Bypass to the left coronary artery system may accelerate left main coronary artery negative remodeling and calcification.

AIMS: This study aimed to use intravascular ultrasound (IVUS) data to reveal the mechanism of lesion progression in the native coronary circulation proximal to bypass grafts after coronary artery bypass grafting (CABG). METHODS AND RESULTS: We reviewed IVUS images in 86 patients with an angiographically significant left main coronary artery (LMCA) stenosis. Overall, 41 patients underwent CABG more than 6 months (mean 8.2 ± 6.1 years) previously and had at least one patent graft to the left coronary artery system. The number of patent grafts to the left coronary artery was 1.4 ± 0.7. Comparing patent graft vs. non-CABG groups, external elastic membrane and lumen areas and remodeling index at the minimum lumen area (MLA) site trended smaller with no difference in the plaque & media area. In addition, patients in the patent graft group had more LMCA calcium whether defined by cross-sectional (arc at the MLA site of 141 ± 109° vs. 88 ± 108°, P = 0.025) or longitudinal measurements (calcium length index, calculated as LMCA calcium length divided by total LMCA length, 0.69 ± 0.38 vs. 0.50 ± 0.42, P = 0.035). CONCLUSIONS: Negative remodeling may be the main mechanism of lesion progression proximal to a patent bypass graft, and more calcium was found in LMCA after CABG compared with non-CABG patients.

Intravascular ultrasound comparison of left main coronary artery disease between white and Asian patients.

We assessed the ethnic differences in coronary atherosclerosis lesion morphology between white and Asian patients. Our hypothesis was that left main coronary artery (LMCA) disease was more focal and less complex in Asian than in Western white patients. We studied 99 Asian patients (Japan and South Korea) and 99 matched control United States white patients with a stable clinical presentation and >30% LMCA angiographic diameter stenosis by visual estimation. The matching parameters included age, gender, and diabetes mellitus. The vessel and lumen areas and calcium arc were analyzed every 0.5 mm and normalized for analysis length. Overall, 75.1% of the patients were men and 34.1% had diabetes. The patient age was 68.0 ± 10 years, with no differences between the Asian and white patients. The Asian patients had a lower prevalence of hyperlipidemia than the white patients (41.4% vs 81.8%; p <0.0001) and were smaller in size, and the white patients were more obese (body mass index 23.7 ± 2.6 vs 27.6 ± 4.1 kg/m(2), p <0.0001). The Asian patients had a smaller lumen area (5.2 ± 1.8 vs 6.2 ± 14 mm(2); p <0.0001), larger vessel area (20.0 ± 4.9 vs 18.4 ± 4.4 mm(2); p <0.0001), and larger plaque burden (72 ± 10 vs 64 ± 12%: p <0.0001) at the minimum lumen site and over the entire LMCA length. The white patients had more calcification, whether assessed by the maximum arc (82° ± 74° vs 49° ± 45°; p <0.0001) or total length (3.6 ± 3.2 vs 2.1 ± 2.1 mm; p <0.0001). In conclusion, after matching well-known risk factors, there appeared to be ethnic differences in coronary atherosclerosis morphology between Asian and white patients, at least as it affected LMCA morphology.

Two-year safety and effectiveness of sirolimus-eluting stents (from a prospective registry).

Uncertainty exists about the long-term safety and efficacy outcomes of sirolimus-eluting stents (SESs) in unselected patients. The present study was performed to evaluate the safety and efficacy of the SES in treatment of patients with coronary artery disease in an unselected population. Over a 2-year period, 1,504 consecutive patients undergoing percutaneous coronary intervention with ≥1 SES were enrolled. The primary end point was the occurrence of target vessel failure (TVF; a composite of cardiac death, myocardial infarction, or clinically driven target vessel revascularization). An independent clinical event committee adjudicated all adverse events up to 2-year follow-up. Dual antiplatelet therapy was recommended for ≥1 year throughout the study period. Mean age was 65 ± 11 years; 75% were men, and 34% were diabetics. SESs were implanted for off-label indications in 86% of cases. TVF rates were 3.3%, 6.9%, 11.5%, and 15.5% at 30-day, 6-month, 1-year, and 2-year follow-ups, respectively. The 2-year cumulative rate of definite/probable stent thrombosis was 0.9%; 0.2% was very late thrombosis, occurring from 1 year to 2 years. Patients off dual antiplatelet therapy at 6 months had a significantly increased rate of subsequent death from noncardiac causes. Patients off dual antiplatelet therapy at 1 year had a significantly decreased rate of subsequent clinically driven target lesion revascularization. In conclusion, use of SESs in unselected patients with coronary artery disease was associated with a low TVF rate at 2 years with an acceptable incidence of stent thrombosis.

Impact of myocardial bridge on clinical outcome after coronary stent placement.

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.

Classification and potential mechanisms of intravascular ultrasound patterns of stent fracture.

We sought to examine the intravascular ultrasound (IVUS) findings of stent fracture. Stent fracture has been implicated as a cause of drug-eluting stent failure. IVUS is more likely to identify mechanisms of stent failure -- including stent fracture -- than angiography. Twenty stent fractures diagnosed by IVUS in 17 patients were evaluated. Eighteen stent fractures (90%) occurred in sirolimus-eluting Cypher stents, and 2 stent fractures (10%) occurred in bare metal stents, but none occurred in paclitaxel-eluting Taxus stents. Half of the stent fractures presented < or =1 year after implantation, and (1/2) presented >1 year after implantation. IVUS analysis showed that 9 stent fractures were complete (45%) and 11 were partial (55%); 10 (50%) were adjacent to stent metal overlap; and 5 occurred in a coronary aneurysm accompanied by malapposition (all Cypher stents) despite the absence of an aneurysm at index stenting. Compared with 60 matched control segments in patients without stent fracture, but with similar clinical events, the stent fracture group had longer stent segments (45.2 +/- 23.0 vs 28.5 +/- 14.9 mm, p = 0.003). Comparing stent fractures associated with an aneurysm (n = 5) with those that did not occur in association with an aneurysm (n = 15) showed that complete stent fracture was more frequent (100% vs 27%, p = 0.008), and all presented >1 year after index stenting (vs 33%, p = 0.03). In conclusion, IVUS is helpful to identify stent fracture as a cause of stent failure and to understand possible mechanisms of stent fracture such as aneurysm formation.

In vivo intravascular ultrasonic assessment of anomalous right coronary artery arising from left coronary sinus.

Anomalous coronary arteries with origins from the contralateral aortic sinus and coursing between the aorta and pulmonary trunk have received much attention because of their association with sudden death. These morphologic features have not been well assessed in vivo. The investigators describe 3 cases of anomalous right coronary arteries arising from the left coronary sinus with intravascular ultrasound findings. In the present patients, characteristic vessel distortion was consistently observed at the ostium of the anomalous right coronary arteries, as well as systolic compression of the intra-arterial segments. In conclusion, the slitlike ostium might be associated with the higher incidence of sudden death under strenuous exercise and exercise-induced myocardial ischemia.

Comparison of angiographic and intravascular ultrasonic detection of myocardial bridging of the left anterior descending coronary artery.

The purpose of this study was to determine the incidence, location, and clinical features of myocardial bridging (MB) detected by intravascular ultrasound (IVUS) and to compare IVUS-detectable versus angiographically detectable MBs. IVUS images were analyzed in 331 consecutive patients with de novo coronary lesions located in the left anterior descending coronary artery (LAD). MB was defined as a segment of coronary artery having systolic compression and echocardiographically lucent muscle surrounding the artery (IVUS) or systolic milking (angiography). Although angiography detected MB in only 3% of patients (11 of 331), 75 MB segments (23%, 75 of 331, p <0.001) were identified by IVUS. Maximum plaque burden within the MB segment measured only 25 +/- 7%, and abnormal intimal thickness (defined as >or=0.5 mm) was not observed within the bridged segment of any patient with MB, although the study population had advanced atherosclerosis. Vessel and lumen areas in the MB segment were significantly smaller than those in adjacent proximal and even distal reference segments. Angiographically detectable MB was significantly longer, located more proximally in the LAD, and had more severe systolic compression by IVUS. Angiographically silent MB more often occurred in the presence of an adjacent proximal stenosis and lower left ventricular ejection fraction. In conclusion, IVUS may provide useful anatomic information for the accurate diagnosis of MBs that are largely angiographically silent. IVUS-detectable MBs were observed in approximately 1/4 of patients undergoing LAD imaging at our center.

Angiographic patterns of drug-eluting stent restenosis and one-year outcomes after treatment with repeated percutaneous coronary intervention.

Patterns of in-stent restenosis (ISR) after drug-eluting stent (DES) implantation and outcomes after treatment have not been studied systematically in all comers. We compared patterns of ISR and outcomes of repeated percutaneous coronary intervention in consecutive patients with DES-ISR. A total of 137 patients with 182 lesions underwent repeated percutaneous coronary intervention for DES-ISR at Columbia University Medical Center from August 2004 to April 2006. DES-ISR was treated with repeated DES placement in 84% of patients and balloon angioplasty in 16%. There was 1 stent thrombosis at 30 days, and at 1 year, major adverse cardiac events occurred in 10% of patients, driven primarily by an 8% rate of target-lesion revascularization. After exclusion of 12 patients with multiple ISR lesions, data were further analyzed from 125 patients with 152 DES-ISR lesions, of which 118 were originally treated with sirolimus-eluting stents and 34 were treated with paclitaxel-eluting stents (PES-ISR). Baseline features were well matched between the 2 groups, except that patients with PES-ISR were older. A focal pattern of ISR was observed in 69.5% of patients overall. However, patients originally treated with a PES had a significantly higher frequency of diffuse-intrastent ISR in comparison with sirolimus-eluting stent ISR (30.3% vs 13.6%, p = 0.03). In conclusion, the pattern of ISR in most DES-ISR in this unselected patient population was focal, with higher rates of diffuse intrastent restenosis seen with PES-ISR. Treatment with either repeated DES implantation or balloon angioplasty for DES-ISR was safe and associated with low overall rates of target-lesion revascularization and major adverse cardiac events at 1 year.

Effectiveness of drug-eluting stent implantation for patients with unprotected left main coronary artery stenosis.

This study was aimed to evaluate outcomes of patients with unprotected left main coronary artery (LMCA) stenosis who were treated with drug-eluting stents. Sixty-three consecutive patients with unprotected LMCA stenosis were treated with sirolimus-eluting stents in 52 (83%) patients and paclitaxel-eluting stents in 11 (17%) patients, in whom percutaneous intervention was considered the sole alternative because of high surgical risk and/or patient preference. Urgent percutaneous coronary intervention within 24 hours after angiography was performed in 6 (10%) patients. The patients were predominantly at high surgical risk with 35 (56%) having EuroSCORE >6 and 39 (62%) having Parsonnet score >15. Involvement of the distal LMCA was observed in 46 (73%) patients. Procedural success was achieved in all patients. Intravascular ultrasound was used in 51 (81%) patients. Single-stenting strategy was adopted in 36 (78%) patients with bifurcation stenosis. There were no death, Q-wave myocardial infarction, stent thrombosis, or urgent repeat revascularization events during hospitalization. Over a mean follow-up of 11.7 +/- 7.7 months, 18 (29%) patients experienced major adverse cardiac events, including 3 (5%) deaths, 7 (11%) myocardial infarctions, and 10 (16%) target lesion revascularizations. Stent thrombosis developed in 1 (0.6%) patient at 35 days after the procedure. Bifurcation involvement was an independent predictor of major adverse cardiac events by multivariate analysis (hazard ratio 12.90, 95% confidence interval 1.36 to 122.45, p = 0.0259). In conclusion, drug-eluting stent placement for unprotected LMCA stenosis may be a feasible therapeutic alternative in patients at high surgical risk. However, bifurcation stenosis remains a significant predictor of unfavorable clinical outcome.

Treatment of restenotic drug-eluting stents: an intravascular ultrasound analysis.

BACKGROUND: The intravascular ultrasound (IVUS) findings during repeat intervention for drug-eluting stent (DES) restenosis have not been well described. METHODS: We identified 62 consecutive DES restenosis lesions (45 sirolimus-eluting stents and 17 paclitaxel-eluting stents) undergoing repeat intervention with pre and postintervention IVUS. Lumen, stent and intimal hyperplasia (stent minus lumen) areas were measured at the minimal lumen area (MLA) site and minimal stent area (MSA) site. RESULTS: Repeat stent implantation was performed in 55 lesions (88.7%). Overall, MLA increased from 2.3 +/- 0.7 mm(2) preintervention to 4.6 +/- 1.6 mm(2) postintervention. Preintervention MLA was seen at exactly the preintervention MSA site in 42%, while 73% of postintervention MLAs were located at the preintervention MSA site. There was a strong correlation between the preintervention MSA and the postintervention MLA (r = 0.79; p < 0.001). Preintervention MSA was the strongest independent predictor of a larger postintervention MLA (coefficient 0.72; p < 0.001). CONCLUSIONS: The preintervention MSA was a major predictor of larger lumen area after repeat intervention for DES restenosis. Several IVUS studies have shown that stent dimensions do not change over time. Therefore, the MSA of the original stent implantation procedure still has the greatest impact on subsequent interventions to treat DES restenosis.

Assessing intermediate left main coronary lesions using intravascular ultrasound.

BACKGROUND: Angiographic assessment of a left main coronary artery stenosis (LMCS) is often difficult and unreliable. We aimed to evaluate the severity of ambiguous LMCSs by intravascular ultrasound (IVUS) and to clarify how frequently significant stenosis occurs in the "real world". METHODS: We retrospectively found 115 consecutive patients in our clinical IVUS database with a de novo, angiographically ambiguous, intermediate LMCS who underwent IVUS evaluation. Quantitative coronary angiography (QCA) and IVUS analyses were performed. We define a significant LMCS as a diameter stenosis >50% by QCA and a minimal lumen area <6.0 mm2 by IVUS. RESULTS: Ostial, mid, and distal LMCSs were seen in 44 (38.3%), 6 (5.2%), and 65 (56.5%) lesions. Overall, IVUS minimal lumen area and plaque burden measured 6.8 +/- 2.6 mm2 and 63% +/- 14%. A significant LMCS was seen in 51 (44.3%) lesions by IVUS but in only 15 (13.0%) lesions by QCA. In particular, only 36.4% of ostial lesions had a significant IVUS stenosis, and minimal lumen diameter by QCA was less well correlated with IVUS in ostial lesions than in other lesion locations. CONCLUSIONS: This real-world IVUS analysis showed that less than half of intermediate LMCSs had significant stenoses by IVUS assessment, especially for lesions located at the left main ostium. Such patients deserve IVUS assessment or physiologic assessment before blindly proceeding to revascularization.