One year clinical and six month angiographic results of drug eluting stents for ST elevation acute myocardial infarction: ‘Real World' comparison between Sirolimus- and Paclitaxel-eluting stents

International Journal of Cardiology 131 (2009) 350 – 355 www.elsevier.com/locate/ijcard

One year clinical and six month angiographic results of drug eluting stents for ST elevation acute myocardial infarction: ‘Real World' comparison between Sirolimus- and Paclitaxel-eluting stents Kyung Woo Park a,b,c,1 , Young-Seok Cho a,c,1 , Jin-Wook Chung a,b,c , Tae-Jin Yeon a,c , In-Ho Chae a,c , Dong-Ju Choi a,c , Byung-Hee Oh a,b , Young-Bae Park a,b , Woo-Young Chung a,b,⁎ a

Department of Internal Medicine, Seoul National University College of Medicine, South Korea b Cardiovascular Center, Seoul National University Hospital, Seoul, South Korea c Cardiovascular Center, Seoul National University Bundang Hospital, Sungnam, South Korea Received 27 August 2007; accepted 20 October 2007 Available online 3 January 2008

Abstract Background: Concerns about safety of drug eluting stents have stirred up controversy on their use in patients with acute STEMI. It is also unknown whether differences in efficacy and safety exist between sirolimus- (SES) and paclitaxel-eluting stents (PES). Objective: To investigate the difference in angiographic results and clinical outcome between SES and PES in the treatment of acute STEMI, we analyzed “real world” 6 months angiographic and 1 year clinical outcome of 244 patients, comparing the results between SES and PES. Methods: 244 consecutive acute STEMI patients were analyzed retrospectively (185 patients in SES group (Group S), 59 patients in PES group (Group P). Immediate post PCI and six month angiographic findings were analyzed by quantitative coronary angiography. Clinical events up to 1 year including cardiovascular death, myocardial infarction, and target lesion revascularization were also analyzed. Results: Baseline clinical and immediate post-procedure angiographic characteristics were similar in the two groups except for mean stent diameter and length which was slightly wider and shorter in group P compared with group S (Mean stent diameter ×length: 3.12 ±0.34 × 24.4 ±5.1 vs. 3.01± 0.34× 26.6± 7.2 mm in group P vs. S, p =0.02, p = 0.03). At six months, late loss was significantly greater in group P compared with group S (0.35± 0.62 vs. 0.07 ±0.42, pb 0.01), although the difference in binary restenosis was not statistically significant. Diameter stenosis, which was similar immediately after PCI, was significantly greater in group P (22.0 ±17.1 vs. 15.6± 13.4%, p =0.02). At 1 year, the incidence of stent thrombosis was similar in both groups (5.1% vs. 3.8% for group P vs. C). There were no differences between the two groups up to 1 year with regard to cardiovascular death, nonfatal myocardial infarction, and TLR. The free from adverse event rate was not statistically different between the two groups (84.2% vs. 90.2%, p= 0.20 for group P vs. C). Conclusion: In this group of Korean acute STEMI patients, SES stent showed lower late loss compared to PES at 6 months angiographic follow up, but there was no difference in clinical outcome up to 1 year. © 2007 Elsevier Ireland Ltd. All rights reserved. Keywords: Acute ST-elevation myocardial infarction; Drug eluting stent; Percutaneous coronary intervention

1. Introduction ⁎ Corresponding author. Cardiovascular Center, Seoul National University Bundang Hospital, 300 Gumi-dong, Bundang-gu, Seongnam, 463-707, South Korea. Tel.: +82 31 787 7016; fax: +82 31 787 4051. E-mail address: [email protected] (W.-Y. Chung). 1 The first two authors contributed equally to this study. 0167-5273/$ - see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2007.10.025

The benefit of percutaneous coronary intervention (PCI) using stents in the treatment of acute ST elevation myocardial infraction (STEMI) has been well documented previously [1–3]. We are now in the era of the drug eluting stent, which has been shown to significantly reduce

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restenosis and decrease the need for revascularization procedures compared with conventional bare metal stents [4–7]. However, concerns about the risk of stent thrombosis associated with drug eluting stents have stirred up controversy on the safety of their use in the setting of a thrombotic milieu such as acute STEMI. Recently, two randomized trials have shown the safety and efficacy of sirolimus and paclitaxel-eluting stents in the treatment of patients with acute STEMI [8,9]. Here, we report the “real world” 6-month angiographic and 1-year clinical outcome of 244 patients with acute STEMI in the SNUBH PCI registry, comparing the results between sirolimus and paclitaxeleluting stents. 2. Method 2.1. Patients This study was a retrospective analysis of consecutive patients with acute ST elevation myocardial infarction who received either sirolimus-eluting stents or paclitaxel-eluting stents at Seoul National University Bundang Hospital (SNUBH) between August 2004 and July 2006. We included all patients with acute STEMI including those with cardiogenic shock and those receiving rescue PCI after failed thrombolysis. The baseline patient, angiographic characteristics along with the one-month clinical, six-month angiographic and one-year clinical outcomes were compared between sirolimus- (SES) and paclitaxel-eluting stents (PES). 2.2. Interventional procedures and follow up All patients were given aspirin and clopidogrel prior to coronary intervention. Aspirin was maintained indefinitely and clopidogrel for at least 6 months. Coronary interventions were performed according to current standard techniques. The choice of the stent, predilatation, post-stent adjunctive balloon inflation, and use of glycoprotein IIb/IIIa inhibitors were all left to the operators' discretion. Follow up angiography was routinely recommended at 6 months after stent implantation or earlier if noninvasive evaluation or clinical presentation suggested the presence of ischemia. Clinical follow up was routinely scheduled every 2 months. All medical records were reviewed by an independent research nurse and telephone interviews were done to check for drug compliance and the development of unexpected events. Coronary angiography was performed at baseline, postintervention, and at six month follow up, and was analyzed by quantitative coronary angiography (QCA). An experienced technician who was not aware of the study purpose performed the QCA using the Quancor QCA system (version 4.0, Pie Medical Imaging, Netherlands). The minimal luminal diameter (MLD), the reference diameter, and percentages of stenosis before, immediately after stent implantation, and at follow up were measured in identical views.

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2.3. Definitions and end points Late loss was defined as the MLD immediately after stent implantation minus the MLD at follow up. Angiographic binary restenosis was defined as a ≥50% luminal diameter stenosis at the treated segment (in-stent and 5 mm proximal or distal to the stent) demonstrated at follow up angiography. The clinical events analyzed included cardiovascular death, nonfatal myocardial infarction, and target lesion revascularization (TLR). Myocardial infarction (MI) was defined as the presence of at least two of the three following data: ischemic symptoms; cardiac enzyme (CK–MB) concentration at least two times the upper limit of normal; or new electrocardiographic changes compatible with myocardial infarction according to the American Heart Association/American College of Cardiology guidelines [10]. Target lesion revascularization (TLR) was defined as a repeat intervention (surgical or percutaneous) to treat a luminal stenosis within the stent or in the 5-mm distal or proximal segments adjacent to the stent. We performed TLR when (1) diameter stenosis (DS) was more than 75% on QCA or (2) DS was more than 50% on QCAwith symptom or sign of ischemia (angina, positive stress test or imaging). Stent thrombosis was defined as definite and probable stent thrombosis according to the Academic Research Consortium (ARC) definition, as widely used in previous reports [11]. Briefly, definite stent thrombosis required the presence of an acute coronary syndrome with angiographic or autopsy evidence of thrombus or occlusion. Probable stent thrombosis included unexplained deaths within 30 days after the procedure or acute myocardial infarction involving the target-vessel territory without angiographic confirmation. Major adverse cardiac event (MACE) was defined as a composite of cardiovascular death, nonfatal MI, and TLR. 2.4. Statistical analysis Data are presented as percentages and mean ± SD for continuous variables, and as frequency (%) for categorical variables. In general, comparisons between groups were tested with χ2 test or Fisher's exact test for categorical variables, and a student t-test for continuous variables. Clinical outcome was analyzed from the time of stent implantation to the first event, according to the Kaplan–Meier method and the difference was evaluated by the log–rank test. All statistical analyses were performed using SPSS (version 11.0 for Windows, SPSS Inc, Chicago Ill), and a p value of b0.05 was considered statistically significant. 3. Results 3.1. Clinical and angiographic characteristics The baseline clinical characteristics are summarized in Table 1. A total of two-hundred forty four patients were treated with either SES (n = 185) or PES (n = 59). There were no significant differences in clinical characteristics between

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Table 1 Baseline clinical characteristics

Male gender Age (years) Hypertension Diabetes Hypercholesterolemia Current smoker Cardiogenic shock Peak CK-MB (mg/dL) Ejection fraction (%) Pain to balloon time (min) Primary PCI

Table 3 Six-month follow up angiographic results SES (n = 185)

PES (n = 59)

p value

76.2% 60.9 ± 13.7 53.5% 27.0% 48.6% 70.8% 10.3% 209.5 ± 229.4 47.3 ± 12.3 344.5 ± 237.6 87.0%

79.7% 61.4 ± 14.3 44.1% 27.1% 55.2% 67.8% 5.1% 215.6 ± 210.4 48.0 ± 12.4 360.5 ± 216.3 76.3%

0.72 0.80 0.23 1 0.45 0.74 0.3 0.86 0.72 0.7 0.06

PCI: percutaneous coronary intervention, CK-MB: creatinine kinase-MB isoenzyme.

the patients treated with SES and PES. There were more males than females, 51% had hypertension, 27% had DM, over 70% were smokers, and 50% of the patients had dyslipidemia. The baseline ejection fraction and mean pain to balloon time was similar between the two groups while there was a statistically insignificant trend for a higher percentage of patients receiving primary PCI in the SES treated group. The baseline and immediate angiographic data are shown in Table 2. The number of diseased vessels, the distribution of infarct related arteries, and the frequency of glycoprotein IIb/IIIa inhibitor use was all similar between the two groups. However, mean nominal stent diameter was slightly larger and the mean inserted stent length was slightly shorter in the PES treated group compared with the SES treated group (mean stent diameter: 3.12 ± 0.34 vs. 3.01 ± 0.34 mm, mean stent length: 24.4 ± 5.1 vs. 26.6 ± 7.2 mm for PES vs. SES, p = 0.02 and 0.03, respectively).

Table 2 Baseline angiographic and immediate post-procedural characteristics SES (n = 185) PES (n = 59) p value Multivessel disease 1 vessel 2 vessel 3 vessel Infarct related vessel LAD LCx RCA Left main stem Mean nominal stent diameter Stented length (mm) Proximal RD Distal RD MLD Diameter Stenosis (%) Glycoprotein IIb/IIIa inhibitor use

0.53 35.7% 35.7% 28.6%

35.6% 42.4% 22.0%

58.4% 10.8% 29.7% 1.1% 3.01 ± 0.34 26.6 ± 7.2 3.25 ± 0.48 2.84 ± 0.47 2.62 ± 0.45 11.9 ± 7.4 12.4%

64.4% 3.4% 32.2% 0.0% 3.12 ± 0.34 24.4 ± 5.1 3.29 ± 0.41 2.96 ± 0.43 2.70 ± 0.58 11.5 ± 8.8 15.3%

0.30

6 months angiographic follow up Mean nominal stent diameter Stented length Lesion length PRD Post PCI 6 months FU DRD Post PCI 6 months FU MLD Post PCI 6 months FU Diameter stenosis (%) Post PCI 6 months FU Late loss (mm) Binary restenosis (%)

SES

PES

p value

149 (86.1%) 3.01 ± 0.34 26.6 ± 7.2 30.8 ± 11.3

49 (87.5%) 3.12 ± 0.34 24.4 ± 5.1 30.4 ± 8.6

0.83 0.02 0.03 0.85

3.25 ± 0.48 3.31 ± 0.51

3.29 ± 0.41 3.32 ± 0.44

0.54 0.84

2.84 ± 0.47 2.89 ± 0.43

2.96 ± 0.43 2.83 ± 0.45

0.07 0.37

2.62 ± 0.45 2.60 ± 0.53

2.70 ± 0.58 2.39 ± 0.65

0.28 0.04

11.9 ± 7.4 15.6 ± 13.4 0.07 ± 0.42 5.3

11.5 ± 8.8 22.0 ± 17.1 0.35 ± 0.62 10.2

0.74 0.02 b0.01 0.31

mo: month, PRD: proximal reference diameter, PCI: percutaneous coronary intervention, FU: follow up, DRD: distal reference diameter, MLD: minimal luminal diameter.

3.2. Six month follow up angiographic results Angiographic follow up was available in 198 patients (86.5%); 149 patients (86.1%) in the SES group and 49 patients (87.5%) in the PES group. The results of the QCA are shown in Table 3. Late luminal loss at six months was significantly higher in the PES group compared with the SES group (0.35 ± 0.62 vs. 0.07 ± 0.42, p b 0.01). Accordingly, the minimal luminal diameter was significantly larger and the diameter stenosis was significantly lower in the SES group. The binary restenosis rate was slightly lower in the SES group compared with the PES group (5.3% vs. 10.2%), although this was not statistically significant (p = 0.31). The difference in late loss between SES and PES was observed all across the different subgroups (Fig. 1), but due to the small number of patients analyzed, was only statistically significant in the subgroup with long stents (stented length ≥ 28 mm) (mean difference in late loss: 0.38 mm, 95% CI: 0.18–0.58 mm p b 0.02), large stents (stent diameter ≥ 3.0 mm) (mean difference 0.27 mm, 95% CI: 0.11–0.43 mm, p = 0.01), and non-DM patients (mean difference 0.36 mm, 95% CI: 0.19–0.53 mm, p b 0.01). 3.3. One month and one year clinical outcome

0.02 0.03 0.54 0.07 0.28 0.74 0.66

LAD: left anterior descending coronary artery, LCx: left circumflex coronary artery, RCA: right coronary artery, RD: reference diameter, MLD: minimal luminal diameter.

The rate of adverse cardiac events up to 1 month including in-hospital death, death up to 1 month, myocardial infarction, and stent thrombosis was not different between the SES and the PES groups (Table 4). At 6 months, the composite of cumulative cardiovascular death, nonfatal myocardial infarction, and target lesion revascularization was also similar between the two groups. Most of the target lesion revascularizations occurred at the time of follow up angiography at 6 months (Table 4).

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Fig. 1. Difference in late luminal loss at six-month follow up angiography between SES and PES according to patient and lesion subgroups. SES: sirolimus eluting stent, PES: paclitaxel eluting stent, diam: diameter.

At 1 year, event free survival, defined as the composite of free from cardiovascular death, nonfatal myocardial infarction, and target lesion revascularization, was slightly better in the SES group although not statistically significant on a log– rank analysis (event free survival: 90.2% vs. 84.2% for SES vs. PES group, p = 0.20, Fig. 2). The slightly lower incidence of adverse clinical events at 1 year in the SES group was primarily due to the decrease in the need for repeat revascularization (TLR rate: 3.5% vs. 7.1% in SES vs. PES, p = 0.26) and the decrease in the incidence of nonfatal myocardial infarction (0% vs. 3.6%, p = 0.17). The cumulative occurrence of stent thrombosis at 1 year was similar in the two groups (3.8% vs. 5.1% for SES vs. PES, p = 0.70).

4. Discussion Randomized trials including TYPHOON and PASSION, along with a recent meta-analysis of randomized trials using DES for treatment of AMI, have shown that DES reduces the need for repeat revascularization while having comparable safety outcomes as compared with BMS [8,9,12]. However, data from the “real world”, including comparisons between SES and PES are scarce. Previously, Serruys and colleagues reported the real world one-year clinical outcome without angiographic follow up of Europeans using their RESEARCH (Rapamycin-Eluting Stent Evaluated At Rotterdam Cardiology Hospital) and T-SEARCH (Taxus Stent Evaluated At Rotterdam Cardiology Hospital) registry [13]. In the present study, we report not only the 1-year clinical outcome but also the 6-month angiographic data of 244

Table 4 Clinical outcome according to the type of stent SES (n = 185) In hospital death One month Death (all cause) Cardiovascular death Nonfatal MI Stent thrombosis Six month (cumulative) Death (all cause) Cardiovascular death Nonfatal MI TLR Composite (CV, MI, TLR) One year (cumulative) Death (all cause) Cardiovascular death Nonfatal MI TLR Composite (CV, MI, TLR) Stent thrombosis

PES (n = 59)

p value

9 (4.9)

1 (1.7%)

0.46

10 (5.4%) 10 (5.4%) 0 (0%) 6 (3.2%)

1 (1.7%) 1 (1.7%) 1 (1.7%) 1 (1.7%)

0.31 0.31 0.24 1.0

12 (6.6) 11 (6.1) 0 (0%) 5 (2.9%) 16 (9.3%)

3 (5.2%) 3 (5.2%) 1 (1.8%) 3 (5.5%) 7 (12.5%)

1.0 1.0 0.24 0.41 0.46

12 (6.6%) 11 (6.0%) 0 (0%) 6 (3.5%) 17 (9.8%) 7 (3.8%)

4 (6.8%) 3 (5.1%) 2 (3.6%) 4 (7.1%) 9 (15.8%) 3 (5.1%)

1.0 1.0 0.06 0.26 0.23 0.70

MI: myocardial infarction, TLR: target lesion revascularization, CV: cardiovascular death.

Fig. 2. Freedom from cardiovascular death, nonfatal myocardial infarction, and target lesion revascularization.

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consecutive acute STEMI patients treated with either SES or PES. We found that at six months angiographically, SES significantly reduced late loss as compared with PES. However, this did not translate into better clinical outcome at 1 year, which was not significantly different between the two types of drug eluting stents. As far as we know, this is the first “real world” comparison of SES and PES in Asian acute STEMI patients. 4.1. Six-month angiographic follow up results In the present study, patients receiving SES implantation had significantly lower late loss at 6 months compared with those receiving PES (0.07 ± 0.42 mm vs. 0.35 ± 0.62 mm, p b 0.01). The fact that SES showed lower late loss at six month follow up compared with PES is expected since previous randomized trials of selected patients with stable angina reported mean late loss rates of − 0.01–0.17 mm for SES [4,5,14] and 0.13–0.36 mm for PES [6,14,15]. In TYPHOON and PASSION, two recently published randomized trials of DES vs. BMS in acute STEMI patients, SES showed similar late loss from the previous studies with a late loss of 0.14 ± 0.49 mm [8] while there were no pre-specified angiographic follow up in the study that used PES [9]. On subgroup analysis, the difference in late loss favored SES in all subgroups whether it was in the subgroup with larger stents or smaller stents, of DM patients or non-DM patients, and with longer stents or shorter stents inserted, although the statistical significance was reached in only the subgroup with larger stents, of non-DM patients, and with longer stents. We believe that the major reason for such findings was due to the modest number of patients in the analysis, and that the difference in late loss would have been significant in the other subgroups had there been enough patients. 4.2. Clinical outcomes up to one year In the present study, there were no significant differences between the SES and PES group in regard to the incidence of cardiovascular death, nonfatal MI, and TLR at both six months and one year. The rate of stent thrombosis was also similar. Because the SES group showed significantly less late loss, there was a slight trend for less TLR in the SES group. This constituted the majority of the statistically insignificant difference in the free from adverse event rate between the two groups (90.2% vs. 84.2%, p = 0.22). These findings in Koreans, is remarkably similar to a previous report from Serruys and colleagues, who reported a free from major adverse cardiac event rate of 90.2% for SES and 85% for PES at one year [13]. The rate of stent thrombosis (ARC definite and probable) at one year was 3.8% in the SES group and 5.1% in the PES group. This is much higher than the previously reported rates of stent thrombosis in selected patients in 8 pivotal DES randomized trials, which showed rates of cumulative stent thrombosis to be 1.5% for SES and 1.8% for PES at 4 years, and 0.6% and 0.9% for SES and PES respectively at 1 year

[16]. It is also higher than the 2.9% reported for PES in patients with STEMI in Europeans by Serruys and colleagues [13]. The discrepancy may be due to several reasons. First, the rate of thrombosis is known to significantly increase in patients with acute STEMI. In a recent randomized comparison of SES and PES in various coronary lesions that included approximately 23% STEMI patients [14], the rate of stent thrombosis at 9 months was 2.0% and 1.8% for SES and PES respectively, which is higher than those from the previous pivotal trials in selected patients which did not include patients with STEMI [16]. In addition, a recent report of a prospective cohort of real world patients showed that the rate of definite and probable thrombosis was 5.1% at six months in patients with STEMI [17], which was significantly higher than that from patients without STEMI (2.3%). Moreover, STEMI has been shown to be a significant independent predictor of stent thrombosis [17,18]. Another reason for the high rate of stent thrombosis in the present analysis is the high occurrence of in hospital thrombotic events, which was 2.7% (5/185) and 1.7% (1/59) for SES and PES, respectively. This may be due to the baseline characteristics of the patients, since three of these six patients were in shock, two had left main thrombotic occlusion, and four of the patients were over 75 years of age at initial admission. Third, the definition of stent thrombosis may be different for different reports. In the report by Hofma et al., they defined stent thrombosis as angiographic documentation of complete occlusion (TIMI flow grade 0 or 1) or a flow limiting thrombus (with TIMI flow 1 or 2) of a previously successfully treated artery, which would not include patients with ARC probable stent thrombosis. Finally, there could also be ethnic differences, which is difficult to address due to the small number of patients analyzed in the present study. We need to be careful to draw any conclusions regarding stent thrombosis from such a small number of patients, and we believe that larger studies in patients with AMI are warranted to address this issue. 4.3. Study limitations There are several limitations to this study. First, this was a retrospective analysis of a single center registry of Korean acute STEMI patients and thus the use of the stents was not randomized, which may be a cause for selection bias. Another short coming of this study was the modest number of patients; there were 244 patients included in the present study. We would need many more patients to show the statistical significance of such small, discrete differences between the different types of drug eluting stents. Also, because this was an analysis of registry data and the selection of DES was up to the operators' discretion, the number of patients receiving SES and PES was unbalanced. This may have been due to the personal preference of some operators regarding less late loss reported for SES in previous studies. SES was used more often in lesions with long length and small diameter as shown in the baseline characteristics. Fourth, the clinical data reported here are up to only one year. Therefore, we cannot make any

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suggestions or speculations on the long term safety of DES, which is a very important issue. To overcome these limitations, we believe that a large scale prospectively randomized trial of acute STEMI patients is warranted. In conclusion, the use of SES and PES, for the treatment of acute STEMI in “real world” Asian patients, seems to be safe and effective. SES showed significantly less late loss at six months compared with PES. However, the clinical outcomes up to one year were comparable between the two groups.

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