Comparison of luminal enlargement by direct coronary stenting versus predilation coronary stenting by three-dimensional volumetric intravascular ultrasound analysis

Direct Stenting in Patients Treated with Orbital Atherectomy: An ORBIT II Subanalysis

BACKGROUND

Direct stenting offers many potential advantages in appropriately selected lesions. Coronary artery calcification increases the complexity and risk of adverse events associated with percutaneous coronary intervention. This study aimed to examine the feasibility of direct stenting after treatment with orbital atherectomy (OA).

METHODS

ORBIT II was a single-arm trial enrolling 443 subjects with de novo severely calcified coronary lesions treated with OA; direct stenting was utilized in 59.0% of cases. Procedural outcomes and 3-year major adverse cardiac event (MACE) rates were compared in subjects treated with pre-stent balloon dilatation versus direct stenting after OA.

RESULTS

Procedural success (84.2% vs. 93.3%; p = 0.004) was significantly higher in the direct stenting cohort. 3-year MACE occurred less frequently in the direct stenting cohort (29.9% vs. 19.1%; p = 0.006), driven by lower rates of myocardial infarction and target lesion revascularization. In a propensity matched analysis, procedural success and 3-year MACE rates were similar in the pre-stent balloon dilatation and direct stenting groups (85.0% vs. 91.8%; p = 0.122 and 28.2% vs. 19.6%; p = 0.078, respectively).

CONCLUSIONS

Orbital atherectomy facilitates direct stenting and is associated with high procedural success and favorable 3-year outcomes in carefully selected patients. Randomized studies are needed to assess the optimal strategy after lesion preparation with OA.

Effectiveness of "direct" stenting without balloon predilatation (from the Multilink Tetra Randomised European Direct Stent Study [TRENDS])

The purpose of the TRENDS trial was to assess the safety, efficacy, and cost effectiveness of a no-predilatation ("direct") stenting strategy in the treatment of de novo native coronary artery lesions using the Multilink Tetra stent system. In this multicenter, prospective clinical trial, 1,000 patients were randomized (1:1) to receive a Multilink Tetra stent with or without balloon predilatation. The primary outcome measurement was major adverse cardiac events (MACEs) at 30 days; secondary end points included resource utilization (including procedural duration, equipment use, and length of hospital stay), MACEs, and angiographic binary restenosis at 180 days. In the predilatation group, 587 stents were implanted in 499 patients; in the direct group, 579 stents were implanted in 501 patients. In the direct group, stents in 31 lesions (5.7%) required predilatation and multivariate analysis identified calcification (odds ratio 5.81), angulation (odds ratio 5.34), and preprocedural minimal lumen diameter (odds ratio 0.09) as direct stenting failure. MACEs at 30 days were similar in the 2 groups, with 19 (3.8%) in the predilatation group and 13 (2.6%) in the direct group (p = NS). Resource utilization favored the direct strategy, with decreases in balloon use, contrast media, and procedure time, but a larger number of guiding catheters was used. The 180-day MACE rate of 9.8% in the direct group was not significantly less than the rate of 10.8% in the predilatation group (p = NS). Quantitative angiographic follow-up at 6 months demonstrated in-stent binary restenotic rates of 11.4% in the predilatation group (late loss 0.88 +/- 0.53 mm) and 12.3% in the direct group (late loss 0.82 +/- 0.51 mm, p = NS) and in-segment restenosis rates of 12.2% and 13.4%, respectively (p = NS). In conclusion, a direct stenting strategy with the Multilink Tetra stent was feasible and safe in 94% of lesions and associated with lower resource utilization compared with a predilatation approach. Direct stenting was not associated with significantly lower MACE and target lesion revascularization rates and had no effect on late angiographic follow-up, with similar late loss reflecting an identical biologic response to bare metal stent placement.

Underexpansion of sirolimus-eluting stents: Incidence and relationship to delivery pressure

We aimed to assess the incidence of underexpansion and the relationship between delivery pressure and expansion with sirolimus-eluting stents. Adequate stent expansion contributes to early and late improved outcomes. In 51 patients (53 lesions) with native coronary artery narrowing, balloon-expandable sirolimus-eluting stents (Cypher) were serially expanded with gradual balloon inflations [14 atm, 20 atm, and in case of minimal stent cross-sectional area (CSA)/reference lumen CSA < 50% at 20 atm, postdilatation with 0.5 mm larger balloon]. Intravascular ultrasound (IVUS) imaging was performed before intervention and after each gradual balloon inflation. Stent expansion (minimal stent CSA/reference lumen CSA) was measured. Stent expansion was 72% +/- 16% after 14 atm balloon inflation, 90% +/- 18% after 20 atm balloon inflation (P < 0.001 vs. 14 atm), and 90% +/- 18% at the end of the procedure (including optional postdilatations with 0.5 mm larger balloon; P = NS vs. 20 atm). Stent expansion addressed by MUSIC criteria (all struts apposed, no tissue protrusion, and final lumen CSA > 80% of the reference or > 90% if minimal lumen CSA was < 9 mm2) was adequate in 15% of the cases after 14 atm balloon inflation, in 60% after 20 atm balloon inflation (P < 0.001 vs. 14 atm), and in 60% at the end of the procedure (P = NS vs. 20 atm). Sirolimus-eluting stent underexpansion is common when deployed at conventional pressures. Increasing balloon delivery pressure or assessing stent expansion with IVUS seems warranted in order to ensure adequate sirolimus-eluting stent deployment.

Compliance matching stent placement in the carotid artery of the swine promotes optimal blood flow and attenuates restenosis

OBJECTIVES

We assessed the value of a gradient-compliant stent in an animal model.

METHODS

Bilateral carotid arteries were stented with nitinol stents having variable-oversizing, variable-stiffness, and with (CMS, 10 animals) and without (SMART, four animals) compliance-matching endings. Angiography, hemodynamic, scanning-electron-microscopic and histological analyses were performed at 3-month. The protocol was completed in 14 among 19 swines.

RESULTS

Transient (1-month) exaggerated recoil, attributable to stress-induced phasic inhibition of vasorelaxation, developed at CMS endings. At mid-term, all stents were endothelialized; CMS-stents, but not SMART-stents, were incorporated into walls (one-strut-thickness). Restenosis developed outside SMART-stents (cell migration+wall-compensatory enlargement) whereas CMS-stents elicited no or focalized cell-accumulations at endings that bulged vascular walls radially outward. SMART-stents were blood-flow neutral, whereas CMS-stents favored (higher-stiffness, higher-oversizing) or opposed (lower-stiffness, less-oversizing) carotid blood flow.

CONCLUSIONS

Direct carotid stenting with stents having compliance-matched endings and specific requirements of stiffness and oversizing can optimize blood flow to the brain and restrict local restenosis.

Experimental assessment of new stent technologies: validation of a comparative paired rabbit iliac artery study model

Preventing coronary in-stent restenosis is a major challenge for physicians and industry. To assess new stent technologies, a comparative paired iliac artery model in rabbits is proposed. One tubular stent was implanted in each external iliac artery in 12 rabbits (i.e., 24 stents). An artery overdilatation level of 20% was strictly observed. Restenosis was examined at 30 days by angiography, intravascular ultrasound (IVUS) examination, and histomorphometry. On quantitative angiography, the mean loss of angiographic diameter was 9.8 +/- 4.4% in the right as compared to 9.3 +/- 55% in the left artery (p = 0.75). On IVUS, the volume of intrastent neointimal proliferation was 26.6 +/- 4.9 mm(3) in the right and 25.8 +/- 3.5 mm(3) in the left artery (p = 0.58). In histomorphometry, the neointimal proliferation area was 0.78 +/- 17 mm(2) in the right and 0.76 +/- 0.17 mm(2) in the left artery (p = 0.87). Intrastent neointimal proliferation was comparable between the left and right arteries of all rabbits. The model has three main advantages: (1) arterial dilatation and thus arterial wall aggression are controlled, (2) pairing makes each animal its own control subject, and (3) the statistical power for comparative testing is maximized. The model enables the effect of a new drug-delivery device to be assessed.

Randomized comparison of direct stenting with predilatation followed by stenting on vessel trauma and restenosis

BACKGROUND

Direct stenting may reduce trauma to the vessel wall, thereby having a positive impact on acute and long-term results. This study evaluated acute vessel trauma and acute and follow-up angiographic and intravascular ultrasound (IVUS) results after direct stenting in comparison to conventional stenting.

METHODS

Two hundred forty-nine patients were randomly assigned to direct stenting (n = 124) or stenting after predilatation (n = 125) and were followed up by angiography at 6 +/- 2 months. Intracoronary serum endothelin (ET-1) levels were determined distal to the lesion before and after coronary intervention to define vessel trauma, and IVUS was performed before and after intervention and at follow-up to determine induced changes in vessel morphology and intimal hyperplasia in a subgroup of 40 patients.

RESULTS

Feasibility of direct stenting was 91%, with 9% requiring crossover to predilatation. There were no differences between the 2 groups in immediate clinical, angiographic, and intravascular ultrasound results. Intracoronary ET-1 levels increased significantly after intervention, without differences between the 2 groups (increase in ET-1 level, 0.79 +/- 1.06 vs 0.96 +/- 1.22 fmol/L, P =.206). At 6-month follow-up, angiographic late loss (0.76 +/- 0.86 vs 0.69 +/- 1.09 mm, P =.788) and restenosis rate (21% vs 20%, P = 1.000) were similar for direct stenting versus conventional stenting, respectively. IVUS demonstrated comparable intimal hyperplasia areas for direct versus conventional stenting (2.0 +/- 1.5 mm(2) vs 2.2 +/- 1.6 mm(2), respectively, P =.243).

CONCLUSIONS

Direct stenting is highly feasible and results in similar vessel trauma and change in vessel morphology and acute lumen dimensions compared with stenting after predilatation. Similar acute angiographic and IVUS results persist at 6-month follow-up.

Intracoronary stenting and angiographic results: Restenosis after direct stenting versus stenting with predilation in patients with symptomatic coronary artery disease (ISAR-DIRECT trial)

The objective of this randomized study was to assess whether direct stenting leads to less restenosis than does conventional stenting (CS) with predilation in clinical practice. We included 910 patients who were randomly assigned to undergo either direct stenting (DS; n = 456) or CS (n = 454). No significant difference was observed in the incidence of angiographic restenosis (primary endpoint): 23.6% for DS and 21.0% for CS (P = 0.41; relative risk = 1.1; 95% CI = 0.8-1.5). The incidence of target vessel revascularization was 17.3% among DS and 14.8% among CS patients (P = 0.29; relative risk = 1.2; 95% CI = 0.8-1.6). The combined incidence of death or myocardial infarction at one year was 9.0% in the DS group and 7.0% in the CS group (P = 0.28). In conclusion, direct stenting is not associated with any reduction of thrombotic and restenotic complications as compared to the conventional stenting.

Impact of intravascular ultrasound-guided direct stenting on clinical outcome of patients treated for native coronary disease

BACKGROUND

Despite the fact that in animal models direct stenting (DS) reduces the vessel injury, in clinical practice this treatment strategy did not reduce late restenosis as compared to conventional strategy with balloon predilatation (PD). However, the influence of DS was not evaluated when stent expansion is optimized by intravascular ultrasound (IVUS) assessment.

METHODS

We analyzed the in-hospital and 1-year outcomes of patients at Washington Hospital Center who were treated with percutaneous coronary interventions and stent implantation when percutaneous intervention was guided by IVUS. Only patients treated for single de novo lesions were included.

RESULTS

In 1386 patients, 251 (18.1%) were treated with DS and 1135 (71.9%) were treated with PD. Pre- and postprocedure characteristics by angiography and IVUS were similar in both groups. Postprocedure non-Q-wave myocardial infarction (MI) occurred in 4.9% of the DS group and in 12.5% of the PD group (P = .005). At 1-year follow-up, target lesion revascularization (TLR) rate was 4.9% in the DS group and 14.8% in the PD group (P = .005). DS strategy (odds ratio = .46, confidence interval = .25-.85, P = .013) was independently correlated to lower risk for revascularization in multivariate analysis.

CONCLUSION

When DS is implemented by IVUS assessment, it is associated with low in-hospital and long-term events.

Effect of direct stenting on clinical outcome in patients treated with percutaneous coronary intervention on saphenous vein graft

BACKGROUND

Percutaneous coronary intervention (PCI) of saphenous vein graft (SVG) is associated with frequent postprocedural enzyme elevation and late cardiac events. New strategies are proposed to minimize distal embolization and to improve the outcome of patients treated with stenting for SVG lesions. The objectives of the current study were to examine direct stenting (DS) strategy of PCI in SVG lesions and its effects on creatine-kinase (CK) release, major adverse cardiac events (MACE), and late outcome when compared to conventional stenting (CS).

METHODS

A consecutive series of 527 patients treated with stent implantation for SVG stenosis was analyzed. In this cohort, 170 patients with 229 lesions were treated with DS and 357 patients with 443 lesions were treated with CS. The inhospital and 12-month follow-up events were recorded and reported.

RESULTS

Baseline clinical and postprocedural angiographic characteristics were similar between the 2 groups except for higher preprocedural prevalence of thrombus-containing lesions in the DS group. Patients in the DS group had less CK-MB release (P <.001), and less non-Q-wave myocardial infarction (P =.024). Multivariate analysis detected unstable angina (odds ratio [OR] = 1.8, P =.03) as a correlate for non-Q-wave MI; DS was inversely associated with non-Q-wave myocardial infarction (OR = 0.65, P =.04). At 1 year, the target lesion revascularization-MACE was significantly lower in the DS group (P =.021). Multivariate analysis showed that DS (OR = 0.47, P =.007) was associated with reduction of the target lesion revascularization-MACE.

CONCLUSIONS

When feasible, DS may be the best approach for treating SVG stenosis.

Preintervention arterial remodeling affects vessel stretch and plaque extrusion during coronary stent deployment as demonstrated by three-dimensional intravascular ultrasound

The mechanisms of lumen enlargement during stent implantation may be significantly affected by arterial remodeling. To assess effects of lesion remodeling, we performed 3-dimensional intravascular ultrasound (IVUS) analyses in 55 coronary lesions before and after deployment of balloon-expandable stents. Standard quantitative analysis was performed, and arterial remodeling was assessed by the remodeling index (target site divided by mean of proximal and distal reference segment vessel areas), which classified lesions into group A (remodeling index < or =1, negative or intermediate remodeling, n = 40) or group B (remodeling index >1, positive remodeling, n = 15) lesions. Characteristics of the 55 patients and the interventional procedures were similar in the 2 groups. IVUS demonstrated that stenting resulted in increased lumen and vessel dimensions and in a reduced plaque size (p < or =0.001 each) in both group A and group B lesions. The extent of lumen increase inside the stents was almost identical, but resulted from different mechanisms: (1) vessel stretch was greater in group A (p <0.002 at minimum lumen site); (2) plaque compression (or embolization) tended to be greater in group B (p = 0.05, along entire stented segment); (3) plaque redistribution within the stent was observed in both groups (p <0.005 both); and (4) significant (p <0.01) plaque extrusion into the distal reference segment was found in group B only. Thus, the remodeling pattern of coronary lesions has a significant impact on the mechanisms of lumen enlargement during stent deployment. Lesions with positive remodeling show more plaque extrusion into the distal reference and less stent-induced vessel stretch than those with negative remodeling.

Impact of moderate lesion calcium on mechanisms of coronary stenting as assessed with three-dimensional intravascular ultrasound in vivo

Axial plaque redistribution is an important mechanism of lumen enlargement after stenting of noncalcified lesions. To assess effects of lesion calcification on mechanisms of coronary stenting, we analyzed 55 lesions with noncircumferential calcification with 3-dimensional intravascular ultrasound (IVUS) (standard qualitative and quantitative analyses) before and after implantation of balloon-expandable stents. Thirty-two plaques (58%) showed arcs of calcium <120 degrees of vessel circumference (group A), whereas 23 lesions (42%) contained arcs of calcium > or =120 degrees of vessel circumference (group B). In the entire cohort of 55 lesions, as well as groups A and B, which were studied separately, both single-slice IVUS analysis (performed at minimum lumen site before intervention) and mean stented segment IVUS analysis showed an increase in lumen and vessel area and a decrease in plaque area (p <0.001). The magnitude of lumen and vessel increase and of plaque decrease was similar in both groups. Group A lesions showed significant plaque extrusion into the distal reference segment that was not observed in group B (increase in plaque area of 1.3 +/- 1.9 vs 0.1 +/- 2.0 mm(2), p <0.04). Stenting did not alter plaque area of the proximal reference segment in either group. In addition, there was an increase in vessel area of the distal reference of both groups, indicating that stent-induced vessel expansion observed within the lesion also affected the distal reference. Thus, longitudinal plaque redistribution and vessel expansion contribute to increased lumen dimensions during stenting of lesions with varying amounts of calcium; however, marked plaque extrusion was found only in lesions with a calcium arc of <120 degrees.

Is coronary stent deployment and remodeling affected by predilatation? An intravascular ultrasound randomized study Stenting with or without predilation: an IVUS study

In this intravascular ultrasound (IVUS) randomized trial we compared a strategy of direct stenting (DS) without predilation (n = 30) vs. conventional stenting with predilation (SWP) (n = 30) in patients with suitable type A or B non-calcified lesions in native vessels > or = 3 mm. Optimal deployment was achieved using angiographic criteria without interactive IVUS. The goal of our study was to determine whether stent expansion and coronary remodeling were similar. Maximal pressure inflation was comparable in the two groups (11.4 +/- 2.2 vs. 11.8 +/- 1.9 atm; NS). Stent deployment was obtained in all patients with complete apposition to the vessel wall. DS and SWP resulted in comparable lumen enlargement (5.4 +/- 2.5 vs. 5.5 +/- 2.1 mm2) with an identical mechanism: 66% of lumen enlargement was due to increased enlarged elastic membrane (EEM)-cross sectional area (CSA) (delta = 3.7 +/- 2.1 mm2 and delta = 2.4 +/- 6.8 mm2, respectively, p < 0.49) and 34% was due to a reduced P + M-CSA (delta = 0.02 +/- 6.9 mm2 and delta = 1.2 +/- 6.3 mm2, respectively, p < 0.50). We conclude that at the same maximal pressure inflation the mechanisms of stent expansion are similar in both DS and SWP groups. In this observational study, the IVUS data showed clearly under-expansion of stents in both groups in comparison with previously published CSA values (minimum stent CSA of 7.5 mm2).