Faculty Bibliography

We compared intravascular ultrasound (IVUS) findings of fractures of sirolimus-eluting stents (SESs) versus paclitaxel-eluting stents (PESs). IVUS findings in 6 PES fractures (all in the right coronary artery) in 6 patients from a clinical trial cohort were compared to 14 SES fractures (8 in the right coronary artery, 2 in the left anterior descending coronary artery, and 4 in the left circumflex coronary artery) in 13 patients from our institutional cohort. Comparing PES fractures to SES fractures, IVUS analysis showed (1) similar frequency of complete stent fracture (1 of 6, 17%, vs 3 of 14, 21%, p >0.99), (2) similar frequency of fracture adjacent to calcified plaque or stent metal overlap (5 of 6, 86%, vs 14 of 14, 100%, p = 0.99), (3) more frequent complete malalignment of proximal and distal fragments in PES strut fractures compared to SES fractures (5 of 6, 83%, vs 1 of 14, 7%, p = 0.002), (4) similar stent lengths (45.2 mm, 23.8 to 50.7, vs 39.3 mm, 22.6 to 73.4, p >0.99), (5) similar fracture lengths (0.5 mm, 0.4 to 0.7, vs 0.7 mm, 0.6 to 1.0, p = 0.14), and (6) larger reference external elastic membrane area (15.0 mm(2), 13.5 to 18.0, vs 10.4 mm(2), 6.8 to 13.6, p = 0.01). In conclusion, malalignment of proximal and distal stent fragments more often occurred in PES fractures compared to SES fractures; otherwise the IVUS features of PES and SES fractures were similar

BACKGROUND: The incidence and mechanisms of acute and late stent malapposition after primary stent implantation in ST-segment elevation myocardial infarction remain unclear. METHODS AND RESULTS: The Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial was a dual-arm, factorial, randomized trial comparing paclitaxel-eluting stents (PES) and otherwise equivalent bare metal stents (BMS) in ST-segment elevation myocardial infarction patients. The intravascular ultrasound substudy enrolled 241 patients with 263 native coronary lesions (201 PES, 62 BMS) with baseline and 13-month follow-up imaging. Postintervention acute stent malapposition (ASM) occurred in 34.3% PES- and 40.3% BMS-treated lesions. Of these, 39.1% PES- and 40.0% BMS-treated lesions resolved at follow-up, especially within the stent body (66.7%); complete resolution was accompanied by a reduction in external elastic membrane area. An ASM area >1.2 mm(2) best separated persistent from resolved ASM. At follow-up, a higher frequency of late stent malapposition was detected in PES-treated lesions (46.8%) mainly because of more late acquired stent malapposition (30.8%) compared with BMS-treated lesions. Late acquired stent malapposition area correlated to the decrease of peri-stent plaque in the subset of lesions without positive remodeling and only to change in external elastic membrane in the group with positive remodeling. Independent predictors of late acquired stent malapposition were plaque/thrombus protrusion (odds ratio, 5.60; 95% confidence interval [CI], 2.32 to 13.54) and PES use (odds ratio, 6.32; 95% CI, 2.15 to 18.62). CONCLUSIONS: The incidence of ASM was similar in PES- and BMS-treated lesions, but late acquired stent malapposition was more common in PES-treated lesions. The reason for resolved ASM was negative remodeling, with larger ASM areas separating persistent from resolved ASM. Late acquired stent malapposition was due mainly to positive remodeling and plaque/thrombus resolution. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00433966

It is not clear whether the thin struts and different alloy of a cobalt chromium stent will cause greater acute stent recoil compared to conventional stainless steel stents. We used postintervention intravascular ultrasound (IVUS) examinations to study 99 patients with 116 stented lesions: 61 Xience/Promus stents (cobalt chromium stent group) and 27 Taxus Liberte and 28 Cypher stents (stainless steel stent group). The IVUS images were obtained before and immediately after stent implantation with only the stent-delivery balloon. The ratio of the IVUS-measured to manufacturer-predicted stent diameter and area was the measure of acute stent recoil and expansion. The baseline patient characteristics, lesion morphology, and procedural details were comparable between the 2 groups. The ratio of the IVUS-measured to manufacturer-predicted stent diameter and area was 0.74 versus 0.73 (p = 0.57) and 0.63 versus 0.63 (p = 0.69), respectively, for the cobalt chromium and stainless steel stents. In conclusion, the acute performance of Xience/Promus was similar to that of previous stainless steel stents, and the thinner cobalt chromium metallic platform did not compromise the radial strength of the stent

BACKGROUND: Implantation of either bare metal stent (BMS) or drug-eluting stent (DES) has been used in every day practice for patients with unprotected left main stenosis (UPLMS). There are still a lack of data regarding the subsequent results of UPLMS in-stent restenosis (ISR). The present study aimed at determining the clinical outcome of UPLMS ISR patients after implantation of either BMS or DES. METHODS: Patients with UPLMS ISR after stenting were included. The primary endpoint was the cumulative major adverse cardiac events (MACE), including cardiac death, myocardial infarction (MI), and target vessel revascularization (TVR). RESULTS: UPLMS ISR rate was 14.8% (n = 73, 15.7% after BMS, 14.5% for DES) after average of (3.89 +/- 2.01) years (range from 1 to 10.5 years) follow-up. Angiographic follow-up between 6 - 8 months was available in 85.3%. Of these, repeat percutaneous coronary intervention (PCI) was used in 62 (84.9%) patients, with medicine only in 9 (12.4%) and coronary artery bypass graft (CABG) in 2 (2.7%). Most repeat PCI patients were with unstable angina (87.0%), and had decreased left ventricular ejection fraction ((42.58 +/- 5.12)%), fewer focal/ostial left circumflex branch (LCX) lesions, in relative to medicine only group. After (31.9 +/- 23.3) months, the MACE, MI, TVR and cardiac death were 31.5%, 1.4%, 24.1% and 8.2%, respectively. Definite and possible stent thrombosis occurred in 1 (1.4%) patient. CONCLUSIONS: Medical therapy for asymptomatic isolated ostial LCX was safe. Repeat PCI for UPLMS ISR was associated with acceptable early and short-term clinical outcome. Further study was needed to elucidate the role of CABG in treating UPLMS ISR

Treatment of left main coronary artery bifurcation lesions might depend on the ostial left circumflex (LC) or ostial left anterior descending (LAD) disease severity. We sought to evaluate whether intravascular ultrasound assessment of the side branch ostium requires direct imaging or is accurate from the main vessel. Our retrospective analysis included 126 patients with left main coronary artery bifurcation disease (plaque burden > or =40% by intravascular ultrasound scanning). We analyzed pullbacks from the LAD and the LC. First, during the main vessel pullback (ie, from the LAD), we evaluated the side branch ostium (ie, of the LC). Second, we compared this oblique view with the direct ostial measurements during LC pullback. Finally, we repeated this process, imaging the ostial LAD from the LC. From the LAD, the oblique LC ostial lumen diameter was 3.0 +/- 0.8 mm compared to the directly measured lumen diameter of 2.9 +/- 0.6 mm. From the LC, the oblique LAD ostial lumen diameter was 2.9 +/- 1.1 mm compared to the directly measured lumen diameter of 2.8 +/- 0.5 mm. However, Bland-Altman plots showed significant variation in the oblique versus direct comparisons. The 95% limits of agreement ranged from -1.84 to 1.14 mm (mean difference -0.35, SD 0.75) for the LAD and -1.69 to 1.22 mm (mean difference -0.23, SD 0.73) for the LC. The 'oblique view' detection of any plaque in the side branch predicted 40% or 70% plaque burden with good sensitivity but poor specificity. In conclusion, intravascular ultrasound evaluation of a side branch ostium from the main vessel is only moderately reliable, especially for distal left main coronary artery lesions. For an accurate assessment of the side branch ostium, direct imaging is necessary

BACKGROUND: Mechanisms underlying the association between myocardial bridge (MB)-stenting and in-stent restenosis (ISR) are still unclear. OBJECTIVE: To assess the impact of MB on ISR using intravascular ultrasound (IVUS). METHODS: In the Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial, 100 left anterior descending artery (LAD) culprit lesions (79 treated with paclitaxel-eluting stents [PES] and 21 treated with bare metal stents) were imaged with serial IVUS immediately postprocedure and at 13 months. RESULTS: At baseline the LAD stent extended into the MB segment beyond the culprit lesion in seven patients (MB-stent group). In the remaining 93 patients the LAD stent was implanted only in the culprit lesion without extending into the MB segment (non-MB-stent group). In PES-treated lesions intimal hyperplasia (IH) was greater in MB-stent group than in non-MB-stent group (1.0 [0.9, 1.3] mm(2) vs. 0.4 [0.2, 0.7] mm(2), P = 0.007). When comparing the MB-stent segment with the non-MB-stent segment in the MB-stent group treated with PES, a significant reduction in lumen area was observed in only the MB-stent segment, owing to an augmented IH within the MB-stent segment (1.56 [1.40, 1.91] mm(2) vs. 0.77 [0.55, 1.23] mm(2) for non-MB-stent segment, P = 0.08), not significant stent recoil (Deltastent area). At follow-up, the minimum lumen area was smaller in the MB-stent group than in the non-MB-stent group (2.9 [2.5, 4.2] mm(2) vs. 5.2 [4.1, 6.7] mm(2), P = 0.02). CONCLUSIONS: Increased incidence of ISR associated with MB-stenting may be attributable to enhanced IH, specific to stented MB segment, not to chronic stent recoil

BACKGROUND: Angiographic classifications of the location and severity of disease in the main vessel and side branch of coronary artery bifurcations have been proposed and applied to distal left main coronary artery (LMCA) bifurcation. METHODS AND RESULTS: We reviewed 140 angiograms of distal LMCA and ostial left anterior descending (LAD) and left circumflex (LCX) artery lesions with preintervention intravascular ultrasound (IVUS) of both the LAD and LCX arteries as well as the LMCA. Of 140 patients, 92.9% had at least 1 cross section with > or =40% IVUS plaque burden versus 57.2% of patients with an angiographic diameter stenosis > or =50%. Contrary to angiographic classifications, IVUS showed that bifurcation disease was rarely focal and that both sides of the flow divider were always disease-free. Continuous plaque from the LMCA into the proximal LAD artery was seen in 90%, from the LMCA into the LCX artery in 66.4%, and from the LMCA into both the LAD and LCX arteries in 62%. Plaque localized to either the LAD or LCX ostium and not involving the distal LMCA was seen in only 9.3% of LAD arteries and 17.1% of LCX arteries. Plaque distribution was not influenced by the LAD/LCX angiographic angle, lesion severity, LMCA length, or remodeling. We proposed an IVUS classification for bifurcation lesions illustrating longitudinal and circumferential spatial plaque distribution. CONCLUSIONS: Angiographic classification of LMCA bifurcation lesions is rarely accurate. IVUS shows that the carina is always spared and that the disease is diffuse rather than focal

BACKGROUND: Vascular responses to drug-eluting stents in ST-segment elevation myocardial infarction are unknown. In the prospective, multicenter Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial, patients with ST-segment elevation myocardial infarction within 12 hours of symptom onset were randomized 3:1 to TAXUS EXPRESS paclitaxel-eluting stents (PES) or EXPRESS bare metal stents (BMS). METHODS AND RESULTS: A formal intravascular ultrasound substudy enrolled 464 patients with baseline and 13-month follow-up imaging at 36 centers. Overall, 446 lesions in 402 patients were suitable for standard qualitative and quantitative analyses, which were performed at an independent blinded core laboratory. The primary prespecified end point was the in-stent percent net volume obstruction at follow-up. Median stent length measured 23.4 mm (first and third quartiles, 18.5 and 31.9 mm). PES compared with BMS significantly reduced 13-month percent net volume obstruction (6.5% [first and third quartiles, 2.2% and 10.8%] versus 15.6% [first and third quartiles, 7.2% and 28.8%]; P<0.0001). PES compared with BMS also resulted in more late-acquired stent malapposition (29.6% versus 7.9%; P=0.0005) resulting from positive vessel remodeling. Plaque and/or thrombus protrusion through stent struts was initially present in 70.4% of PES and 64.8% of BMS; all resolved during follow-up. New aneurysm formation, stent fracture, and subclinical thrombus were uncommon, although seen only in PES. CONCLUSIONS: PES compared with BMS significantly reduce neointimal hyperplasia in patients with ST-segment elevation myocardial infarction but also result in a high frequency of late-acquired stent malapposition as a result of positive vessel remodeling. Ongoing long-term follow-up is required to establish the clinical significance of these findings. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00433966

OBJECTIVES: We used intravascular ultrasound (IVUS) to assess incidence, predictors, morphology, and angiographic findings of edge dissections after drug-eluting stent (DES) implantation. BACKGROUND: DES implantation strategies differ compared with bare-metal stenting; coronary dissections after DES implantation have not been well studied. METHODS: We studied 887 patients with 1,045 non-in-stent restenosis lesions in 977 native arteries undergoing DES implantation with IVUS imaging. RESULTS: Eighty-two dissections were detected; 51.2% (42 of 82) involved the proximal and 48.8% (40 of 82) the distal stent edge. Residual plaque area (8.0 +/- 4.3 mm(2) vs. 5.2 +/- 3.0 mm(2), p < 0.0001); plaque burden (52.2 +/- 11.7% vs. 36.2 +/- 15.3%, p < 0.0001); plaque eccentricity (8.4 +/- 5.5 vs. 4.0 +/- 3.4, p < 0.0001); and stent edge symmetry (1.2 +/- 0.1 vs. 1.1 +/- 0.1, p = 0.02) were larger; plaque burden > or =50% was more frequent (62.0% vs. 17.2%, p < 0.0001); calcium deposits (52.1% vs. 35.2%, p = 0.03) more common; and lumen-to-stent-edge-area ratio (0.9 +/- 0.2 vs. 1.0 +/- 0.2, p < 0.0001) was smaller in the edge dissection group compared with the nondissection group. Intramural hematomas occurred in 34.1% (28 of 82) of dissections. When compared with nonhematoma dissections, residual plaque and media area (6.4 +/- 2.5 mm(2) vs. 8.9 +/- 4.6 mm(2), p = 0.04) was smaller, and stent edges less asymmetric (1.1 +/- 0.1 vs. 1.2 +/- 0.1, p = 0.009) in the dissection with hematoma group. Independent predictors of any stent edge dissection were residual plaque eccentricity (odds ratio [OR]: 1.4, p = 0.02), lumen-to-stent-edge-area ratio (OR: 0.0, p = 0.007), and stent edge symmetry (OR: 1.2, p = 0.02 for each 0.01 increase). CONCLUSIONS: IVUS identified edge dissections after 9.2% of DES implantations. Residual plaque eccentricity, lumen-to-stent-edge-area ratio, and stent edge symmetry predicted coronary stent edge dissections. Dissections in less diseased reference segments more often evolved into an intramural hematoma

Most intravascular ultrasound (IVUS)-identifiable myocardial bridges (MBs) were not appreciated angiographically, especially when they occurred adjacent to fixed proximal obstructive disease. The impact of MB stent placement on clinical outcome was determined in 317 consecutive patients with obstructive left anterior descending coronary artery lesions undergoing coronary stent placement. In these patients, IVUS identified 70 MBs, defined as a segment of coronary artery with both systolic compression and perivascular echolucent muscle. IVUS showed that the stent extended into the MB segment beyond the obstructive lesion in 24 patients (34%; MB stent group), although significant plaque was not observed within any MB segment. In the remaining 46 patients, the left anterior descending artery stent was implanted in only the obstructive lesion, avoiding the distal MB segment (non-MB stent group). Minimum stent area was significantly smaller in the MB stent group than non-MB stent group (4.8 +/- 1.1 vs 5.8 +/- 1.8 mm(2); p = 0.02). Rates of target-lesion revascularization, target-vessel revascularization, and composite end point (death/myocardial infarction/target-lesion revascularization/target-vessel revascularization, evaluated at a mean follow-up of 358 +/- 252 days) were more common in patients with versus without MB stent placement. Specifically, target-lesion revascularization rates were 24% versus 3%, respectively (log-rank p = 0.003). In-stent restenosis occurred within the stented MB segment in 3 of 5 MB stent group patients who required target-lesion revascularization (60%). In conclusion, inadvertent MB stent placement in left anterior descending artery lesions occurred commonly and may have been associated with an increased incidence of late events