Safety and efficacy of angiography-guided stent placement in small native coronary arteries of < 3.0 mm in diameter

Which DES is the most appropriate for very small target vessels? Experimental study of stent expandable performance with SES, PES, ZES and EES

The restenosis rate of coronary stent has significantly decreased by implantation of the drug-eluting stent (DES). We often experienced the DES implantation for very small target vessels. The minimum size of DES in Japan and USA is 2.5 mm-diameter, but there were no reports of the expandability of DESs for the very small target vessels with reference diameter <2.2 mm. We clarify the expandable performance of 2.5 mm-DESs for very small target vessels with reference diameter <2.2 mm in vitro and vivo study. We studied 3 pieces in each kind of DES (Sirolimus-eluting stent; SES, Paclitaxel-eluting stent; PES, Zotarolimus-eluting stent; ZES and Everolimus-eluting stent; EES) in vitro and vivo study of the porcine coronary artery with reference diameter <2.2 mm. By using the delivery balloon, each stent was initially dilated with 3.5 atm. And the pressure of 0.5 atm. was applied until it reached the maximum pressure of 12 atm. The minimum pressure of the full expanded stent balloon was estimated as the minimum expandable pressure. The stent-inner diameter and area on each pressure were measured by IVUS. The average minimum expandable pressure (atm.) in vitro/vivo was 4.7/4.5 in SES, 7.2/6.8 in PES, 4.3/4.5 in ZES and 3.8/3.8 in EES. The inner diameter (mm) in vitro/vivo at minimum expandable pressure was 1.81 ± 0.07/1.84 ± 0.05 in SES, 2.31 ± 0.10/2.13 ± 0.13 in PES, 2.41 ± 0.13/1.98 ± 0.31 in ZES and 2.13 ± 0.11/1.88 ± 0.22 in EES. The stent inner-diameter (mm) of DESs at 8 atm. in vivo was 2.16/2.21/2.45/2.25 in SES/PES/ZES/EES. All kinds of DES could be delivered to very small target vessels with reference diameter <2.2 mm at the minimum expandable pressure in vivo study, but the stent which presented adequate stent inner-diameter at 8 atm. was only SES. We have to implant the 2.5 mm-DESs for very small target vessels according to the data based on this expandability of DESs to bail out threatening occlusion due to coronary dissection or elastic recoil.

Coronary artery stenting and non-cardiac surgery--a prospective outcome study

BACKGROUND

A 45% complication rate and a mortality of 20% were reported previously in patients undergoing non-cardiac surgery after coronary artery stenting. Discontinuation of antiplatelet drugs appeared to be of major influence on outcome. Therefore we undertook a prospective, observational multicentre study with predefined heparin therapy and antiplatelet medication in patients undergoing non-cardiac procedures after coronary artery stenting.

METHODS

One hundred and three patients from three medical institutions were enrolled prospectively. Patients received coronary artery stents within 1 yr before non-cardiac surgery (urgent, semi-urgent or elective). Antiplatelet drug therapy was not, or only briefly, interrupted. Heparin was administered to all patients. All patients were on an intensive/intermediate care unit after surgery. Main outcome was the combined (cardiac, bleeding, surgical, sepsis) complication rate.

RESULTS

Of 103 patients, 44.7% (95% CI 34.9-54.8) suffered complications after surgery; 4.9% (95% CI 1.6-11.0) of the patients died. All but two (bleeding only) adverse events were of cardiac nature. The majority of complications occurred early after surgery. The risk of suffering an event was 2.11-fold greater in patients with recent stents (<35 days before surgery) as compared with percutaneous cardiac intervention more than 90 days before surgery.

CONCLUSIONS

Despite heparin and despite having all patients on intensive/intermediate care units, cardiac events are the major cause for new perioperative morbidity/mortality in patients undergoing non-cardiac surgery after coronary artery stenting. The complication rate exceeds the re-occlusion rate of stents in patients without surgery (usually <1% annually). Patients with coronary artery stenting less than 35 days before surgery are at the greatest risk.

Rationale for off-pump coronary revascularization to small branches—angiographic study of 1,283 anastomoses in 408 patients

BACKGROUND

Off-pump coronary artery bypass grafting (OPCAB) has gained wide acceptance in tandem with the development of the stabilizer and associated operative techniques. However bypass grafting to the small branches of a beating heart is technically demanding and remains controversial. In the present study we evaluated the graft patency and quality of anastomoses to small coronary arteries by early postoperative angiography.

METHODS

Between March 2000 and December 2002 a total of 1,328 anastomosed sites to coronary branches were studied angiographically in 404 patients representing 88.6% of all cases who underwent OPCAB in this period. The coronary artery branches were categorized as large (>1.5 mm, group L: 1,028 anastomoses sites) or small (< 1.5 mm, group S: 300 sites) by intraoperative measurement. As in situ grafts the internal thoracic artery (ITA) and the gastroepiploic artery (GEA) were used at 504 and 28 distal anastomosis sites respectively. The radial artery (RA) was used as a composite graft for 739 distal anastomosis sites. Sequential bypass grafting was performed at 388 anastomosis sites in side-to-side fashion. Arterial grafts were used in 96.1% of total bypass grafting.

RESULTS

The percentage of male gender was 78.3% in group S and 87.2% in group L (p = 0.025). The ITA was used in 43.7% of group L and 18.3% of group S (p < 0.0001). The RA was used in 49.4% of group L and 77% of group S (p < 0.0001). The overall patency and stenosis free rates (FitzGibbon Type A) were 97.2% and 96.2%. Graft patency and stenosis free rates in group S (96.7% and 93.3%) were as good as those in group L (97.5% and 97.1%). In group S, the patency and stenosis free rates of SV grafts were 71.4% and 57.1%. On the other hand, those of ITA grafts were 100% and 98.3% (p = 0.53 vs. saphenous vein graft [SVG]) and RA grafts were 95.8% and 92.1% (p = 0.61 vs. SVG) respectively. In group S, the graft patency and stenosis free rates of bypass to the obtuse marginal (OM) (93.7% and 87.5%) were slightly lower than those to other implantation sites left anterior descending (LAD: 100% and 97.3%; PL: 96.5% and 92.3%; DI: 98.0% and 96%; PDA: 97.0% and 97.0%; right coronary artery [RCA]: 100% and 100%) although there was no statistical significance. The graft patency and stenosis free rates were slightly better with side-to-side anastomosis than with end-to-side anastomosis (side-to-side: 98.1% and 95.8% vs. end-to-side 96.3% and 86.3%) in group S.

CONCLUSIONS

OPCAB to small coronary artery branches with arterial grafts provided satisfactory graft patency and stenosis free rates.

Early and late outcome of stenting in a consecutive series of patients with coronary lesions in vessels less than 2.8 mm in diameter

In an attempt to determine the early and late outcomes of small vessel stenting, we retrospectively evaluated our database on 51 consecutive patients (41 males, mean age, 57.1 +/- 10.1 years) who underwent stenting of at least one significant lesion in a coronary artery with a reference vessel diameter (RVD) <2.8 mm between March 1999 and March 2001. Sixty balloon expandable tubular stents were implanted in 57 lesions (29 Type B2/C, mean RVD: 2.54 +/- 0.16 mm) without intravascular ultrasound guidance under a heparin-aspirin-ticlopidine regimen. The mean diameter stenosis (DS) decreased from 75.8 +/- 13.6% to 4.2 +/- 1.9% (P<0.0001) with stenting at a mean deployment pressure of 13.6 +/- 1.7 atm and a final balloon to RVD ratio (FB/RVD) of 1.08 +/- 0.03. All stents were deployed successfully. Acute stent thrombosis occurred in 3 patients (6%), one died, and 2 developed non-Q-wave myocardial infarction (procedural success 94%). Clinical follow-up, available in 48 patients, revealed a 29% target lesion revascularization rate, a 2% myocardial infarction rate, and a 71% event-free survival at a mean of 11.6 months. Angiographic follow-up, available in 40 patients, showed a DS of 48.8 +/- 31.3% and a binary restenosis rate of 50% at a mean of 7.7 months. The FB/RVD ratio was significantly lower in the group with restenosis than in the group without (1.06 +/- 0.02 vs 1.1 +/- 0.05, P = 0.04). Subgroup analysis yielded a significantly greater rate of restenosis in diabetics with complex (Type B2/C) lesion morphology compared to nondiabetics with simple (Type A/B1) lesions (75% vs 21%, P < 0.05). In conclusion, stenting in vessels <2.8 mm was found to be associated with a high rate of acute stent thrombosis and in-stent restenosis. Further analysis detected a subgroup of patients without diabetes or complex lesions who could be stented with an acceptable in-stent restenosis rate.

Final results of the CAPAS trial

BACKGROUND

The Cutting Balloon (Interventional Technologies Inc) is a new-concept balloon that incorporates 3 to 4 blades to create sharp incisions on the luminal surface of the lesion during dilation without causing severe tearing injury to the vessel wall. It may reduce restenosis and improve clinical outcome.

METHODS

Two hundred forty-eight lesions were randomly assigned to Cutting Balloon angioplasty (CBA, 120 lesions) or conventional balloon angioplasty (PTCA, 128 lesions). Inclusion criteria were type B/C lesions (American College of Cardiology/American Heart Association classification) and reference diameter <3.0 mm by visual image on angiogram. Quantitative coronary angiography was performed before and after percutaneous coronary angioplasty and at 3-month follow-up. The primary end point was restenosis, defined as >/=50% diameter stenosis at follow-up. Clinical event rates at 1 year were assessed.

RESULTS

Baseline characteristics were similar. Reference diameter was small in both groups (2.16 vs 2.18 mm, CBA vs PTCA). Preprocedural percent diameter stenosis (%DS) was similar (69.8% vs 69.6%). However, postprocedural and follow-up %DS were lower (26.2% vs 28.9%, P =.072; 40.8% vs 47.5%, P =.011) in the CBA group. Restenosis was significantly lower (25.2% vs 41.5%, P =.009) in the CBA group. At 1 year, event-free survival was achieved in 72.8% of the CBA group and in 61.0% of the PTCA group (P =.047).

CONCLUSION

These findings suggest that CBA provides superior angiographic and clinical outcomes in comparison with PTCA in small coronary arteries.

Comparison of immediate and one-year outcome after coronary angioplasty of narrowing < 3 mm with those > or =3 mm ( the National Heart, Lung, and Blood Institute Dynamic Registry)

Balloon angioplasty of small coronary artery lesions has been associated with lower success and higher complication rates than large coronary artery lesions. This study evaluates the in-hospital and 1-year outcome of the treatment of small coronary artery lesions in the modern era of interventional cardiology and compares it with the outcome of treating large coronary artery lesions. Of 1,658 patients with a single lesion treated from July 1997 to February 1998 in the National Heart, Lung, and Blood Institute (NHLBI) Dynamic Registry, there were 587 patients with small coronary artery lesions (<3 mm) and 1,071 patients with large coronary artery lesions (> or =3 mm). Success, in-hospital, and 1-year outcomes between both groups were compared. Patients with lesions in small coronary arteries were more often women, insulin-treated diabetics, and had undergone more prior coronary bypass graft surgery. Conventional angioplasty alone was performed more often and angioplasty with stents was performed less often in the small coronary artery than in the large coronary artery group. Angiographic success was slightly lower in the small coronary artery group (94.2% vs 96.9%, p <0.05). Periprocedural and in-hospital complication rates were similar in both groups. Likewise, at 1-year follow-up, major adverse cardiac events including death, myocardial infarction, and coronary artery bypass graft surgery were relatively low and comparable between the 2 groups, although patients with small coronary arteries were more likely to undergo repeat revascularization (17.4% vs 13.6%, p <0.05). Treatment of lesions in small coronary arteries in the modern era is associated with high success and low complication rates, comparable to the treatment of large coronary artery lesions, although the incidence of repeat revascularization was significantly greater at follow-up even if stents were used.

Immediate and one-year outcome of intracoronary stent implantation in small coronary arteries with 2.5-mm stents

BACKGROUND

The role of coronary stenting in the treatment of stenoses in small coronary arteries with use of 2.5-mm stents is not well defined.

METHODS AND RESULTS

Between January 1995 and August 1999, 651 patients with stenoses in small coronary arteries were treated with 2.5-mm stents (n = 108) or 2.5-mm conventional balloon angioplasty (BA) (n = 543). Patients who received treatment with both 2.5-mm and > or =3.0-mm stent placement or balloons were excluded. Procedural success and complication rates as well as 1-year follow-up outcomes were examined. Baseline clinical characteristics were similar between the two groups, except patients in the stent group were more likely to have hypertension and a family history of coronary artery disease and less likely to have prior myocardial infarction. Angiographic success rates were higher in the stent group (97.2% vs 90.2%, P =.02). In-hospital complication rates were comparable between the two groups. Among successfully treated patients, 1-year follow-up revealed no significant differences in the survival (96.2% vs 95.2%, P =.89) or the frequency of Q-wave myocardial infarction (0% vs 0.4%, P =.60) or coronary artery bypass grafting (8.4% vs 6.8%, P =.89) between the stent and BA groups, respectively. However, patients in the stent group were more likely to have adverse cardiac events (35.4% vs 22.1%, P =.05). Stent use after excluding GR II stent use, however, was not independently associated with reduced cardiac events at follow-up (relative risk 1. 3 [95% confidence interval 0.8-2.3], P =.30).

CONCLUSIONS

Intracoronary stent implantation of stenoses in small coronary arteries with 2.5-mm stents can be carried out with high success and acceptable complication rates. However, compared with BA alone, stent use was not associated with improved outcome through 1 year of follow-up.

Stent placement for non-STRESS/BENESTENT lesions: a critical review

Stenting lesions with favorable characteristics as required for inclusion in the STRESS/BENESTENT trials have yielded superior results to that of PTCA alone. Results for less favorable lesions such as in small vessels, diffuse disease, ostial disease, and saphenous vein grafts are less well established. This review seeks to analyze available data for stent placement in this subset of non-STRESS/BENESTENT lesions.

Clinical and angiographic outcome after angiography-guided stent placement in small coronary vessels

BACKGROUND

Although it is widely accepted that stenting confers favorable angiographic and clinical results in coronary arteries >/=3.0 mm in diameter, the outcome of stent placement in smaller vessels remains largely unclear.

METHODS AND RESULTS

We sought to specifically determine the early and long-term clinical outcomes in a large series of 197 consecutive patients who underwent stent placement in 207 vessels <3.0 mm in diameter. Procedural success, accomplished in 97.3%, was accompanied by a significant reduction in lesion severity from 85% +/- 9% before to 3% +/- 7% diameter stenosis after the procedure (P =.0001) and a 0.5% incidence of subacute stent thrombosis. At 1 and 2 years of follow-up, survival rate without major target lesion-driven events was observed in 77.3% and 73.9% of patients, respectively. Repeat revascularization procedures accounted for most of these events; cardiac deaths (including those related to subacute stent thrombosis) and late (>30 days) myocardial infarctions were infrequent (2.4% and 1.0%, respectively). The 6-month angiographic binary instent restenosis rate was 30.1%. On multivariate analysis, diabetes mellitus (P =. 0275), small baseline reference vessel size (P =.0300), and stent size </=2.7 mm (P =.0111) were independently associated with an increased instent restenosis rate.

CONCLUSIONS

Optimal angiography-guided coronary stenting of vessels <3.0 mm in diameter in association with the stringent use of a poststent combined aspirin-ticlopidine antiplatelet regimen confers a low risk of stent thrombosis, an acceptable incidence of angiographic instent restenosis, and a favorable long-term clinical outcome.

Angiographic and clinical outcome of a new self-expanding intracoronary stent (RADIUS): results from multicenter experience in Japan

The RADIUS coronary stent featuring a multisegmented slotted tube design and self-expanding nitinol delivery system has a high radial force and flexibility, uniform expansion, and contours to the shape of the vessel. Successful stent deployment was achieved in 104 stable angina patients (106 lesions; 44% LAD, 19% circumflex, and 37% RCA). Mean minimal lumen diameter (MLD) increased from 0.77 +/- 0.46 mm to 2.88 +/- 0.61 mm and mean percent diameter stenosis (% DS) decreased from 73 +/- 14% to 6 +/- 13% immediately after the procedure. At 6-month follow-up, two patients (2%) underwent urgent target revascularization, and cerebral bleeding occurred in one patient (1%). Angiographic follow-up was performed in 94 lesions (89%) and mean MLD and mean % DS were 2.08 +/- 0.92 mm and 30% +/- 24%, respectively. Stent restenosis (>50% diameter stenosis at follow-up) was observed in 16 (17%) of all lesions. The high success rate for stent deployment, low incidence of major adverse cardiac event, and lower restenosis rate after stent implantation indicate that the RADIUS stent is useful for coronary intervention.

Mid-term clinical and angiographic follow-up outcome after placement of a new balloon expandable stent in native coronary arteries

The widely disparate characteristics that exist among the different stent designs currently available for clinical use may impact on their acute and late angiographic and clinical results. The BeStent (Medtronic Instent, MN) is a relatively new stainless steel, laser-cut, serpentine stent design with only very limited data regarding its performance. In this report, we examined the results of 74 consecutive patients (54 men, 20 women; mean age, 58 years) treated with 76 BeStents in 75 native coronary arteries with a mean reference size of 2.8 mm. Successful stenting without 30-day major adverse cardiac complications was achieved in 97.3% of procedures, resulting in a significant improvement in diameter stenosis from 85% to 2% (P = 0.0001). Six-month angiographic restudy in 88% of patients revealed a per-lesion in-stent restenosis rate of 27%. At a mean follow-up period of 9.3 months, there were no deaths or myocardial infarctions. In summary, the present study demonstrates that the BeStent has an excellent performance profile, is associated with a low risk of stent thrombosis, and yields an acceptable restenosis rate despite the inclusion of a high proportion of patients with diabetes (41%) and small vessels (< 3.0 mm in diameter; 77%).

Acute and late outcome after use of 2.5-mm intracoronary stents in small (< 2.5 mm) coronary arteries

We describe the high-pressure deployment of 2.5-mm stents in small (< 2.5 mm) coronary vessels. Forty-three lesions in 40 patients were treated. The mean reference vessel diameter was 2.3 +/- 0.2 mm. The mean % luminal stenosis was 90 +/- 9. The mean lesion length was 11. 7 +/- 9.1 mm. Sixteen lesions were pretreated with rotational atherectomy, and the remainder with PTCA. The rate of successful stent deployment was 41/43 (95%). The mean postintervention % stenosis was -1 +/- 10. There were no in-hospital deaths or procedure-related Q-wave MI. The patients were followed for a mean of 18 months. Eight patients (or 21%) developed recurrent chest pain and/or angiographically proven restenosis. One patient (3%) developed intermediate restenosis. Twenty-nine patients (or 76%) either remain symptom-free or have patent target sites on repeat angiography. It appears that reasonable acute and long-term results can be achieved with 2.5-mm stents in small coronary arteries using high-pressure deployment techniques. Cathet. Cardiovasc. Intervent. 49:121-126, 2000.

Immediate and mid-term results after MultiLink stent implantation in native coronary arteries

Different stent designs have widely disparate characteristics that may exert a positive or negative impact on their early and mid-term outcomes. The MultiLink stent (Guidant/Advanced Cardiovascular Systems, Santa Clara, CA) is a new coronary stent with only very limited data. In this report, we examined the results of 50 consecutive patients treated with 57 premounted sheathless MultiLink stents in 53 native coronary arteries with reference diameter > or =2.7 mm. Successful stenting was achieved in 98% of patients, resulting in an improvement in diameter stenosis from 91%+/-11% to 1%+/-3% (P = 0.0001). At 1 month, there was no death, myocardial infarction, or stent thrombosis. Angiographic restudy at a mean of 5.0+/-1.8 months in 94% of patients revealed an in-stent restenosis rate of 20.7%. The restenosis rates for diabetic patients (vs. nondiabetic patients), type C lesions (vs. type A/B1 lesions), and the use of 35-mm-long stents (vs. 15-mm-long stents) were 45.4% (14.3%), 56% (< or =11%), and 80% (8.8%), respectively (P < 0.05). In conclusion, the present study demonstrates that the MultiLink stent has an excellent performance profile, is associated with a low risk of stent thrombosis in native coronary vessels, and yields a favorable restenosis rate, particularly after the use of short (15 mm) stents to treat simple lesions.

Angiographic restenosis rate in patients with chronic total occlusions and subtotal stenoses after initially successful intracoronary stent placement

The 5-month angiographic in-stent restenosis rate did not differ between patients with chronic total occlusions (n = 43) and subtotal stenoses (n = 43) equally matched for diabetes status, exact stent design, final expanded stent diameter, stent length, and residual percent diameter stenosis after stent placement; it was 32.5% and 27.9% for those with chronic total occlusions and subtotal stenoses, respectively (p = 0.638). Furthermore, the stent occlusion rate (4.6% vs 6.9%, respectively) was low in both patient groups.

Midterm angiographic outcome of single-vessel intracoronary stent placement in diabetic versus nondiabetic patients: a matched comparative study

BACKGROUND

It remains controversial whether diabetes is associated with an increased risk of restenosis after intracoronary stenting.

METHODS AND RESULTS

We selected 42 diabetic patients and an equal number of nondiabetic patients with follow-up angiographic restudy after single-vessel stenting, matched for 4 important stent-related and angiographic variables (stent design, reference vessel size and expanded stent diameter, coronary vessel treated, and poststent residual diameter stenosis). The 2 patient groups did not differ in their baseline lesion severity and acute luminal gain. At 5-month angiographic assessment, the observed in-stent restenosis rate was significantly higher in diabetic than nondiabetic patients (40.5% vs 16.7%, P = 0.0157). It was highest in diabetic patients who received small stents <3.0 mm in diameter and intermediate in diabetic patients who received larger stent sizes (55% vs 27%, P = 0.0675). The frequency of restenosis in nondiabetic patients, however, was low; it was 18% and 15% in those who received small stents and larger stents, respectively (P = 0.7823).

CONCLUSIONS

Our data suggest that diabetes predisposes to an increased risk of in-stent restenosis, particularly in small vessels.

Treatment of in-stent restenosis with high speed rotational atherectomy and IVUS guidance in small <3.0 mm vessels

The management of in-stent restenosis remains a subject for debate because no one revascularization option is considered the most appropriate. Since a high restenosis rate still occurs after repeat balloon angioplasty, new techniques are attempted in order to reduce this rate. A combination of high speed rotational atherectomy (HSRA) and adjunctive balloon angioplasty is likely to achieve good results. In small (<3.0 mm diameter) vessels, the risk of interaction between the burr and the stent increases. We thus used intravascular ultrasound (IVUS) guidance in the treatment of in-stent restenosis with HSRA in small <3.0 mm small diameter vessels. Nine patients with in-stent restenosis in small vessels were referred for repeat angioplasty. Initial IVUS examination was used to assess the minimal stent struts diameter and to guide the burr size selection. A combination of HSRA and additional balloon angioplasty was performed under IVUS and angiographic guidance. Mean angiographic reference diameter was 2.25 +/- 0.35 mm and mean stent struts diameter was 2.38 +/- 0.20 mm. Burr size was selected approximately 0.5 mm smaller than stent struts diameter and ranged from 1.75 to 2.5 mm, with a 0.88 +/- 0.12 mean burr/artery ratio (range 0.71, 1.08). In two patients, a second larger burr was used. In 4/9 patients, the burr size chosen under IVUS guidance was close to angiographic MLD at stent implantation and thus larger than what would be used without IVUS guidance. Additional balloon angioplasty was decided in all cases, using a 1.1 +/- 0.15 balloon/artery ratio. No complication occurred. Mean relative gain in minimal lumen diameter (MLD) was 94 +/- 90% after HSRA and 54 +/- 34% after balloon angioplasty (total relative gain 180 +/- 100%). IVUS guidance allowed safe management of in-stent restenosis in small vessels using combination of HSRA and balloon angioplasty. Long-term follow-up and comparison with other techniques are necessary to assess whether this technique should be used routinely.