Jonathan Tobis

Intracoronary Stenting Without Anticoagulation Accomplished With Intravascular Ultrasound Guidance

BACKGROUND The placement of stents in coronary arteries has been shown to reduce restenosis in comparison to balloon angioplasty. However, clinical use of intracoronary stents is impeded by the risk of subacute stent thrombosis and complications associated with the anticoagulant regimen. To reduce these complications, the hypothesis that systemic anticoagulation is not necessary when adequate stent expansion is achieved was prospectively evaluated on a consecutive series of patients who received intracoronary stents. METHODS AND RESULTS From March 1993 to January 1994, 359 patients underwent Palmaz-Schatz coronary stent insertion. After an initial successful angiographic result with < 20% stenosis by visual estimation had been achieved, intravascular ultrasound imaging was performed. Further balloon dilatation of the stent was guided by observation of the intravascular ultrasound images. All patients with adequate stent expansion confirmed by ultrasound were treated only with antiplatelet therapy (either ticlopidine for 1 month with short-term aspirin for 5 days or only aspirin) after the procedure. Clinical success (procedure success without early postprocedural events) at 2 months was achieved in 338 patients (94%). With an inflation pressure of 14.9 +/- 3.0 atm and a balloon-to-vessel ratio of 1.17 +/- 0.19, optimal stent expansion was achieved in 321 of the 334 patients (96%) who underwent intravascular ultrasound evaluation, with these patients receiving only antiplatelet therapy after the procedure. Despite the absence of anticoagulation, there were only two acute stent thromboses (0.6%) and one subacute stent thrombosis (0.3%) at 2-month clinical follow-up. Follow-up angiography at 3 to 6 months documented two additional occlusions (0.6%) at the stent site. At 6-month clinical follow-up, angiographically documented stent occlusion had occurred in 5 patients (1.6%). At 6-month clinical follow-up, there was a 5.7% incidence of myocardial infarction, a 6.4% rate of coronary bypass surgery, and a 1.9% incidence of death. Emergency intervention (emergency angioplasty or bailout stent) for a stent thrombosis event was performed in 3 patients (0.8%). The overall event rate was relatively high because of intraprocedural complications that occurred in 16 patients (4.5%). Intraprocedural complications, however, decreased to 1% when angiographically appropriately sized balloons were used for final stent dilations. There was one ischemic vascular complication that occurred at the time of the procedure and one ischemic vascular complication that occurred at the time of angiographic follow-up. By 6 months, repeat angioplasty for symptomatic restenosis was performed in 47 patients (13.1%). CONCLUSIONS The Palmaz-Schatz stent can be safely inserted in coronary arteries without subsequent anticoagulation provided that stent expansion is adequate and there are no other flow-limiting lesions present. The use of high-pressure final balloon dilatations and confirmation of adequate stent expansion by intravascular ultrasound provide assurance that anticoagulation therapy can be safely omitted. This technique significantly reduces hospital time and vascular complications and has a low stent thrombosis rate.

Intravascular ultrasound imaging of human coronary arteries in vivo : analysis of tissue characterizations with comparison to in vitro histological specimens

BackgroundIntravascular ultrasound imaging was performed in 27 patients after coronary balloon angioplasty to quantify the lumen and atheroma cross-sectional areas. Methods and ResultsA 20-MHz ultrasound catheter was inserted through a 1.6-mm plastic introducer sheath across the dilated area to obtain real-time images at 30 times/sec. The ultrasound images distinguished the lumen from atheroma, calcification, and the muscular media. The presence of dissection between the media and the atheroma was well visualized. These observations of tissue characterization were compared with an in vitro study of 20 human atherosclerotic artery segments that correlated the ultrasound images to histological preparations. The results indicate that high-quality intravascular ultrasound images under controlled in vitro conditions can provide accurate microanatomic information about the histological characteristics of atherosclerotic plaques. Similar quality cross-sectional ultrasound images were also obtained in human coronary arteries in vivo. Quantitative analysis of the ultrasound images from the clinical studies revealed that the mean cross-sectional lumen area after balloon angioplasty was 5.0 ± 2.0 mm2. The mean residual atheroma area at the level of the prior dilatation was 8.7 ± 3.4 mm2, which corresponded to 63% of the available arterial cross-sectional area. At the segments of the coronary artery that appeared angiographically normal, the ultrasound images demonstrated the presence of atheroma involving 4.7 ± 3.2 mm2, which was a mean of 35 ± 23% of the available area bounded by the media. ConclusionsIntravascular ultrasound appears to be more sensitive than angiography for demonstrating the presence and extent of atherosclerosis and arterial calcification. Intracoronary imaging after balloon angioplasty reveals that a significant amount of atheroma is still present, which may partly explain why the incidence of restenosis is high after percutaneous transluminal coronary angioplasty. (Circulation 1991;83:913–926)

Intracoronary ultrasound observations during stent implantation.

Intracoronary Ultrasound Observations During Stent Implantation Shigeru Nakamura, MD; Antonio Colombo, MD; Antonio Gaglione, MD; Yaron Almagor, MD; Steven L. Goldberg, MD; Luigi Maiello, MD; Leo Finci, MD; Jonathan M. Tobis, MD T he Palmaz-Schatz stent has been used success- fully to improve primary angioplasty results, to treat large coronary dissections, or to prevent impending closure of the lumen.-1-5 The determination of successful stent implantation is based on the angio- graphic appearance. However, angiographic projection imaging may not reveal the three-dimensional geometry that is necessary to appreciate full expansion of a cylindrical meshwork device such as the intracoronary stent. Intravascular ultrasound (IVUS) imaging has the advantage of providing detailed cross-sectional images from within the vessel lumen, allowing better evaluation of stent expansion.16-21 Based on angiographic assess- ment, it has been recommended to overdilate the ste- nosis about 10% greater than the reference vessel diameter.1 There is no quantitative guideline for IVUS assessment of successful stent implantation. The pur- pose of this study was to compare the observations of IVUS with standard angiography after stent implanta- tion and to develop recommendations for guiding stent implantation by IVUS. Methods Population and Stent Type The study population consisted of 63 consecutive patients who underwent Palmaz-Schatz stent insertion for native cor- onary arteries and received IVUS imaging at two institutions from January 1, 1993, to April 16, 1993. There were 55 men and 8 women. The mean patient age was 58.6±9.6 years. All patients had coronary artery stenosis with objective evidence of ischemia. Of the 65 lesions treated, the indications for stent insertion were elective implantation in 60 (92%) and emer- gency implantation in 5 (8%). Emergency stent deployment was defined as the presence of a large dissection with threat- ened closure after coronary angioplasty, as evidenced by chest pain and ischemic ECG changes. The target lesion was in the left anterior descending coronary artery (LAD) in 40 lesions, the left circumflex artery (LCx) in 10 lesions, the right coronary artery (RCA) in 14 lesions, and the left main artery in 1 lesion. A standard-length (15 mm) Palmaz-Schatz stent (Johnson and Johnson Interventional Systems) was used in 12 lesions (18%). A short version (7 mm) of the Palmaz-Schatz stent was made by cutting the articulation site22 and was used in 48 lesions (74%). A 10-mm-long biliary Palmaz stent was Received October 8, 1993; revision accepted November 16, From Centro Cuore Columbus (A.C., Y.A., L.M., L.F.), Milan, Italy; Villa Bianca and University of Bari (A.G.), School of Medicine, Bari, Italy; and the Division of Cardiology (S.N., S.L.G., J.M.T.), University of California Irvine. Correspondence to Antonio Colombo, MD, Centro Cuore Co- lumbus, Via Buonarotti 48, 20145 Milan, Italy. inserted in 10 lesions (15%). One stenosis was treated with a 10-mm renal Palmaz stent. The biliary and renal stents were used in heavily calcified lesions because of the additional strength of these larger devices. A single stent was implanted in 18 lesions (28%), and multiple stents were used in 47 lesions (72%). Anticoagulation All patients received aspirin 325 mg and a calcium channel antagonist before stent implantation. Heparin (10 000 U) was administrated intra-arterially at the beginning of the proce- dure and was followed by intravenous infusion to maintain the activated clotting time .300 seconds. Low-molecular-weight dextran 40 (10%) was administrated (100 mLIhr for 2 hours) and continued at 50 mIlhr for a total dose of 1 L. The sheaths were pulled 1 day after the procedure. Patients were main- tained on a heparin infusion for 4 to 5 days until a therapeutic warfarin dose was achieved with a prothrombin time between 16 and 18 seconds. Patients stayed in the hospital for 7 days after the procedure. Dipyridamole and sodium warfarin were continued for 2 months. Insertion Procedure When the lesion was severe, predilatation was performed with a 2.0-mm balloon using standard percutaneous coronary angioplasty techniques. All stents were manually mounted on a balloon that matched the angiographic reference lumen diameter. The stent was then overdilated with a balloon approximately 0.5 mm larger than the reference lumen diam- eter. To avoid balloon inflation outside of the stented segment of the vessel, a 9-mm-long balloon (Short Speedy, Schneider Europe) was used for final dilatation. The final dilatation was performed at higher pressures, if necessary. The procedure end point was achieved when the operator determined that maximal stent expansion had occurred based on the angiographic evidence of a step up into the stented area and a step down into the distal unstented segment. Ordinarily, the procedure would be terminated at this point, but for the purpose of this study, IVUS imaging was then performed using a 3.9-F monorail system with a 25-MHz ultrasound transducer (Interpret Catheter, InterTherapy/CVIS). The imaging cathe- ter was positioned under fluoroscopic guidance distal to the stent, and images were recorded continuously as the catheter was withdrawn manually through the stented segment. After the stented area was interrogated with a single pullback, the catheter was repositioned to identify the tightest segments within the stented portion. If the operator and ultrasound reviewer believed that there was a possibility to improve stent expansion, further balloon dilatations were performed using a larger balloon or higher pressure. The initial concept was to obtain a lumen cross-sectional area (CSA) approximately 70% of the expected CSA of the chosen balloon. IVUS imaging and balloon dilatation were repeated until a satisfactory lumen area and uniform expansion were achieved or no further improvement could be obtained. Downloaded from http://circ.ahajournals.org/ at CONS CALIFORNIA DIG LIB on October 10, 2015

Bifurcation lesions: two stents versus one stent—immediate and follow-up results

OBJECTIVES The purpose of this study was to evaluate two different techniques of stent placement in bifurcation lesions. BACKGROUND Although stent placement with dedicated techniques has been suggested to be a useful therapeutic modality for bifurcation lesions, limited information is available if stent placement on the side branch and on the parent branch provides any advantage over a simpler strategy of stenting the parent vessel and balloon angioplasty of the side branch. METHODS Between March 1993 and April 1999, we treated a total of 92 patients with bifurcation lesions with two strategies: stenting both vessels (group B, n = 53) or stenting the parent vessel and balloon angioplasty of the side branch (group P, n = 39). Paired angiograms were analyzed by quantitative angiography, and clinical follow-up was obtained. RESULTS Stent placement on both branches resulted in a lower residual stenosis (7.4 +/- 10.9% vs. 23.4% +/- 18.7%, p < 0.001) in the side branch. Acute procedural success was similar in the two groups (group B: 87% vs. Group P: 92%). In-hospital major adverse cardiac events (MACE) occurred only in group B (13% vs. 0%, p < 0.05). At the six-month follow-up, the angiographic restenosis rate (group B: 62% vs. Group P: 48%) and the target lesion revascularization rate (38% vs. 36%, respectively) were similar in the two groups. There was no difference in the incidence of six-month total MACE (51% vs. 38%). CONCLUSIONS For the treatment of true bifurcation lesions, a complex strategy of stenting both vessels provided no advantage in terms of procedural success and late outcome versus a simpler strategy of stenting only the parent vessel.

Morphological effects of coronary balloon angioplasty in vivo assessed by intravascular ultrasound imaging.

BACKGROUND Histological examination of the effects of balloon angioplasty have been described from in vitro experiments and a limited number of pathologic specimens. Intravascular ultrasound imaging permits real time cross-sectional observation of the effect of balloon dilation on the atherosclerotic plaque in vivo. METHODS AND RESULTS The morphological effects of coronary angioplasty were visualized at 66 lesions in 47 patients immediately after balloon dilatation with an intravascular ultrasound imaging catheter. Cross-sectional images were obtained at 30 frames per second as the catheter passed along the length of the artery. Quantitative and qualitative assessments of the dilated atherosclerotic plaque were made from the angiograms and the ultrasound images. Six morphological patterns after angioplasty were appreciated by ultrasound imaging. Type A consists of a linear, partial tear of the plaque from the lumen toward the media (seven lesions); Type B is defined by a split in the plaque that extends to the media (12 lesions); Type C demonstrates a dissection behind the plaque that subtends an arc of up to 180 degrees around the circumference (18 lesions); Type D was a more extensive dissection that encompasses an arc of more than 180 degrees (four lesions); and Type E may be present in either concentric (Type E1, 14 lesions) or eccentric (Type E2, 11 lesions) plaque and is defined as an ultrasound study without any evidence of a fracture or a dissection in the plaque. There was a large amount of residual atheroma in each type of morphology (7.8 +/- 2.9 mm2, 61.6 +/- 15.4% of cross-sectional area); there was no difference, however, in lumen or atheroma cross-sectional area among these six patterns. There was a good correlation between ultrasound and angiography for the recognition of a dissection. Calcification was seen in only 14% of lesions on angiography, whereas most lesions (83%) revealed calcification on ultrasound imaging. As determined by intravascular ultrasound, calcified plaque was more likely to fracture in response to balloon dilatation than noncalcified plaque (p less than 0.01). Thirteen of 66 lesions (20%) developed clinical and angiographic restenosis. Restenosis was more likely to occur when the original dilatation left a concentric plaque without a fracture or dissection (Type E1, 50% incidence) compared with a mean restenosis rate of 12% in the remaining morphological patterns (p = 0.053). CONCLUSIONS Intravascular ultrasound provides a more complete quantitative and qualitative description of plaque geometry and composition than angiography after balloon angioplasty. In addition, intravascular ultrasound identified a subset of atherosclerotic plaque that has a higher incidence of restenosis. This information could be used prospectively to consider other therapeutic options in this subset. Intravascular ultrasound provides a method to describe the effects of angioplasty that will be useful in comparing future coronary intervention studies.

Subacute Stent Thrombosis in the Era of Intravascular Ultrasound-Guided Coronary Stenting Without Anticoagulation: Frequency, Predictors and Clinical Outcome

OBJECTIVES This study was performed to determine predictors of subacute stent thrombosis (SST) in the era of intravascular ultrasound (IVUS)-guided coronary stenting without anticoagulation. BACKGROUND The incidence of stent thrombosis has declined with the application of high pressure stent deployment with only antiplatelet therapy. However, no data are available on predictors of stent thrombosis in this era. METHODS Between March 30, 1993 and July 31, 1995, 1,042 consecutive patients underwent coronary stenting without anticoagulation. For this analysis, we excluded patients who underwent coronary artery bypass surgery, died or had acute stent thrombosis within the 1st 24 h after stenting (41 patients). A total of 1,001 patients (1,334 lesions) were included; 982 patients (1,315 lesions) without SST and 19 patients (19 lesions) with SST. RESULTS The rate of SST was 1.9% (per patient). There was no difference between the SST and No SST groups in rescue stenting (12% vs. 13.5%, p = 1.0) or mean +/- SD reference diameter (3.11 +/- 0.58 vs. 3.19 +/- 0.53 mm, p = 0.54). A preexisting thrombus was present in 12% of the SST group and in 4.5% of the No SST group (p = 0.19). Predictors of SST by univariate analysis were low ejection fraction (p = 0.004), more stents per lesion (p = 0.049), use of combination of different stents (p = 0.012), smaller balloon size (p = 0.012) and suboptimal result in terms of smaller lumen dimensions by angiography (p = 0.016) and IVUS (p = 0.004), residual dissections (p = 0.027) and slow flow (p = 0.0001). In stepwise logistic regression analysis, ejection fraction (p = 0.019), use of a combination of different stents (p = 0.013) and postprocedure dissections (p = 0.014) and slow flow (p = 0.0001) were predictive of SST. CONCLUSIONS In the present era of stent implantation, factors that may predispose to SST are low ejection fraction, intraprocedural complications leading to utilization of more stents, particularly with different stent designs, and suboptimal final result in terms of smaller lumen dimensions and persistent slow flow and dissections.

Intravascular ultrasound cross-sectional arterial imaging before and after balloon angioplasty in vitro.

A prototype ultrasound imaging catheter was evaluated in vitro using 17 human atherosclerotic artery segments before and after balloon dilatation angioplasty. The catheter was 1.2 mm in diameter and incorporated a single 20-MHz ultrasound transducer to obtain cross-sectional images of the arterial lumen. In 15 of the 17 (88%) arteries, high quality images were obtained, which demonstrated clear demarcation between the lumen and the endothelium, the atheroma plaque, the muscular media, and the adventitia. Qualitative characteristics of plaque disruption, dissection, and residual flaps were readily visible. In addition, quantitative information about cross-sectional lumen area was obtained before and after balloon dilatation. The mean cross-sectional lumen area increased from 8.7 to 15.1 mm2 (p less than 0.01) following balloon dilatation. The lumen area measured from the ultrasound images following dilatation correlated closely with the area measured from histologic sections (r = 0.88). The results from this study indicate that a small-diameter ultrasound imaging catheter can be developed that will provide high-resolution qualitative and quantitative information during peripheral and coronary angioplasty.

Coronary stenting after rotational atherectomy in calcified and complex lesions. Angiographic and clinical follow-up results.

BACKGROUND Treatment of calcified (in contrast to simple) lesions with PTCA has been associated with a lower success rate and more procedural complications. Rotablation can improve acute results, but the high restenosis rate remains a problem. The purpose of this study was to evaluate the clinical and angiographic outcome of patients with complex and calcified lesions treated with a combination of rotablation and stenting. METHODS AND RESULTS Seventy-five consecutive patients with 106 lesions had rotablation prior to coronary stenting. Intravascular ultrasound-guided stenting was used without subsequent anticoagulation in 93% of patients. Procedural success was achieved in 93.4% of lesions. Acute stent thrombosis occurred in two lesions (1.9%), and subacute stent thrombosis in one lesion (0.9%). Angiographic follow-up was performed in 82.5% of lesions at 4.6 +/- 1.9 months with an angiographic restenosis rate of 22.5%. Clinical follow-up was performed in all patients at 6.4 +/- 3 months; target lesion revascularization was needed in 18% of lesions; Q-wave myocardial infarction occurred in 1.3%, coronary bypass surgery in 4.0%, and death in 1.3%. CONCLUSIONS Optimal coronary stenting after rotablation in calcified and complex lesions can be performed with a high success rate, an acceptable rate of procedural complications, and a low rate of stent thrombosis. This approach was associated with a low incidence of angiographic restenosis compared with results usually obtained with other interventional strategies in calcified and complex lesion subsets.

Angiographic and intravascular ultrasound predictors of in-stent restenosis

OBJECTIVES This study was performed to determine predictors of in-stent restenosis from a high volume, single-center practice. BACKGROUND Intracoronary stents have been shown to reduce the restenosis rate as compared with balloon angioplasty, but in-stent restenosis continues to be an important clinical problem. METHODS Between April 1993 and March 1997, 1,706 patients with 2,343 lesions were treated with a variety of intracoronary stents. The majority of stents were placed with high pressure balloon inflations and intravascular ultrasound (IVUS) guidance. Angiographic follow-up was obtained in 1,173 patients with 1,633 lesions (70%). Clinical, angiographic and IVUS variables were prospectively recorded and analyzed by univariate and multivariate models for the ability to predict the occurrence of in-stent restenosis defined as a diameter stenosis > or =50%. RESULTS In-stent restenosis was angiographically documented in 282 patients with 409 lesions (25%). The restenosis group had a significantly longer total stent length, smaller reference lumen diameter, smaller final minimal lumen diameter (MLD) by angiography and smaller stent lumen cross-sectional area (CSA) by IVUS. In lesions where IVUS guidance was used, the restenosis rate was 24% as compared with 29% if IVUS was not used (p < 0.05). By multivariate logistic regression analysis, longer total stent length, smaller reference lumen diameter and smaller final MLD were strong predictors of in-stent restenosis. In lesions with IVUS guidance, IVUS stent lumen CSA was a better independent predictor than the angiographic measurements. CONCLUSIONS Achieving an optimal stent lumen CSA by using IVUS guidance during the procedure and minimizing the total stent length may reduce in-stent restenosis.

Assessment of normal and atherosclerotic arterial wall thickness with an intravascular ultrasound imaging catheter

A prototype intravascular ultrasound imaging catheter with a 20 MHz transducer was used to obtain 59 cross-sectional images in 14 segments of human atherosclerotic arteries. Three distinct components of the arterial wall were visualized on the ultrasound images: a highly reflective intima, an echolucent media, and a moderately reflective adventitia. Images were obtained at 1 mm increments in vitro and were compared with histologic sections at the same levels. Measurements of the arterial layers showed a close correlation between ultrasound images and histologic sections for the thickness of the intimal plaque (r = 0.91), the media (r = 0.83), and the total wall thickness (r = 0.85). The ultrasound images overestimated the mean intimal and total wall thickness by 0.3 mm and 0.7 mm compared to measurements in histologic sections (p less than 0.001). Intravascular imaging with high-frequency ultrasound is an accurate method for measuring microanatomic arterial dimensions and the extent of atheromatous involvement of the arterial wall. This method could represent an important adjunct to traditional angiographic techniques for assessing the severity of atherosclerosis.