Abstract
Purpose
We compared the efficacy of drug-eluting stents (DESs) versus bare-metal stents (BMSs) in de novo and native aorto-ostial lesions (AOLs) guided by intravascular ultrasound (IVUS).
Method
Thirty-eight patients underwent DES implantation for 38 AOLs; 35 with sirolimus-eluting stents, and three with paclitaxel-eluting stents (DES group). The control group was composed of 40 AOLs treated by BMS. The incidence of the primary composite end point of all-cause mortality, Q-wave myocardial infarction and target vessel revascularization (TVR) as TVR-major adverse cardiac event (TVR-MACE) was evaluated during a 1-year follow-up. Clinical and IVUS parameters were compared between the DES and BMS groups, and Cox hazards model was used to calculate hazard ratios of several factors for the 1-year TVR-MACE.
Results
Although the vessel, plaque, and stent volumes were significantly larger after the procedures in the DES group owing to longer lesions (18.3±5.1 vs. 13.2±5.9 mm, P <.001), the stent volume index (10.8±2.6 vs. 12.4±3.3, P =.024) was much smaller than that in the BMS group. During the 1-year follow-up, there were 13 TVR-MACEs in all patients (13% in DES vs. 20% in BMS, P =.4 by Kaplan–Meier analysis). The Cox hazards model did not indicate any specific unfavorable factor for the 1-year TVR-MACE.
Conclusions
The present study showed equality between DES and BMS on de novo and native AOLs about the 1-year TVR-MACE rate, even though a DES was used in longer and bulkier lesions as compared to BMS.
1
Introduction
Drug-eluting stents (DESs) have drastically decreased the neointimal growth leading to a marked reduction in the restenosis rate . As a result, the availability of DESs has spread to more complicated and complex lesions, such as aorto-ostial lesions (AOLs), which were thought to be challenging in the bare-metal stent (BMS) era. AOLs are uniquely cumbersome because of their rigidity and elastic recoil . Tsunoda et al. reported that because of the special anatomical characteristic of AOLs, there is a high possibility that after stenting tissue proliferation with chronic recoil might occur from the aortic wall this has been demonstrated by intravascular ultrasound (IVUS) analysis. Thus far, several studies have reported that a DES might be superior to a BMS for the treatment of AOLs in terms of angiographic and clinical outcomes. On the contrary, it was also suspected that the outcomes of using DES for AOLs might be inferior for the treating the proximal lesions of the same vessel and that AOL is the most powerful predictor for target lesion revascularization (TLR) after DES implantation . The purpose of this study was to evaluate whether IVUS guidance can modify the efficacy of DES implantation in AOLs as compared to that of BMS implantation. We also wanted to evaluate if there is any unfavorable factor among the clinical and IVUS parameters for cardiovascular events of stented AOLs within 1 year after implantation.
2
Methods
2.1
Patient population
We retrospectively identified 38 patients who underwent DES implantation for 38 de novo and native AOLs from October 2004 to July 2008. Sirolimus-eluting stents (Cypher, Cordis, Johnson and Johnson, Miami Lakes, FL, USA) were implanted in 35 patients and paclitaxel-eluting stents (Taxus, Boston Scientific, Natick, MA, USA) were implanted in three patients (DES group). The control group composed of 40 patients with 40 de novo and native AOLs who underwent BMS implantation from just before the introduction of the DES to July 2008. Patients with cardiogenic shock or contraindication to antiplatelet agents were excluded from this study. Patients who required emergent coronary artery bypass immediately after stent implantation were also excluded. Baseline clinical characteristics and procedural variables were recorded and entered prospectively by the staff. All patients gave written informed consent before the procedure.
2.2
Percutaneous coronary intervention procedures
Percutaneous coronary intervention (PCI) was performed in patients with stable angina and acute coronary syndrome, or in patients with evidence of ischemia. An AOL was defined as stenotic lesion (≥75% diameter stenosis, angiographically) at the junction between the aorta and the orifice of the right coronary artery or left main coronary artery within 3 mm of the ostium of the vessel. All stents were employed with protrusion into the aorta to fully and appropriately cover the lesion after predilatation. Intraprocedural anticoagulation included administration of unfractionated heparin with an activated clotting time of >250 s. The type of stent and the use of other devices were at the discretion of the operator. All patients were pretreated with aspirin (100 mg) before the procedures; the treatment was continued indefinitely. Ticlopidine (200 mg) before 2007 and clopidogrel (75 mg) after 2007 were prescribed additionally for at least 1 and 12 months after BMS and DES implantation, respectively.
2.3
IVUS
IVUS was performed using the Boston Scientific (Minneapolis, MN, USA) system that incorporated a 40 MHz single-element beveled transducer (Atlantis SR Pro2) which rotated at 1,800 rpm and was coupled with ClearView Ultra. All IVUS images were recorded after intracoronary administration of 2–5 mg of isosorbide dinitrate. The ultrasound catheter was advanced distally and was pulled back to the aorto-coronary ostium using a motorized transducer pullback at 0.5 mm/s after stent deployment. Postdilatation was performed if deemed necessary according to the IVUS examinations. All IVUS images were recorded on s-VHS videotapes for offline analysis.
The IVUS data were analyzed by an experienced cardiologist (T.O.) who was blinded to the short- and long-term outcomes of the patients and also to the type of stent used. Calcium was identified by its echogenicity and acoustic shadowing. The arc of calcium was measured by using an electronic protractor that was centered on the lumen. Cross-sectional area (CSA) measurements of the external elastic membrane (EEM), lumen, plaque plus media (P&M) (EEM CSA-lumen CSA), and plaque burden (P&M CSA/EEM CSA) were performed every 1 mm over the existing plaque using the planimetry system installed in the ClearView Ultra. The minimum luminal area (MLA) of the target lesion was determined. Each volume of the EEM, lumen, and plaque was calculated according to Simpson’s method. The volume index was defined as volume divided by lesion length .
2.4
Definitions and follow-up
Angiographic success was defined as successful stent deployment with Thrombolysis in Myocardial Infarction Grade 3 flow and residual stenoses of <30% by visual estimate. Additionally, full stent expansion, sufficient apposition to the vessel, and full coverage over the lesions by IVUS analysis were also required. Target lesion revascularization was defined as repeated percutaneous revascularization within the original stent segment or within 5 mm of the stent edges. Target vessel revascularization (TVR) was defined as repeated revascularization that was caused by any stenosis in the initially treated coronary artery. Major adverse cardiac events (MACE) were composed of all-cause death, Q-wave myocardial infarction, and TVR.
2.5
Statistical analysis
Statistical analysis was performed with SPSS Version 11.0 (SPSS, Chicago, IL, USA). Continuous variables were reported as mean±1 S.D. and compared using Student’s t test. The Mann–Whitney U test was used when nonparametric analysis was needed. Categorical variables were reported as frequencies and compared using chi-square statistics or Fisher’s Exact test. P <.05 was considered statistically significant. Cumulative incidences of different adverse events during the 1-year follow-up were estimated by the Kaplan–Meier method and compared by using of the log-rank test. Cox regression analysis was performed for the stent type (DES vs. BMS) and the four variables that we thought could be of potential relevance to TVR-MACE during the 1-year follow-up (acute coronary syndrome, left main trunk lesion, lesion length, and stent volume index).
2
Methods
2.1
Patient population
We retrospectively identified 38 patients who underwent DES implantation for 38 de novo and native AOLs from October 2004 to July 2008. Sirolimus-eluting stents (Cypher, Cordis, Johnson and Johnson, Miami Lakes, FL, USA) were implanted in 35 patients and paclitaxel-eluting stents (Taxus, Boston Scientific, Natick, MA, USA) were implanted in three patients (DES group). The control group composed of 40 patients with 40 de novo and native AOLs who underwent BMS implantation from just before the introduction of the DES to July 2008. Patients with cardiogenic shock or contraindication to antiplatelet agents were excluded from this study. Patients who required emergent coronary artery bypass immediately after stent implantation were also excluded. Baseline clinical characteristics and procedural variables were recorded and entered prospectively by the staff. All patients gave written informed consent before the procedure.
2.2
Percutaneous coronary intervention procedures
Percutaneous coronary intervention (PCI) was performed in patients with stable angina and acute coronary syndrome, or in patients with evidence of ischemia. An AOL was defined as stenotic lesion (≥75% diameter stenosis, angiographically) at the junction between the aorta and the orifice of the right coronary artery or left main coronary artery within 3 mm of the ostium of the vessel. All stents were employed with protrusion into the aorta to fully and appropriately cover the lesion after predilatation. Intraprocedural anticoagulation included administration of unfractionated heparin with an activated clotting time of >250 s. The type of stent and the use of other devices were at the discretion of the operator. All patients were pretreated with aspirin (100 mg) before the procedures; the treatment was continued indefinitely. Ticlopidine (200 mg) before 2007 and clopidogrel (75 mg) after 2007 were prescribed additionally for at least 1 and 12 months after BMS and DES implantation, respectively.
2.3
IVUS
IVUS was performed using the Boston Scientific (Minneapolis, MN, USA) system that incorporated a 40 MHz single-element beveled transducer (Atlantis SR Pro2) which rotated at 1,800 rpm and was coupled with ClearView Ultra. All IVUS images were recorded after intracoronary administration of 2–5 mg of isosorbide dinitrate. The ultrasound catheter was advanced distally and was pulled back to the aorto-coronary ostium using a motorized transducer pullback at 0.5 mm/s after stent deployment. Postdilatation was performed if deemed necessary according to the IVUS examinations. All IVUS images were recorded on s-VHS videotapes for offline analysis.
The IVUS data were analyzed by an experienced cardiologist (T.O.) who was blinded to the short- and long-term outcomes of the patients and also to the type of stent used. Calcium was identified by its echogenicity and acoustic shadowing. The arc of calcium was measured by using an electronic protractor that was centered on the lumen. Cross-sectional area (CSA) measurements of the external elastic membrane (EEM), lumen, plaque plus media (P&M) (EEM CSA-lumen CSA), and plaque burden (P&M CSA/EEM CSA) were performed every 1 mm over the existing plaque using the planimetry system installed in the ClearView Ultra. The minimum luminal area (MLA) of the target lesion was determined. Each volume of the EEM, lumen, and plaque was calculated according to Simpson’s method. The volume index was defined as volume divided by lesion length .
2.4
Definitions and follow-up
Angiographic success was defined as successful stent deployment with Thrombolysis in Myocardial Infarction Grade 3 flow and residual stenoses of <30% by visual estimate. Additionally, full stent expansion, sufficient apposition to the vessel, and full coverage over the lesions by IVUS analysis were also required. Target lesion revascularization was defined as repeated percutaneous revascularization within the original stent segment or within 5 mm of the stent edges. Target vessel revascularization (TVR) was defined as repeated revascularization that was caused by any stenosis in the initially treated coronary artery. Major adverse cardiac events (MACE) were composed of all-cause death, Q-wave myocardial infarction, and TVR.
2.5
Statistical analysis
Statistical analysis was performed with SPSS Version 11.0 (SPSS, Chicago, IL, USA). Continuous variables were reported as mean±1 S.D. and compared using Student’s t test. The Mann–Whitney U test was used when nonparametric analysis was needed. Categorical variables were reported as frequencies and compared using chi-square statistics or Fisher’s Exact test. P <.05 was considered statistically significant. Cumulative incidences of different adverse events during the 1-year follow-up were estimated by the Kaplan–Meier method and compared by using of the log-rank test. Cox regression analysis was performed for the stent type (DES vs. BMS) and the four variables that we thought could be of potential relevance to TVR-MACE during the 1-year follow-up (acute coronary syndrome, left main trunk lesion, lesion length, and stent volume index).
3
Results
3.1
Comparison of clinical and lesion characteristics between the BMS and DES groups ( Table 1 )
There were no significant differences between the two groups, except for the fact that the DES group tended to have more patients with hypertension ( P =.06) and a family history of coronary artery disease ( P =.06) as compared to the BMS group. The lesions were predominantly located at the orifice of the right coronary artery in both groups (84% in DES vs. 85% in BMS, P =1.0). Lesions at the left main trunk orifice were also equally observed in both groups (16% in DES vs. 15% in BMS, P =1.0) without any unprotected lesions. As mentioned above, the majority of DESs which were used in this study were Cypher stents (92%).
| BMS (n = 40) | DES (n = 38) | P value | |
|---|---|---|---|
| Age (years) | 65±13 | 68±11 | .3 |
| Male/female | 29/11 | 33/5 | .2 |
| Hypertension (%) | 19 (48) | 26 (68) | .06 |
| Diabetes mellitus (%) | 13 (33) | 14 (37) | .7 |
| Smoking (%) | 15 (38) | 11 (28) | .4 |
| Hyperlipidemia (%) | 28 (70) | 24 (63) | .5 |
| Family history of coronary artery disease (%) | 6 (15) | 9 (24) | .06 |
| Prior myocardial infarction (%) | 15 (38) | 18 (47) | .4 |
| Acute coronary syndrome (%) | 7 (18) | 3 (8) | .3 |
| Prior PCI for other lesion (%) | 7 (18) | 2 (5) | .2 |
| Prior CABG (%) | 6 (15) | 4 (11) | .7 |
| Chronic renal failure (%) | 8 (20) | 11 (29) | .4 |
| Hemodialysis (%) | 4 (10) | 4 (11) | 1.0 |
| Lesion | |||
| Left main trunk (%) | 6 (15) | 6 (16) | 1.0 |
| Right coronary artery (%) | 34 (85) | 32 (84) | 1.0 |
| Stent | |||
| Cypher (%) | 35 (92) | ||
| Taxus (%) | 3 (8) | ||
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