Evolution of coronary atherosclerosis in patients with mild coronary artery disease studied by serial quantitative coronary angiography at 2 and 4 years follow-up. The Multicenter Anti-Atheroma Study (MAAS) Investigators

AIMS

Angiographic studies on the natural course of both focal and diffuse coronary atherosclerosis have not been performed before, but can both be assessed by quantitative coronary angiography. The objective of this study was to describe the natural course of focal and diffuse coronary atherosclerosis over time.

METHODS AND RESULTS

In 129 patients with mild coronary artery disease, but not on lipid-lowering medication, three coronary angiograms were made each 2 years apart. Nine hundred and sixty five angiographically diseased and non-diseased segments were analysed by quantitative coronary angiography. Mean lumen diameter and minimal lumen diameter were used as measures of diffuse and focal coronary atherosclerosis. Mean lumen diameter and minimum lumen diameter decreased by 0.02 and 0.03 mm per year. The rate of progression was similar in the angiographically non-diseased, as in the mildly and moderately diseased segments. Progression of diffuse coronary atherosclerosis was largest in severely stenosed lesions (percentage diameter stenosis > or = 50%) and in the right coronary artery with a loss of 0.19 mm and 0.16 mm in mean lumen diameter. Progression of focal disease was most prominent in new and mild lesions and the right coronary artery, with a decrease in minimum lumen diameter of 0.34 mm and 0.22 mm. In most subgroups, progression occurred gradually over time. On a per segment level, progression and the occurrence of new lesions occurred in 4.4% and 4.2%. Regression and disappearance of a lesions was found in 2.3% and 1.9%. On a per patient level, 36% were progressors, 12% had a mixed response, 36% were stable, and 16% were regressors.

CONCLUSION

Diffuse and focal coronary atherosclerosis progressed at the same rate in the first and second 2 years in stenosed and non-stenosed segments. The rate of coronary atherosclerosis progression was small, but was higher for focal than for diffuse disease. A minority of lesions progressed and spontaneous regression was rare.

Simpson's rule for the volumetric ultrasound assessment of atherosclerotic coronary arteries: a study with ECG-gated three-dimensional intravascular ultrasound

BACKGROUND

Volumetric intravascular ultrasound (IVUS) assessment provides complementary information on atherosclerotic plaques. The volumes can be calculated by applying Simpson's rule to cross-sectional area data of multiple IVUS images, acquired with a fixed sample spacing, which is the distance (along the vessel's axis) between two images.

OBJECTIVE

To evaluate the effect of different sample spacings on the results of volumetric IVUS measurements.

METHODS

A stepwise electrocardiographically gated IVUS image-acquisition and automated three-dimensional analysis approach was applied to 26 patients. Twenty-eight coronary segments with mild-to-moderate coronary atherosclerosis were examined. Volumetric measurements of five images per mm (i.e. sample spacing 0.2 mm), representing a complete scanning of the coronary segment, were considered the optimal standard, against which volumetric measurements of three, one, and one-half images per mm (i.e. larger sample spacings) were compared.

RESULTS

The lumen, total vessel, and plaque volumes obtained with five images per mm were 183.3 +/- 2.8, 350.6 +/- 141.6, and 167.3 +/- 89.2 mm3. There was an excellent correlation (r = 0.99, P < 0.001) between these data and volumetric measurements with larger sample spacings. The volumetric measurements with larger sample spacings differed on average only by a little (< 0.7%) from the optimal standard measurements. However, a relatively small, but significant, increase in SD of these differences was associated with the wider sample spacings (< 3.6%, P < 0.05).

CONCLUSIONS

The width of the sample spacing has a relatively small but significant impact on the variability of volumetric intravascular ultrasound measurements. This should be considered when designing future volumetric studies. The electrocardiographically gated acquisition of five IVUS images per mm axial length during a stepwise transducer pull-back is an ideal approach, particularly when addressing with IVUS volumetric changes that are assumed small, such as those expected in studies of the progression and regression of atherosclerosis.

Atherosclerotic changes in the carotid artery bulb as measured by B-mode ultrasound are associated with the extent of coronary atherosclerosis

BACKGROUND AND PURPOSE

Ultrasound is increasingly used to measure atherosclerotic development in carotid and femoral arteries. The aim of this study was to investigate the relationship between coronary atherosclerosis as measured by quantitative angiography and peripheral atherosclerosis as measured by ultrasound in three different arterial regions.

METHODS

Patients (n = 32) with at least two coronary segments with visible signs of atherosclerosis as defined in a computer-assisted analysis of coronary angiograms were also examined with B-mode ultrasound. The extent of coronary atherosclerosis was expressed as the average diameter stenosis of coronary segments, and peripheral atherosclerosis was defined as intima-media thickness (IMT) and plaque occurrence in the common carotid artery, the carotid bulb, and the common femoral artery.

RESULTS

The results showed a significant correlation between the ultrasound measurement of IMT of the carotid bulb and diameter stenosis of the included coronary segments (r = .68, P = .01) and of carotid plaques and diameter stenosis (P < .001). The correlation between common carotid IMT and diameter stenosis of included coronary segments was not statistically significant (r = .31, NS). There were no significant relationships between common femoral IMT or femoral plaques and diameter stenosis of included coronary segments.

CONCLUSIONS

Although this study is small, it points to a very important aspect of ultrasound measurements of atherosclerosis: measurements performed in the common carotid artery or the femoral artery may not relate to coronary atherosclerosis in the same way as measurements performed in the carotid bulb. The findings underline the importance of measuring IMT not only in the common carotid artery but also in the carotid bulb and present data separately. These results have to be confirmed in a larger-scale study.

Is quantitative angiography sufficient to guide stent implantation? A comparison with three-dimensional reconstruction of intracoronary ultrasound images

Intracoronary ultrasound (ICUS) frequently reveals stent underexpansion despite a satisfactory angiographic result by visual assessment. Whether on-line quantitative coronary angiography (QCA) alone can guide optimal stent deployment is still unknown. The aim of the study was to assess the usefulness of quantitative coronary angiography in the evaluation of optimal stent expansion, confirmed with a new on-line system of 3-D reconstruction of ICUS. The results obtained with 3-D ICUS were compared with the measurements achieved with QCA analyses in 49 patients (70 stents: 31 Palmaz-Schatz, 22 Wallstent, 7 Cordis, 6 Micro-stent, 2 Gianturco-Roubin, 2 Multi-Link). Following delivery of the stent, high pressure intrastent balloon inflation (14.2 +/- 3.3 atmospheres) was performed in all 70 stents. Optimal stent implantation by QCA was defined as minimal lumen diameter post-stenting > or = 90% of the reference diameter preintervention. Percent diameter stenosis (% DS) post-stenting was defined as minimal lumen diameter divided by the reference diameter post-stenting. The on-line 3-D ICUS reconstructions and measurements were performed processing the images on-line in the catheterization laboratory with an automated contour detection algorithm based on acoustic quantification. ICUS criteria for optimal stent expansion were defined as: 1) complete apposition of stent struts to vessel wall; 2) minimal stent lumen cross-sectional area > or = 80% of the average lumen area of the proximal and distal reference segments; 3) symmetry index (minimum divided by maximum lumen diameter) > 0.7. Ninety-seven percent of the deployed stents met the QCA criteria. Whilst 3-D ICUS documented complete stent apposition to the vessel wall in all cases and a symmetric expansion in 65 of 70 lesions (93%), the stent minimal lumen area was > or = 80% only in 30 out of 70 stents (43%). The diagnostic sensitivity and specificity at 10% residual diameter stenosis provided by QCA for optimal stent expansion compared to 3-D ICUS criteria were 86 and 45%, respectively. In conclusion 3-D ICUS criteria of adequate stent expansion were achieved only in 43% of patients despite the application of aggressive strategies of stent deployment leading to optimal results with quantitative angiography. Ten percent residual diameter stenosis provided by QCA may be an acceptable alternative for optimal stent deployment in clinical practice. The clinical benefit of an ICUS guided approach of stent deployment and of a lower cost strategy using on-line QCA guidance should be compared in large prospective randomized studies.

Is intravascular ultrasound after coronary stenting a safe procedure? Three cases of stent damage attributable to ICUS in a tantalum coil stent

The use of coronary stents decreases the morbidity associated with acute closure and restenosis after balloon angioplasty. Intracoronary ultrasound (ICUS) guidance of stent implantation has been advocated to improve stent deployment and thereby to further improve the clinical outcome after stenting, over and above balloon angioplasty. Whereas the merits of intracoronary ultrasound in this respect still remain to be proven, the present paper illustrates that ICUS itself may also entail complications. This paper reports on three cases of stent damage induced or aggravated by the ICUS procedure.

True reconstruction of vessel geometry from combined X-ray angiographic and intracoronary ultrasound data

At present a rapidly expanding variety of methods appear to provide three-dimensional (3-D) reconstructions of blood vessels in a patient. Generally the results of such methods look very realistic. However, only a few produce a true 3-D reconstruction. We strongly suggest that for a true 3-D reconstruction of a blood vessel the following criteria should at least be fulfilled: (1) the arterial wall rather than the lumen must be reconstructed; (2) the spatially curved course of the vessel must be included; and (3) the orientation of local vessel wall characteristics, for example, plaque eccentricity, with respect to the luminal course must be correctly maintained. Currently, only methods combining biplane X-ray angiography and intravascular ultrasound imaging (IVUS) have succeeded in providing true 3-D reconstruction of a segment of a vessel. Accuracy of those reconstructions is derived from studies using phantoms having precisely known geometry. In patients, data on accuracy are more difficult to obtain. Nevertheless, a comparison can be made between the actual length of an IVUS pull-back trajectory and its reconstructed length showing relative differences of less than 3%. Further knowledge can be obtained by comparing simulated angiograms derived from the 3-D reconstruction with the real contrast angiograms. True 3-D reconstruction methods of the vessel wall and lumen, applicable in the individual patient, have become feasible and produce accurate results. Application of such a method will be helpful to understand immediate and long-term vessel remodelling induced by all types of catheter interventions and in the study of progression or regression of atherosclerotic wall disease.

Computerized assessment of coronary lumen and atherosclerotic plaque dimensions in three-dimensional intravascular ultrasound correlated with histomorphometry

Intravascular ultrasound (IVUS), which depicts both lumen and plaque, offers the potential to improve on the limitations of angiography for the assessment of the natural history of atherosclerosis and progression or regression of the disease. To facilitate measurements and increase the reproducibility of quantitative IVUS analyses, a computerized contour detection system was developed that detects both the luminal and external vessel boundaries in 3-dimensional sets of IVUS images. To validate this system, atherosclerotic human coronary segments (n = 13) with an area obstruction > or = 40% (40% to 61%) were studied in vitro by IVUS. The computerized IVUS measurements (areas and volumes) of the lumen, total vessel, plaque-media complex, and percent obstruction were compared with findings by manual tracing of the IVUS images and of the corresponding histologic cross sections obtained at 2-mm increments (n = 100). Both area and volume measurements by the contour detection system agreed well with the results obtained by manual tracing, showing low mean between-method differences (-3.7% to 0.3%) with SDs not exceeding 6% and high correlation coefficients (r = 0.97 to 0.99). Measurements of the lumen, total vessel, plaque-media complex, and percent obstruction by the contour detection system correlated well with histomorphometry of areas (r = 0.94, 0.88, 0.80, and 0.88) and volumes (r = 0.98, 0.91, 0.83, and 0.91). Systematic differences between the results by the contour detection system and histomorphometry (29%, 13%, -9%, and -22%, respectively) were found, most likely resulting from shrinkage during tissue fixation. The results of this study indicate that this computerized IVUS analysis system is reliable for the assessment of coronary atherosclerosis in vivo.

Excimer laser angioplasty versus balloon angioplasty in functional and total coronary occlusions

Registries of excimer laser coronary angioplasty have reported good results in the treatment of complex coronary artery disease, including total or subtotal coronary occlusions. One hundred three patients (103 lesions) with a functional or total coronary occlusion were included in a randomized trial (Amsterdam-Rotterdam [AMRO] trial, total of 308 patients), 49 patients were allocated to laser angioplasty and 54 patients to balloon angioplasty. The primary clinical end points were death, myocardial infarction, coronary bypass surgery, or repeated coronary angioplasty of the randomized segment during a 6-month follow-up period. The primary angiographic end point was the minimal lumen diameter at follow-up in relation to the baseline value (net gain), as determined by an automated contour-detection algorithm. Laser angioplasty was followed by balloon angioplasty in all procedures. The angiographic success rate was 65% in patients treated with excimer laser-assisted balloon angioplasty compared with 61% in patients treated with balloon angioplasty alone. No deaths occurred. There were no significant differences between the laser angioplasty group and the balloon angioplasty group in the incidence of myocardial infarctions (1 patient vs 3, respectively, p = 0.36), coronary bypass surgery (4 patients vs 2, respectively, p = 0.34), repeat angioplasty (10 patients vs 8, respectively, p = 0.46) or primary clinical end point (15 patients vs 12, respectively, p = 0.34). The net gain in minimal lumen diameter and restenosis rate (>50% diameter stenosis at follow-up) were 0.81 +/- 0.74 mm and 66.7%, respectively, in patients treated with laser angioplasty compared with 1.04 +/- 0.68 mm and 48.5%, respectively, in patients treated with balloon angioplasty (p = 0.59 and p = 0.15, respectively). Excimer laser-assisted balloon angioplasty demonstrated no benefit over balloon angioplasty with respect to initial and long-term clinical and angiographic outcome in the treatment of patients with functional or total coronary occlusions of >10 mm in length.

Significance of automated stenosis detection during quantitative angiography. Insights gained from intracoronary ultrasound imaging

BACKGROUND

Automated stenosis analysis is a common feature of commercially available quantitative coronary angiography (QCA) systems, allowing automatic detection of the boundaries of the stenosis, interpolation of the expected dimensions of the coronary vessel at the point of obstruction, and angiographically derived estimation of atheromatous plaque size. However, the ultimate meaning of this type of analysis in terms of the degree of underlying atherosclerotic disease remains unclear. We investigated the relationship between stenosis analysis performed with QCA and the underlying degree of atherosclerotic disease judged by intracoronary ultrasound (ICUS) imaging.

METHODS AND RESULTS

In 40 coronary stenoses, automated identification of the sites of maximal luminal obstruction and the start of the stenosis was performed with QCA by use of curvature analysis of the obtained diameter function. Plaque size at these locations also was estimated with ICUS, with an additional ICUS measurement immediately proximal to the start of the stenosis. Crescentlike distribution of plaque, indicating an atheroma-free arc of the arterial wall, was recorded. At the site of the obstruction, total vessel area measured with ICUS was 16.65 +/- 4.04 mm2, whereas an equivalent measurement obtained from QCA-interpolated reference dimensions was 7.48 +/- 3.30 mm2 (P = .0001). Plaque area derived from QCA data was significantly less than that calculated from ICUS (6.32 +/- 3.21 and 13.29 +/- 4.22 mm2, respectively; mean difference, 6.92 +/- 4.43 mm2; P = .0001). At the start of the stenosis identified by automated analysis, ICUS plaque area was 9.38 +/- 3.17 mm2, and total vessel area was 18.77 +/- 5.19 mm2 (50 +/- 11% total vessel area stenosis). The arterial wall presented a disease-free segment in 28 proximal locations (70%) but in only 5 sites (12%) corresponding to the start of the stenosis and none at the obstruction (P = .0001). At the site of obstruction, all vessels showed a complete absence of a disease-free segment, and the atheroma presented a cufflike or all-around distribution with a variable degree of eccentricity.

CONCLUSIONS

At the site of maximal obstruction, QCA underestimated plaque size as measured with ICUS. Atherosclerotic disease was consistently present at the start of the stenosis and was used as a reference site by automated stenosis analysis. At the start of the stenosis, ICUS demonstrated a mean 50 +/- 11% total vessel area stenosis, with a characteristic loss of disease-free arcs of arterial wall present in proximal locations. Thus, the site identified by automated stenosis analysis as the start of the stenosis does not represent a disease-free site but rather the place where compensatory vessel enlargement fails to preserve luminal dimensions, a phenomenon that seems related to the observed loss of a remnant arc of normal arterial wall.

Quantification of the minimal luminal cross-sectional area after coronary stenting by two- and three-dimensional intravascular ultrasound versus edge detection and videodensitometry

The use of 2-dimensional intravascular ultrasound (2-D IVUS) to improve the outcome of coronary stenting has gained clinical acceptance, and recently 3-D IVUS has been introduced to clinical practice. However, there have been no comprehensive studies comparing the measurements of the coronary dimensions after stenting obtained by the different approaches of IVUS and quantitative coronary angiography. We examined the minimal luminal cross-sectional area of 38 stents using 2-D IVUS, 3-D IVUS, and 2 standard methods of quantitative coronary angiography, edge detection (ED) and videodensitometry (VD). Correlations between 2-D IVUS and ED (r = 0.72; p < 0.0001), VD (r = 0.87; p < 0.0001), and 3-D IVUS (r = 0.81; p < 0.0001) were higher than the correlations seen between 3-D IVUS and ED (r = 0.58; p < 0.0005) and VD (r = 0.70; p < 0.0001). The measurements by 2-D and 3-D IVUS (8.32 +/- 2.50 mm2 and 8.05 +/- 2.66 mm2) were larger than the values obtained by the quantitative angiographic techniques ED and VD (7.55 +/- 2.22 mm2 and 7.27 +/- 2.21 mm2). Thus, concordance was seen among all of the 4 techniques, confirming the validity of using IVUS for determination of the minimal luminal cross-sectional area after coronary stenting. A particularly good correlation was found between VD and IVUS, perhaps because measurement of the luminal area is the basic quantification approach of both techniques, whereas the lower correlations of ED with IVUS and VD may be explained by the dependence of ED on the angiographic projections used, which is especially important in eccentric stent configurations.

Morphometric analysis in three-dimensional intracoronary ultrasound: an in vitro and in vivo study performed with a novel system for the contour detection of lumen and plaque

Currently, automated systems for quantitative analysis by intracoronary ultrasound (ICUS) are restricted to the detection of the lumen. The aim of this study was to determine the accuracy and reproducibility of a new semiautomated contour detection method, providing off-line identification of the intimal leading edge and external contour of the vessel in three-dimensional ICUS. The system allows cross-sectional and volumetric quantification of lumen and of plaque. It applies a minimum-cost algorithm and the concept that edge points derived from previously detected longitudinal contours guide and facilitate the contour detection in the cross-sectional images. A tubular phantom with segments of various luminal dimensions was examined in vitro during five catheter pull-backs (1 mm/sec), and subsequently 20 diseased human coronary arteries were studied in vivo with 2.9F 30 MHz mechanical ultrasound catheters (200 images per 20 mm segment). The ICUS measurements of phantom lumen area and volume revealed a high correlation with the true phantom areas and volumes (r = 0.99); relative mean differences were -0.65% to 3.86% for the areas and 0.25% to 1.72% for the volumes of the various segments. Intraob-server and interobserver comparisons showed high correlations (r = 0.95 to 0.98 for area and r = 0.99 for volume) and small mean relative differences (-0.87% to 1.08%), with SD of lumen, plaque, and total vessel measurements not exceeding 7.28%, 10.81%, and 4.44% (area) and 2.66%, 2.81%, and 0.67% (volume), respectively. Thus the proposed analysis system provided accurate measurements of phantom dimensions and can be used to perform highly reproducible area and volume measurements in three-dimensional ICUS in vivo.

Women fare no worse than men 10 years after attempted coronary angioplasty

A retrospective review of cardiac events occurring in all patients who underwent attempted coronary angioplasty in the first 5 years of our experience (1980-1985) was undertaken. Follow-up data were obtained from the civil registry, hospital records, patient, family, and referring physician. Patient survival curves were constructed and the outcome of women and men was compared. Eight hundred fifty-six patients, 172 women and 684 men with a mean age of 60.0 and 55.3 years, respectively, underwent attempted coronary angioplasty with an overall procedural success rate of 82%, 77.7% in women and 83.1% in men. Follow-up data were obtained in 837 patients (97.8%) with a mean period of 9.6 years (range 0-13.3 years). The estimated 10 year survival in women was identical to men [79%, 95% confidence interval (CI) 72.6-85.4% vs. 78%, 95% CI 74.6-81.4%] as was the 10 year event-free survival (men 36%, 95% CI 32.0-40.0% vs. women 37%, 95% CI 29.2-44.8%), with a similar proportion of major cardiac events-death, myocardial infarction, coronary artery bypass surgery, and repeat angioplasty. When women were matched to men for age and previous myocardial infarction, factors found to be associated with an adverse outcome, there was no significant difference. Additionally, outcome was compared after patients were matched for maximum nominal balloon size as an estimate of vessel size, with no significant difference between women and men. At follow-up, women complained of significantly more anginal symptoms than men (59.2% vs. 44.0%, P < 0.05) and took significantly more antianginal medication.

Clinical outcome 10 years after attempted percutaneous transluminal coronary angioplasty in 856 patients

OBJECTIVES

This study reports the 10-year outcome of 856 consecutive patients who underwent attempted coronary angioplasty at the Thoraxcenter during the years 1980 to 1985.

BACKGROUND

Coronary balloon angioplasty was first performed in 1977, and this procedure was introduced into clinical practice at the Thoraxcenter in 1980. Although advances have been made, extending our knowledge of the long-term outcome in terms of survival and major cardiac events remains of interest and a valuable guide in the treatment of patients with coronary artery disease.

METHODS

Details of survival, cardiac events, symptoms and medication were retrospectively obtained from the Dutch civil registry, medical records or by letter or telephone or from the patient's physician and entered into a dedicated data base. Patient survival curves were constructed, and factors influencing survival and cardiac events were identified.

RESULTS

The procedural clinical success rate was 82%. Follow-up information was obtained in 837 patients (97.8%). Six hundred forty-one patients (77%) were alive, of whom 334 (53%) were symptom free, and 254 (40%) were taking no antianginal medication. The overall 5- and 10-year survival rates were 90% (95% confidence interval [CI] 87.6% to 92.4%) and 78% (95% CI 75.0% to 81.0%), respectively, and the respective freedom from significant cardiac events (death, myocardial infarction, coronary artery bypass surgery and repeat angioplasty) was 57% (95% CI 53.4% to 60.6%) and 36% (95% CI 32.4% to 39.6%). Factors that were found to adversely influence 10-year survival were age > or = 60 years (> or = 60 years [67%], 50 to 59 years [82%], < 50 years [88%]), multivessel disease (multivessel disease [69%], single-vessel disease [82%]), impaired left ventricular function (ejection fraction < 50% [57%], > or = 50% [80%]) and a history of previous myocardial infarction (previous myocardial infarction [72%], no previous infarction [83%]). These factors were also found to be independent predictors of death during the follow-up period by a multivariate stepwise logistic regression analysis. Other factors tested, with no influence on survival, were gender, procedural success and stability of angina at the time of intervention.

CONCLUSIONS

The long-term prognosis of patients after coronary angioplasty is good, particularly in those <60 years old with single-vessel disease and normal left ventricular function. The majority of patients are likely to experience a further cardiac event in the 10 years after their first angioplasty procedure.

Utilization of translesional hemodynamics: comparison of pressure and flow methods in stenosis assessment in patients with coronary artery disease

Aim of this study is the assessment of feasibility and clinical usefulness of a new index of stenosis severity, the slope of the instantaneous transstenotic pressure gradient/velocity relationship. Twenty-one patients scheduled for percutaneous revascularization procedures were studied with simultaneous measurement of poststenotic coronary pressure and flow velocity, in basal condition and during maximal hyperemia induced with intracoronary papaverine. Reliable measurements of the transstenotic pressure gradient/velocity relationship could be obtained in 11 patients. In 64% of the cases, a quadratic equation showed the best fit for the data. Steeper increases of the transstenotic pressure gradient at any given velocity increase were observed in the lesions with the smallest cross-sectional area measured with quantitative angiography. A comparison of this new index with coronary flow reserved, maximal hyperemic velocity, stenosis flow reserve derived from quantitative angiography, basal and hyperemic transstenotic pressure gradient and fractional flow reserve is presented and the relative merits of all these parameters are discussed. This pilot experience suggests that the instantaneous relationship between pressure gradient and flow velocity changes during the cardiac cycle can accurately characterize the stenosis hemodynamics in the catheterization laboratory.

Optimized expansion of the Wallstent compared with the Palmaz-Schatz stent: on-line observations with two- and three-dimensional intracoronary ultrasound after angiographic guidance

Optimized stent expansion by high-pressure inflations of oversized balloons has initially been derived from experience obtained with the Palmaz-Schatz stent, whereas there is little experience with this strategy in the Wallstent. By using this approach with quantitative coronary angiographic guidance, 20 Wallstents and 20 Palmaz-Schatz stents were implanted in 34 patients and consecutively examined by conventional two-dimensional (2D) intracoronary ultrasound (ICUS) and three-dimensional (3D) ICUS on the basis of the application of a pattern recognition algorithm. Ultrasound criteria of adequate stent expansion were defined as a complete apposition of the stent to the vessel wall, a stent symmetry index (SSI = minimum/maximum lumen diameter) > or = O.7, and a stent-reference lumen area ratio (SRR = Minimum intrastent lumen area/Average of proximal and distal reference lumen area) > or = O.8. In all cases a smooth angiographic lumen and a negative diameter stenosis, on the basis of a distal reference, was achieved. For the Wallstents ICUS showed a higher SSI (2D, 0.95 +/- 0.04 vs 0.85 +/- 0.09; p < 0.001; 3D, 0.90 +/- 0.09 vs 0.82 +/- 0.11, p < 0.05) and a lower SRR (2D, 0.66 +/- 0.12 vs 0.81 +/- 0.13, p < 0.005; 3D, 0.63 +/- 0.14 vs 0.74 +/- 0.15, p < 0.05) than for the Palmaz-Schatz stents. Ninety percent of failure in meeting these criteria resulted from a low SRR. The incidence of incomplete stent apposition (one in both stents) or SSI <0.7 was low and generally associated with an SRR <0.8. The Wallstents met the ICUS criteria less often (2D, 2(1O%) vs 10(50%), p < 0.01; 3D, 3(15%) vs 9(45%), p < 0.05), were significantly longer (35.1 +/- 7.7 mm and 14.3 +/- 3.3 mm, p < 0.0001), and generally demonstrated a larger vessel tapering, measured as proximal minus distal ICUS reference lumen area (1.33 +/- 2.91 mm2 vs 0.44 +/- 1.97 mm(2), not significant). Wallstents meeting the ICUS criteria, however, showed less vessel tapering (0.18 +/- 1.64 mm(2)). Thus optimized stent expansion was followed by excellent angiographic results for both Palmaz-Schatz and Wallstent. Although angiographic results and visual assessment of the ICUS examination suggested a good outcome, few Wallstents met the ICUS criteria in contrast to the Palmaz-Schatz stents. The low value of the SRR in the Wallstents is likely to be caused by vessel tapering, suggesting that this criterion may be unsuitable in assessing the adequacy of the expansion of relatively long stents such as the Wallstent.

The laser guidewire experience: 'crossing the Rubicon'

Despite continued improvements in mechanical hardware for coronary angioplasty, chronic total occlusions (CTO) remain a true challenge in the field of interventional cardiology. Therefore, new guidewire technology, which made use of the unique forward debulking properties of excimer laser light, was designed and introduced into clinical practice in 1993. After an initial pilot-study phase, a European Multicenter Surveillance Study was initiated to evaluate the performance of the new laser guidewire. A short overview is given of the incidence of CTO. The limitations of the percutaneous treatment with various mechanical guidewires and the clinical and angiographic follow-up of CTO are discussed. Furthermore, the initial experience with the laser guidewire during the pilot-phase and preliminary results of the European Multicenter Surveillance Study are presented. At the introduction of yet another new (and costly) device, the key question is: 'Yes, but does it allow us to expand the battle field of interventional cardiology?'

Repeat interventions as a long-term treatment strategy in the management of progressive coronary artery disease

OBJECTIVES

This study investigates whether repeat coronary interventions, applied over an extended time period, can successfully curtail the progression of ischemic symptoms and angiographic lumen narrowing.

BACKGROUND

Coronary artery disease is a chronic and generally progressive disorder, and potential treatment strategies should be examined and compared with this chronicity in mind. Percutaneous interventional revascularization procedures could theoretically be useful in controlling progression of the disease through repeated use as new coronary lesions arise. However, the outcome of this long-term management concept has not previously been subjected to detailed investigation.

METHODS

From a consecutive series of 4,357 interventional cardiac procedures, 544 patients were identified who received two or more interventions during the 13-year study period. These patients were categorized into one of three groups: restenosis (repeat interventions limited to the same target segment, n = 261), new stenosis (all repeat interventions directed to stenoses not previously treated, n = 155) or both (repeat interventions directed both to the same and to different target lesions, n = 128).

RESULTS

Two to five procedures were performed per patient; the time period (mean +/- SD) separating each procedure was significantly less (p < 0.0001) for the restenosis group (4.2 +/- 2.3 months) than for the new stenosis (24.2 +/- 23.5 months) or the "both" groups (11.4 +/- 11.0 months). Despite the need for repeat procedures, the severity of angina (mean New York Heart Association functional class 1.6 +/- 0.9) after 6.2 +/- 2.3 years of follow-up was substantially better than before the initial procedure (mean functional class 3.2 +/- 0.8), with a similar magnitude of change found in all three groups. This long-term functional improvement was mirrored by a corresponding anatomic improvement, with the mean number of diseased vessels remaining constant at the time of each procedure (1.5 +/- 0.7, 1.5 +/- 0.7 and 1.6 +/- 0.7, respectively, for the first, second and third procedures, p = NS). The restenosis and the new stenosis groups also demonstrated statistically similar annual rates of mortality (1.9% vs. 1.8%) and coronary surgery (2.3% vs. 2.6%), although the restenosis group had a lower rate of infarction (1.4% vs. 3.2%, p = 0.002).

CONCLUSIONS

Repeat interventional treatment of newly acquired stenoses provides a rational approach for the long-term management of chronic coronary artery disease. In addition to yielding a favorable late outcome, the use of this strategy can result in sustained functional improvement and can check the progression of clinically significant stenoses.

Usefulness of on-line three-dimensional reconstruction of intracoronary ultrasound for guidance of stent deployment

The additional information provided by automated on-line 3-dimensional (3-D) reconstruction of intracoronary ultrasound (ICUS) was assessed in 42 patients (62 stents) who underwent stent deployment after achieving an optimal quantitative angiographic result. In 10 of 42 patients, 3-D ICUS was also performed before stenting. ICUS images of stents and adjacent reference segments were acquired by using a motorized pullback at a constant speed (1 mm/s) and immediately processed in the catheterization laboratory. Optimal stent expansion was detected by 3-D ICUS in case of complete apposition of stent struts to the vessel wall. Furthermore, an attempt was made to maximize the intrastent lumen area to match lumen area of the reference segment and to cover with stents all the segments with residual significant lesions (plaque burden >50%). Three-dimensional automated reconstruction of ICUS was successful in 8 of 10 patients (80%) before, and in 36 of 42 patients (86%) after stent deployment. In all 8 patients who underwent successful 3-D ICUS assessment before stent implantation, the selection of stent length was facilitated by accurately measuring the lesion length. After stenting, 3-D ICUS modified the management strategy in 21 of 36 patients (58%), triggering additional high-pressure dilatations in 13 patients (36%) and additional stent deployment in 8 (22%). In conclusion, on-line 3-D ICUS facilitates stent selection and strongly modifies the revascularization strategy by accurately detecting stent underexpansion and presence of uncovered lesions.

Randomised trial of excimer laser angioplasty versus balloon angioplasty for treatment of obstructive coronary artery disease

BACKGROUND

Excimer laser coronary angioplasty is reported to give excellent procedural results for treatment of complex coronary lesions, but this method has not been compared with balloon angioplasty in a randomised trial.

METHODS

Patients (n = 308) with stable angina and coronary lesions longer than 10 mm on visual assessment were included. 151 patients (158 lesions) were assigned randomly to laser angioplasty and 157 (167 lesions) to balloon angioplasty. The primary clinical endpoints were death, myocardial infarction, coronary bypass surgery, or repeat coronary angioplasty of the randomised segment during 6 months of follow-up. The primary angiographic endpoint was the minimal lumen diameter at follow-up in relation to the baseline value (net gain), as determined by quantitative coronary angiography.

FINDINGS

Laser angioplasty was followed by balloon angioplasty in 98% of procedures. The angiographic success rate was 80% in patients treated with laser angioplasty compared with 79% in patients treated with balloon angioplasty. There were no deaths. Myocardial infarction, coronary bypass surgery, and repeat angioplasty occurred in 4.6%, 10.6%, and 21.2%, respectively, of the patients in the laser angioplasty group compared with 5.7%, 10.8%, and 18.5% of the balloon angioplasty group. Net mean (SD) gain in minimal lumen diameter was 0.40 (0.69) mm in patients treated with laser angioplasty and 0.48 (0.66) mm in those treated with balloon angioplasty (p = 0.34). The restenosis rate (> 50% diameter stenosis) was 51.6% in the laser angioplasty group versus 41.3% in the balloon angioplasty group (p = 0.13).

INTERPRETATION

Excimer laser angioplasty followed by balloon angioplasty provides no benefit additional to balloon angioplasty alone with respect to the initial and long-term clinical and angiographic outcome in the treatment of obstructive coronary artery disease.

Volumetric intracoronary ultrasound: a new maximum confidence approach for the quantitative assessment of progression-regression of atherosclerosis?

Quantitative assessment of atherosclerosis during its natural history and following therapeutic interventions is important, as cardiovascular disease remains the most significant cause of morbidity and mortality in industrial societies. While coronary angiography delineates the vessel lumen, permitting only the indirect determination of atherosclerotic wall changes encroaching upon the lumen, intracoronary ultrasound permits direct plaque assessment and quantification. The angiographic percent diameter stenosis, previously suggested as measure of a maximum confidence approach, is still commonly used to quantify stenosis severity, but the reference segments which are required for angiographic interpolation of the normal vessel dimensions are frequently involved in the general process of atherosclerosis, including progression or regression. Considering also the variability of vascular remodeling during the evolution of atherosclerosis, including compensatory enlargement and paradoxical arterial shrinkage, intracoronary ultrasound appears currently to be the only reliable technique to measure plaque burden and progression or regression of atherosclerosis. However, correct matching of the site of measurement at follow-up with the site of the initial ultrasound study is often difficult to achieve, but is significantly facilitated by the use of volumetric intracoronary ultrasound. This approach permits not only area measurement, but also measurement of plaque volume, which appears to be the ideal measure for quantifying the atherosclerotic plaque, as it is highly reproducible and directly reflects the changes of an entire arterial segment.

Antiplatelet therapy in therapy-resistant unstable angina. A pilot study with REO PRO (c7E3)

Patients with unstable angina, refractory to intensive medical therapy, are at high risk of developing thrombotic complications, such as myocardial infarction and coronary occlusion during coronary angioplasty. As platelet aggregation and thrombus formation play an important role in this ongoing ischaemic process, a monoclonal platelet GPIIb/IIIa receptor antibody (c7E3) has been designed to modify the clinical course and underlying coronary lesion morphology. To evaluate whether c7E3 could influence the incidence of complications, we randomized 60 patients to c7E3 or placebo after initial angiography had demonstrated a culprit lesion amenable for angioplasty. All patients exhibited dynamic ECG changes and recurrent pain attacks, despite intensive medical therapy. After study drug bolus and infusion, angiography was repeated and angioplasty performed. Recurrent ischaemia during study drug infusion occurred in nine and 16 patients from the c7E3 and placebo groups, respectively (P = 0.06). Major events defined as death, myocardial infarction or urgent intervention occurred in one and seven patients, respectively (P = 0.03). One patient from the placebo group died as a result of recurrent infarction. Resolution of clots was only observed in the c7E3 group, combined with improvement in TIMI flow grade in 20% of patients. Quantitative angiography showed an improvement in percentage diameter stenosis in the c7E3 group, which was not observed in the placebo group, although the difference between the two treatment groups was not significant. No excess bleeding was observed in the treatment group. Thus, c7E3 bolus and infusion, combined with heparin and aspirin improved the clinical course, the coronary lesion morphology and rheology in patients with unstable angina, refractory to medical treatment.

Coronary intervention: risk stratification and management of abrupt coronary occlusion

Balloon angioplasty is associated with an often unpredictable risk of abrupt coronary occlusion, which is the leading cause of in-hospital death and myocardial infarction. Clinical, angiographic and lesion variables predictive of risk of abrupt occlusion are reviewed and a low, medium and high risk profile stratification is developed. Current management of abrupt occlusion is discussed.

Differences in restenosis propensity of devices for transluminal coronary intervention. A quantitative angiographic comparison of balloon angioplasty, directional atherectomy, stent implantation and excimer laser angioplasty. CARPORT, MERCATOR, MARCATOR, PARK, and BENESTENT Trial Groups

With the increasing clinical application of new devices for percutaneous coronary revascularization, maximization of the acute angiographic result has become widely recognized as a key factor in maintained clinical and angiographic success. What is unclear, however, is whether the specific mode of action of different devices might exert an additional independent effect on late luminal renarrowing. The purpose of this study was to investigate such a difference in the degree of provocation of luminal renarrowing (or 'restenosis propensity') by different devices, among 3660 patients, who had 4342 lesions successfully treated by balloon angioplasty (n = 3797), directional coronary atherectomy (n = 200), Palmaz-Schatz stent implantation (n = 229) or excimer laser coronary angioplasty (n = 116) and who also underwent quantitative angiographic analysis pre- and post-intervention and at 6-month follow-up. To allow valid comparisons between the groups, because of significant differences in coronary vessel size (balloon angioplasty = 2.62 +/- 0.55 mm, directional coronary atherectomy = 3.28 +/- 0.62 mm, excimer laser coronary angioplasty = 2.51 +/- 0.47 mm, Palmaz-Schatz = 3.01 +/- 0.44 mm; P < 0.0001), the comparative measurements of interest selected were the 'relative loss' in luminal diameter (RLoss = loss/vessel size) to denote the restenosis process, and the 'relative lumen at follow-up' (RLfup = minimal luminal diameter at follow up/vessel size) to represent the angiographic outcome. For consistency, lesion severity pre-intervention was represented by the 'relative lumen pre' (RLpre = minimal luminal diameter pre/vessel size) and the luminal increase at intervention was measured as 'relative gain' (relative gain = gain/ vessel size). Differences in restenosis propensity between devices was evaluated by univariate and multivariate analysis. Multivariate models were constructed to determine relative loss and relative lumen at follow-up, taking account of relative lumen pre-intervention, lesion location, relative gain, vessel size and the device used. In addition, model-estimated relative loss and relative lumen at follow-up at given relative lumen pre-intervention relative gain and vessel size, were compared among the four groups. Significant differences were detected among the groups both with respect to these estimates, as well as in the degree of influence of progressively increasing relative gain, on the extent of renarrowing (relative loss) and angiographic outcome (relative lumen at follow-up), particularly at higher levels of luminal increase (relative gain). Specifically, lesions treated by balloon angioplasty or Palmaz-Schatz stent implantation (the predominantly 'dilating' interventions) were associated with more favourable angiographic profiles than directional atherectomy or excimer laser (the mainly 'debulking' interventions). Significant effects of lesion severity and location, as well as the well known influence of luminal increase on both luminal renarrowing and late angiographic outcome were also noted. These findings indicate that propensity to restenosis after apparently successful intervention is influenced not only by the degree of luminal enlargement achieved at intervention, but by the device used to achieve it. In view of the clinical implications of such findings, further evaluation in larger randomized patient populations is warranted.

Ischemia-related lesion characteristics in patients with stable or unstable angina. A study with intracoronary angioscopy and ultrasound

BACKGROUND

Postmortem-derived findings support the common beliefs that lipid-rich coronary plaques with a thin, fibrous cap are prone to rupture and that rupture and superimposed thrombosis are the primary mechanisms causing acute coronary syndromes. In vivo imaging with intracoronary techniques may disclose differences in the characterization of atherosclerotic plaques in patients with stable or unstable angina and thus may provide clues to which plaques may rupture and whether rupture and thrombosis are active.

METHODS AND RESULTS

We assessed the characteristics of the ischemia-related lesions with coronary angiography and intracoronary angioscopy and determined their compositions with intracoronary ultrasound in 44 patients with unstable and 23 patients with stable angina. The angiographic images were classified as noncomplex (smooth borders) or complex (irregular borders, multiple lesions, thrombus). Angioscopic images were classified as either stable (smooth surface) or thrombotic (red thrombus). The ultrasound characteristics of the lesion were classified as poorly echo-reflective, highly echo-reflective with shadowing, or highly echo-reflective without shadowing. There was a poor correlation between clinical status and angiographic findings. An angiographic complex lesion (n = 33) was concordant with unstable angina in 55% (24 of 44); a noncomplex lesion (n = 34) was concordant with stable angina in 61% (14 of 23). There was a good correlation between clinical status and angioscopic findings. An angioscopic thrombotic lesion (n = 34) was concordant with unstable angina in 68% (30 of 44); a stable lesion (n = 33) was concordant with stable angina in 83% (19 of 23). The ultrasound-obtained composition of the plaque was similar in patients with unstable and stable angina.

CONCLUSIONS

Angiography discriminates poorly between lesions in stable and unstable angina. Angioscopy demonstrated that plaque rupture and thrombosis were present in 17% of stable angina and 68% of unstable angina patients. Currently available ultrasound technology does not discriminate stable from unstable plaques.

Angiographic, ultrasonic, and angioscopic assessment of the coronary artery wall and lumen area configuration after directional atherectomy: the mechanism revisited

The purpose of the present study was to use the complementary information of angiography, intravascular ultrasound, and intracoronary angioscopy before and after directional atherectomy to characterize the postatherectomy appearance of vessel wall contours and the mechanism of lumen enlargement. Directional coronary atherectomy aims at debulking rather than dilating a coronary artery lesion. The selective removal of the plaque may potentially minimize the vessel wall damage and lead to subsequent better late outcome. Whether plaque removal is the main mechanism of action has only to be assessed indirectly by angiography and warrants further investigation with detailed analysis of luminal changes and vessel wall damage by ultrasound and direct visualization with angioscopy. Twenty-six patients have been investigated by quantitative angiography, intravascular ultrasound, and intracoronary angioscopy (n = 19) before and after atherectomy. In addition, all retrieved specimens were microscopically examined. Ultrasound imaging showed an increase in lumen area from 1.95 +/- 0.70 mm2 to 7.86 +/- 2.16 mm2 at atherectomy. The achieved gain mainly resulted from plaque removal because plaque plus media area decreased from 18.16 +/- 4.47 mm2 to 13.13 +/- 3.10 mm2. Vessel wall stretching (i.e., change in external elastic lamina area) accounted for only 15% of lumen area gain. Luminal gain was higher in noncalcified (6.52 +/- 2.12 mm2) lesions than in lesions containing deeply located calcium (5.19 +/- 0.99 mm2) and lowest in superficially calcified lesions (5.41 +/- 2.41 mm2). Ultrasound imaging identified an atherectomy byte in 85% of the cases, whereas angioscopy revealed such a crevice in 74%. The complementary use of the three techniques revealed an underestimation of the presence of dissection/tear and new thrombus by angiography (10% and 4%) and ultrasound imaging (12% and 0%) compared with angioscopy (26% and 21%). The combined use of angiography, ultrasound, and angioscopy reveals that the postatherectomy luminal lining is not as regular and smooth as that seen by angiography. Luminal enlargement with atherectomy is achieved by plaque excision rather than arterial expansion.

Progression and regression of the atherosclerotic plaque

In animals in which atherosclerosis was induced experimentally (by a high cholesterol diet) regression of the atherosclerotic lesion was demonstrated after serum cholesterol was reduced by cholesterol- lowering drugs or a low-fat diet. Whether regression of advanced coronary arterly lesions also takes place in humans after a similar intervention remains conjectural. However, several randomized studies, primarily employing lipid-lowering intervention or comprehensive changes in lifestyle, have demonstrated, using serial angiograms, that it is possible to achieve less progression, arrest or even (small) regression of atherosclerotic lesions. The lipid-lowering trials (NHBLI, CLAS, POSCH, FATS, SCOR and STARS) studied 1240 symptomatic patients, mostly men, with moderately elevated cholesterol levels and moderately severe angiographic-proven coronary artery disease. A variety of lipid-lowering drugs, in addition to a diet, were used over an intervention period ranging from 2 to 3 years. In all but one study (NHBLI), the progression of coronary atherosclerosis was less in the treated group, but regression was induced in only a few patients. The overall relative risk of progression of coronary atherosclerosis was 0 x 62 and 2 x 13, respectively. The induced angiographic differences were small and did not produce any significant haemodynamic benefit. The most important result was tht the disease process could be stabilized in the majority of patients. Three comprehensive lifestyle change trials (the Lifestyle Heart study, STARS and the Heidelberg Study) studied 183 patients, who were subjected to stress management, and/or intensive exercise, in addition to a low fat diet, over a period ranging from 1 to 3 years. All three trials demonstrated less progression, and more regression with overall relative risks of 0 x 40 and 2 x 35 respectively, in the intervention groups. Angiographic trials demonstrated that retardation or arrest of coronary atherosclerosis was possible after an intervention, but the ultimate goal, regression of the lesion, was only achieved in a small number of patients. However, the ability to stabilize coronary atherosclerosis is a considerable achievement for those patients with coronary atherosclerosis.

Antiplatelet, antithrombotic, and lytic therapy for unstable angina, and the appropriate role of revascularization

The management of unstable angina continues to be a challenge for the clinician. Evidence is accumulating that inflammation plays an important role in plaque rupture and thrombosis. Thrombolytic treatment is not indicated in unstable angina, and in fact may even be harmful. The use of new platelet glycoprotein IIb/IIIa receptor antagonists and direct thrombin inhibitors offers great potential in the management of unstable angina. Balloon angioplasty for unstable angina is associated with a high major complication rate, which can be reduced by the use of these novel agents. New techniques such as directional atherectomy do not appear to be safer than balloon angioplasty.

Quantitative angiographic measurements of isolated left anterior descending coronary artery stenosis. Correlation with exercise echocardiography and technetium-99m 2-methoxy isobutyl isonitrile single-photon emission computed tomography

OBJECTIVES

This study sought to assess the value of quantitative coronary arteriography in predicting an ischemic response at exercise echocardiography and technetium-99m 2-methoxy isobutyl isonitrile (mibi) single-photon emission computed tomography (SPECT) in patients with single-vessel disease of the left anterior descending coronary artery.

BACKGROUND

The relation between severity of coronary stenosis and ischemic response to exercise echocardiography and perfusion scintigraphy in patients with single-vessel left anterior descending coronary artery disease is not well established.

METHODS

Thirty-one patients without a previous myocardial infarction who had isolated stenosis of varying degrees in the proximal or midportion of the left anterior descending coronary artery were studied. Quantitative arteriographic analysis was used for measurements of percent diameter stenosis and minimal lumen diameter. Exercise-induced wall motion abnormalities by echocardiography and transient perfusion defects by mibi SPECT were considered a positive response. The analysis of sensitivity/specificity and receiver operating characteristic curves was applied to establish the diagnostic power of quantitative coronary arteriography to predict an ischemic response to exercise echocardiography and mibi SPECT:

RESULTS

The "best" angiographic cutoff values for predicting a positive exercise echocardiographic and scintigraphic response were similar (diameter stenosis 52%, minimal lumen diameter 1.12 mm for echocardiography; diameter stenosis 49%, minimal lumen diameter 1.20 mm for SPECT). However, the sensitivity/specificity at the cross point was slightly higher (even if not statistically significant) for echocardiography than for SPECT, both for diameter stenosis (81% vs. 67%) and minimal lumen diameter (81% vs. 74%), suggesting that quantitative coronary arteriographic measurements are more closely related to echocardiographic than scintigraphic exercise test results.

CONCLUSIONS

The functional significance of a proximal/mid-left anterior descending coronary artery stenosis measured by quantitative coronary arteriography is slightly better related to echocardiographic than scintigraphic markers of exercise-induced myocardial ischemia.

Three dimensional reconstruction of cross sectional intracoronary ultrasound: clinical or research tool?

Images

Quantitative assessment with intracoronary ultrasound of the mechanisms of restenosis after percutaneous transluminal coronary angioplasty and directional coronary atherectomy

The mechanisms of immediate and late changes after percutaneous transluminal coronary angioplasty (PTCA) and directional coronary atherectomy (DCA) were assessed by serial ultrasound imaging in 18 patients treated with PTCA and 16 treated with DCA before, immediately after, and 6 months after coronary interventions. A reduction in plaque area was the main operative mechanism of DCA, explaining 66% of lumen enlargement. In the PTCA group, the increase in lumen area was the result of a more balanced combination of plaque reduction (52% of lumen increase) and increase in total lumen area (48%); p < 0.05 versus DCA. In the PTCA group, this last mechanism was prevalent (p < 0.05) in the lesions showing wall fracture or dissection after treatment and in the lesions with a mixed or calcific composition. In the PTCA group, concentric lesions showed a greater plaque compression than eccentric lesions (p < 0.02). Plaque increase was responsible for 92% and 32% of the late lumen loss after DCA and after PTCA, respectively (p < 0.05). In PTCA patients, a chronic reduction in total vessel area was the main operative mechanism of lumen reduction (67%) and was prevalent in lesions with a mixed or calcific composition. (p < 0.05).

Can intracoronary ultrasound correctly assess the luminal dimensions of coronary artery lesions? A comparison with quantitative angiography

In 62 patients with angina pectoris Canadian Class III and IV, the luminal dimensions of 25 pre-PTCA and 56 post-PTCA lesions without occlusion were examined with a 4.3 F 30 MHz mechanical ultrasound imaging catheter, and analysed off-line using ultrasound cross-sectional area (U-CSA) measurements from s-VHS video images (n = 81). In addition, 42 angiographically normal coronary segments were examined. At the site of the examination, the U-CSA was integrated centrally to the leading edge echo of the inner contour of the vessel wall and the corresponding angiographic cinefilm images were analysed by edge detection using the Cardiovascular Angiography Analysis System. The obstruction diameter (at the lesion) and the mean vessel diameter (at normal sites) were used to calculate the angiographic cross-sectional area (A-CSA) assuming a circular model. U-CSA values were compared with the corresponding A-CSA values using t-test and linear regression analysis. The study showed that larger CSA are measured with ultrasound than with angiography. (P < 0.0001). An acceptable correlation was found between U-CSA and A-CSA values in normal coronary segments (correlation coefficient: r = 0.73, mean diff. = 1.44 +/- 1.22 mm2). However, the correlation was poor at the site of pre-PTCA lesions (r = 0.62, mean diff. = 1.81 +/- 1.14 mm2) and deteriorated following PTCA (r = 0.47, mean diff. = 1.28 +/- 2.20 mm2). No correlation was found between the degree of lumen eccentricity measured with intracoronary ultrasound (ICUS) and the individual differences between U-CSA and A-CSA values.(ABSTRACT TRUNCATED AT 250 WORDS)

Immediate and long-term clinical outcome of coronary angioplasty in patients aged 35 years or less

OBJECTIVE

To study the immediate and long-term clinical success of percutaneous transluminal coronary angioplasty in patients aged 35 years or less.

DESIGN

Patients undergoing percutaneous transluminal angioplasty were prospectively entered into a dedicated database. Clinical and angiographic data on all patients aged 35 years or less were reviewed. Follow up data were collected by interview during outpatient visits, by questionnaire, or from referring physicians.

SETTING

A tertiary referral cardiac centre.

PATIENTS

57 patients aged 35 years or less (median 33, range 22-35) underwent coronary angioplasty because of unstable angina (32 patients), stable angina (23 patients), acute myocardial infarction (1 patient), and documented ischaemia in a cardiac transplant patient.

RESULTS

The primary clinical success rate (reduction in diameter stenosis to < 50% without in-hospital events) was 88%. A major procedure related complication occurred in 5 patients (9%): one patient died, two patients sustained an acute myocardial infarction, two patients underwent emergency bypass surgery, and in three patients repeat angioplasty was performed before hospital discharge. In 2 patients (4%) coronary angioplasty did not significantly reduce the diameter stenosis but there were no associated complications. A total of 60 lesions were attempted (balloon angioplasty in 57, directional atherectomy in 2). The initial angiographic success rate was 92%. The median (SD) follow up was 4.7 (3.0) years. During follow up 7 patients (12%) died, 10 sustained a myocardial infarction (18%), and 28 patients (49%) underwent repeat revascularisation (coronary artery bypass grafting in 7 (12%) and repeat angioplasty in 21 (37%)). The estimated 5 year survival and event-free survival (Kaplan-Meier method) was 87 (9)% and 50 (13)%, respectively. Multivariate logistic regression analysis showed that hypertension and the extent of vessel disease were the only independent predictive factors for event free survival.

CONCLUSIONS

In young patients coronary angioplasty had a high immediate success rate but many needed repeat revascularisation procedures during the follow up period and survival was not improved. Coronary angioplasty in young patients should be regarded as a palliative procedure.

Designing of trials: power calculations based on matching as a surrogate for randomization

In the design of clinical trials we strive to extract the maximum amount of information from a minimum number of patients and yet retain statistical validity. Matching has become acknowledged as a useful and valid surrogate for the randomized trial. By using data from matched trials along with power calculations we can accurately predict the number of patients required to achieve statistical significance in a related randomized trial.

Acute and long-term outcome of directional coronary atherectomy for stable and unstable angina

The clinical efficacy and safety of directional coronary atherectomy for the treatment of stable and unstable angina were assessed in 82 patients with stable and 68 patients with unstable angina. Therefore, clinical and angiographic follow-up was obtained in a prospectively collected consecutive series of 150 atherectomy procedures. Restenosis was assessed clinically and by quantitative angiography. The overall clinical success rate of atherectomy for patients with unstable and stable angina was 88% and 91%, respectively. No significant differences were found for in-hospital event rates between the unstable and stable angina groups: death (1.5% vs 0%), myocardial infarction (10% vs 6%), and emergency bypass operation (3% vs 2%). These clinical events were related to the occurrence of abrupt occlusions (8.8% in patients with stable and 6.1% in those with unstable angina; p = NS). Clinical follow-up was achieved in 100% of the patients with stable and unstable angina at a mean interval of 923 and 903 days, respectively. Two-year survival rates were 96% and 97% in the populations with unstable and stable angina, respectively. There were no significant differences with respect to bypass surgery and angioplasty, but event-free survival at 2 years was significantly lower in the unstable (54%) than the stable (69%) angina group. Quantitative coronary angiography did not detect any difference in luminal renarrowing during the 6-month angiographic follow-up period. Although directional coronary atherectomy can be performed effectively in patients with unstable and stable angina, the long-term clinical outcome was less favorable in the unstable angina group.(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation between clinical course and quantitative analysis of the ischemia related artery in patients with unstable angina pectoris, refractory to medical treatment. Results of two randomized trials. The European Cooperative Study Group

Patients with unstable angina, refractory to intensive medical therapy, are at high risk for developing thrombotic complications, such as recurrent ischemia, myocardial infarction and coronary occlusion during coronary angioplasty. As both platelet aggregation and/or thrombus formation play an important role in this ongoing ischemic process, a monoclonal platelet GPIIb/IIIa receptor antibody (c7E3) or thrombolytic therapy (alteplase) might be able to modify the clinical course and underlying coronary lesion morphology. To evaluate whether alteplase or c7E3 could influence the incidence of complications, we randomized 36 and 60 patients, respectively to alteplase or placebo, or c7E3 or placebo. All patients exhibited dynamic ECG changes and recurrent pain attacks, despite maximal tolerated medical therapy. Patients were randomized in both studies after initial angiography had demonstrated a culprit lesion amenable for angioplasty. After study drug infusion quantitative angiography was repeated and angioplasty performed. Recurrent ischemia during study drug infusion occurred in 5, 6, 9 and 16 patients from the alteplase, placebo, c7E3 and placebo group, respectively. Major events defined as death, myocardial infarction or urgent intervention occurred in 7, 3, 1 and 7 patients, respectively. Two patients died: one in the alteplase group and one in the placebo group from the c7E3 study. The first patient due to retroperitoneal hemorrhage, the second as a result of recurrent infarction. Qualitative angiography showed resolution of clots in the c7E3 group only, while the same group of patients showed in 20% an improvement in TIMI flow grade, without deterioration in any patient from this group.(ABSTRACT TRUNCATED AT 250 WORDS)

Three-dimensional reconstruction of intracoronary ultrasound images. Rationale, approaches, problems, and directions

Although intracoronary ultrasonography allows detailed tomographic imaging of the arterial wall, it fails to provide data on the structural architecture and longitudinal extent of arterial disease. This information is essential for decision making during therapeutic interventions. Three-dimensional reconstruction techniques offer visualization of the complex longitudinal architecture of atherosclerotic plaques in composite display. Progress in computer hardware and software technology have shortened the reconstruction process and reduced operator interaction considerably, generating three-dimensional images with delineation of mural anatomy and pathology. The indications for intravascular ultrasonography will grow as the technique offers the unique capability of providing ultrasonic histology of the arterial wall, and the need for a three-dimensional display format for comprehensive analysis is increasingly recognized. Consequently, three-dimensional imaging is being rapidly implemented in the catheterization laboratories for guidance of intracoronary interventions and detailed assessment of their results. However exciting the prospects may be, three-dimensional reconstructions at present remain partially artificial because the true spatial position of the imaging catheter tip is not recorded, and shifts in its location and curves of the arterial lumen result in pseudoreconstructions rather than true reconstructions. In this report, we address the principles of three-dimensional reconstruction with a critical review of its limitations. Potential solutions for refinement of this exciting imaging modality are presented.

Intracoronary ultrasound and angioscopic imaging facilitating the understanding and treatment of post-infarction angina

We report on the use of intravascular ultrasound, coronary angioscopy and on-line quantitative angiography in an unstable patient soon after myocardial infarction. Combined intracoronary imaging made it possible to solve the therapeutic problem posed by an unusual angiographic appearance secondary to intracoronary thrombolysis during coronary recanalization. The pathological validation of the observations performed with angioscopy and intravascular ultrasound was made possible with the concomitant use of directional atherectomy.

Reduction of radiation exposure while maintaining high-quality fluoroscopic images during interventional cardiology using novel x-ray tube technology with extra beam filtering

BACKGROUND

Radiographic technology plays an integral role in interventional cardiology. The number of interventions continues to increase, and the associated radiation exposure to patients and personnel is of major concern. This study was undertaken to determine whether a newly developed x-ray tube deploying grid-switched pulsed fluoroscopy and extra beam filtering can achieve a reduction in radiation exposure while maintaining fluoroscopic images of high quality.

METHODS AND RESULTS

Three fluoroscopic techniques were compared: continuous fluoroscopy, pulsed fluoroscopy, and a newly developed high-output pulsed fluoroscopy with extra filtering. To ascertain differences in the quality of images and to determine differences in patient entrance and investigator radiation exposure, the radiated volume curve was measured to determine the required high voltage levels (kVpeak) for different object sizes for each fluoroscopic mode. The fluoroscopic data of 124 patient procedures were combined. The data were analyzed for radiographic projections, image intensifier field size, and x-ray tube kilovoltage levels (kVpeak). On the basis of this analysis, a reference procedure was constructed. The reference procedure was tested on a phantom or dummy patient by all three fluoroscopic modes. The phantom was so designed that the kilovoltage requirements for each projection were comparable to those needed for the average patient. Radiation exposure of the operator and patient was measured during each mode. The patient entrance dose was measured in air, and the operator dose was measured by 18 dosimeters on a dummy operator. Pulsed compared with continuous fluoroscopy could be performed with improved image quality at lower kilovoltages. The patient entrance dose was reduced by 21% and the operator dose by 54%. High-output pulsed fluoroscopy with extra beam filtering compared with continuous fluoroscopy improved the image quality, lowered the kilovoltage requirements, and reduced the patient entrance dose by 55% and the operator dose by 69%.

CONCLUSIONS

High-output pulsed fluoroscopy with a grid-switched tube and extra filtering improves the image quality and significantly reduces both the operator dose and patient dose.

Response of conductance and resistance coronary vessels to scalar concentrations of acetylcholine: assessment with quantitative angiography and intracoronary Doppler echography in 29 patients with coronary artery disease

Abnormal vasoreactivity of the large conductance arteries has been observed in the presence of impaired endothelial function. More recently, experimental and clinical reports have shown that in early coronary atherosclerosis the impairment of the endothelium-mediated vasodilatation also involves the resistance arteries. The aim of this study is the correlation of endothelium-dependent vasodilatation of conductance and resistance vessels in coronary arteries without significant stenoses. In 29 patients (aged 57 +/- 9 years, 24 men and 5 women) undergoing coronary angioplasty, a Doppler guide wire and a perfusion catheter were introduced into the proximal segment of an artery with less than 30% diameter stenosis. Selective infusions of papaverine (bolus of 7 mg), acetylcholine (continuous infusion of 0.036, 0.36, and 3.6 micrograms/ml at a flow rate of 2 ml/min), and isosorbide dinitrate (bolus of 3 mg) were sequentially performed. Heart rate, aortic blood pressure, and blood flow velocity were continuously measured. Mean cross-sectional areas of a proximal and a distal arterial segment were measured in baseline conditions, at the end of each infusion of acetylcholine, and at the peak effect of isosorbide dinitrate with quantitative angiography (CAAS System; Pie Medical Data, Maastricht, The Netherlands). Coronary blood flow was calculated from the time-averaged flow velocity and the cross-sectional area at the site of the Doppler sample volume. Coronary flow resistance was calculated as mean aortic pressure divided by coronary flow. All of the concentrations of acetylcholine induced a significant vasoconstriction of the studied artery. At the maximal concentration of acetylcholine all but three patients (90%) showed a reduction of cross-sectional area (-24% +/- 20% and -22% +/- 20% for the proximal and distal segments, respectively, p < 0.00001). Flow velocity showed a significant increase only with the two highest concentrations of acetylcholine. The maximal concentration induced a 105% +/- 138% increase from the baseline flow velocity (p < 0.001). The coronary flow changes after acetylcholine showed a large interpatient variability, with a mean increase from baseline after the highest dose of +43% +/- 85% (range, -60% +/- 239%), with the presence of a flow reduction in 10 patients (35%). No clinical or angiographic variables showed a significant correlation with the cross-sectional area, flow velocity, and flow changes after infusion of acetylcholine.(ABSTRACT TRUNCATED AT 400 WORDS)

Incidence, predictors, and management of acute coronary occlusion after coronary angioplasty

Acute coronary occlusion occurs in 4.3% to 8.3% of patients during coronary angioplasty. Its occurrence is difficult to predict in an individual patient. At high risk are patients with unstable angina, intracoronary thrombus, extreme age, long complex lesions, and diffuse disease. "Standard" management including redilation (prolonged perfusion) thrombolytic treatment and emergency bypass surgery is only successful in approximately 50% of the patients and is associated with a high mortality and myocardial infarction rate of < 6% and 30%, respectively. Bail-out stent implantation appears to emerge as an effective alternative in suitable patients and might reduce mortality, the apparent progression to myocardial infarction, or might decrease the need for emergency bypass. New techniques including directional atherectomy, rotational ablation, or the excimer laser are associated with a similar frequency of acute occlusion. Immediate access to a surgical back-up facility remains necessary to treat refractory acute occlusions.

Predictive value of reactive hyperemic response on reperfusion on recovery of regional myocardial function after coronary angioplasty in acute myocardial infarction

BACKGROUND

The objective of the study was to determine the coronary vasodilatory reserve in reperfused myocardium in patients with acute myocardial infarction and its relation to regional myocardial function.

METHODS AND RESULTS

The study population consisted of 22 patients with acute myocardial infarction who underwent successful coronary angioplasty. The vasodilatory reserve in the reperfused myocardium was assessed quantitatively using computer-assisted digital subtraction cine-angiography immediately after angioplasty and at follow-up angiography before hospital discharge. Myocardial contrast medium appearance time and density were determined before and after pharmacological hyperemia induced by an intracoronary injection of 12.5 mg papaverine. Global and regional left ventricular functions were determined from contrast angiography. After papaverine, the mean contrast medium appearance time decreased significantly from 3.5 +/- 0.7 to 2.7 +/- 0.7 cardiac cycles (P < .000005) immediately after successful coronary angioplasty and from 3.8 +/- 0.7 to 2.7 +/- 0.9 cardiac cycles (P < .000005) at angiography before hospital discharge. The mean contrast medium density increased significantly from 48.7 +/- 13.8 to 61.0 +/- 19.0 pixels (P < .003) and from 49.6 +/- 19.7 to 80.3 +/- 29.6 pixels (P < .000005), respectively. As a consequence, the calculated coronary flow reserve increased significantly from 1.8 +/- 0.7 to 2.6 +/- 1.0 (P < .0008). The global ejection fraction increased significantly from 52 +/- 12% to 58 +/- 14% (P < .03), primarily because of a significant improvement in the regional myocardial function of the infarct zone from 20.8 +/- 9.0% to 26.0 +/- 10.5% (P < .001). Coronary flow reserve correlated well with regional myocardial function both during the acute phase (R = .79, P < .002) and at follow-up angiography (R = .82, P < .000004). Interestingly, coronary flow reserve measurement on reperfusion, immediately after angioplasty, correlated significantly with regional myocardial function at follow-up angiography (R = .81, P < .00003).

CONCLUSIONS

The results indicate that there is a pharmacologically inducible vasodilatory reserve in reperfused ischemic myocardium after successful coronary angioplasty in patients with acute myocardial infarction and that this is increased at 10-day follow-up angiography. More important, the degree of reactive hyperemic response on reperfusion has a predictive value regarding the ultimate degree of recovery of regional myocardial function. Quantitative assessment of reperfusion may be useful in investigating the role of coronary reperfusion and salvage of myocardial function.

Clinical, histologic and quantitative angiographic predictors of restenosis after directional coronary atherectomy: a multivariate analysis of the renarrowing process and late outcome

OBJECTIVES

To characterize predictors of restenosis after successful directional atherectomy, we reviewed the clinical, angiographic and procedural data obtained during 132 consecutive procedures.

METHODS

Clinical and angiographic follow-up data were obtained in a prospectively collected and consecutive series of 125 patients who underwent 132 atherectomy procedures for de novo (89%) or restenotic (11%) lesions in native coronary arteries. Restenosis was assessed clinically and by quantitative coronary angiography. A dual approach to data analysis was taken to gain insight into factors affecting the clinical outcome and vessel wall healing response. Therefore, multivariate analysis was performed to 1) determine the correlates of residual lumen diameter at follow-up (angiographic outcome), and 2) characterize the determinants of the late lumen loss (renarrowing process).

RESULTS

Clinical and angiographic follow-up data after successful atherectomy were obtained in 100% and 95%, respectively. Atherectomy achieved an acute lumen gain of 1.28 +/- 0.48 mm (mean +/- SD), resulting in a minimal lumen diameter of 2.44 +/- 0.47 mm. At follow-up, the minimal lumen diameter decreased to 1.78 +/- 0.64 mm. The angiographic restenosis rate was 28% if the traditional 50% stenosis cutoff criterion was applied. Larger vessel size and postatherectomy minimal lumen diameter and right coronary or left circumflex artery lesions were independent predictors of a larger minimal lumen diameter (angiographic outcome). Lumen loss during follow-up (renarrowing process) was independently predicted by relative lumen gain and preprocedural minimal lumen diameter.

CONCLUSIONS

In analyzing the long-term results of new interventional techniques such as directional atherectomy, the late lumen loss during follow-up (renarrowing process), which is characterized by the vessel wall healing response after an intervention, should be considered together with the residual lumen diameter at follow-up (clinical outcome). It is clear that whereas improved clinical outcome is associated with larger vessel size and postprocedural lumen diameter and non-left anterior descending artery location, greater relative gain at intervention is predictive of more extensive lumen renarrowing.