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Biomedical subjects

M B Leon

Publications and source records attributed to M B Leon.

At least 199 records · Page 11Linked to original sources
PubMed1997

Determinants and correlates of target lesion calcium in coronary artery disease: a clinical, angiographic and intravascular ultrasound study.

OBJECTIVES: This report used intravascular ultrasound and quantitative coronary angiography to explore the relation between lesion-associated calcium and risk factors, clinical presentation and angiographic severity of coronary artery stenoses. BACKGROUND: Coronary artery calcium is a marker for significant coronary atherosclerosis. Noninvasive procedures are being proposed as screening tests for coronary artery disease. Intravascular ultrasound identification of tissue calcium has been validated in vitro. METHODS: Independent chart review, preintervention intravascular ultrasound imaging and coronary angiography were used to study primary native vessel lesions in 1,442 patients. Target lesions and reference segments were evaluated according to previously published quantitative and qualitative methods. Results are presented as mean value +/- SD. RESULTS: Overall, 1,043 lesions contained target lesion calcium (72%); the arc of target lesion calcium was 110 +/- 109 degrees. Lesions with an ultrasound plaque burden > 0.75 or an angiographic diameter stenosis > 0.25 had a prevalence of calcium of at least 65%, with a mean arc > 100 degrees. Intermediate lesions had as much target lesion calcium as did angiographically severe lesions. Using multivariate linear regression analysis, patient age, stable (vs. unstable) angina and the intravascular ultrasound lesion site and reference segment plaque burden (but not the angiographic diameter stenosis) were the independent predictors of the arc of target lesion calcium (all p < 0.0001). CONCLUSIONS: Intravascular ultrasound analysis shows that coronary calcification correlates with plaque burden but not with degree of lumen compromise. Thus, the noninvasive detection of coronary calcium is predictive of future cardiac events, presumably because coronary calcification is a marker for overall atherosclerotic plaque burden. Coronary calcium increases with increasing patient age and is less common in unstable lesion subsets.

Adult↗
PubMed1997

First international new intravascular rigid-flex endovascular stent study (FINESS): clinical and angiographic results after elective and urgent stent implantation. The FINESS Trial Investigators.

OBJECTIVES: The purpose of this study was to determine the feasibility, safety and efficacy of elective and urgent deployment of the new intravascular rigid-flex (NIR) stent in patients with coronary artery disease. BACKGROUND: Stent implantation has been shown to be effective in the treatment of focal, new coronary stenoses and in restoring coronary flow after coronary dissection and abrupt vessel closure. However, currently available stents either lack flexibility, hindering navigation through tortuous arteries, or lack axial strength, resulting in suboptimal scaffolding of the vessel. The unique transforming multicellular design of the NIR stent appears to provide both longitudinal flexibility and radial strength. METHODS: NIR stent implantation was attempted in 255 patients (341 lesions) enrolled prospectively in a multicenter international registry from December 1995 through March 1996. Nine-, 16- and 32-mm long NIR stents were manually crimped onto coronary balloons and deployed in native coronary (94%) and saphenous vein graft (6%) lesions. Seventy-four percent of patients underwent elective stenting for primary or restenotic lesions, 21% for a suboptimal angioplasty result and 5% for threatened or abrupt vessel closure. Fifty-two percent of patients presented with unstable angina, 48% had a previous myocardial infarction, and 45% had multivessel disease. Coronary lesions were frequently complex, occurring in relatively small arteries (mean [+/-SD] reference diameter 2.8 +/- 0.6 mm). Patients were followed up for 6 months for the occurrence of major adverse cardiovascular events. RESULTS: Stent deployment was accomplished in 98% of lesions. Mean minimal lumen diameter increased by 1.51 +/- 0.51 mm (from 1.09 +/- 0.43 mm before to 2.60 +/- 0.50 mm after the procedure). Mean percent diameter stenosis decreased from 61 +/- 13% before to 17 +/- 7% after intervention. A successful interventional procedure with < 50% diameter stenosis of all treatment site lesions and no major adverse cardiac events within 30 days occurred in 95% of patients. Event-free survival at 6 months was 82%. Ninety-four percent of surviving patients were either asymptomatic or had mild stable angina at 6 month follow-up. CONCLUSIONS: Despite unfavorable clinical and angiographic characteristics of the majority of patients enrolled, the acute angiographic results and early clinical outcome after NIR stent deployment were very promising. A prospective, randomized trial comparing the NIR stent with other currently available stents appears warranted.

Aged↗
PubMed1997

Acute and chronic effects of self-expanding nitinol stents in porcine coronary arteries.

BACKGROUND: There is a paucity of experimental data regarding self-expanding stents. This study evaluated the acute and chronic effects of CardioCoil, a self-expanding nitinol coil stent, in porcine coronary arteries. METHODS: Twenty-three self-expanding nitinol stents were implanted without associated balloon angioplasty in normal coronary arteries of 12 pigs, which were serially sacrificed up to 6 months. Angiographic and histologic analyses were performed to evaluate the deployment characteristics, patency rates, neointimal response, and unique features of the self-expanding nature of the CardioCoil stent. RESULTS: All stents were successfully deployed and remained patent acutely. Three undersized stents migrated proximally and there was one episode of subacute thrombosis in an oversized stent. The remaining stents were patent throughout the survival period and neointimal responses were favorable for up to 6 months (all mean neointima < 200 microns up to 6 months). There was evidence of continuing stent expansion over time (stent diameter 2.85 +/- 0.78 mm immediately after deployment and 3.24 +/- 0.97 mm at follow-up) and the majority of stent struts were in the adventitia by 6 months. Re-endothelization occurred starting one week after implantation and was complete by 8 weeks. CONCLUSIONS: This study shows that the CardioCoil self-expanding nitinol coil stent, is associated with favorable deployment characteristics and patency rates, although appropriate sizing is more crucial than with balloon-expandable stents. More importantly, there appears to be a "dissociation' between the deep vessel wall injury by the chronic strut expansion process and the neointimal reaction, unlike balloon-expandable stents.

Alloys↗
PubMed1997

Single-dose intramuscular administration of sustained-release Angiopeptin reduces neointimal hyperplasia in a porcine coronary in-stent restenosis model.

BACKGROUND: In-stent restenosis results primarily from neointimal hyperplasia. In a previous study we showed that continuous subcutaneous Angiopeptin infusion for 1 week significantly reduces neointimal hyperplasia in a porcine coronary overstretch in-stent restenosis model. The present study evaluated the relative efficacy of immediate-release and sustained-release Angiopeptin in the same model. METHODS: Thirty pigs (n = 10 in each group) were randomly assigned to three groups: controls receiving no Angiopeptin (Group 1); a sustained-release treatment group receiving one time intramuscular administration of 20 mg of Angiopeptin (Group 2); and a systemic treatment group receiving continuous Angiopeptin over a 1-week period via a subcutaneous osmotic pump (200 micrograms/kg total dose) (Group 3). One oversized Palmaz-Schatz stent (mean stent/artery = 1.25) was subsequently implanted in the left anterior descending coronary artery. The degree of neointimal reaction was evaluated 4 weeks later by angiography (maximal per cent diameter stenosis) and histology (maximal neointimal area corrected for injury score). RESULTS: A trend towards a reduction in diameter stenosis was observed by angiography, despite a similar degree of injury (25 +/- 17% in Group 1, 13 +/- 8% in Group 2, and 14 +/- 9% in Group 3; P = 0.072 by ANOVA). Histology demonstrated that both Angiopeptin treatment strategies significantly reduced in-stent neointimal area compared with the control group (1.65 +/- 0.97 mm2 in Group 1 versus 0.93 +/- 0.41 mm2 in Group 2 versus 0.85 +/- 0.28 mm2 in Group 3; P = 0.016 by ANOVA). Measurement of plasma Angiopeptin levels revealed comparable levels in both treatment groups, which persisted for up to 2 weeks. CONCLUSIONS: This study shows that single-dose intramuscular administration of sustained-release Angiopeptin reduces in-stent restenosis as effectively as the prolonged systemic treatment requiring a subcutaneous pump. Thus, a practical, effective, pharmacologic therapy for preventing in-stent restenosis may be available and should be evaluated in patients.

Animals↗
PubMed1997

A randomized animal study evaluating the efficacies of locally delivered heparin and urokinase for reducing in-stent restenosis.

BACKGROUND: In-stent restenosis is primarily due to neointimal hyperplasia. Results from recent nonrandomized studies suggest that local delivery of heparin or urokinase to the site of angioplasty or stenting results in a lower rate of restenosis. OBJECTIVE: To determine whether local delivery of heparin or urokinase reduces in-stent restenosis. METHODS AND RESULTS: Thirty-three pigs were assigned randomly to one of three groups: controls (n = 9) administered local saline infusion, the heparin group (n = 15) administered local heparin (6000 u/10 min), and the urokinase group (n = 9) administered local urokinase (250000 u/10 min), via a local delivery catheter (Dispatch) at the site of subsequent stent implantation. Prior to local delivery, all of the animals were subjected to balloon injury (balloon:artery diameter ratio approximately or = 1.3) to facilitate intramural drug impregnation. After local therapy, one Palmaz-Schatz stent (mean stent: artery diameter ratio approximately or = 1.25) was implanted within the left anterior descending coronary artery. The degree of neointimal hyperplasia was evaluated 4 weeks later by angiography (as the maximal percentage diameter stenosis) and histology (as the maximal neointimal area stenosis). We found no difference in percentage diameter stenosis (46 +/- 18% control, 42 +/- 27% heparin group, and 37 +/- 20% urokinase group, P = 0.7) and corrected neointimal area (1.06 +/- 0.42 mm2 control, 0.94 +/- 0.29 mm2 heparin, and 0.88 +/- 0.26 mm2 urokinase group, P = 0.7) among groups at follow-up. The activated clotting time rose slightly for heparin-treated animals, suggesting that systemic delivery had occurred, whereas fibrinogen levels did not change in urokinase-treated animals. CONCLUSIONS: Local deliveries of heparin and urokinase via the Dispatch catheter, at the chosen dosages, do not reduce in-stent neointimal hyperplasia in this porcine model.

Animals↗
PubMed1997

Altered compliance and residual strain precede angiographically detectable early atherosclerosis in low-density lipoprotein receptor deficiency.

BACKGROUND: This study was performed to detect changes in vascular biomechanical properties early in atherogenesis. METHODS AND RESULTS: Age- and weight-matched LDL-receptor deficient Watanabe hypercholesterolemic male rabbits (Group I: n = 11) and normal rabbits (Group II: n = 11) were studied. Fasting plasma lipoprotein concentrations, aortic angiography and intravascular ultrasound, in vivo aortic compliance evaluation, ex vivo aortic residual strain measurements, aortic lipid content and histopathology were determined. Plasma cholesterol was increased 9.8 fold and aortic cholesterol content was increased from 20 to 43 fold in Group I compared to Group II, respectively (P < .00005). Angiography revealed no stenoses in either group, whereas intravascular ultrasound and histological studies of Group I showed small circumferential plaques with < 10% cross-sectional area involvement. The residual strain in Group I was significantly increased in the ascending thoracic aorta (22.1 +/- 6.9% versus 10.4 +/- 3.2% in Group II, P < .0001), descending thoracic aorta (15.7 +/- 7.2% versus 4.8 +/- 1.3% in Group II, P < .0001), and abdominal aorta (18.0 +/- 4.8% versus 8.3 +/- 6.3% in Group II, P < .005). Changes in residual strain were inversely correlated with the aortic cholesterol content in the ascending thoracic aorta (r = -.72; P = -.001), descending thoracic aorta (r = -.95; P < .001), and abdominal aorta (r = -.51; P = .019). CONCLUSIONS: Early atherosclerosis in LDL-receptor deficient rabbits, undetectable by angiography yet observed by intravascular ultrasound imaging and histology, is associated with marked changes in ex vivo residual strain. Alterations in vascular biomechanical properties, associated with changes in cholesterol content, may have physiologic consequences and may be useful in detecting and quantitating early atherosclerosis.

Animals↗
PubMed1996

Chronic arterial responses to stent implantation: a serial intravascular ultrasound analysis of Palmaz-Schatz stents in native coronary arteries.

OBJECTIVES: We used intravascular ultrasound (IVUS) imaging to evaluate the chronic vessel responses to Palmaz-Schatz stents. BACKGROUND: Palmaz-Schatz stents have been shown to inhibit early elastic recoil and late arterial remodeling while triggering neointimal hyperplasia. However, changes occurring in native vessels surrounding stent struts have not been well studied. METHODS: Postintervention and follow-up (mean [+/-SD] 5.4 +/- 3.8 months) serial IVUS imaging was performed in 25 stents without restenosis and 24 with in-stent restenosis. Intravascular ultrasound imaging using automatic transducer pullback at 0.5 mm/s allowed measurement at 1-mm axial increments of external elastic membrane (EEM), stent and lumen cross-sectional areas (CSAs) and calculation of peristent plaque plus media (P + M = EEM - stent) CSA, intrastent plaque (stent-lumen) CSA, arterial remodeling (delta EEM CSA), tissue growth outside the stent (delta P + M CSA) and tissue growth within the stent (delta stent-lumen CSA). Volumes were calculated using the Simpson rule. RESULTS: Mean EEM CSA increased significantly from 16.9 +/- 5.0 mm2 after intervention to 18.4 +/- 4.9 mm2 at follow-up (p < 0.0001), reflecting an increase in P + M CSA surrounding the stent (1.6 +/- 1.3 mm2). Greater tissue growth within the stent (2.4 +/- 2.2 mm2) correlated weakly, but directly with tissue growth surrounding the stent (r = 0.356, p = 0.0121). The ratio of peristent/intrastent tissue growth correlated weakly with arterial remodeling (r = 0.282, p = 0.0525). Restenotic stents had more tissue growth both within and surrounding the stent than did nonrestenotic stents. Volumetric measurements, which could be obtained in 15 lesions, showed similar results. CONCLUSIONS: After implantation there is a chronic increase in plaque mass both within and surrounding the stents. The increase in peristent plaque mass is associated with adaptive remodeling.

Aged↗
PubMed1996

Mechanisms and results of balloon angioplasty for the treatment of in-stent restenosis.

Restenosis within tubular slotted stents is secondary to intimal hyperplasia and is usually treated with percutaneous transluminal coronary angioplasty (PTCA). Sequential intravascular ultrasound (IVUS) was used to assess the mechanisms and results of PTCA for in-stent restenosis. Sixty-four restenotic Palmaz-Schatz stents were studied by IVUS imaging before and after PTCA. IVUS measurements of stent and lumen cross-sectional areas (CSAs) at 5 segments (proximal and distal stent edges, proximal and distal stent bodies, and the central articulation) were used to calculate intimal hyperplasia CSA (stent-lumen CSA). The results of the 5 segments were then averaged. Mean and minimum CSAs were compared before and after PTCA. Quantitative angiographic measurements showed a minimal lumen diameter increase from 1.05 +/- 0.63 mm (mean +/- 1 SD) before intervention to 2.77 +/- 0.51 mm after PTCA (p < 0.0001). Conversely, the diameter stenosis decreased from 63 +/- 19% to 18 +/- 12% (p < 0.0001). IVUS measurements showed a minimum lumen CSA increase from 2.3 +/- 1.3 mm2 to 6.1 +/- 2.2 mm2 (p < 0.0001) as a result of an increased minimum stent CSA (7.2 +/- 2.4 mm2 to 8.7 +/- 2.6 mm2, p < 0.0001) and a decreased intimal hyperplasia CSA within the stent (4.9 +/- 2.2 mm2 to 2.7 +/- 2.0 mm2, p < 0.0001). Of the total mean lumen enlargement, 56 +/- 28% was the result of additional stent expansion and 44 +/- 28% was the result of a decrease in neointimal tissue. The minimum lumen CSA after PTCA was significantly smaller than the minimum stent CSA before PTCA (presumably an accurate reflection of lumen dimensions immediately after stent implantation; p = 0.0002). The mechanism of PTCA for restenosis is a combination of additional stent expansion and tissue extrusion out of the stent; there is a relatively high residual stenosis (angiographic diameter stenosis of 18 +/- 12%).

Aged↗
PubMed1996

Patterns and mechanisms of in-stent restenosis. A serial intravascular ultrasound study.

BACKGROUND: Studies have suggested that restenosis within Palmaz-Schatz stents results from neointimal hyperplasia or chronic stent recoil and occurs more frequently at the articulation. METHODS AND RESULTS: Serial intravascular ultrasound (IVUS) was performed after intervention and at follow-up in 142 stents in 115 lesions. IVUS measurements (external elastic membrane [EEM], stent, and lumen cross-sectional areas [CSAs] and diameters) were performed, and plaque CSA (EEM lumen in reference segments and stent lumen in stented segments), late lumen loss (delta lumen), remodeling (delta EEM in reference segments and delta stent in stented segments), and tissue growth (delta plaque) were calculated. After intervention, the lumen tended to be smallest at the articulation because of tissue prolapse. At follow-up, tissue growth was uniformly distributed throughout the stent; the tendency for greater neointimal tissue accumulation at the central articulation reached statistical significance only when normalized for the smaller postintervention lumen CSA. In stented segments, late lumen area loss correlated strongly with tissue growth but only weakly with remodeling. Stents affected adjacent vessel segments; remodeling progressively increased and tissue growth progressively decreased at distances from the edge of the stent. These findings were similar in native arteries and saphenous vein grafts and in lesions treated with one or two stents. There was no difference in the postintervention or follow-up lumen (at the junction of the two stents) when overlapped were compared with nonoverlapped stents. CONCLUSIONS: Late lumen loss and in-stent restenosis were the result of neointimal tissue proliferation, which tended to be uniformly distributed over the length of the stent.

Aged↗
PubMed1996

Association between prior cytomegalovirus infection and the risk of restenosis after coronary atherectomy.

BACKGROUND: Restenosis occurs commonly after coronary angioplasty and atherectomy, but the causes of restenosis are poorly understood. Recently, it has been found that cytomegalovirus (CMV) DNA is present in restenotic lesions from atherectomy specimens. This and other evidence suggest that CMV may have a role in the process of restenosis. METHODS: We prospectively studied 75 consecutive patients undergoing directional coronary atherectomy for symptomatic coronary artery disease. Before atherectomy was performed, we measured blood levels of anti-CMV IgG antibodies to determine whether previous exposure to CMV increased the risk of restenosis, as determined by coronary angiography performed six months after atherectomy. RESULTS: After atherectomy, the mean (+/- SD) minimal luminal diameter of the target vessel was greater in the 49 patients who were seropositive for CMV than in the 26 patients who were seronegative (3.18 +/- 0.51 mm vs. 2.89 +/- 0.45 mm, P=0.01). After six months, however, the seropositive patients had a greater reduction in the luminal diameter (1.24 +/- 0.83 mm vs. 0.68 +/- 0.69 mm, P = 0.003), resulting in a significantly higher rate o restenosis in the seropositive patients (43 percent vs. 8 percent, P = 0.002). In a multivariable logistic-regression model, CMV seropositivity and the CMV titer were independently predictive of restenosis (odds ratios, 12.9 and 8.1, respectively). There was no evidence of acute infection, since the titer of anti-CMV IgG antibodies did not increase over time and tests for anti-CMV IgM antibodies were negative in all patients. CONCLUSIONS: Prior infection with CMV is strong independent risk factor for restenosis after coronary atherectomy. If confirmed, these findings may help identify patients at risk for restenosis.

Adult↗
PubMed1996

Intravascular ultrasound to discern device-specific effects and mechanisms of restenosis.

Restenosis continues to be the "Achilles heel" of transcatheter interventions. While attempts to reduce restenosis by inhibiting cellular proliferation through pharmacologic or mechanical means have been unsuccessful, stents, which inhibit acute recoil and chronic remodeling, have been shown convincingly to reduce restenosis in 2 randomized clinical trials. Intravascular ultrasound (IVUS) allows transmural, tomographic imaging of coronary arteries in humans in vivo to subdivide restenosis into the two basic underlying components: tissue proliferation and arterial remodeling. In studies performed at the Washington Hospital Center, in nonstented lesions 73% of late lumen loss was due to arterial remodeling (a decrease in arterial, or external elastic membrane cross-sectional area) and 27% was due to tissue growth (an increase in plaque plus media cross-sectional area). These findings were confirmed by 2 other studies: the Optimal Atherectomy Restenosis Study (OARS) and the Serial Ultrasound analysis of REstenosis (SURE) Trial. IVUS was also used to study the mechanisms by which stents reduce restenosis. Stents created a larger final lumen cross-sectional area and, for all practical purposes, abolished arterial remodeling to offset a stent-related increase in neointimal tissue accumulation. Neointimal hyperplasia is solely responsible for in-stent restenosis and therefore appears to be a pure model for studying strategies to limit tissue proliferation.

Angioplasty, Balloon, Coronary↗
PubMed1996

Arterial remodeling after coronary angioplasty: a serial intravascular ultrasound study.

BACKGROUND: Restenosis occurs after 30% to 50% of transcatheter coronary procedures; however, the natural history and pathophysiology of restenosis are still incompletely understood. METHODS AND RESULTS: Serial (postintervention and follow-up) intravascular ultrasound imaging was used to study 212 native coronary lesions in 209 patients after percutaneous transluminal coronary angioplasty, directional coronary atherectomy, rotational atherectomy, or excimer laser angioplasty. The external elastic membrane (EEM) and lumen cross-sectional areas (CSA) were measured; plaque plus media (P+M) CSA was calculated as EEM minus lumen CSA. The anatomic slice selected for serial analysis had an axial location within the target lesion at the smallest follow-up lumen CSA. At follow-up, 73% of the decrease in lumen (from 6.6+/-2.5 to 4.0+/-3.7 mm2, P<.0001) was due to a decrease in EEM (from 20.1+/-6.4 to 18.2+/-6.4 mm2, P<.0001); 27% was due to an increase in P+M (from 13.5+/-5.5 to 14.2+/-5.4 mm2, P<.0001). Delta Lumen CSA correlated more strongly with delta EEM CSA (r=.751, P<.0001) than with delta P+M CSA (r=.284, P<.0001). Delta EEM was bidirectional; 47 lesions (22%) showed an increase in EEM. Despite a greater increase in P+M (1.5+/-2.5 versus 0.5+/-2.0 mm2, P=.0009), lesions exhibiting an increase in EEM had (1) no change in lumen (-0.1+/-3.3 versus 3.6+/-2.3 mm2, P<.0001), (2) a reduced restenosis rate (26% versus 62%, P<.0001), and (3) a 49% frequency of late lumen gain (versus 1%, P<.0001) compared with lesions with no increase in EEM. CONCLUSIONS: Restenosis appears to be determined primarily by the direction and magnitude of vessel wall remodeling (delta EEM). An increase in EEM is adaptive, whereas a decrease in EEM contributes to restenosis.

Aged↗
PubMed1996

In vivo validation of intravascular ultrasound length measurements using a motorized transducer pullback system.

Using sonoreflective endovascular targets of known length (stainless steel tubular slotted stents), we have validated in vivo the accuracy and reproducibility of intravascular ultrasound length measurements using a system incorporating motorized transducer pullback through a stationary imaging sheath. The correlation was r = 0.936, with a measurement error of only +/- 5.2%, minimal intraobserver variability, and variability of sequential measurements of only +/- 4.8%.

Aged↗
PubMed1996

Limitations of angiography in the assessment of plaque distribution in coronary artery disease: a systematic study of target lesion eccentricity in 1446 lesions.

BACKGROUND: Plaque distribution (eccentricity) may be a determinant of the success of transcatheter therapy, and certain devices may be better suited to treating severely eccentric lesions than others. However, no study has compared methods for assessing plaque distribution or systematically studied the validity of the angiographic assessment of plaque distribution. METHODS AND RESULTS: We studied 1446 native vessel target lesions in 1349 patients by intravascular ultrasound and coronary angiography. Angiographic and intravascular ultrasound criteria for lesion eccentricity were compared. Angiography showed that 795 of 1446 (55.0%) of target lesions were eccentric. When intravascular ultrasound was used, only 219 lesions (15.1%) had an arc of normal arterial wall within the lesion (equivalent to the pathological definition of lesion eccentricity). When an eccentricity index of >/= 3.0 was used, intravascular ultrasound classified 659 lesions (45.6%) as eccentric. The concordance rates of classification were only 47.7% (versus lesions containing an arc of normal arterial wall) and 53.8% (versus lesions with an ultrasound eccentricity index of >/= 3.0). More eccentric lesions had larger lumen cross-sectional areas, smaller plaque plus media and external elastic membrane cross-sectional areas, and smaller arcs of calcium, suggesting that they may represent less advanced atherosclerotic disease. CONCLUSIONS: There was significant discordance between angiography and ultrasound in assessing plaque distribution. Angiography appeared to detect lesion eccentricity more often than intravascular ultrasound. Furthermore, markedly eccentric lesions, in which there is an arc of normal vessel wall, were uncommon.

Coronary Angiography↗