The Use of Intravascular Ultrasound and Spot Stenting for the Treatment of Long Lesions and Small Vessels

IAGS 1998 Proceedings The Use of Intravascular Ultrasound and Spot Stenting for the Treatment of Long Lesions and Small Vessels Issam Moussa, MD, Joseph De Gregorio, MD, Carlo Di Mario, PhD, MD, Antonio Colombo, MD Treatment of focal lesions in vessels with an angiographic reference diameter > 3.0 mm with coronary stenting may reduce restenosis when compared to balloon angioplasty. 1 3 Improvements in stent implantation technique and post-procedural pharmacological treatment reduced stent thrombosis and bleeding complications 4 6 leading to broader application of coronary stenting to more complex lesions, such as long lesions and lesions located in small vessels. These lesion subsets have been shown to have poor immediate and long-term outcome when treated with traditional balloon angioplasty. 7 In addition, initial reports using coronary stenting (in a manner that the lesion is covered from a proximalnormalsegmenttoadistalnormalsegment) indicate improved immediate outcome in terms of low incidence of acute and subacute occlusion, but still have high restenosis rates. 8 12 Apart from the intrinsic lesion characteristics that predispose to restenosis, stent length and/or the number of stents implanted have been implicated as contributing factors in this process. 13, 14 The purpose of this study was to test a new approach for treatment of long lesions and lesions located in small From the Centro Cuore Columbus, Milan, Italy. Presented at the Fifth Biennial International Andreas Gruentzig Society Meeting, Punta del Este, Uruguay. Address reprint requests to: Antonio Colombo, MD, Centro Cuore Columbus, Via M. Buonarotti 48, 20145 Milan, Italy. vessels utilizing intravascular ultrasound, balloon angioplasty, and stenting as synergistic devices, rather than competitive modalities. This approach is based on the premise that the use of intravascular ultrasound guidance for coronary intervention will allow the following: 1) to maximize the probability of achieving pre-specified criteria of lumen enlargement with balloon angioplasty alone, therefore removing the need for stenting; and 2) to identify the segment or segments where the lumen is not optimal and to focally implant a stent at that site. METHODS Study design and patient population. This pilot prospective registry was performed in Centro Cuore Columbus,Milan,Italywhereatotalof71patients (109 lesions) were included. All patients with critical angiographic coronary artery disease referred for elective coronary intervention were screened for entry in this study (patients with myocardial infarction within 48 hours or hemodynamic instability were not eligible). Patients were included if the culprit lesion was located in a small vessel (< 3.0 mm) or was longer than 15 mm by visual estimate. The IVUS-guided coronary intervention. Patients were treated with aspirin and ticlopidine Vol 11 No 1 January 1999 47

MOUSSA, et al. started at least on the day of the procedure. During the procedure, the activated clotting time (ACT) was maintained between 200 and 250 seconds according to the usual routine followed in our laboratory. Balloon angioplasty was initially performed using an angiographically oversized balloon inflated until achieving full balloon expansion and then an IVUS interrogation was performed. If the pre-specified IVUS criteria were met, the procedure was terminated. IVUS success criteria were defined as: A) achievement of a lumen cross-sectional area > 50% of the vessel cross-sectional area at the lesion site; or B) a true minimum lumen CSA > 5.5 mm 2.This success is defined independently of the presence of adissectionaslongastimigrade3flowispresent. On the other hand, if the IVUS criteria were not met, the operator was required to repeat balloon angioplasty at least one time with a larger balloon according to the vessel size as measured by IVUS or by utilizing higher inflation pressure. After this step, IVUS interrogation was repeated again; if IVUS criteria were met, the procedure was terminated, otherwise a stent would be implanted focally at the site where IVUS criteria were not met. If stent implantation was decided, the operator used the shortest stent length necessary to obtain an optimal result. Stents were expanded using a balloon sized appropriately according to IVUS media to media diameter in order to achieve a minimum lumen CSA > 60% of the vessel CSA at the lesion site or of the average reference vessel (average between proximal and distal vessel CSA). If these criteria were met, the procedure was terminated. If the criteria were not met, the operator was free to use a larger balloon if clinically and procedurally acceptable. IVUS was performed at the end of the procedure to document final lumen dimensions. Coronary stenting was performed using stents with slotted tubular or cellular design. The PUVA stent (Devon Medical, Hamburg, Germany) was implanted in 17 lesions; the DART stent (Global Therapeutics, Broomfield, Colorado) was implanted in 6 lesions; the Palmaz-Schatz coronary stent (Johnson & Johnson Interventional systems, Warren, New Jersey) was implanted in 6 lesions, the NIR stent (Scimed, Inc., Minneapolis, Minnesota) was implanted in 4 lesions, the Bard XT stent (Bard Ireland Ltd., Galway, Ireland) was implanted in 4 lesions; and other stent combinations were implanted in 15 lesions. Coronary angiography. Coronary angiography was performed in a routine manner. Patients received intracoronary nitroglycerin prior to initial and final angiograms to achieve maximal vasodilatation. Angiographic measurements were performed as p r eviously described with an automated computerbased system by experienced angiographers not involved in the stenting procedure. 15 Image calibration was performed with a contrast-filled catheter. The external diameter of the catheter was used as the calibration standard. Coronary end-diastolic frames from matched views obtained on initial, final, and follow-up angiograms were analyzed using a contour detection minimum cost algorithm (QCA-CMS version 3.0, MEDIS, Leiden, The Netherlands). The interpolated reference lumen diameter, the lesion minimal lumen diameter and lesion length were measured. The percent diameter stenosis was calculated as the reference lumen diameter minus the minimum lumen diameter divided by the reference lumen diameter. Lesions were characterized according to the modified American College of Cardiology-American Heart Association (ACC-AHA) classification. 16 L o n g lesions were defined as a single continuous narrowing > 15 mm. Dissections were recorded and classified as follows: Type A: minor radiolucencies within the coronary lumen during contrast injection with minimal or no persistence after dye clearance; Type B: parallel tracts or double lumen separated by a 30 area during contrast injection with minimal or no persistence after dye clearance; Type C: extraluminal cap with persistence of contrast after dye clearance from the coronary lumen; Type D: spiral luminal filling defects; Type E: new persistent filling defects; Type F: those non-a-e types that lead to impaired flow or total occlusion. Intravascular ultrasound equipment and meas u r e m e n t s. Intravascular ultrasound imaging was performed using a 3.2 Fr Monorail system with 30 MHz transducer-tipped catheter (Ultracross 3.2, Boston Scientific Corporation, Sunnyvale, California). All images were obtained with an automatic pull back system at 0.5 mm/second. The position of the catheter on fluoroscopy was used to correlate the ultrasound image and the angiogram. Data were stored on 0.5 inch super VHS videotape. On-line quantitative measurements were performed during the procedure. Lumen and vessel minimal and maximal diameters and cross-sectional areas were measured with the use of a trackball to outline the lumen-intimal interface and the media-adventitia interface, respectively. The part of the lesion with the smallest lumen area was selected for measurements for each pass of the intravascular ultrasound catheter. Reference lumen cross-sectional areas were measured proximal and distal to the treated segment in the closest most normal appearing segments. The average reference lumen CSA was calculated as the mean of the proximal and distal reference lumen CSA. The average ref- 48 The Journal of Invasive Cardiology

IVUS and Spot Stenting for Long Lesions and Small Vessels erence vessel CSA was calculated as the mean of the proximal and distal reference vessel CSA. D e f i n i t i o n s. Procedural clinical success w a s defined by achieving angiographic success in the absence of death, coronary artery bypass surgery, or Q-wave myocardial infarction. D e a t h was defined as any death irrespective of cause; Q-wave myocardial i n f a r c t i o n was defined by the presence of new Q waves (> 0.4 seconds) on an ECG in conjunction with elevation in creatine kinase to greater than twice of normal; emergency coronary bypass s u r g e r y was defined by the need for immediate transfer of the patient from the catheterization laboratory to the operating room, or within 24 hours of the procedure; and elective coronary bypass surgery was defined as bypass surgery performed more than 24 hours after a stent procedure for procedural failure in the absence of ischemia. Non-Q wave myocar - dial infarction was defined by an elevation of cardiac enzymes to greater than twice of normal without new pathological Q wave. Cerebral events were defined as any cerebrovascular accident including transient ischemic attacks occurring during the hospitalization for the stent procedure. A c u t e t h r o m b o s i s was defined as angiographically documented occlusion at the stent site occurring within 24 hours of the stent procedure. Subacute thrombo - sis events were angiographically documented occlusions at the stent site occurring beyond 24 hours and within one month from the stent procedure. G r o i n c o m p l i c a t i o n s were defined as the occurrence of any of the following clinical events: 1) surgical vascular repair of the access site; 2) external compression of a pseudoaneurysm or an arteriovenous fistula; 3) blood transfusions necessary because of bleeding at the access site. Target lesion revascularization w a s defined as any revascularization procedure to the stented lesion performed within six months from the stenting procedure. Post-procedure management. Patients who underwent balloon angioplasty only received aspirin at a dose of 325 mg daily. Patients who underwent successful spot stenting received aspirin at the dose of 325 mg four times daily long term and ticlodipine at 250 mg twice daily for two weeks. The date for angiographic follow-up was given to each patient at the time of discharge. A complete blood count was performed after 2 weeks to evaluate any side effects from ticlopidine. Statistics and data analysis. Statistical analysis was performed using the StatView statistical package (StatView 4.51, Abacus Concepts Inc., Berkeley, California). Continuous normally distributed data were Table 1. Patient characteristics expressed as mean ± one standard deviation. Comparisons of continuous variables between groups were performed by unpaired student s t-test. Subgroup c o mparisons of categorical variables were performed by chi square analysis. Differences were considered statistically significant at p < 0.05. RESULTS Total (n = 71) Age (years) 60 ± 10 Male (%) 66 (93) Risk factors Hypertension (%) 38 (53) Hypercholesterolemia (%) 43 (61) Diabetes (%) 15 (21) Smoker (%) 47 (68) Family history (%) 37 (52) Prior myocardial infarction 38 (54) Previous angioplasty (%) 4 (6) Previous coronary bypass (%) 9 (13) LVEF (%) 57 ± 12 Unstable angina (%) 26 (37) Multivessel disease (%) 55 (77) Antiplatelet therapy Ticlopidine + Aspirin (%) 43 (61) Aspirin alone (%) 28 (39) LVEF = left ventricular ejection fraction Patient and lesion characteristics. Patient s clinical data for the total cohort are shown in Table 1. The majority of patients had multi-vessel disease and 37% had unstable angina. Angiographic and procedural characteristics are shown in Table 2. A total of 54 lesions underwent balloon angioplasty alone, while 55 lesions underwent balloon angioplasty and spot stenting. Type B2 or C lesions were present in 75 cases (58% of the total cohort), but type C lesions were more common in the group that underwent a combination of angioplasty and spot stenting (49% vs 26%, p < 0.04). Calcifications were present in 33 lesions (30% of the total cohort), but they were also more common in the group that underwent spot stenting (40% vs 20%, p < 0.03). Procedural variables. The procedural characteristics for the total cohort and the two subgroups are shown in Table 2. Lesions in both the angioplasty and spot stenting groups were dilated using oversized balloons with similar balloon to artery ratio (1.29 ± 0.23 vs. 1.27 ± 0.22; p = ns). High inflation pressure was needed for final lesion dilatation in both group, nevertheless, higher inflation pressure was utilized in the Vol 11 No 1 January 1999 49

MOUSSA, et al. Table 2. Angiographic and procedural characteristics Total Balloon Stent (n = 109) (n = 54) (n = 55) p value Stented vessel, n (%) NS LAD 54 (49) 25 (46) 29 (53) RCA 24 (22) 15 (28) 9 (16) LCx 30 (28) 14 (26) 16 (29) Left main 1 (.9) 0 (0) 1 (1.8) Vein graft 0 (0) 0 (0) 0 (0) Lesion site, n (%) NS Ostial 6 (6) 2 (4) 4 (7) Proximal 39 (36) 18 (33) 21 (38) Midvessel 48 (44) 22 (41) 26 (47) Distal 16 (15) 12 (22) 4 (7) Modified AHA/ACC lesion type (%) < 0.04 A 3 (3) 2 (4) 1 (2) B1 31 (39) 21 (39) 10 (18) B2 34 (32) 17 (32) 17 (31) C 41 (26) 14 (26) 27 (49) Calcified lesion, n (%) 33 (30) 11 (20) 22 (40) < 0.03 Rotablation, n (%) 14 (13) 6 (11) 8 (15) NS Final balloon size (mm) 3.69 ± 0.49 3.55 ± 0.45 3.82 ± 0.48 < 0.05 Final B/V ration (mm) 1.28 ± 0.23 1.29 ± 0.23 1.27 ± 0.22 NS Maximal inflation pressure (atm) 15.4 ± 3.6 14.5 ± 3.8 16.3 ± 3.2 < 0.05 Data presented are mean value ± SD or number (%) of lesions; LAD = left anterior descending; RCA = right coronary artery; LCX = left circumflex artery; AHA/ACC = American Heart Association/American College of Cardiology; B/V = balloon to vessel ratio. spot stenting group (14.5 ± 3.8 atm vs. 16.3 ± 3.2 atm; p < 0.05). In the spot stenting group, a mean of 1.2 ± 0.5 stent was implanted per lesion with a mean stented length of 19 ± 11.8 mm. Quantitative angiographic and intravascular ultrasound analysis. Pre- and post-intervention quantitative angiographic measurements are shown in Table 3. Fifty-eight lesions (53%) were located in vessels < 3.0 mm and 24 lesions (22%) were located in vessels > 3.0 mm but were longer than 15 mm. The final residual percent diameter stenosis was 19 ± 14% in the balloon alone group compared to 2 ± 13% in the spot stenting group (p < 0.01). Angiographic dissections at the end of the procedure were present in 60 lesions (55% of the total cohort) with similar distribution in both groups. Intravascular ultrasound measurements are shown in Table 4. There was no difference between the two subgroups with respect to proximal and distal reference lumen and vessel dimensions. Post-intervention minimum lumen CSA was significantly larger for lesions that underwent spot stenting compared to lesions that underwent balloon angioplasty alone. Procedural success, complications and shortterm outcome. Clinical procedural success was achieved in 68/71 patients (96%). Procedural c o mplications occurred in 5 patients; one patient had vessel rupture during stent optimization, underwent emergency bypass surgery and died post surgery (1.4%), 2 patients (2.8%) had Q wave myocardial infarction, and 2 other patients (2.8%) had non-q wave myocardial infarction. Short-term clinical follow-up was available for all patients at 1 month. One patient (1.4%) in the spot stenting group had subacute stent thrombosis 2 days post intervention, and a second patient (1.4%) in the balloon angioplasty alone group had sudden cardiac death 2 weeks post procedure. Cumulative MACE (death, CABG, and Q-wave MI) at 1 month occurred in 5 patients, 2 patients in the balloon angioplasty alone group, and 3 patients in the spot stenting group. Intermediate-term outcome. Forty-three out of 71 patients (63%) were eligible for 5 months clinical follow-up. Cumulative MACE (death, CABG, Q- wave MI, and the need for target lesion revascularization) occurred in 12 patients (28%). As shown in Table 6, six month angiographic follow-up was performed in 20 out of 30 eligible patients (75%) with 29 out of 39 eligible lesions (74%). Angiographic restenosis (defined as > 50% diameter stenosis) occurred in 8 out of 29 lesions (27%), 5 lesions in the balloon angioplasty alone group and 3 lesions in the spot stenting group (p =ns). 50 The Journal of Invasive Cardiology

IVUS and Spot Stenting for Long Lesions and Small Vessels Table 3. Quantitative angiographic measurements Total Balloon Stent (n = 109) (n = 54) (n = 55) p Value Pre-intervention Reference vessel diameter (mm) 2.97 ± 0.58 2.80 ± 0.52 3.12 ± 0.60 < 0.05 Minimal lumen diameter (mm) 0.76 ± 0.53 0.81 ± 0.47 0.71 ± 0.59 NS Diameter stenosis (%) 75 ± 16 72 ± 13 77 ± 17 NS Lesion length (mm) 19.7 ± 11.7 18.6 ± 11 20.7 ± 12.3 NS Post-intervention Reference vessel diameter (mm) 3.17 ± 0.54 3.02 ± 0.42 3.31 ± 0.60 < 0.05 Minimal lumen diameter (mm) 2.84 ± 0.72 2.44 ± 0.54 3.22 ± 0.66 < 0.01 Stenosis (%) 11 ± 16 19 ± 14 2 ± 13 NS Dissection, n (%) 60 (55) 31 (57) 29 (53) NS Type A 2 (3) 1 (3) 1 (4) NS Type B 49 (81) 26 (83) 23 (79) Type C 9 (15) 4 (12) 5 (18) >Type D 0 (0) 0 (0) 0 (0) Acute gain (mm) 2.08 ± 0.77 1.63 ± 0.60 2.51 ± 0.65 < 0.01 DISCUSSION The major findings of this study are the following: 1) treatment of small vessels and long lesions with IVUS-guided balloon angioplasty assisted with focal stenting have a procedural success rate that is higher than historical success rates reported with traditional PTCA and similar to success rates reported with contemporary coronary stenting (where the lesion is covered from a proximal normal segment to a distal normal segment); 2) the subacute closure rate with this approach is similar to contemporary stenting; 3) preliminary intermediate-term follow-up data suggest that the need for target lesion revascularization (26%) with this approach is at least similar, if not better, than traditional stenting when applied in small vessels and long lesions; and 4) angiographic dissections with preserved lumen dimensions documented by IVUS could be left not stented without increased risk of acute closure. The concept of IVUS-guided PTCA. R e c e n t l y, the concept of IVUS-guided PTCA has been gaining ground. Stone et al. 1 7 reported the early angiographic andclinicalresultsofivus-guidedptcainthe CLOUT pilot trial. On the basis of the vessel size and extent of plaque burden in the reference segment evaluated by IVUS, 73% of the lesions needed upsized balloons (final balloon-to-artery ratio 1.30 ± 0.17) even after achieving an optimal angiographic result. The success rate of IVUS-guided PTCA was 99%. This angiographic oversized balloon angioplasty, guided by IVUS, resulted in a large final minimal lumen diameter without increased rates of significant dissections or ischemic complications. Abizaid et a l. 18 reported a pilot work of IVUS-guided balloon angioplasty utilizing balloons sized according to the media-to-media diameter as determined by IVUS. The endpoint used in this study was achieving in MLCSA > 70% AvgVref area with no lumen compromising dissections. Crossover to stenting was needed in 61% of lesions. Final lumen area in the PTCA group was 6.0 ± 2.0 mm 2 with no incidence of abrupt vessel closure. Target lesion revascularization was needed in 17% of lesions. Frey et al. 19 reported on a total of 269 pts (358 lesions) who were randomized to IVUS-guided intervention and angiography-guided intervention. Stenting was performed in about 50% of lesions in both groups. MACE during hospitalization was less in the IVUS guided interventions. These studies provided numerous interesting and innovative concepts, however, our study differs in two ways: 1) we addressed primarily long lesions and lesions located in small vessels; 2) we utilized the Table 4. Intravascular ultrasound quantitative measurements Total PTCA Stent n = 109 n = 55 n = 54 Proximal reference Lumen CSA 7.70 ± 2.54 7.45 ± 2.60 7.96 ± 2.51 Vessel CSA 12.78 ± 4.07 12.59 ± 4.49 13.08 ± 3.38 Lesion site Lumen CSA 6.51 ± 2.53 5.40 ± 1.86 * 7.52 ± 2.65 * Vessel CSA 11.49 ± 3.88 11.38 ± 4.27 11.64 ± 3.37 Distal reference Lumen CSA 6.92 ± 2.18 6.73 ± 2.37 7.11 ± 1.99 Vessel CSA 10.38 ± 4.12 9.79 ± 4.03 10.99 ± 4.18 * p < 0.01; CSA = cross-sectional area (mm 2 ). Vol 11 No 1 January 1999 51

MOUSSA, et al. Table 5. Procedural outcomes and clinical events Total Patients n = 71 Procedural success (%) 68 (96) Angiographic success (%) 70 (99) Procedural QMI (%) 2 (2.8) Procedural CABG (%) 0 (0) Procedural death (%) 1 (1.14) Acute closure (%) 0 (0) Subacute thrombosis (%) 1 (0.9) MI = myocardial infarction; CABG = coronary artery bypass grafting spot stenting technique to optimize results in lesions that did not meet the pre-specified IVUS criteria for angioplasty success. The strategy of IVUSguided PTCA with spot stenting could be viewed as a modification of provisional stenting in order to allow its application for treatment of small vessels and long lesions. With this approach, if optimal PTCA fails, then coronary stenting will be performed focally at the segment where lumen dimensions do not meet the pre-specified criteria or where there is a flow limiting dissection. The reason for using this approach, instead of traditional stenting where a lesion is covered from a proximal normal segment to a distal normal segment, is to avoid the use of long or multiple stents in small vessels or long lesions where high restenosis rates continue to be a problem. When the concept of provisional stenting is used in any form, it is imperative to remember that it is inappropriate to compare stenting to balloon angioplasty alone as potential alternative strategies. The reason is that lesions that are treated successfully with balloon angioplasty alone, most probably represent a subset that is at lower risk for restenosis. In other words, lesions that respond optimally to balloon angioplasty might have a lower plaque burden or a soft plaque that responds well to balloon dilatation alone. On the other hand, lesions that proceed to undergo stenting because they did not respond to balloon alone are more resistant to dilatation (large plaque burden, calcified or severely fibrotic lesions). For these reasons, the fact that PTCA may perform equally to stenting does not mean equality of the two procedures, it means only that PTCA has selected out a lesion subset with a lower pre-intervention probability of restenosis compared to the lesion subset that proceeded to undergo stenting. Procedural safety. Historically, balloon angioplasty performed with oversized balloons without IVUS guidance has been reported to be associated with poor outcome. 20, 21 In addition, placing a stent without fully covering the lesion was viewed as dangerous because of the theoretical risk of acute and subacute stent thrombosis due to the potential inflow and outflow turbulence. However, when IVUS is used to guide the intervention, any flow limiting segments or dissections could be more accurately identified and treated. In this study, clinical procedural success was achieved in 96% of patients despite a rather complex lesion subset. Coronary bypass surgery was needed in one patient who had vessel perforation after dilatation of a highly resistant lesion using oversized balloon (B/V=1.4 and inflation pressure = 18 atm), unfortunately this patient died after surgery. Q-wave MI occurred in 2 patients (2.8%) and non-q wave MI in 2 other patients (2.8%). The rate of major procedural complications in this study does not seem to be different from what has been reported with traditional coronary stenting in focal lesions. In the STRESS t r i a l, 1 Q-wave MI occurred in 2.9% of patients, and emergency bypass surgery in 2% of patients. Therefore, it seems that this approach does not increase the incidence of major procedural complications in spite of treating more complex lesion subset. Intermediate-term outcome. In this study, cumulative Major Adverse Cardiac Events (death, CABG, Q-wave MI, and the need for target lesion revascularization) at 5 months occurred in 12 patients (28%). Seven patients in the PTCA alone Table 6. Angiographic follow-up Total PTCA Stent p Value Angiographic follow-up * 29 (74) 14 (70) 15 (78) NS Minimum lumen diameter (mm) 1.73 ±.15 1.70 ±.80 1.76 ±.80 NS Mean reference diameter (mm) 2.70 ±.07 2.5 ±.37 2.9 ±.31 0.02 Diameter stenosis (%) 36.5 ± 5.1 34.3 ± 27 38.9 ± 26 NS Restenosis n (%) 8 (27) 5 (33) 3 (21) NS TLR n (%) ** 10 (26) 6 (30) 4 (21) NS MLD = minimum lumen diameter; TLR = target lesion revascularization; * Number of eligible lesions (n = 39). ** Two patients who underwent PTCA had lesions that did not demonstrate to be critical at QCA. 52 The Journal of Invasive Cardiology

IVUS and Spot Stenting for Long Lesions and Small Vessels group and 5 patients in the spot stenting group. Target lesion revascularization was the only event in 7 out of these 12 patients. Six months angiographic follow-up was performed in 20 out of 30 eligible patients (75%) with 29 out of 39 eligible lesions (74%). Angiographic restenosis occurred in 8 out of 29 lesions (27%), 5 lesions in the balloon angioplasty alone group and 3 lesions in the spot stenting group (p = ns). However, this restenosis rate might be artificially high because of the low rate of angiographic follow-up. Considering that lesions treated in this patient cohort had a mean vessel diameter of 2.97 mm and a mean length of 20 mm, an incidence of a binary restenosis rate of 27% seems favorable in comparison to what has been reported in the literature with respect to coronary stenting of small vessel and long lesions. 1 0 1 2, 2 2 Implications for management of dissections after coronary interventions. Traditionally, it has been said that a dissection after PTCA is a marker of acute closure. This concept was extended to coronary stenting where even small edge dissections that were detected only by IVUS were being stented because of the fear of subacute stent thrombosis. However, inducing dissections is an integral part of lumen enlargement with PTCA and not all dissections should be judged equally. Theoretically, a dissection represents an adverse event when it compromises the lumen. There is no doubt that if a dissection in associated with < TIMI 3 flow, it should be treated. However, when dissections are associated with TIMI 3 flow, its evaluation should go beyond angiographic assessment to other modalities, such as intravascular ultrasound interrogation or coronary flow measurements. A recent study that compared the degree of agreement between angiography and IVUS has reported large discrepancy between these two modalities particularly when dissections are p r e s e n t. 2 3 In this study, residual dissections were present in 55% of lesions (81% type B), both in the angioplasty alone group and the spot stenting group. This high rate of dissections was not associated with an increased risk of acute or subacute closure in either group. These result are consisted with other studies that used IVUS guided coronary interventions. 17 19 Study limitations. Several limitations should be noted when interpreting the results of this study: 1) the number of patients is relatively small; 2) even though this was a prospective study, there was no control arm of coronary intervention without IVUS g u i dance. Despite these shortcomings, this study demonstrates that the use of IVUS-guided PTCA and focal stenting is safe and effective in long lesions and small vessels. CONCLUSION Intravascular ultrasound guided balloon angioplasty assisted by focal stenting can be safely applied in small vessels and long lesions. The clinical success rate and intermediate-term outcome is better than traditional balloon angioplasty and is at least comparable to traditional stenting (covering the lesion from normal segment to normal segment). REFERENCES 1. Fischman DL, Leon MB, Baim D, et al. A randomized comparison of coronary stent placement and balloon angioplasty in the treatment of coronary artery disease. N Engl J Med 1 9 9 4 ; 3 3 1 : 4 9 6 5 0 1. 2. Serruys P, Jaegere P, Kiemeneij F, et al. A comparison of balloon expandable stent implantation with balloon angioplasty in patients with coronary artery disease. N Engl J Med 1 9 9 4 ; 3 3 1 : 4 8 9 4 9 5. 3. Garcia E, Serruys PW, Dawkins K, et al. BENESTENT II trial: Final results of visit II & III: a 7-months follow-up (Abstr). Eur Heart J 1997;18(Suppl):1960. 4. Colombo A, Hall P, Nakamura S, et al. 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MOUSSA, et al. 1 5. Reimers B, Di Mario C, Di Francesco L, et al. New approach to quantitative angiographic assessment after stent implantation. Cathet Cardiovasc Diagn 1997;40:343 347. 1 6. Ryan TJ, Faxon DP, Gunnar RM, et al. Guidelines for percutaneous transluminal coronary angioplasty. A report of the American College of Cardiology/American Heart Association Task Force on assessment of diagnostic and therapeutic cardiovascular procedures. C i r c u l a t i o n 1 9 8 8 ; 7 8 : 4 8 6 5 0 2. 1 7. Stone GW, Hodgson JM, St Goar FG, et al. for the Clinical Outcomes With Ultrasound Trial (CLOUT) investigators. Improved procedural results of coronary angioplasty with intravascular-ultrasound guided balloon sizing. C i r c u l a t i o n 1 9 9 7 ; 9 5 : 2 0 4 4 2 0 5 2. 1 8. Abizaid A, Mehran R, Pichard AD, et al. Results of high pressure ultrasound-guided over-sized balloon PTCA to achieve Stent-like results. J Am Coll Cardiol 1 9 9 7 ; 2 9 ( S u p p l A ) : 2 8 0 A. 1 9. Frey AW, Muller Ch, Hodgson J, Roskamm H. Fewer acute major adverse cardiac events (MACE) by ultrasound guided interventions: Findings from the strategy of intracoronary ultrasound guided PTCA and stenting (SIPS) trial (Abstr). E u r Heart J 1997;18 (Suppl):862. 2 0. Roubin GS, Douglas JS, King SB, et al. Influence of balloon size on initial success, acute complications, and restenosis after percutaneous transluminal coronary angioplasty. C i r c u l a t i o n 1 9 8 8 ; 7 8 : 5 5 7 5 6 5. 2 1. Nichols AB, Smith R, Berke AD, et al. Importance of balloon size in coronary angioplasty. J Am Coll Cardiol 1 9 8 9 ; 1 3 : 1 0 9 4 1 1 0 0. 2 2. Mehran R, Hong M, Lansky A, et al. Vessel size and lesion length influence late clinical outcomes after native coronary artery stent placement (Abstr). C i r c u l a t i o n 1997;96:1520. 2 3. Ozaki Y, Violaris A, Kobayashi T, et al. Comparison of coronary luminal quantitation obtained from intracoronary ultrasound and both geometric and videodensitometric quantitative angiography before and after balloon angioplasty and directional atherectomy. C i r c u l a t i o n 1 9 9 7 ; 9 6 : 4 9 1 4 9 9. PANEL DISCUSSION GARY ROUBIN: We re always seeking new ways to do things to improve the results. In terms of the focal stenting, I think it s been very clear to those of us who have had access to long stents for a couple of years that there is a difference, and if you can just place a shorter stent along the section in the critical area the patient does much better. In the GR II trial, it was very clear that there was an interaction between stenting and lesion length. This was across the slotted tubeless stents and the coiled stents. For every stent length and for every given lesion length, the longer the stent the longer the stent material. This is true whether it was 12 compared to 20, or 22 J & J stents compared to 3 giant J & J stents. Two giant J & J stents always increased TLR rights with the longer stent materials. I think we have to strive to work out ways to place the stents effectively and justify the segments that absolutely need them. I think Antonio s on the right track, whether it is the pressure wire or IVUS in out practicing. In my practice, I use high quality Integris angiography to make this determination thing work. KIRK GARRATT: Gary and Antonio, I think the question that we all had for a long time about multiple stenting in areas with long and diffuse disease, or in the areas after your dilated section is: Which is the chicken and which is the egg? We put in a lot of stents. Those patients come back more frequently; is it because we put in a lot of stents or is it because we were treating the damaged vessel badly? I think the data that you are presenting today suggests that it is really the stent. Perhaps it is possible to leave a fair bit of dissection behind if it is not flowing, if it is not severe, or if CFR is good. Focal stent implantation is a bit of a change in our thinking from a year ago, when we would have said that you don t want to leave any significant dissection behind. GARY ROUBIN: Good question. We looked at this data very carefully. If, for some reason, you just pull the force in stent later than a short lesion. I m not sure why this was done, but it was. You put most of the stent in the normal vessel; you did not increase the restenosis rate. It is an interesting interaction between the length of the stent and the diffuse disease. The more stretch medial injury you produce over the longer distance, and that is going to increase as the diffusion of the disease increases for more restenosis. TED FELDMAN: Another way to look at this without worrying about which is the chicken and whichtheeggisanideathathasbeenintheperipheral literature. Secondary patency can be the longterm goal without being concerned about focal restenosis. The focus is on the one year outcome. You often get a patient back who does not have diffuse restenosis, but who does have a small focal area that can be treated again. We need to start looking at the results of the second round of therapy to see if we can tell our patients that at the end of the year with one repeat procedure they will have an open artery. ANTONIO COLOMBO: The restenosis was sometimes at the PTCA side. Most of the time we saw restenosis when the residual lumen following angioplasty was still around 5 5.5 mm 2. For this reason, we decided to move the cut-off to 6 mm 2.This means that we will consider an optimal PTCA result if the lumen achieved is at least 50% of the reference vessel size or reaches an absolute value of 6 mm 2. We decided to accept an absolute value, because in large vessels it may not be as important to achieve a 54 The Journal of Invasive Cardiology

IVUS and Spot Stenting for Long Lesions and Small Vessels 50% cross-sectional area. The bottom line is that when you achieve a very good PTCA result by IVUS, it is very rare to have restenosis. KIRK GARRATT: One quick question for Antonio. You said the restenosis that you saw was principally focal restenosis. Was it in the stent? Or was it outside the stent? ANTONIO COLOMBO: No. Sometimes it was the PTCA side. I would say most of the time it was the PTCA side. Recently, instead of 5.5 mm 2 we went to 6 m m 2 because almost all of the patients who got restenosis after PTCA got a result following PTCA 5.6 or 5.5 m m 2 that just barely met the criteria. So I think you really need a good result. SPEAKER: So far the IVUS criteria haven t been wonderfully accurate in predicting restenosis in nonstented segments. ANTONIO COLOMBO: No, unless you have a really good result. I mean if you have a final IVUS which is large, it is really unlikely to restenose. Vol 11 No 1 January 1999 55