Performance standards and edge detection with computerized quantitative coronary arteriography. The Lovastatin Restenosis Trial Group

Portable-type signal-averaged electrocardiography with dipyridamole to detect patients with coronary artery disease

BACKGROUND

In a retrospective study portable-type signal-averaged electrocardiography (SAECG) with dipyridamole stress was found to identify patients with coronary artery disease (CAD) at their bedside with high sensitivity and specificity, so the utility of this method was prospectively investigated in the present study.

METHODS AND RESULTS

Standard 12-lead QRS wave SAECG was performed before and after dipyridamole stress at the bedside in 71 patients with chest pain (43 males, mean age 63 +/-9 years). The filtered QRS duration (fQRSd) before and after dipyridamole stress was determined by multiphasic oscillation method for each of the standard 12 leads, and the maximal value of changes in fQRSd (MAX DeltafQRSd) among the 12 leads was determined. The positive test was defined as MAX DeltafQRSd >or=5 ms, and negative as MAX DeltafQRSd <5 ms based on the previous study. Selective coronary arteriography was performed next. In the positive group (n=31), 25 patients had significant stenosis of the coronary artery and 6 did not. In the negative group (n=40), 5 patients had significant stenosis and 35 did not. The sensitivity, specificity, positive predictive accuracy and negative predictive accuracy for CAD detection by SAECG was 83%, 85%, 81% and 88%, respectively.

CONCLUSIONS

Dipyridamole-stress portable SAECG is useful for detecting CAD at the patient's bedside with high sensitivity and specificity.

Improved analysis of brachial artery ultrasound using a novel edge-detection software system

Brachial artery ultrasound is commonly employed for noninvasive assessment of endothelial function. However, analysis is observer dependent and susceptible to errors. We describe studies on a computerized edge-detection and wall-tracking software program to allow more accurate and reproducible measurement. In study 1, three purpose-built Perspex phantom arteries, 3.00, 4.00, and 6.00 mm in diameter, were measured with the software. There was a mean bias of 11 microm (P < 0.001 at each level) between known and measured values; the mean resolving power of the software was estimated as 8.3 microm. In study 2, the mean intraobserver coefficient of variation of repeated measures of flow-mediated dilation (FMD) using the software (6.7%) was significantly lower than that for traditional manual measurements using the intima-lumen interfaces (24.8%, P < 0.05) and intima-media interfaces (32.5%, P < 0.05). In study 3, 24 healthy volunteers underwent repeat testing twice within 1 wk; the coefficients of variation for between-visit reproducibility of FMD and response to glyceryl trinitrate using the software were 14.7 and 17.6%, respectively. Assuming 80% power and an alpha of 0.05, eight subjects with matched controls would be required, in a parallel designed study, to detect an absolute 2.5% change in FMD. In summary, we have developed a semiautomated computerized vascular ultrasound analysis system that will improve the power of clinical intervention studies to detect small changes in arterial diameter.

Inter-observer variability in the angiographic assessment of renal artery stenosis. DRASTIC study group. Dutch Renal Artery Stenosis Intervention Cooperative

OBJECTIVE

To assess inter-observer agreement in the interpretation of renal angiograms.

DESIGN

Comparison of the assessment of renal angiograms by three experienced radiologists, who evaluated the number of renal arteries and the presence, location, aspect and severity of a renal artery stenosis.

SETTING

General hospital and university hospital serving urban and rural populations.

PATIENTS

Patients with difficult-to-treat hypertension referred for diagnostic work-up; 312 angiograms with the intra-arterial digital subtraction technique were obtained from 289 consecutive patients.

MAIN OUTCOME MEASURES

Inter-observer agreement was tested for the following parameters: number of arteries per kidney, presence of stenosis, location of stenosis (truncal, ostial), aspect of stenosis (concentric, eccentric, post-stenotic dilatation), severity of stenosis (reduction of lumen diameter in categories of 30%, 40%, etc. to 100%), and overall quality of the angiographic images. Kappa (kappa) values and weighted kappa between the three pairs of radiologists were used as estimates of inter-observer agreement

RESULTS

Agreement about the number of renal arteries was reasonable (kappa = 0.50-0.72), as was agreement about the presence of stenosis (kappa = 0.68-0.86). Agreement about stenosis location and aspect was poor (kappa = 0.26-0.47 and kappa = 0.15-0.26, respectively). There was general agreement about the severity of stenosis (weighted kappa = 0.65-0.70), but it was not possible to distinguish between 50 and 60% stenosis or between 60 and 70% stenosis (kappa < 0.40). No correlation was found between agreement on severity of stenosis and the quality of the images.

CONCLUSIONS

It is not realistic to make statements about what degree of renal artery stenosis is clinically significant, as long as the intra-arterial angiogram with digital subtraction remains the gold standard. It is likewise risky to rely too strongly on stenosis morphology as visualized by renal angiography in choosing between balloon angioplasty and stent deployment.

Effects of intracoronary beta-radiation therapy after coronary angioplasty: an intravascular ultrasound study

BACKGROUND

Endovascular radiation is emerging as a potential solution for the prevention and treatment of restenosis. Its effects on the morphology of unstented vessels cannot be determined by angiography and therefore require the use of intravascular ultrasound.

METHODS AND RESULTS

Through a 5F noncentered catheter for delivery of a 90Sr/Y source train, 12, 14, or 16 Gy at 2 mm was delivered to native coronary arteries after successful balloon angioplasty in 30 patients. Four patients required stent deployment in the first week. Quantitative coronary angiography and IVUS were performed during the initial procedure and at 6-month follow-up. Binary angiographic restenosis was present in 3 of 30 patients, with target lesion and vessel revascularization performed in 3 and 5 patients, respectively. Angiographic late loss was -0.02+/-0.60 mm, with a -0.09+/-0.46 loss index. IVUS demonstrated no significant reduction in lumen area (from 5.69+/-1.72 mm2 after treatment to 6. 04+/-2.63 mm2 at follow-up), with no significant change in external elastic membrane area (13.71+/-4.54 to 14.22+/-4.71 mm2) over the 6-month follow-up. Wall area was 8.01+/-3.85 mm2 after radiation therapy and 8.19+/-3.44 mm2 at follow-up (P=NS). No significant differences were noted between the different dose groups.

CONCLUSIONS

beta-Radiation therapy resulted in a low restenosis rate with negligible late loss by angiography. By IVUS, beta-radiation was shown to inhibit neointima formation, with no reduction of total vessel area at 6-month follow-up.

Video networking of cardiac catheterization laboratories

BACKGROUND

The purpose of this study was to assess the feasibility and accuracy of a video telecommunication network to transmit coronary images to provide on-line interaction between personnel in a cardiac catheterization laboratory and a remote core laboratory.

METHODS

A telecommunication system was installed in the cardiac catheterization laboratory at Kaiser Hospital, Los Angeles, and the core laboratory at the University of California, Irvine, approximately 40 miles away. Cineangiograms, live fluoroscopy, intravascular ultrasound studies and images of the catheterization laboratory were transmitted in real time over a dedicated T1 line at 768 kilobytes/second at 15 frames/second. These cases were performed during a clinical study of angiographic guidance versus intravascular ultrasound (IVUS) guidance of stent deployment. During the cases the core laboratory performed quantitative analysis of the angiograms and ultrasound images. Selected images were then annotated and transmitted back to the catheterization laboratory to facilitate discussion during the procedure.

RESULTS

A successful communication hookup was obtained in 39 (98%) of 40 cases. Measurements of angiographic parameters were very close between the original cinefilm and the transmitted images. Quantitative analysis of the ultrasound images showed no significant difference in any of the diameter or cross-sectional area measurements between the original ultrasound tape and the transmitted images. The telecommunication link during the interventional procedures had a significant impact in 23 (58%) of 40 cases affecting the area to be treated, the size of the inflation balloon, recognition of stent underdeployment, or the existence of disease in other areas that was not noted on the original studies.

CONCLUSIONS

Current video telecommunication systems provide high-quality images on-line with accurate representation of cineangiograms and intravascular ultrasound images. This system had a significant impact on 58% of the cases in this small clinical trial. Telecommunication networks between hospitals and a central core laboratory may facilitate physician training and improve technical skills and judgement during interventional procedures. This project has implications for how multicenter clinical trials could be operated through telecommunication networks to ensure conformity with the protocol.

Efficacy of beta radiation in prevention of post-angioplasty restenosis. An interim report from the beta energy restenosis trial

Restenosis remains a major limitation of coronary angioplasty in spite of major advances in techniques and technology. Recent studies have demonstrated that ionizing radiation may limit the degree of this problem. Gamma radiation has been shown to be effective in reducing in stent restenosis in humans, and beta radiation following encouraging results in animals has been shown to be feasible in humans. The objective of this study was to assess the feasibility of a 5 F non-centered catheter to deliver beta radiation emitting seeds to the lesion site post angioplasty and its effect on restenosis. Following successful angioplasty, patients were randomized to treatment with 12, 14 or 16 Gy at the angioplasty site. This was delivered with a 5 F non-centered catheter. Twelve beta radiation emitting seeds (90Sr/Y) were delivered to an area 3 cm in length to cover the angioplasty site. Angiographic follow-up was performed at 6 months. Baseline and follow-up angiograms were performed by blinded investigators at a core laboratory. This interim report comprises the first 35 patients to complete 6-month angiographic follow-up. There were no major radiation incidents. Four patients had evidence of angiographic restenosis. The MLD (mm) and percent stenosis were 0.77 +/- 0.27/72.5 +/- 8.6 pre angioplasty, 2.08 +/- 0.4/25.7 +/- 9.8 post angioplasty and radiation and 2.05 +/- 0.59/25.7 +/- 19.8 at follow-up respectively.

CONCLUSION

Beta radiation can be feasibly and safely delivered post coronary angioplasty with a very encouraging reduction of restenosis.

Endovascular beta-radiation to reduce restenosis after coronary balloon angioplasty: results of the beta energy restenosis trial (BERT)

BACKGROUND

In the porcine overstretch injury model of restenosis, endovascular beta-radiation reduces neointima formation. To determine whether this therapy could be applied to patients with coronary artery disease, a special device was developed to allow delivery of 12 encapsulated 90Sr/Y sources, measuring a total of 30 mm, to various sites within the coronary arterial tree. This study was designed to evaluate the feasibility of the delivery of 12, 14, or 16 Gy at 2 mm after balloon angioplasty of stenoses of native coronary vessels.

METHODS AND RESULTS

Delivery of beta-radiation was attempted in 23 patients after successful balloon angioplasty. Source delivery was successful in 21 of the 23 patients (91%). There was no in-hospital or 30-day morbidity or mortality. Follow-up quantitative coronary arteriography in 20 patients demonstrated a late loss of 0.05 mm, a late loss index of 4%, and a restenosis rate of 15%. The use of the beta-emitter 90Sr/Y significantly reduced treatment time and operator exposure compared with previous trials with the gamma-emitter 192Ir.

CONCLUSIONS

In this study, the administration of endovascular beta-radiation after angioplasty was safe and feasible and substantially altered the postangioplasty late lumen loss, resulting in a lower-than-expected rate of restenosis. On the basis of these encouraging results, a multicenter, randomized trial with operators and patients blinded to treatment assignment is planned.

[Quantification of myocardial ischemia in regions dependent on occluded coronary arteries in patients without previous infarction]

INTRODUCTION AND OBJECTIVES

The aim of this study is to assess myocardial ischemia in regions with no infarction dependent occluded coronary arteries.

PATIENTS AND METHODS

149 patients with proved coronary artery disease and without previous myocardial infarction were studied by 99mTc-MIBI SPECT (long protocol) and coronary angiography. The extent of the uptake reversibility was quantified in 3 regions (antero-septal, inferior and lateral) of the polar maps, assessing the percentage of each region that had a > 10% difference resulting from the rest uptake minus the stress uptake. The regions dependent on one occluded artery were compared to those dependent on non-occluded arteries. In the regions dependent on one occluded artery a comparison was also made between those which had a good collateral circulation and those which did not.

RESULTS

Fifty-four out of 149 patients (36%) had at least one occluded coronary artery (20 anterior descending, 22 right and 27 circumflex coronary arteries). In the visual analysis, reversible defects were observed in all patients with occlusion of the anterior descending and the right coronary artery, but only in half of the occlusions of the circumflex coronary artery. The extent of this reversibility was significantly higher in the regions dependent on occluded arteries and was highly variable, though lower when good collateral circulation was present.

CONCLUSIONS

Reversible defects were always observed in the occlusions of the left anterior descending and right coronary arteries, but only in half of those of the circumflex artery. The extent of the ischemia was higher in the regions dependent on one occluded coronary artery, mainly when there was an absence of good collateral circulation.

A quantitative evaluation of the three dimensional reconstruction of patients' coronary arteries

BACKGROUND

Through extensive training and experience angiographers learn to mentally reconstruct the three dimensional (3D) relationships of the coronary arterial branches. Graphic computer technology can assist angiographers to more quickly visualize the coronary 3D structure from limited initial views and then help to determine additional helpful views by predicting subsequent angiograms before they are obtained.

METHODS

A new computer method for facilitating 3D reconstruction and visualization of human coronary arteries was evaluated by reconstructing biplane left coronary angiograms from 30 patients. The accuracy of the reconstruction was assessed in two ways: 1) by comparing the vessel's centerlines of the actual angiograms with the centerlines of a 2D projection of the 3D model projected into the exact angle of the actual angiogram; and 2) by comparing two 3D models generated by different simultaneous pairs on angiograms. The inter- and intraobserver variability of reconstruction were evaluated by mathematically comparing the 3D model centerlines of repeated reconstructions.

RESULTS

The average absolute corrected displacement of 14,662 vessel centerline points in 2D from 30 patients was 1.64 +/- 2.26 mm. The average corrected absolute displacement of 3D models generated from different biplane pairs was 7.08 +/- 3.21 mm. The intraobserver variability of absolute 3D corrected displacement was 5.22 +/- 3.39 mm. The interobserver variability was 6.6 +/- 3.1 mm.

CONCLUSIONS

The centerline analyses show that the reconstruction algorithm is mathematically accurate and reproducible. The figures presented in this report put these measurement errors into clinical perspective showing that they yield an accurate representation of the clinically relevant information seen on the actual angiograms. These data show that this technique can be clinically useful by accurately displaying in three dimensions the complex relationships of the branches of the coronary arterial tree.

Aggressive lipid lowering in postcoronary angioplasty patients with elevated cholesterol (the Lovastatin Restenosis Trial)

A substudy of the Lovastatin Restenosis Trial in patients with elevated cholesterol (>200 mg/dl) showed no evidence of an effect of aggressive lipid lowering on restenosis, confirming the results of the main trial.

[Methods for coronary functional assessment]

Functional evaluation of coronary vasomotion encompasses the assessment of dynamic changes in coronary lumen, vessel wall, blood flow, intracoronary pressure and myocardial perfusion in response to specific pharmacologic stimuli. These parameters are obtained to characterize mechanisms of physiologic regulation and to evaluate pathophysiologic processes and potential therapeutic strategies, especially with regard to the development of coronary atherosclerosis. To this end, a variety of direct (invasive) and indirect (non-invasive) diagnostic tools are employed. Among the invasive methods are registration of intracoronary Doppler flow, coronary pressure measurements, quantitative coronary angiography and intravascular ultrasound. The non-invasive modalities consist of coronary Doppler echocardiography, positron emission tomography, myocardial scintigraphy and magnetic resonance imaging. Because of the different technical and physiological principles involved, these methods are complementary by providing independent access to different aspects. The combined invasive functional testing as employed in the cardiac catheterization laboratory allows for a simultaneous synopsis of high-resolution coronary imaging and direct measurement of physiologic parameters during local application of defined pharmacologically active substances. However, the demands in terms of equipment, time and operator skills are high and limit this combined invasive approach to specialized centers. Besides these research purposes, a number of functional methods has entered the clinical arena. They are employed to evaluate the hemodynamic significance of coronary lesions and to assess functional outcome of therapeutic interventions in the catheterization laboratory. The underlying principles and applications of the different methods are described and an overview of selected results is presented.

Usefulness of the substitution of nonangiographic end points (death, acute myocardial infarction, coronary bypass and/or repeat angioplasty) for follow-up coronary angiography in evaluating the success of coronary angioplasty in patients with angina pectoris

Historically, restenosis after coronary angioplasty has been assessed angiographically at about 6 months. The desirability of avoiding routine follow-up angiography as well as the recognition that angiographic and clinical assessments are not necessarily the same has prompted greater interest in following patients clinically after angioplasty. Clinical restenosis has been defined as the composite of death, myocardial infarction, coronary surgery, or additional angioplasty within 6 months of the index procedure. Clinical restenosis was observed in 2,340 of 11,473 patients (20.4%). The mortality at 6 months was only 1%. Although there were somewhat more acute myocardial infarctions and coronary surgical procedures, the most frequent event was additional angioplasty. Angiographic restenosis was noted in 30% of patients without clinical restenosis and in 87% of patients with clinical restenosis (p < 0.0001). Patients with clinical restenosis were less likely to be women, had more systemic hypertension, diabetes mellitus, more severe angina originally, fewer prior myocardial infarctions, more multivessel and left anterior descending artery disease, more multisite procedures, more branch site procedures, and longer and tighter stenoses both before and after the procedure. The year of the procedure did not correlate with restenosis. Clinical restenosis is less common than angiographic restenosis and the most common event is additional angioplasty. Although clinical restenosis is rarely fatal, it does result in inconvenience and additional resource consumption.

Relation of systemic arterial pulse pressure to coronary atherosclerosis in patients with mitral stenosis

The relation of a wide systemic arterial pulse pressure to coronary atherosclerosis has not been fully defined. One hundred fifty-nine patients > 40 years old with symptomatic mitral stenosis (MS) who received routine coronary angiography were classified into 2 groups according to the presence of > or = 50% diameter narrowing of > or = 1 coronary artery (n = 48) or no significant disease (n = 111). Pulse pressure was determined both by noninvasive sphygmomanometer and invasive catheterization methods. There were no significant differences in risk factors of coronary artery disease (CAD) or the severity of MS between the 2 groups. From multivariate logistic regression analysis, independent predictors of development of CAD in MS were age (standardized coefficient beta = 1.3437, p = 0.0025), gender (beta = 0.0107, p = 0.0105), mean blood pressure (beta = 1.1839, p = 0.0105), and pulse pressure (beta = 1.3157, p = 0.0008). A wide pulse pressure (> or = 60 mm Hg) correlated with the presence of angiographically significant CAD with a sensitivity and specificity of 88% and 77%. The negative predictive value was 93%. Pulse pressure assessed by sphygmomanometry provided important clinical information. A wide pulse pressure in patients with MS was associated with a high incidence of CAD.

Long-term angiographic and clinical outcome after percutaneous transluminal coronary angioplasty and intracoronary radiation therapy in humans

BACKGROUND

Ionizing radiation has been shown to reduce neointimal formation after balloon angioplasty in experimental models of restenosis. This study was designed to evaluate the feasibility, safety, and effectiveness of intracoronary radiation therapy (ICRT) after percutaneous transluminal coronary angioplasty (PTCA) for preventing restenosis in human coronary arteries.

METHODS AND RESULTS

Twenty-one patients (22 arteries) with unstable angina underwent standard balloon angioplasty. ICRT was performed with the use of an 192Ir source wire that was hand delivered to the angioplasty site. Angiographic follow-up was performed at 24 hours, between 30 and 60 days, and at 6 months. Angioplasty was successful in 19 of 22 lesions, and insertion of the radioactive source wire was successful at all treated sites. Angiographic study at 24 hours demonstrated early late loss of the luminal diameter from 1.92+/-0.55 to 1.40+/-0.27 mm. Between 30 and 60 days, repeat angiography demonstrated total occlusion in 2 arteries, a new pseudoaneurysm in 1 artery, and significant dilatation at the treatment site in 2 additional vessels. At > or = 6 months' follow-up, all remaining arteries (n=20) maintained patent, with a mean lumen diameter of 1.65+/-0.8 mm. The calculated late lumen loss was 0.27+/-0.56 mm, and the late loss index was 0.19. Clinical events at 1 year included myocardial infarction in 1 patient, repeat angioplasty to the treated site in 3 patients, and persistent angina in 7 patients.

CONCLUSIONS

These preliminary results demonstrate that ICRT after coronary intervention is feasible and is associated with an acceptable degree of complications and lower rates of angiographic restenosis indexes.

Intracoronary stent implantation using a single high-pressure perfusion balloon catheter

Currently, the recommended strategy for Palmaz-Schatz intracoronary stent implantation is to use two balloons: an undersized balloon for predilation to facilitate a channel for the stent and a high pressure balloon for postdilation to obtain good apposition of the struts into the vessel wall. We reported our experience using the perfusion balloon as the initial balloon to dilate intracoronary lesions and demonstrated a reduction in the total number of balloons used per angioplasty procedure. The objective of this study was to examine whether a single balloon could effectively be used for stent implantation. The study population included 95 patients who underwent elective intracoronary stent placement to 100 lesions using 110 Palmaz-Schatz stents by nine individual operators. Lesions were predilated with an ACS RX LIFESTREAM balloon at a low pressure of 4-6 atm (mean 5.7 +/- 2.6). After stent deployment, the same balloon was used at a high pressure (mean 16.2 +/- 1.2). Mean balloon size, which was chosen as the stent size, was 3.4 +/- 0.4 mm. Comparison of this strategy with the recommended strategy of 68 consecutive elective stent deployments at a single center during the same time was performed. Stent implantation using a single balloon strategy was angiographically successful in 99 of 100 (99.0%) lesions. The single balloon strategy was associated with a balloon burst rate of 9.1%. The number of balloons used per stent deployment was 1.2 vs. 2.4 using the recommended strategy (P < 0.0001). There was no evidence of stent thrombosis, any MI, or target lesion revascularization during the procedure and hospitalization. One in-hospital death as a result of nonhemorrhagic stroke was documented in the treated group. We concluded that using a single high pressure perfusion balloon for pre and postdilation in patients undergoing elective stent placement is safe and reduces the number of balloons used per procedure.