1

Introduction

Drug-eluting stents (DESs) were developed in order to reduce the re-stenosis rate associated with bare-metal stents (BMSs), with randomized studies showing significant reductions in the rate of repeat revascularization with similar rates of death and MI . These improvements led to the expanded use of DESs in patients with complex coronary anatomy as well as in patients with multivessel disease . Despite advances in stent technology and adjuvant pharmacotherapy, the development of in-stent restenosis (ISR) and its subsequent treatment have remained a clinical challenge .

As compared to first generation DESs, second generation DESs have been associated with superior clinical outcomes in a variety of lesion subsets . The aim of the present study was to compare the clinical outcome of patients presenting with sirolimus-eluting ISR (S-ISR) and who were treated with implantation of either everolimus-eluting stent (EES), SES, or plain old balloon angioplasty (POBA).

2

Methods

This single-center, retrospective study comprised 310 consecutive patients (444 lesions) who had undergone coronary artery stent implantation with EES (XienceV; Abbott Vascular, Santa Clara, CA, or PROMUS; Boston Scientific Corporation, Natick, MA) (n = 43), SES (Cypher; Cordis Corporation, Miami Lakes, FL) (n = 102), or POBA (n = 165) following presentation with S-ISR at the MedStar Washington Hospital Center from January 2007 to December 2011. The POBA group included the treatments using compliant, non-compliant and cutting balloon. Patients presenting with ST-elevation myocardial infarction (MI), stent thrombosis (ST) or cardiogenic shock secondary to S-ISR were excluded. All patients provided written informed consent. The study complied with the Declaration of Helsinki for investigation in human beings and was approved by the institutional ethics committee of the Medstar Washington Hospital Center. The procedures were performed according to standard clinical guidelines. In all cases, the interventional strategy, as well as the use of adjunctive devices and pharmacotherapy, was at the discretion of the operating interventional cardiologist. All patients received aspirin 325 mg pre-procedure and were recommended to continue this regimen indefinitely. In addition clopidogrel 75 mg daily following a 300-mg or 600-mg loading dose was commenced pre-procedurally and continued for 12 months. Follow-up data at 30 days, 6 months and 12 months were obtained by telephone contact, mailed questionnaire or outpatient review.

The analyzed clinical parameters were the 1-year rates of death, Q-wave MI, target lesion revascularization (TLR), target vessel revascularization (TVR) definite ST, and major adverse cardiac event (MACE), defined as the composite of death, Q-wave myocardial infarction, or TLR. MACE free survival was also analyzed for focal and non-focal restenosis as well as initial and recurrent restenosis.

ISR was defined as ≥ 50% luminal stenosis within the stent segment or stent edge. Focal restenosis was defined as a lesion length of < 10 mm, and non-focal restenosis was defined as a lesion length ≥ 10 mm in length. Initial restenosis was defined as the first restenotic lesion following SES implantation, whereas recurrent restenosis was defined as any lesion that had previously been treated with POBA following S-ISR. Q-wave MI was defined as evidence of new Q-waves on the electrocardiogram at the time of MI; the latter being defined as a total creatinine kinase increase ≥ 2 × the upper limit of normal and/or creatinine kinase (MB fraction) ≥ 20 ng/ml together with symptoms and/or ischemic electrocardiogram changes. Hypercholesterolemia was defined as fasting cholesterol > 250 mg/dl or the use of lipid lowering therapy. Systemic hypertension was defined as blood pressure > 140/90 mmHg or the use of anti-hypertensive therapy. Renal impairment was defined as serum creatinine > 1.2 mg/dL. Congestive heart failure was defined as evidence of fluid retention due to cardiac causes prior to admission. Angiographic success was defined as post-procedural stenosis ≤ 30% and Thrombolysis in Myocardial Infarction flow grade 3. TLR was defined as ischemia-driven percutaneous or surgical repeat intervention in the stent or within 5 mm proximal or distal to the stent. TVR was defined as percutaneous or surgical revascularization of the stented epicardial vessel. ST was defined in accordance with the Academic Research Consortium definitions as definite, probable, or possible.

Statistical analysis was performed using SAS version 9.2 (SAS institute Inc., Cary, North Carolina). Continuous variables and categorical variables were expressed as mean ± standard deviation and percentages, and analyzed using the chi-square test or Fisher’s exact test. Multivariable analyses were performed using multivariate Cox Regression analysis, evaluating predictors of TLR-MACE. One-year MACE-free rate was obtained using the Kaplan–Meier method, and differences in parameters were assessed using the log-rank test. The results of the multivariate analysis are expressed as hazard ratio (HR) with 95% confidence interval (CI). A p value < 0.05 was considered statistically significant.

2

Methods

This single-center, retrospective study comprised 310 consecutive patients (444 lesions) who had undergone coronary artery stent implantation with EES (XienceV; Abbott Vascular, Santa Clara, CA, or PROMUS; Boston Scientific Corporation, Natick, MA) (n = 43), SES (Cypher; Cordis Corporation, Miami Lakes, FL) (n = 102), or POBA (n = 165) following presentation with S-ISR at the MedStar Washington Hospital Center from January 2007 to December 2011. The POBA group included the treatments using compliant, non-compliant and cutting balloon. Patients presenting with ST-elevation myocardial infarction (MI), stent thrombosis (ST) or cardiogenic shock secondary to S-ISR were excluded. All patients provided written informed consent. The study complied with the Declaration of Helsinki for investigation in human beings and was approved by the institutional ethics committee of the Medstar Washington Hospital Center. The procedures were performed according to standard clinical guidelines. In all cases, the interventional strategy, as well as the use of adjunctive devices and pharmacotherapy, was at the discretion of the operating interventional cardiologist. All patients received aspirin 325 mg pre-procedure and were recommended to continue this regimen indefinitely. In addition clopidogrel 75 mg daily following a 300-mg or 600-mg loading dose was commenced pre-procedurally and continued for 12 months. Follow-up data at 30 days, 6 months and 12 months were obtained by telephone contact, mailed questionnaire or outpatient review.

The analyzed clinical parameters were the 1-year rates of death, Q-wave MI, target lesion revascularization (TLR), target vessel revascularization (TVR) definite ST, and major adverse cardiac event (MACE), defined as the composite of death, Q-wave myocardial infarction, or TLR. MACE free survival was also analyzed for focal and non-focal restenosis as well as initial and recurrent restenosis.

ISR was defined as ≥ 50% luminal stenosis within the stent segment or stent edge. Focal restenosis was defined as a lesion length of < 10 mm, and non-focal restenosis was defined as a lesion length ≥ 10 mm in length. Initial restenosis was defined as the first restenotic lesion following SES implantation, whereas recurrent restenosis was defined as any lesion that had previously been treated with POBA following S-ISR. Q-wave MI was defined as evidence of new Q-waves on the electrocardiogram at the time of MI; the latter being defined as a total creatinine kinase increase ≥ 2 × the upper limit of normal and/or creatinine kinase (MB fraction) ≥ 20 ng/ml together with symptoms and/or ischemic electrocardiogram changes. Hypercholesterolemia was defined as fasting cholesterol > 250 mg/dl or the use of lipid lowering therapy. Systemic hypertension was defined as blood pressure > 140/90 mmHg or the use of anti-hypertensive therapy. Renal impairment was defined as serum creatinine > 1.2 mg/dL. Congestive heart failure was defined as evidence of fluid retention due to cardiac causes prior to admission. Angiographic success was defined as post-procedural stenosis ≤ 30% and Thrombolysis in Myocardial Infarction flow grade 3. TLR was defined as ischemia-driven percutaneous or surgical repeat intervention in the stent or within 5 mm proximal or distal to the stent. TVR was defined as percutaneous or surgical revascularization of the stented epicardial vessel. ST was defined in accordance with the Academic Research Consortium definitions as definite, probable, or possible.

Statistical analysis was performed using SAS version 9.2 (SAS institute Inc., Cary, North Carolina). Continuous variables and categorical variables were expressed as mean ± standard deviation and percentages, and analyzed using the chi-square test or Fisher’s exact test. Multivariable analyses were performed using multivariate Cox Regression analysis, evaluating predictors of TLR-MACE. One-year MACE-free rate was obtained using the Kaplan–Meier method, and differences in parameters were assessed using the log-rank test. The results of the multivariate analysis are expressed as hazard ratio (HR) with 95% confidence interval (CI). A p value < 0.05 was considered statistically significant.

3

Results

The baseline characteristics and procedural indication of the patients are summarized in Table 1 . The three groups were well matched for the conventional risk factors for coronary artery disease and their clinical presentations, except for their smoking habit (EEE = 34.9%, SES = 52%, POBA = 58.8%; p = 0.02).

The angiographic and procedural characteristics are summarized in Table 2 . The three cohorts differed in the number of treated lesions, post-TLR diameter stenosis, stent-length used in the treatment of the target lesion, and the use of intravascular ultrasound.

Table 2

Lesion and procedural characteristics.

	EES (n = 58)	SES (n = 166)	POBA (n = 220)	p-value
Number of treated lesions	1.4 ± 0.7	1.6 ± 0.7	1.3 ± 0.6	0.008
Lesion location
Right coronary artery	23 (39.7)	56 (33.7)	72 (32.7)	0.61
Left anterior descending	14 (24.1)	53 (31.9)	65 (29.5)	0.53
Left circumflex	16 (27.6)	38 (22.9)	49 (22.3)	0.69
Saphenous vein graft	4 (6.9)	12 (7.2)	25 (11.4)	0.31
Lesion location
Ostial	2 (3.4)	10 (6.1)	13 (5.9)	0.74
Proximal	17 (29.3)	56 (33.9)	65 (29.7)	0.64
Mid	23 (39.7)	62 (37.6)	100 (45.7)	0.26
Distal	14 (24.1)	37 (22.4)	34 (15.5)	0.14
Pre-TLR diameter stenosis	0.83 ± 0.10	0.82 ± 0.09	0.82 ± 0.10	0.73
Initial SES diameter	3.05 ± 0.33	2.91 ± 0.35	2.93 ± 0.34	0.09
Initial SES length	21.1 ± 8.4	22.3 ± 7.4	22.9 ± 7.7	0.45
ISR pattern a				0.07
Focal (< 10 mm)	23 (60.5)	44 (44.0)	88 (57.1)
Non-focal (> 10 mm)	15 (39.5)	56 (56.0)	66 (42.9)
Post-TLR diameter stenosis	0.03 ± 0.05	0.03 ± 0.04	0.07 ± 0.11	< 0.001
Stent diameter of TLR	3.1 ± 0.4	3.0 ± 0.4	–	0.16
Stent length of TLR	15.5 ± 5.5	18.5 ± 5.8	–	0.01
Number of implanted stents	1.5 ± 0.9	1.7 ± 0.8	–	0.07
Initial restenotic lesion b	36 (94.7)	83 (83.8)	130 (83.9)	0.21
IVUS guidance	29 (50.0)	97 (59.5)	100 (45.7)	0.03
Angiographic success	58 (100.0)	166 (100.0)	215 (97.7)	0.1

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