Abstract
Objective
To compare the clinical outcomes of patients undergoing percutaneous intervention for stent thrombosis (ST) or saphenous vein graft (SVG) occlusion.
Background
Patients presenting with ST or SVG occlusion are at increased risk of adverse outcomes. There is limited literature comparing the outcome of such patients.
Methods
A cohort of 415 consecutive patients presenting to the MedStar Washington Hospital Center undergoing percutaneous coronary intervention (PCI) for an acute coronary syndrome secondary to ST (n = 136) or SVG occlusion (n = 279) was studied. The SVG group was subdivided into patients who underwent PCI in the occluded SVG (SVG-PCI: n = 75) or in the subtended native coronary artery (NC-PCI: n = 204). The analyzed clinical parameters were in-hospital complications as well as 30-day and 1-year major adverse cardiac events (MACE). MACE was defined as all-cause mortality, Q-wave myocardial infarction, or target vessel revascularization.
Results
The rates of death, major bleeding, and length of hospital stay were significantly different between the ST and NC-PCI groups. The SVG-PCI group had a shorter hospital stay. The 30-day MACE rate was significantly different in the ST and NC-PCI groups (18.9% vs. 7.5%; risk ratio = 0.40, 95% CI = 0.20–0.81, p = 0.03) but not in the ST and SVG-PCI groups (18.9% vs. 15.1%; p = 0.55, risk ratio = 0.80, 95% CI = 0.38–1.68). There were no differences in the 1-year MACE rate.
Conclusions
As compared to patients undergoing NC-PCI, patients with ST have greater rates of in-hospital mortality and major bleeding as well as 30-day MACE rate. The 1-year MACE rate is similar in patients with ST and SVG occlusion who undergo PCI.
1
Introduction
Percutaneous coronary intervention (PCI) has become standard practice for the management of symptomatic, obstructive coronary artery disease (CAD). Although drug-eluting stents (DES) have provided superior clinical efficacy to bare-metal stents (BMS), stent thrombosis (ST) has remained the “Achilles Heel” of interventional cardiology . Despite advances in stent technology and pharmacotherapy, coronary artery bypass grafting (CABG) remains the gold-standard therapy in patients with left-main disease and multi-vessel CAD . The efficacy of CABG, predominantly provided by the use of the internal mammary conduit, may decline over time due to the development of athero-degenerative disease within saphenous venous grafts (SVG) as well as atherothromotic disease in un-grafted coronary arteries . Patients presenting with ST and SVG occlusion represent one of the highest risk subgroups undergoing PCI . There is currently limited data comparing the clinical outcome of such patients undergoing PCI. The aim of this study was to compare the in-hospital complications as well as the 30-day and 1-year clinical outcome of patients presenting with an acute coronary syndrome (ACS) due to ST or SVG occlusion and undergoing PCI.
2
Methods
This single-center, retrospective study comprised 415 consecutive patients undergoing PCI for an ACS secondary to ST or an SVG occlusion at the MedStar Washington Hospital Center from 2000 to 2013. The ST group consisted of 136 patients and were classified into early (0–30 days, n = 80), late (30–360 days, n = 17) and very late (> 360 days, n = 48) ST. The SVG group was divided into patients who underwent PCI in the occluded SVG (SVG-PCI: 75 patients) and those who underwent PCI in the subtended native coronary artery (NC-PCI: 204 patients) ( Fig. 1 ). 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. 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 regime 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 were obtained by telephone contact, mailed questionnaire or outpatient review.
The analyzed clinical parameters were in-hospital complications including death, Q-wave myocardial infarction (MI), cerebrovascular events, procedure-related renal impairment, major bleeding, blood transfusion, and vascular complications, 30-day, and 1-year major adverse cardiac events (MACE). MACE was defined as all-cause mortality, Q-wave MI or target vessel revascularization (TVR).
ST was defined as definite ST according to the Academic Research Consortium (ARC) definition. SVG occlusion was defined as thrombolysis in myocardial infarction (TIMI) flow grade 0 or 1. 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. Procedure-related renal impairment was defined as an in-hospital increase in creatinine of ≥ 0.5 mg/dl following the procedure. Congestive heart failure was defined as evidence of fluid retention due to cardiac causes prior to admission. TVR was defined as any clinically driven PCI or CABG of the target vessel. Major bleeding was defined according to the TIMI Study Group definition and consisted of intracranial haemorrhage or clinically overt bleeding with a decrease in haemoglobin ≥ 5 g/dl or in haematocrit ≥ 15%. Vascular complication was defined as any of the following at the access site: hematoma ≥ 5 cm in diameter, arterio-venous fistula, vascular perforation or laceration requiring surgery, pseudo-aneurysms, retroperitoneal bleeding, and acute limb ischemia. Angiographic success was defined as post-procedural stenosis ≤ 30% and TIMI flow grade 3.
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 respectively. Analyses of difference amongst the 3 groups of patients were performed using analysis of variance for continuous variables, and the chi-square test or Fisher’s exact test for categorical variables. After univariate analysis for baseline clinical and procedural characteristics, the following characteristics with p < 0.1 were incorporated into the multivariate analysis to identify predictors of 1-year MACE: diabetes mellitus, chronic renal impairment, cardiogenic shock on admission, and ST vs. NC-PCI. For variables with a 3-group p value < 0.05, 2 subsequent pair wise comparisons were performed using Bonferroni’s correction for p value significance (p < 0.025). Survival analysis was calculated using the Kaplan–Meier method and differences in parameters were assessed using the log-rank test. A p value < 0.05 was considered statistically significant.
2
Methods
This single-center, retrospective study comprised 415 consecutive patients undergoing PCI for an ACS secondary to ST or an SVG occlusion at the MedStar Washington Hospital Center from 2000 to 2013. The ST group consisted of 136 patients and were classified into early (0–30 days, n = 80), late (30–360 days, n = 17) and very late (> 360 days, n = 48) ST. The SVG group was divided into patients who underwent PCI in the occluded SVG (SVG-PCI: 75 patients) and those who underwent PCI in the subtended native coronary artery (NC-PCI: 204 patients) ( Fig. 1 ). 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. 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 regime 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 were obtained by telephone contact, mailed questionnaire or outpatient review.
The analyzed clinical parameters were in-hospital complications including death, Q-wave myocardial infarction (MI), cerebrovascular events, procedure-related renal impairment, major bleeding, blood transfusion, and vascular complications, 30-day, and 1-year major adverse cardiac events (MACE). MACE was defined as all-cause mortality, Q-wave MI or target vessel revascularization (TVR).
ST was defined as definite ST according to the Academic Research Consortium (ARC) definition. SVG occlusion was defined as thrombolysis in myocardial infarction (TIMI) flow grade 0 or 1. 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. Procedure-related renal impairment was defined as an in-hospital increase in creatinine of ≥ 0.5 mg/dl following the procedure. Congestive heart failure was defined as evidence of fluid retention due to cardiac causes prior to admission. TVR was defined as any clinically driven PCI or CABG of the target vessel. Major bleeding was defined according to the TIMI Study Group definition and consisted of intracranial haemorrhage or clinically overt bleeding with a decrease in haemoglobin ≥ 5 g/dl or in haematocrit ≥ 15%. Vascular complication was defined as any of the following at the access site: hematoma ≥ 5 cm in diameter, arterio-venous fistula, vascular perforation or laceration requiring surgery, pseudo-aneurysms, retroperitoneal bleeding, and acute limb ischemia. Angiographic success was defined as post-procedural stenosis ≤ 30% and TIMI flow grade 3.
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 respectively. Analyses of difference amongst the 3 groups of patients were performed using analysis of variance for continuous variables, and the chi-square test or Fisher’s exact test for categorical variables. After univariate analysis for baseline clinical and procedural characteristics, the following characteristics with p < 0.1 were incorporated into the multivariate analysis to identify predictors of 1-year MACE: diabetes mellitus, chronic renal impairment, cardiogenic shock on admission, and ST vs. NC-PCI. For variables with a 3-group p value < 0.05, 2 subsequent pair wise comparisons were performed using Bonferroni’s correction for p value significance (p < 0.025). Survival analysis was calculated using the Kaplan–Meier method and differences in parameters were assessed using the log-rank test. 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 traditional risk factors for CAD except for their smoking habit. The three groups also differed in their age, prevalence of chronic renal impairment, left ventricular ejection fraction, and mode of presentation. In the ST group, the initial stent type was a BMS in 19.2% and a DES in 80.1% and of 8.2% of the patients had previously undergone surgical revascularization.
| Variable | Stent thrombosis (n = 136) | SVG-occlusion NC-PCI (n = 204) | SVG-occlusion SVG-PCI (n = 75) | p-value |
|---|---|---|---|---|
| Age (yrs) | 61.9 ± 11.4 | 69.8 ± 11.3 | 67.6 ± 11.4 | < 0.001 |
| Male | 88 (64.7%) | 146 (71.6%) | 52 (69.3%) | 0.41 |
| Body mass index (kg/m 2 ) | 28.8 ± 6.4 | 29.1 ± 5.6 | 29.8 ± 5.6 | 0.56 |
| Hypertension | 123 (90.4%) | 194 (95.1%) | 73 (97.3%) | 0.08 |
| Diabetes mellitus | 63 (46.3%) | 112 (55.2%) | 35 (46.7%) | 0.21 |
| Hyperlipidemia | 121 (89.0%) | 192 (94.1%) | 67 (91.8%) | 0.23 |
| Chronic renal impairment | 29 (21.5%) | 74 (36.3%) | 15 (20.3%) | 0.003 |
| Hemodialysis | 12 (8.9%) | 21 (10.3%) | 4 (5.4%) | 0.45 |
| Current smoker | 53 (39.0%) | 33 (16.2%) | 18 (24.0%) | < 0.001 |
| History of myocardial infarction | 59 (44.0%) | 83 (45.9%) | 33 (47.8%) | 0.87 |
| History of coronary artery bypass graft surgery | 11 (8.2%) | 204 (100.0%) | 75 (100.0%) | < 0.001 |
| Graft age (yrs) | – | 9.1 ± 7.2 | 9.8 ± 6.8 | |
| Left ventricular ejection fraction | 0.37 ± 0.14 | 0.42 ± 0.16 | 0.42 ± 0.15 | 0.03 |
| Patient presentation | ||||
| Unstable angina | 16 (11.8%) | 87 (42.6%) | 20 (26.7%) | < 0.001 |
| Acute myocardial infarction | 104 (76.5%) | 62 (30.4%) | 44 (58.7%) | < 0.001 |
| Cardiogenic shock | 33 (24.3%) | 7 (3.5%) | 5 (6.8%) | < 0.001 |
| Type of stent | ||||
| Bare metal stent | 28 (19.2%) | – | – | – |
| Drug eluting stent | 117 (80.1%) | – | – | – |
| Unknown | 1 (0.7%) | – | – | – |
The lesion and procedural characteristics of the three cohorts are summarised in Table 2 . Patients undergoing PCI for ST, NC-PCI, and SVG-PCI demonstrated significant differences in the target vessel, lesion location, the presence of type C lesions, number and type of stents used, stent diameter, and their procedural characteristics. Of note, there were significant differences in the use of rotablation (0% vs . 6.6% vs . 0%; p < 0.001), distal protection devices (1.4% vs . 1.2% vs . 13.3%; p < 0.001), thrombectomy (53.4% vs . 2.9% vs . 62.7%; p < 0.001), intra-aortic balloon pump or the Impella device (30.9% vs . 5.9% vs . 12%; p < 0.001), as well as contrast volume (152 ± 68 ml vs . 171 ± 87 ml vs . 199 ± 93 ml; p < 0.001), fluoroscopic time (15.5 ± 11.1 min vs . 18.9 ± 15.0 min vs . 23.3 ± 16.1 min; p < 0.001) and procedural time (61.9 ± 32.5 min vs . 70.1 ± 34.8 min vs . 77.5 ± 38.4 min; p = 0.005).
| Variable | ST (n = 136) | SVG occlusion NC-PCI (n = 204) | SVG occlusion SVG-PCI (n = 75) | p-value |
|---|---|---|---|---|
| Target vessel | n = 146 | n = 244 | n = 75 | < 0.001 |
| Right coronary artery | 56 (38.4%) | 90 (36.9%) | 36 (48.0%) | |
| Left anterior descending | 72 (49.3%) | 24 (9.8%) | 8 (10.7%) | |
| Left circumflex | 18 (12.3%) | 116 (47.5%) | 31 (41.3%) | |
| Left main stem | 0 (0%) | 14 (5.7%) | 0 (0%) | |
| Lesion location | 0.03 | |||
| Ostial | 0 (0.0%) | 14 (5.7%) | 5 (6.7%) | |
| Proximal | 72 (50.0%) | 90 (36.9%) | 29 (38.7%) | |
| Mid | 55 (37.7%) | 99 (40.6%) | 27 (36.0%) | |
| Distal | 19 (13.0%) | 41 (16.8%) | 14 (18.7%) | |
| Type C lesions | 93 (63.7%) | 113 (46.3%) | 54 (72.0%) | < 0.001 |
| Stent data | ||||
| Number of stents | 1.1 ± 1.1 | 1.6 ± 1.1 | 1.4 ± 1.3 | 0.001 |
| Bare metal stents | 61.0 (41.8%) | 49.0 (20.1%) | 33.0 (44.0%) | < 0.001 |
| Drug eluting stents | 31.0 (21.2%) | 156.0 (63.9%) | 21.0 (28.0%) | < 0.001 |
| Stent diameter (mm) | 3.1 ± 0.5 | 2.9 ± 0.4 | 3.2 ± 0.6 | 0.002 |
| Stent length (mm) | 20.8 ± 7.0 | 18.2 ± 6.2 | 19.8 ± 6.2 | 0.08 |
| Procedural characteristics | ||||
| Rotablation | 0 (0%) | 16 (6.6%) | 0 (0%) | < 0.001 |
| Distal protection | 2 (1.4%) | 3 (1.2%) | 10 (13.3%) | < 0.001 |
| Thrombectomy | 78 (53.4%) | 8 (2.9%) | 47 (62.7%) | < 0.001 |
| Intra-aortic balloon pump/Impella | 43 (30.9%) | 12 (5.9%) | 9 (12.0%) | < 0.001 |
| Contrast volume (ml) | 152 ± 68 | 171 ± 87 | 199 ± 93 | < 0.001 |
| Fluoroscopic time (min) | 15.5 ± 11.1 | 18.9 ± 15.0 | 23.3 ± 16.1 | < 0.001 |
| Procedural time (min) | 61.9 ± 32.5 | 70.1 ± 34.8 | 77.5 ± 38.4 | 0.005 |
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