Coronary lumen at six-month follow-up of a new radiopaque Cordis tantalum stent using quantitative angiography and intracoronary ultrasound

Novel stents for the prevention of restenosis

Since the introduction of Interventional Cardiology in 1976, there has been rapid expansion both in its clinical application and the tools of the trade. This growth was accelerated with the introduction of the intra-coronary stent in 1987. The demonstration that stents may reduce the incidence of restenosis after percutaneous coronary revascularization has further stimulated the search for the perfect endovascular prosthesis. By creating a hybrid stent, incorporating natural coatings and local drug delivery in the design, it is hoped that the complications associated with stent thrombosis and restenosis can be eradicated. (Trends Cardiovasc Med 1997;7:245-249). © 1997, Elsevier Science Inc.

Involvement of rho-kinase activation in the pathogenesis of coronary hyperconstricting responses induced by drug-eluting stents in patients with coronary artery disease

BACKGROUND

Activation of Rho-kinase plays a central role in the pathogenesis of drug-eluting stents (DES)-induced coronary hyperconstricting responses in pigs in vivo has been previously demonstrated. In the present study, Rho-kinase activation involved in those responses in patients with coronary artery disease (CAD) is examined.

METHODS AND RESULTS

In 24 patients with CAD who underwent coronary intervention with either DES or bare-metal stents (BMS), coronary vasomotor responses to intracoronary acetylcholine (ACh) before and after intracoronary pre-treatment with a Rho-kinase inhibitor, fasudil was examined. Coronary vasomotor responses by quantitative coronary angiography (QCA) and coronary vascular structure by optical coherence tomography (OCT) was evaluated. QCA showed that the coronary vasoconstricting responses to ACh were significantly enhanced in the DES group compared with the BMS group both at the proximal and the distal segments adjacent to the stents (proximal: BMS -13.0±10.7% vs. DES -25.4±14.3%, P=0.036; distal: BMS -24.4±12.2% vs. DES -43.8±14.7%, P=0.003). Importantly, fasudil markedly attenuated the enhanced vasoconstricting responses to ACh in the DES group (proximal 10.2±11.7%, distal 14.4±10.5% vs. before fasudil, both P<0.01). In the OCT imaging analysis, there was no significant correlation between intimal thickness and coronary vasoconstriction to ACh.

CONCLUSIONS

These results indicate that Rho-kinase activation is substantially involved in the pathogenesis of the DES-induced coronary hyperconstricting responses in patients with CAD, suggesting the therapeutic importance of Rho-kinase pathway.

Coronary stents: a materials perspective

The objective of this review is to describe the suitability of different biomaterials as coronary stents. This review focuses on the following topics: (1) different materials used for stents, (2) surface characteristics that influence stent-biology interactions, (3) the use of polymers in stents, and (4) drug-eluting stents, especially those that are commercially available.

The NUGGET study: NIR ultra gold-gilded equivalency trial

This study should clarify whether the gold-coated NIROYAL stent is equivalent to the stainless steel NIR stent. Patients were randomized to either NIR stent (n = 298) or a NIROYAL stent (n = 305). The primary endpoint was the minimum lumen diameter of the target lesion at 6 months postprocedure. Secondary endpoints focused on clinical events. At 30 days, adverse events were similar in both groups. At 6 months, the minimal lumen diameter was 1.83/1.64 mm (P < 0.001; 95% CI = 0.08-0.30) and the angiographic restenosis rate was 20.6%/37.7% (P < 0.001; 95% CI = -24.7 to -9.3) for NIR/NIROYAL. The 6-month MACE rates were NIR 7.4% and NIROYAL 10.5% (95% CI = -7.7 to 1.4). Compared to stainless steel stent, the NIROYAL stent demonstrated a smaller minimal lumen diameter, a higher late loss (i.e., higher neointimal hyperplasia in spite of a significantly better initial gain), with higher restenosis and similar MACE rates at 6 months.

Initial and long-term results with the CrossFlex stent--data from a national registry

The Cordis CrossFlex trade mark stent is a balloon expandable helical coil made of stainless steel. OBJECTIVE: To assess the short- and long-term safety and efficacy of this stent by conducting a multi-center national registry. METHODS: One hundred and sixteen stents were implanted in 109 patients (mean age 59 3 10 years, 95 males). The lesions were classified as type B2 or C in 56 patients (51%). Successful deployment was achieved in 103 patients (94.5%). Failure was due to damage to the stent (two patients) or inability to reach the lesion (four patients). High-pressure deployment (>14 atm) was used in 68% of cases. RESULTS: Edge dissections occurred in nine patients after high-pressure deployment and necessitated implantation of a second stent. One patient with a large acute myocardial infarction died during hospitalization. Side branch occlusion occurred in five patients (4.6%). Subacute thrombosis occurred in two patients (1.8%) during the first four weeks. During a six-month follow-up period, 18 patients (16.5%) were rehospitalized with recurrent angina. Fifteen patients had coronary angiography and 13 (12.1%) needed additional target lesion revascularization (TLR). Twelve patients required a second PTCA for in-stent restenosis, and one needed a coronary artery bypass graft operation. CONCLUSIONS: The CrossFlex coronary stent can successfully be used in complex coronary lesions, with few short-term complications and a low TLR rate. Operators should be aware of the possibility of edge dissection during high-pressure implantation.

Patterns of in-stent restenosis after placement of NIR gold-coated stents in unselected patients

The aim of this study was to assess the incidence and angiographic patterns of in-stent restenosis 6 months after the implantation of NIR gold-coated stents in an unselected patient population. One hundred and sixteen consecutive patients were treated with the implantation of 149 NIR gold-coated stents. The majority of the patients (52%) had unstable angina or acute myocardial infarction. The baseline lesion morphology was complex in 78% of cases; the mean lesion length was 18 +/- 5 mm. The procedural success rate was 97%. Subacute stent thrombosis occurred in three patients (2.6%). During the 6-month follow-up, there were 2 deaths and 22 subjects (19.5%) underwent target vessel revascularization. The 6-month event-free survival was 60%. The angiographic restenosis rate was 32%. In 83% of the cases, the morphology of the restenosis was proliferative; in the remaining 17%, it presented as total occlusion. In conclusion, the restenosis rate after NIR gold-coated stent implantation in high-risk patients is similar to that reported using other stent designs. However, restenosis was always diffuse, involving the overall stent length and extending beyond the margins, thus indicating a greater proliferative neointimal response to this device.

Improved reproducibility of intravascular ultrasound assessment of coronary in-stent neointima with the use of an echogenic contrast agent

The present study evaluated a new technique that has the potential to improve the border detection of in-stent neointima using an echogenic contrast agent during intravascular ultrasound (IVUS). To confirm the reproducibility of IVUS imaging for measuring the cross-sectional in-stent neointima area, inter- and intra-observer variability and correlation were determined. Conventional IVUS (plain IVUS) and IVUS using a contrast agent (contrast IVUS) were performed in 24 subjects 6.5+/-1.5 months after undergoing a Palmaz-Schatz coronary stent implant. Conventional IVUS delineated completely the in-stent neointima in 6 subjects (25%). In the remaining 18 subjects (75%), delineation of the neointima was incomplete despite the use of various combinations of imaging conditions (eg, transmission, compress, post-process). With contrast IVUS, the boundary of the neointima, and therefore the neointima area, was clearly distinguishable, and this resulted in complete delineation of the neointima in all 24 subjects. With a contrast agent, inter- and intra-observer variability significantly decreased (0.94+/-0.69mm2 conventional IVUS vs 0.37+/-0.40mm2 contrast IVUS, p<0.001; 0.69+/-0.56mm2 conventional IVUS vs 0.07+/-0.10mm2 contrast IVUS, p<0.0001; respectively). Thus, contrast IVUS provides a reproducible method for the quantitative analysis of in-stent neointima with excellent inter- and intra-observer correlation.

Accuracy and reliability of quantitative measurements in coronary arteries by multi-slice computed tomography: experimental and initial clinical results

AIM

To evaluate the accuracy of non-invasive measurements within coronary arteries by multi-slice computed tomography (MSCT). We present experimental as well as clinical data.

MATERIALS AND METHODS

Silicon tubes simulating coronary arteries (outer diameter 6 mm, lumen diameter within stenotic area 2 mm) were used for experimental studies. Clinical data were derived from 15 patients in whom vessel diameters were assessed by MSCT, intracoronary ultrasound (ICUS) and quantitative coronary angiography (QCA). MSCT were performed in a Somatom Volume Zoom(trade mark)CT system (Siemens, Forchheim, Germany) at 2 collimated slice widths (2.5 mm, 1.0 mm).

RESULTS

Outer silicon tube diameters were overestimated by MSCT (6.56 mm +/- 0.32 mm). All measurements revealed significantly better results on 1.0 collimation compared to 2.5 mm collimation (outer diameter: 6.36 mm +/- 0.22 mm vs 6.76 mm +/- 0.27 mm, P < 0.0001; lumen diameters: 1.83 mm +/- 0.14 mm vs 1.51 mm +/- 0.19 mm, P < 0.0001). The comparison of vessel diameters within human coronary arteries revealed comparable results between ICUS and MSCT (4.89 mm +/- 0.67 mm vs 4.91 mm +/- 0.71 mm, P = 0.79, r = 0.79, P < 0.0001). QCA-measurements showed significantly lower results (3.67 +/- 0.71, P < 0.0001, r = 0.62, P < 0.001).

CONCLUSIONS

Experimental as well as initial clinical results indicate acceptable reliability and accuracy of quantitative measurements by MSCT, when using thin collimated slice widths. Partial volume effects lead to a systematic overestimation of vessel size. MSCT has the potential to become an important non-invasive diagnostic tool in patients with coronary artery disease.

Angiographic and clinical one-year follow-up of the Cordis tantalum coil stent in a multicenter international study demonstrating improved restenosis rates when compared to pooled PTCA and BENESTENT-I data: the European Antiplatelet Stent Investigation (EASI)

The Cordis tantalum coil stent was assessed in a nonrandomized multicenter trial: 275 patients with stable or unstable angina were entered. Clinical follow-up was for 1 year, with repeat angiography at 6 months. The major adverse cardiac event rates (MACE) were 3%, 14%, and 17% at 1, 7, and 13 months, respectively. The procedural success rate was 96% and the subacute occlusion rate 1.5%, in a group of patients over 60% of whom had ACC/AHA type B2 or C lesions. The binary restenosis rate at 6 months was 17.3%. Minimum lumen diameter increased from 1.07 +/- 0.28 mm preprocedure to 2.93 +/- 0.34 mm poststenting and at 6 months was 1.99 +/- 0.69 mm. These results demonstrate that the Cordis tantalum stent can be used to treat complex lesions with good procedural success and low rates of subacute thrombosis and restenosis at 6 months.

Acute stent recoil: in vivo evaluation of different stent designs

This study sought to investigate the degree of acute recoil of four different stents by means of quantitative coronary angiography. Four hundred and six patients underwent stent implantation for single discrete coronary artery lesion: 105 received a 16 mm Paragon stent, 112 an 18 mm Multilink Duet, 97 a 16 mm NIR Primo stent, and 92 a 15 or 18 mm NIR Royal Advance. Elastic recoil was defined as the difference between mean balloon cross-sectional area (CSA) at the highest pressure and mean CSA after PTCA. The mean stent recoil was 13% +/- 10% CSA (P < 0.001), being statistically greater for the nitinol Paragon stent (21% +/- 11%), intermediate for the multicellular Multilink Duet stent (14% +/- 7%), and minimum for the NIR family (9% +/- 6% and 8% +/- 7%, respectively). The recoil was not homogeneously distributed along the stent length but was lower at the two ends (11% +/- 12% and 13% +/- 11%) and highest in the central part (15% +/- 12%)(P < 0.001). Thus, acute recoil is a significant phenomenon regardless of the mechanical properties and design of new-generation tubular stents.

Coronary artery restenosis after atherectomy is primarily due to negative remodeling

The primary cause of restenosis following directional coronary atherectomy (DCA) remains obscure. "Negative remodeling," a decrease in vessel area, is believed to be more causative than is increase in plaque area. The DCA technique used in these patients, designed to facilitate the removal of plaque, should allow a more precise evaluation of the relative roles of these two mechanisms. Twenty-five patients underwent DCA. In 17, complete angiographic and intravascular ultrasound (IVUS) images were obtained before and after DCA and at follow-up (6 to 9 months). Internal elastic lamina (IEL), lumen, and plaque areas were calculated at preatherectomy, postatherectomy, and follow-up. Postatherectomy, the mean IEL area increased by 32% and the mean plaque area decreased by 51%, resulting in a significant mean increase in lumen area, 500%. At follow-up when compared to postatherectomy, the change in IEL area was variable; however, the mean did not change significantly (p = 0.58). Plaque area change, when standardized for initial vessel size, was small (mean increase 2.8 +/- 3.5%). The mean lumen area did not decrease significantly at follow-up (p = 0.43). A highly significant correlation (r = 0.96) was noted between IEL area change and lumen area at follow-up. In contrast, the correlation between plaque area change and lumen area change over the same period was much less significant (r = 0.64). These data indicate that decrease in IEL area primarily is responsible for restenosis.

Coronary stents: In vitro aspects of an angiographic and ultrasound quantification with in vivo correlation

BACKGROUND

The validity of quantitative coronary angiography (QCA) after stent placement has been questioned because the optical density of a metallic stent, added to the density of a contrast-filled lumen, could affect border definition.

METHODS AND RESULTS

We deployed 3.0- and 4.0-mm Palmaz-Schatz, Wiktor, Multilink, NIR, and InStent stents in precision-cast phantoms. Central lumens of 2.0 mm were created. There was no difference between the "true" diameters of any stented lumen by both QCA and quantitative ultrasonic (QCU) measurement poststenting. QCA systematic error (SE) varied from 0.01 for the Wiktor stents to 0.14 mm for the Palmaz-Schatz stents; the random error (RE) was 0.03 to 0.14 mm. QCU SE varied from 0.05 to 0.11 mm, and RE ranged from 0.01 to 0.07 mm. At the next stage, 4.0-mm Wiktor and Palmaz-Schatz stents were deployed into the phantom lumens; 1.5-, 2.0-, 2.5- and 3.0-mm lumens were created inside the stents. QCA and QCU measurements of 1.5- to 2.5-mm residual lumens were overestimated by 0.1 to 0.3 mm. In the 3. 0-mm residual lumen within the Wiktor stent, QCA underestimated the luminal size by -0.1 mm. There was no QCA inaccuracy for a 3.0-mm lumen within the Palmaz-Schatz stent. In patients, in 25 stented segments in both the Palmaz-Schatz and Wiktor groups, there was no difference between QCA and QCU diameters.

CONCLUSIONS

QCU is sufficiently precise for the assessment of the coronary lumen after stenting. QCA can be used as an accurate method of poststent assessment, except when a very mild recurrence within a highly opaque stent is measured. In that instance, QCA may underestimate the luminal diameter.

Transjugular intrahepatic portosystemic shunt in a porcine model: histologic characteristics at the early stage

RATIONALE AND OBJECTIVES

The authors attempted to determine the histologic processes that take place during development of stenosis after transjugular intrahepatic portosystemic shunt (TIPS) creation.

MATERIALS AND METHODS

TIPS were created with metallic stents in 20 healthy domestic pigs (tantalum stents in 10, stainless steel stents in 10). The animals were sacrificed 2-16 days later. All the shunts were examined by means of venography both immediately after placement of the stents and before sacrifice. All histologic sections were assessed with modified Giemsa and basic fuchsin stains. Anti-smooth-muscle-cell alpha-actin stain was used in three specimens. The stenotic reaction was quantified by using standard planimetry techniques and a computerized image-analysis system.

RESULTS

Within 16 days after TIPS placement, 15 (75%) of the 20 shunts were completely occluded, four (20%) of 20 shunts were partially occluded, and one (5%) of 20 shunts remained widely patent (animal died of unknown cause 2 days after the TIPS procedure). Stent occlusion was caused primarily by pseudointimal hyperplasia, which was similar morphologically in the portal, middle, and hepatic portions of the stent. Myofibroblastic proliferation was the most striking feature of the pseudointimal hyperplasia. The average thickness of the proliferation was 2.14 mm, which was 67% of the total diameter of the stent. A mild fibrous or lymphocytic reaction occurred around the stent wires and between the pseudointimal hyperplasia and the liver parenchyma.

CONCLUSION

The histologic features of pseudointimal formation in this swine TIPS model closely resemble those in humans. This model may prove useful for evaluating stents and other devices and improving the understanding of restenosis after vascular interventions.

Quantitative videodensitometric technique for verification of optimal coronary stent implantation

Coronary angiography is not sensitive enough to define the results of stent implantation. Intravascular ultrasound defines accurately the anatomy of the vessel and the stent within the vessel and is thus considered the gold standard for defining the results of stent implantation. However intravascular ultrasound is an additional invasive procedure that is time consuming and expensive. This study describes a new simple quantitative videodensitometric technique, developed specifically to assess the results of stent implantation and compares the findings to intravascular ultrasound. In the proposed algorithm for the videodensitometric analysis, density profiles were constructed perpendicular to the long axis of the stented segment and each one was compared (after background subtraction) with a theoretic profile of a normal artery at that location. Density deficit index was determined at each point from the actual and theoretic profiles and a global volumetric density deficit index was calculated for each stent by integrating the deficit indices at all points along the stent. Similarly an area stenosis was determined at each point along the stent (using the stent and normal vessel cross sectional areas as defined by intravascular ultrasound) and the global volumetric stent stenosis was calculated by integrating the values of area stenosis along the stent. Twenty-five patients were evaluated immediately before and after coronary stent implantation. Global density deficit index improved from 66.1+/-16.4% before (after last balloon inflation) to 44.4+/-11.1% after stenting (P < 0.001). The shape of the curves of densitometric deficit indices along each stent were similar to the equivalent area stenosis curves as determined by intravascular ultrasound. The correlation (R = 0.74) between the global volumetric density deficit index and the global volumetric stent stenosis is statistically significant (P < 0.001). In conclusion, in this preliminary report we describe a new algorithm for videodensitometric analysis of the results of coronary stent implantation. As compared with intravascular ultrasound this method does not require an additional invasive procedure and it is quick cheap and easy to carry out.

Late clinical outcomes of cordis tantalum coronary stenting without anticoagulation

This study was performed to evaluate clinical and angiographic restenosis rates after successful Cordis coronary stent implantation and intravascular ultrasound images were acquired to compare results with quantitative angiographic findings in a subgroup of patients. We conclude that (1) the angiographic restenosis rate of Cordis stent was 19%, which was comparable to that of other slotted-tube stents, and (2) the quantitative coronary angiographic calliper method is reliable for assessing Cordis in-stent restenosis, especially diffuse in-stent restenosis.

Comparison of coronary luminal quantification obtained from intracoronary ultrasound and both geometric and videodensitometric quantitative angiography before and after balloon angioplasty and directional atherectomy

BACKGROUND

Debate exists regarding the relationship between angiographic and intracoronary ultrasound (ICUS) measurements of minimal luminal cross-sectional area after coronary intervention. We investigated this and the factors that may influence it by using ICUS and quantitative angiography.

METHODS AND RESULTS

Patients who underwent successful balloon angioplasty (n=100) or directional atherectomy (n=50) were examined by using ICUS and quantitative angiography (edge-detection [ED] and videodensitometry [VID]) before and after intervention. Luminal damage postintervention was qualitatively graded into three categories based on angiographic results (smooth lumen, haziness, or dissection). Correlation of minimal luminal cross-sectional area measurements by ICUS and ED was .59 before and .47 after balloon angioplasty. Correlation between ICUS and VID was .50 before and .63 after balloon angioplasty. Postintervention, the difference between ICUS and VID was less than the difference between ICUS and ED (P<.01). Additionally, the correlation was .74 between ICUS and ED measurements and .78 between ICUS and VID measurements in the smooth lumen group, .46 and .63, respectively, in the presence of haziness, and .26 and .46, respectively, in lesions with dissection. Similar results were obtained after directional atherectomy: the agreement between ICUS and quantitative angiography deteriorated according to the degree of vessel damage, but less so with VID than ED.

CONCLUSIONS

Complex morphological changes induced by intervention may contribute to discordance between the two quantitative imaging techniques. In the absence of ICUS, VID may be a complementary technique to ED in lesions with complex morphology after balloon angioplasty and directional atherectomy.

Is intravascular ultrasound after coronary stenting a safe procedure? Three cases of stent damage attributable to ICUS in a tantalum coil stent

The use of coronary stents decreases the morbidity associated with acute closure and restenosis after balloon angioplasty. Intracoronary ultrasound (ICUS) guidance of stent implantation has been advocated to improve stent deployment and thereby to further improve the clinical outcome after stenting, over and above balloon angioplasty. Whereas the merits of intracoronary ultrasound in this respect still remain to be proven, the present paper illustrates that ICUS itself may also entail complications. This paper reports on three cases of stent damage induced or aggravated by the ICUS procedure.

Endovascular stents: a 'break through technology', future challenges

Coronary stents were developed to overcome the two main limitations of balloon angioplasty, acute occlusion and long term restenosis. Coronary stents can tack back intimal flaps and seal the dissected vessel wall and thereby treat acute or threatened vessel closure after unsuccessful balloon angioplasty. Following successful balloon angioplasty stents can prevent late vessel remodeling (chronic vessel recoil) by mechanically enforcing the vessel wall and resetting the vessel size resulting in a low incidence of restenosis. All currently available stents are composed of metal and the long-term effects of their implantation in the coronary arteries are still not clear. Because of the metallic surface they are also thrombogenic, therefore rigorous antiplatelet or anticoagulant therapy is theoretically required. Furthermore, they have an imperfect compromise between scaffolding properties and flexibility, resulting in an unfavourable interaction between stents and unstable or thrombus laded plaque. Finally, they still induce substantial intimal hyperplasia which may result in restenosis. Future stent can be made less thrombogenic by modifying the metallic surface, or coating it with an antithrombotic agent or a membrane eluting an antithrombotic drug. The unfavourable interaction with the unstable plaque and the thrombus burden can be overcome by covering the stent with a biological conduit such as a vein, or a biodegradable material which can be endogenous such as fibrin or exogenous such as a polymer. Finally the problem of persisting induction of intimal hyperplasia may be overcome with the use of either a radioactive stent or a stent eluting an antiproliferative drug.

Recent progress in coronary interventions--assessment by quantitative coronary angiography

Coronary balloon angioplasty is now well accepted as an effective therapy for patients with significant coronary artery stenosis. However, a number of deficiencies, including short-term complications, long-term restenosis, and limited application to complex morphologic lesions, restrict the widespread use of this technique. The precise lesion measurement provided by quantitative coronary angiography and intracoronary ultrasonography is a prerequisite for the optimization of balloon dilation or stent implantation. The short-term outcome may be improved by stent implantation, as this can prevent acute closure by acting as a scaffold for the disrupted vessel wall. The indications for percutaneous revascularization have been extended to chronic total occlusion by using a special guidewire, a laser wire and a coronary stent. Local drug delivery techniques to distribute agents to target revascularization sites may play a role in reducing the restenosis rate. Although the limitations of balloon angioplasty have led to the introduction of new devices, it remains to be seen whether these new devices can demonstrate, in a scientific manner, their safety, feasibility and superiority over conventional balloon angioplasty. Percutaneous coronary revascularization therapy may be an acceptable alternative to coronary bypass surgery in the future. However, to confirm this, a large multicenter randomized study is necessary to compare new percutaneous coronary interventional devices with bypass surgery. Additionally, further studies are required to demonstrate the most effective device for treating specific lesions in each individual patient.

New stent technologies

Coronary stents were developed to overcome the two main limitations of balloon angioplasty, acute occlusion and long-term restenosis. Coronary stents can tack back intimal flaps and seal the dissected vessel wall, thereby treating acute or threatened vessel closure after unsuccessful balloon angioplasty. After successful balloon angioplasty, stents can prevent late vessel remodeling (chronic vessel recoil) by mechanically enforcing the vessel wall and resetting the vessel size, resulting in a low incidence of restenosis. All currently available stents are composed of metal, and the long-term effects of their implantation in the coronary arteries are still not clear. Because of the metallic surface, they are also thrombogenic; therefore, rigorous antiplatelet or anticoagulant therapy is theoretically required. Furthermore, they have an imperfect compromise between scaffolding properties and flexibility, resulting in an unfavorable interaction between stents and unstable or thrombus-laden plaque. Finally, they still induce substantial intimal hyperplasia that may result in restenosis. Future stents can be made less thrombogenic by modifying the metallic surface or coating it with an antithrombotic agent or a membrane eluting an antithrombotic drug. The unfavorable interaction with the unstable plaque and the thrombus burden can be overcome by covering the stent with a biological conduit, such as a vein, or a biodegradable material that can be endogenous, such as fibrin, or exogenous, such as a polymer. Finally, the problem of persisting induction of intimal hyperplasia may be overcome with the use of either a radioactive stent or a stent eluting an antiproliferative drug.

Short- and long-term clinical and quantitative angiographic results with the new, less shortening Wallstent for vessel reconstruction in chronic total occlusion: a quantitative angiographic study

OBJECTIVES

This study was designed to examine whether oversized implantation of the new, less shortening Wallstent provides a more favorable long-term clinical and angiographic outcome in chronic total occlusions than does conventional coronary balloon angioplasty.

BACKGROUND

Restenosis and reocclusion remain major limitations of balloon angioplasty for chronic total occlusions. Enforced mechanical remodeling by implantation of the oversized Wallstent may prevent elastic recoil and improve accommodation of intimal hyperplasia.

METHODS

Lumen dimension was measured by a computer-based quantitative coronary angiography system (CAAS II). These measurements (before and after intervention and at 6-month follow-up) were compared between the groups with Wallstent implantation (20 lesions, 20 patients) and conventional balloon angioplasty (266 lesions, 249 patients) for treatment of chronic total occlusion. Acute gain (minimal lumen diameter after intervention minus that before intervention), late loss (minimal lumen diameter after intervention minus that at follow-up) and net gain (acute gain minus late loss) were examined.

RESULTS

Wallstent deployment was successful in all patients. High pressure intra-Wallstent balloon inflation (mean +/- SD 14 +/- 3 atm) was performed in all lesions. Although vessel size did not differ between the Wallstent and balloon angioplasty groups, acute gain was significantly greater in the Wallstent group (2.96 +/- 0.55 vs. 1.61 +/- 0.34 mm, p < 0.0001). Although late loss was also significantly larger in the Wallstent group (0.81 +/- 0.95 vs. 0.43 +/- 0.68 mm, p < 0.05), net gain was still significantly greater in this group (2.27 +/- 1.00 vs. 1.18 +/- 0.69 mm, p < 0.0001). Angiographic restenosis (> or = 50% diameter stenosis) occurred at 6 months in 29% of lesions in the Wallstent group and in 45% of those in the balloon angioplasty group (p = 0.5150).

CONCLUSIONS

Implantation of the oversized Wallstent, with full coverage of the lesion length, ensures resetting of the vessel size to its original caliber before disease and allows greater accommodation of intimal hyperplasia and chronic vessel recoil. Wallstent implantation provides a more favorable short- and long-term clinical and angiographic outcome than does conventional balloon angioplasty for chronic total occlusions.

Six-month clinical and angiographic outcome of the new, less shortening Wallstent in native coronary arteries

BACKGROUND

The new, less shortening, self-expanding Wallstent is characterized by longitudinal flexibility, a protective membrane, a low profile, and a customized range of diameters (3.5 to 6.0 mm). The recent modification of the braiding angle of the Wallstent has resulted in a new device with less shortening on expansion and a concomitant reduction in radial force. We hypothesized that the enforced mechanical remodeling produced by the selection of an oversized Wallstent might result in improved accommodation of subsequent reactive intimal hyperplasia and prevention of chronic recoil of the vessel.

METHODS AND RESULTS

To prove this hypothesis, we recently implanted 44 new, less shortening Wallstents in 35 native coronary arteries in 35 patients with acute or threatened closure after balloon angioplasty, according to a strategy of oversizing of Wallstent diameter and complete coverage of the lesion length. The initial and 6-month follow-up angiograms were analyzed with a computer-based quantitative coronary angiography (QCA) system. Acute gain (minimal luminal diameter [MLD] post minus MLD pre) and late loss (MLD post minus MLD at follow-up) were examined. Stent deployment was successful in 44 of 44 attempts (100%). Nominal stent diameter used was 1.40 mm larger than the maximal vessel diameter. One patient (3%) with a dilated but unstented lesion proximal to the stented segment sustained a subacute occlusion on day 1 associated with myocardial infarction. Event-free survival at 30 days after stent implantation was 97% (34 of 35 patients). Of the 34 patients eligible for 6-month angiographic follow-up, 3 who were asymptomatic declined repeat angiography. MLD (and percent diameter stenosis [% DS]) changed from 0.83 +/- 0.50 mm (72%) pre through 3.06 +/- 0.48 mm (15%) post to 2.27 +/- 0.74 mm (28%) at follow-up. Acute gain was 2.23 +/- 0.63 mm, and late loss was 0.78 +/- 0.61 mm. Angiographic restenosis ( > 50% DS) was observed in 5 of 31 patients (16%) at 6 months, all of whom underwent repeat angioplasty. Thus, the overall event-free survival at 6-month follow-up was 83% (29 of 35 patients).

CONCLUSIONS

The oversized Wallstent implantation with complete coverage of the lesion length conveyed a favorable 6-month clinical and angiographic outcome. The large acute gain obtained by the Wallstent afforded greater accommodation of the subsequent late loss. The enforced mechanical remodeling by oversized new Wallstents may result in prevention of acute and chronic recoil of the vessel wall and subsequently a lower restenosis rate at follow-up.

Relation of basal coronary tone and vasospastic activity in patients with variant angina

OBJECTIVE

To examine the vasoconstrictor response to ergonovine and the vasodilator response to isosorbide dinitrate in spastic and non-spastic coronary segments from 31 patients undergoing serial angiographic follow up of variant angina.

METHODS

Coronary angiograms and ergonovine provocation tests were repeated at an interval of 45 (SD 15) months apart. While all 31 patients showed a positive response to ergonovine initially, vasospastic responsiveness persisted in only 16 patients at follow up (group 1) and not in the other 15 patients in whom symptoms of variant angina had resolved (group 2). Mean luminal diameter of 170 normal or near normal entire coronary segments (American Heart Association classification) were measured (a) at baseline, (b) after the administration of ergonovine, and (c) after the administration of isosorbide dinitrate, during both the initial and follow up angiograms using a computer based quantitative angiography analysis system (CAAS II).

RESULTS

In vasospastic patients (initial and follow up angiograms in group 1, and initial angiogram in group 2), basal tone was significantly higher in spastic segments compared to adjacent segments or segments in non-spastic vessels. The diagnostic sensitivity and specificity at 20% increase in basal coronary tone for the prediction of vasospasm were 77% and 73%, respectively.

CONCLUSIONS

Coronary artery tone may change in proportion to the activity of variant angina over several years. Contrary to some previous reports, the estimation of basal coronary tone may be useful in the assessment of vasospastic activity in patients with variant angina.