Bruce treadmill protocol), dobutamine (up to 40 mcg/kg/min) and dipyridamole (0.84 mg/kg over 10 min) stress echocardiography tests were performed. Stress echocardiography test was considered positive for myocardial ischemia when a new wall motion abnormality was observed. One-vessel coronary stenosis ranging from mild stenosis to complete obstruction of the vessel was present in 153 patients, and 15 patients had normal coronary arteries. The observed angiographic variables included particular coronary vessel, stenosis location, the presence of collaterals, plaque morphology according to Ambrose classification, percent diameter stenosis and obstruction diameter as assessed by quantitative coronary arteriography.

RESULTS

Covariates significantly associated with the results of physical and pharmacological stress tests included for all three stress modalities presence of collateral circulation, percent diameter stenosis and obstruction diameter, as well as lesion morphology (p < 0.05 for all, except collaterals for dobutamine stress test, p = 0.06). By stepwise multiple logistic regression analysis, the strongest predictor of the outcome of exercise echocardiography test was only percent diameter stenosis (p = 0.0002). However, both dobutamine and particularly dipyridamole stress echocardiography results were associated not only with stenosis severity - percent diameter stenosis (dobutamine, p = 0.04; dipyridamole, p = 0.003) - but also, and even more strongly, with lesion morphology (dobutamine, p = 0.006; dipyridamole, p = 0.0009). As all of stress echocardiography results were significantly associated with percent diameter stenosis, the best angiographic cutoff in relation to the results of stress echocardiography test was: exercise, 54%; dobutamine, 58% and dipyridamole, 60% (p < 0.05 vs. exercise).

CONCLUSIONS

Integrated evaluation of angiographic variables have shown that the results of dobutamine and dipyridamole stress echocardiography are not only influenced by stenosis severity but also, and even more importantly, by plaque morphology. The results of exercise stress echocardiography, although separately influenced by plaque morphology, are predominantly influenced by stenosis severity, due to a stronger exercise capacity in provoking myocardial ischemia in milder forms of coronary stenosis.

Histopathology of coronary lesions with early loss of minimal luminal diameter after successful percutaneous transluminal coronary angioplasty: is thrombus a significant contributor?

BACKGROUND

Early loss of minimal luminal diameter of >0.3 mm after successful percutaneous transluminal coronary angioplasty (PTCA) is associated with a higher incidence of restenosis. The underlying mechanism of this early loss is unknown and thrombus may be a contributing factor.

METHODS

We performed a prospective study using quantitative computerized planimetry on coronary tissue specimens obtained by directional coronary atherectomy of 24 lesions in which early loss occurred 22+/-9 minutes after successful PTCA.

RESULTS

Thrombus was present in 9 (37%) of 24 coronary specimens. Segmental areas (mm2) and percentage of total area were distributed as follows: sclerotic tissue, 4.07+/-0.7 mm2 (63%+/-6%); fibrocellular tissue, 0.97+/-0.27 mm2 (16%+/-4%); hypercellular tissue, 0.99+/-0.29 mm2 (12%+/-3%); atheromatous gruel, 0.18+/-0.07 mm2 (3%+/-0.1%); and thrombus, 0.24+/-0.15 mm2 (6%+/-0.4%). There was no difference in the relative early loss index between lesions with or without thrombus (35%+/-7% vs 26%+/-2%, respectively; P= .87). Multiple stepwise regression analysis did not identify any histologic predictors of relative early loss index.

CONCLUSION

Histopathologic analysis of coronary lesions with early loss after successful PTCA suggests that thrombus may not play a significant role in this angiographic phenomenon.

Diabetes Atherosclerosis Intervention Study (DAIS): quantitative coronary angiographic analysis of coronary artery atherosclerosis

The primary objective of the Diabetes Atherosclerosis Intervention Study (DAIS) is to determine by quantitative coronary angiography whether long-term correction of the dyslipoproteinemia of diabetes with micronized fenofibrate results in evidence of decreased progression or regression of angiographically measured obstructive coronary atherosclerosis. The purpose of this communication is to describe the angiographic methodology for the DAIS project, and to present data documenting the reproducibility of measurements that will determine the primary outcome of DAIS. Four hundred eighteen subjects between the ages of 40 and 65 were entered from 11 centers in Canada, France, Finland, and Sweden, with 305 males and 113 females. Thirty-two percent of subjects had undergone a previous coronary artery intervention, either PTCA or bypass grafting. Subjects underwent coronary arteriography at baseline according to a strictly defined protocol. The coronary tree was divided into AHA segments and quantitative analysis of segments was performed using the cardiovascular measurement system described by Reiber. Geometric parameters including mean lumen diameter, minimum lumen diameter, maximum lumen diameter, and segment length were determined. In 15 studies, measurements were carried out on the same frame by two observers, and at least 1 week apart by the same observer. In 13 studies, measurements were performed by the same observer on two separate injections of the same coronary artery. The mean of the standard deviation of the differences of measurements of all segments for the primary study analyst was 0.029 mm, with a mean of correlation coefficients of 1.00. Between two observers, the mean of the standard deviations of segmental mean lumen diameters was 0.347 mm with a mean of coefficients of variation of 0.78. The mean of standard deviations for measurements of segmental mean lumen diameter from two separate coronary injections was 0.122, with a mean of correlation coefficients of 0.94. The mean of correlation coefficients for minimum lumen diameter were 0.98 for intraobserver variability, 0.77 for inter-observer variability, and 0.96 for inter-angiogram variability. For segment length the corresponding values were 0.99, 0.79, and 0.94. These data demonstrate that a high level of reproducibility and precision may be achieved in a multicenter study in assessment of the coronary tree in carefully performed studies using this methodology. We anticipate the results will provide a statistically powerful conclusion with new and unique data to answer the question of the effect of long-term correction of dyslipoproteinemia on coronary atherosclerosis in type II diabetic patients with dyslipoproteinemia.

Heterogeneous vasomotor responses of coronary conduit and resistance vessels in hypertension

OBJECTIVES

The purpose of our study was to investigate the relation between conductance and resistance coronary vasomotor responsiveness in hypertensive patients without atherosclerosis.

BACKGROUND

Although similar in morphology, conduit and resistance coronary vessels differ importantly in size, function and local environment and appear to be differentially affected in certain disease processes, such as atherosclerosis and hypertension. However, little is known about the effect of hypertension on contiguous coronary conduit and resistance vessels in humans.

METHODS

Changes in coronary blood flow (a measure of resistance vessel reactivity) and coronary artery diameter (a measure of conduit vessel reactivity) were investigated in response to graded infusion of the endothelium-dependent agonist acetylcholine (ACh) in 98 patients with normal coronary arteries.

RESULTS

In 31 normotensive, euglycemic patients, conduit and resistance coronary artery responses to intracoronary infusion of ACh were significantly correlated (r = 0.73, p = 1 x 10[-6]), although eight patients (26%) had constriction of conduit but dilation of resistance arteries at peak effect. In 28 hypertensive patients without left ventricular hypertrophy (LVH), conduit and resistance artery responses to ACh remained significantly correlated (r = 0.5, p = 0.006), although 12 patients (43%) had discordant findings. Finally, in 39 hypertensive patients with LVH, conduit and resistance artery responses to ACh displayed the lowest correlation (r = 0.38, p = 0.02), with 22 patients (56%) demonstrating conduit artery constriction and resistance artery dilation.

CONCLUSIONS

Despite angiographically normal coronary arteries, heterogeneous vasomotor responses (dilation and constriction) were demonstrated in contiguous conduit and resistance arteries in normotensive and hypertensive patients referred for cardiac catheterization because of chest pain. In addition to more severe endothelial dysfunction among conduit and resistance arteries, a greater frequency of discordant conduit and resistance artery responses and resistance vessel constriction was found with increasing severity of hypertension. Our study suggests differing mechanisms of endothelium responsiveness to ACh among conduit and resistance coronary arteries.

Quantitative coronary angiography with deformable spline models

Although current edge-following schemes can be very efficient in determining coronary boundaries, they may fail when the feature to be followed is disconnected (and the scheme is unable to bridge the discontinuity) or branch points exist where the best path to follow is indeterminate. In this paper, we present new deformable spline algorithms for determining vessel boundaries, and enhancing their centerline features. A bank of even and odd S-Gabor filter pairs of different orientations are convolved with vascular images in order to create an external snake energy field. Each filter pair will give maximum response to the segment of vessel having the same orientation as the filters. The resulting responses across filters of different orientations are combined to create an external energy field for snake optimization. Vessels are represented by B-Spline snakes, and are optimized on filter outputs with dynamic programming. The points of minimal constriction and the percent-diameter stenosis are determined from a computed vessel centerline. The system has been statistically validated using fixed stenosis and flexible-tube phantoms. It has also been validated on 20 coronary lesions with two independent operators, and has been tested for interoperator and intraoperator variability and reproducibility. The system has been found to be specially robust in complex images involving vessel branchings and incomplete contrast filling.

Reproducibility of quantitative coronary analysis, Assessment of variability due to frame selection, different observers, and different cinefilmless laboratories

Because of limited storage capacity for digital images, angiographic laboratories without cinefilm are dependent on locally performed quantitative coronary angiography (QCA) in clinical studies. In the present study the intra- and interobserver variability, as well as variability between different laboratories and variability due to frame selection was analyzed. A total of 20 coronary lesions were studied in two different laboratories 12 +/- 8 days apart. Images were analyzed on-line and after being transferred to a Cardiac Work Station (CWS). There was no significant difference between the measurement situations. For minimal luminal diameter (MLD) precision (SD of signed errors) ranged from 0.12 mm to 0.20 mm, for reference diameter (RD) from 0.15 mm to 0.28 mm, and for percent diameter stenosis (DS) from 4.2% to 5.8%. Overall relative precision was obtained by normalizing the QCA parameters, as well 11.9% for MLD, 7.0% for RD and 8.5% for DS (p < 0.001, Rd and DS compared to MLD). The overall variability in the interobserver and in the interlaboratory comparisons was 11.2% and 10.4%, respectively (n.s) (n.s.). Thus the variability of QCA performed in cinefilmless, digital laboratories is small, and within a range making it an useful tool for clinical practice and group comparisons in clinical studies. However, the error range of QCA measurements must be taken into consideration when judging results from individual patients.

Excimer laser angioplasty vs. balloon angioplasty in saphenous vein bypass grafts: quantitative angiographic comparison of matched lesions

Technologies which ablate or debulk tissue may result in better angiographic outcomes by altering the elastic properties of the vessel wall. Accordingly, the procedural outcomes of 88 vein graft lesions treated by either excimer laser angioplasty with adjunct balloon angioplasty (PELCA + PTCA, n = 44) (Spectranetics CVX-300, 1.4-, 1.7-, or 2.0-MM catheters) or balloon angioplasty alone (PTCA, n = 44) were analyzed by quantitative angiography (Cardiac Measurement System). Lesions were individually matched for vessel position, reference diameter (RD), and minimal luminal diameter (MLD). Matching was deemed adequate as the preprocedure MLD (PELCA + PTCA, 1.14 +/- 0.48 mm; PTCA, 1.20 +/- 0.47 mm) and RD (PELCA + PTCA, 3.23 +/- 0.56 mm; PTCA, 3.25 +/- 0.57 mm) were not significantly different. There were also no significant differences between PELCA + PTCA- and PTCA-treated lesions with respect to patient age, graft age, lesion length, symmetry, and plaque area. Balloon diameter at maximal inflation was 2.77 +/- 0.55 mm (PELCA + PTCA group) and 2.84 +/- 0.59 mm (PTCA group), P = NS. Final MLD postprocedure was 2.17 +/- 0.54 mm and 2.19 +/- 0.55 mm for PELCA + PTCA- and PTCA-treated lesions (P = NS), respectively. Vessel stretch [(balloon diameter - MLD pre)/RD], elastic recoil [(balloon diameter - MLD post)/RD], and acute gain [(MLD post - MLD pre)/RD] were calculated and normalized for vessel size (RD). Vessel stretch (PELCA + PTCA, 0.60 +/- 0.22; PTCA, 0.59 +/- 0.24; P = NS), elastic recoil (PELCA + PTCA, 0.28 +/- 0.18; PTCA, 0.26 +/- 0.16), and acute gain (PELCA + PTCA, 0.34 +/- 0.24; PTCA, 0.31 +/- 0.23; P = NS) were not significantly different between the two treatment groups. In a matched population of successfully treated vein graft lesions, PELCA + PTCA did not reduce elastic recoil or improve immediate angiographic outcome, as compared with PTCA alone.

Coronary stenting in patients undergoing percutaneous transluminal coronary angioplasty during acute myocardial infarction

Although coronary stenting has been useful in the treatment of patients with suboptimal results, abrupt closure, and threatening occlusion after percutaneous transluminal coronary angioplasty (PTCA), its use in patients with acute myocardial infarction (AMI) is controversial because of the presence of intracoronary thrombus. In this study intracoronary stenting was used to treat suboptimal results and complications in 30 patients (35 lesions) undergoing PTCA during AMI. There were 28 men and 2 women, mean age 58 +/- 12 years. Thirteen patients (43%) had undergone rescue PTCA because of unsuccessful thrombolysis. Four patients had Killip's grade IV, 5 Killip's grade III, and 21 Killip's grade < or = 2 heart failure. Stents were placed in the 35 lesions because of suboptimal result (n = 19), early loss (n = 9), abrupt closure (n = 2), and coronary dissection with threatening occlusion (n = 5). All stents were deployed successfully. In-hospital complications included 1 in-hospital death (3.0%); no patient required emergency coronary artery bypass graft surgery. One patient (3.0%) developed abrupt closure and was successfully treated with PTCA and intracoronary thrombolysis. Vascular complications requiring blood transfusion developed in 3 of 30 patients (10%). At 11.8 months (range 4 to 24) follow-up, there were no deaths or myocardial infarction. One patient underwent coronary artery bypass grafting. The remaining patients were free of angina at follow-up. Thus, intracoronary stents can be used successfully to treat both suboptimal results and complications occurring in patients undergoing PTCA during AMI.

Early and late quantitative angiographic results of vein graft lesions treated by excimer laser with adjunctive balloon angioplasty

BACKGROUND

Percutaneous excimer laser coronary angioplasty (PELCA) has been approved for treatment of diseased saphenous vein bypass grafts. However, detailed and complete quantitative angiographic analysis of immediate procedural and late follow-up results has not been performed.

METHODS AND RESULTS

PELCA using the CVX-300 excimer laser system was performed in 125 bypass lesions (mean graft age, 96 +/- 53 months; range, 2 to 240 months) in 106 consecutive patients at eight centers. Quantitative analyses of the procedural and follow-up angiograms were done with the Cardiac Measurement System. Stand-alone PELCA was done in 21 lesions (17%). Lesions were located at the ostium (20%), body (67%), or distal anastomosis (13%). The graft reference diameter was 3.26 +/- 0.79 mm (mean +/- SD). Minimal lumen diameter increased from 1.09 +/- 0.52 mm before treatment to 1.61 +/- 0.69 mm after laser and 2.18 +/- 0.63 mm after adjunctive balloon dilation (P < .001) but had declined at follow-up to 1.40 +/- 1.17 mm. Dissections were evident in 45% of lesions after laser treatment (types A and B, 27%; types C through F, 18%), including 7% occlusions. Angiographic success (< or = 50% diameter stenosis [% DS]) was 54% after laser and 91% after adjunctive PTCA, with an overall clinical success rate of 89%. In-hospital complications were death, 0.9%; myocardial infarction (Q-wave and non-Q-wave), 4.5%; and bypass surgery, 0.9%. Independent predictors of % DS after laser were reference diameter, lesion length, and minimal lumen diameter before laser. At angiographic follow-up in 83% of eligible patients, the restenosis rate per lesion (DS > 50%) was 52%, including 23 occlusions (24%). The only independent predictor of increased % DS at follow-up was lesion symmetry. Logistic regression indicated that smaller reference diameter was an independent predictor of late occlusion. Overall 1-year mortality was 8.6%. Actuarial event-free survival (freedom from death, myocardial infarction, bypass surgery, or target vessel percutaneous transluminal coronary angioplasty) was 48.2% at 1 year.

CONCLUSIONS

Excimer laser angioplasty with adjunctive balloon angioplasty can be safely and successfully performed in diseased, old saphenous vein bypass graft lesions considered at high risk for reintervention. The extent of laser ablation remains limited by the diameter and effectiveness of the catheters. Late restenosis and, in particular, total occlusion mitigate the early benefits of the procedure. Other approaches such as the routine use of additional anticoagulation (eg, warfarin) should be considered to reduce the risk of late occlusions and restenosis after laser angioplasty of bypass grafts.