Remodeling and Restenosis: Observations from Serial Intravascular Ultrasound Studies.

Late responses to nonstent coronary interventions are determined less by intimal hyperplasia than by the direction and magnitude of arterial remodeling, except in diabetic patients. Negative arterial remodeling is a late event, is often preceded by an early (nonsustained) positive remodeling, and is distinct from passive elastic recoil. Diabetic patients have an exaggerated intimal hyperplastic response. Plaque burden may play an important role in the restenosis process by amplifying the negative remodeling. Stents reduce restenosis by opposing the late negative remodeling to offset a stent-related increase in neointimal hyperplasia. Both probucol and radiation appear to reduce late lumen loss after balloon angioplasty by promoting positive remodeling.

Intravascular Ultrasound Assessment of the Mechanisms and Predictors of Restenosis Following Coronary Angioplasty.

Restenosis occurs after 30% to 50% of transcatheter coronary procedures; its mechanisms remain incompletely understood. Intravascular ultrasound (IVUS) studies were analyzed in 360 nonstented native coronary artery lesions in which follow-up quantitative angiographic and/or IVUS data was available. Pre-intervention, post-intervention, and follow-up, the external elastic membrane (EEM) and lumen cross-sectional areas (CSA) were measured; plaque+media (P+M=EEM Ð lumen CSA), and cross-sectional narrowing (CSN=P+M/EEM CSA) were calculated. The anatomic slice selected for serial analysis had an axial location within the lesion at the smallest follow-up lumen CSA. At follow-up, 73% of the decrease in lumen CSA was due to a decrease in EEM CSA; 27% was due to an increase in P+M CSA. The change in lumen CSA correlated more strongly with the change in EEM CSA than with the change in P+M CSA. The change in EEM CSA was bidirectional; 47 lesions (22%) showed an increase in EEM CSA. Despite a greater increase in P+M CSA, lesions exhibiting an increase in EEM CSA had (1) no change in lumen CSA, (2) decreased restenosis, and (3) a 49% frequency of late lumen gain. The independent clinical, angiographic, and IVUS predictors of angiographic restenosis (³ 50% diameter stenosis at follow-up) were the IVUS reference lumen CSA, angiographic pre-intervention diameter stenosis, and post-intervention IVUS CSN. Restenosis appeared to be determined primarily by the direction and magnitude of the change in EEM CSA. An increase in EEM CSA was adaptive while a decrease in EEM CSA contributed to restenosis. The most powerful predictor of restenosis was the IVUS post-procedural CSN. The importance of the post-procedural CSN was related to the change in EEM CSA as a mechanism of restenosis.

Intravascular Ultrasound Assessment of the Mechanisms and Predictors of Restenosis Following Coronary Angioplasty.

Restenosis occurs after 30% to 50% of transcatheter coronary procedures; its mechanisms remain incompletely understood. Intravascular ultrasound (IVUS) studies were analyzed in 360 non-stented native coronary artery lesions in which follow-up quantitative angiographic and/or IVUS data was available. Pre-intervention, post-intervention, and follow-up, the external elastic membrane (EEM) and lumen cross-sectional areas (CSA) were measured; plaque + media (P + M = EEM - lumen CSA), and cross-sectional narrowing (CSN = P + M/EEM CSA) were calculated. The anatomic slice selected for serial analysis had an axial location within the lesion at the smallest follow-up lumen CSA. At follow-up, 73% of the decrease in lumen CSA was due to a decrease in EEM CSA; 27% was due to an increase in P+M CSA. The change in lumen CSA correlated more strongly with the change in EEM CSA than with the change in P + M CSA. The change in EEM CSA was bidirectional; 47 lesions (22%) showed an increase in EEM CSA. Despite a greater increase in P + M CSA, lesions exhibiting an increase in EEM CSA had (1) no change in lumen CSA, (2) decreased restenosis, and (3) a 49% frequency of late lumen gain. The independent clinical, angiographic, and IVUS predictors of angiographic restenosis (³ 50% diameter stenosis at follow-up) were the IVUS reference lumen CSA, angiographic pre-intervention diameter stenosis, and post-intervention IVUS CSN. Restenosis appeared to be determined primarily by the direction and magnitude of the change in EEM CSA. An increase in EEM CSA was adaptive while a decrease in EEM CSA contributed to restenosis. The most powerful predictor of restenosis was the IVUS post-procedural CSN. The importance of the post-procedural CSN was related to the change in EEM CSA as a mechanism of restenosis.

Angiographic Results and Late Clinical Outcomes Utilizing a Stent Synergy (Pre-Stent Atheroablation) Approach in Complex Lesion Subsets.

To investigate the strategy of ÒdebulkingÓ in complex lesions before stent implantation (stent synergy) to improve procedural safety and achieve optimal acute and long-term results, we reviewed our experience in 389 patients with 504 lesions undergoing a combined stent procedure (45% rotational atherectomy, 24% laser angioplasty, 20% directional atherectomy, and 11% transluminal extraction atherectomy before stent implantation). Procedural success was achieved in 94.5%, with 4% major ischemic complications (1.1% death, 1.9% Q-wave myocardial infarction, and 2.3% emergency coronary artery bypass surgery). Overall, subacute stent thrombosis occurred in 1.5% of patients. Target-lesion revascularization during follow-up was required in 9.8% of the patients. We conclude that a strategy of selective pre-stent atheroablation in complex lesion subsets results in excellent procedural outcomes with acceptable complications and favorable long-term results.

Carotid Stent-Assisted Angioplasty: Preliminary Technique, Angiography, and Intravascular Ultrasound Observations.

Currently, surgical carotid endarterectomy has been the standard therapy for symptomatic and asymptomatic patients with significant carotid artery stenoses. However, there are high surgical risk and other patient subsets, wherein a Òlesser invasiveÓ catheter-based procedure may be worthwhile. Carotid stent-assisted angioplasty (CSSA) is a percutaneous interventional treatment approach for appropriately selected patients with common and internal carotid artery lesions. The present report discusses preliminary technique-related, angiographic, and intravascular ultrasound observations of CSSA. Five symptomatic patients (with six carotid stenoses) with other co-morbid states were treated by a multidisciplinary team under the aegis of an approved protocol using conventional equipment and available Palmaz tubular slotted stents. On-line quantitative angiography and intravascular ultrasound imaging was performed to guide stent insertion and monitor results. There were no procedure-related complications and angiographic results were excellent (final mean diameter stenosis 5%). Intravascular ultrasound imaging was feasible and safe. In two cases, the findings obtained from ultrasound images assisted in subsequent operator decisions. Thus far, there have been no additional clinical sequelae in these patients (@ 30 days). This preliminary experience with CSSA indicates that interventional neurovascular therapies may provide a useful alternative for selected patients requiring endoluminal reconstruction of carotid stenoses. Extensive additional studies are required to establish the appropriate clinical application of this technique.

Frequency and Prognostic Importance of Creatine Phosphokinase Myocardial Isoforms after Successful Balloon and New Device Coronary Angioplasty.

The frequency and prognostic importance of subclinical myocardial necrosis after new device coronary intervention is not known. To identify the frequency of CPK-MB release after balloon and single new device angioplasty in native coronary arteries, we reviewed the course of 810 patients who underwent successful single lesion, native vessel angioplasty using balloon angioplasty (N=174), Gianturco-Roubin stent placement for suboptimal angioplasty results (N=31), Palmaz-Schatz stent deployment (N=320), directional coronary atherectomy (N=102), or rotational atherectomy (N=183). All patients had serial measurements of CPK-MB isoenzymes 6 and 18Ð24 hours after coronary intervention; absolute CPK-MB levels were determined by radioimmunoassay (normal assay < 4 ng/ml). CPK-MB isoenzymes were > 2 times normal (> 8 ng/dl) in 15.6% of procedures, > 3 times normal (³ 12 ng/ml) in 11.5% of procedures, > 4 times normal (³ 16 ng/ml) in 8.6% of procedures, and > 5 times normal (³ 20 ng/ml) in 7.7% of procedures. CPK-MB elevation > 2 times normal was more common in those undergoing directional atherectomy (20.8%) and Gianturco-Roubin stent placement (34,4%) than in those undergoing balloon angioplasty (11.7%). No significant differences were noted in patients undergoing rotational atherectomy (13.2%) or Palmaz-Schatz stent placement (15.6%) than in those undergoing balloon angioplasty. CPK-MB > 5 times normal occurred after 7.7% of procedures, but did not vary significantly among the devices used in this study. We conclude that CPK-MB elevations > 2 times normal are highest in patients undergoing directional coronary atherectomy and ÒbailoutÓ use of the Gianturco-Roubin stent. No significant differences in CPK-MB elevation were seen in patients undergoing balloon angioplasty, Palmaz-Schatz stent deployment, or rotational atherectomy. Identification of the prognostic importance of these CPK-MB elevations is currently under study.