Rescue percutaneous coronary intervention (PCI) with bare metal stent (BMS) implantation is useful in patients with acute myocardial infarction (AMI) and failed thrombolysis. Drug-eluting stent (DESs) are more effective in reducing restenosis compared to BMS. No data are available comparing the clinical outcomes between the 2 types of stents nor has information ever been provided about the predictors of events in patients treated with rescue PCI in the current era. The aims of the present study were to evaluate the outcomes of patients undergoing rescue PCI with DES implantation compared to BMS implantation and to determine the independent predictors of events during 1 year of follow-up. The study population consisted of 311 consecutive patients with ST-segment elevation AMI and evidence of failed fibrinolysis undergoing successful revascularization with DES (n = 134) or BMS (n = 177) implantation. The end point of the present study was the incidence of major adverse cardiac events (MACE) defined as death, recurrent AMI, and target vessel revascularization. No differences were found in the number of MACE at 1 year of follow-up between the DES and BMS groups (n = 10 and 19, respectively, p = 0.29). The Cox proportional hazards model identified cardiogenic shock (adjusted hazard ratio 7.05, 95% confidence interval 2.08 to 23.9, p = 0.001), age (hazard ratio 1.51, 95% CI 1.09 to 2.08, p = 0.011), and final minimal lumen diameter (hazard ratio 0.42, 95% confidence interval 0.21 to 0.83, p = 0.013) as independent predictors of MACE at 1 year of follow-up. After propensity score adjustments, the predictors did not change. In conclusion, we found no differences between DESs and BMSs with respect to MACE at 1 year of follow-up in patients with AMI treated with rescue PCI. Cardiogenic shock, age, and final minimal luminal diameter were identified as predictors of MACE.
A large amount of data have demonstrated that drug-eluting stents (DESs) are more effective in reducing restenosis compared to bare metal stents (BMS) in various patient and lesion subsets, including patients with acute myocardial infarction (AMI). However, it has never been established whether the benefits of DES compared to BMS also extend to patients with failed thrombolysis. Moreover, few data are available regarding the predictors of medium-term adverse events in patients undergoing rescue percutaneous coronary angioplasty (PCI) using the current strategies. The present study evaluated the clinical outcomes of patients undergoing rescue PCI with DES implantation compared to BMS implantation and determined the independent predictors of events during 1 year of follow-up.
Methods
The study population consisted of 311 consecutive patients with ST-segment elevation AMI referred from other hospitals to our institution with evidence of failed fibrinolysis (performed within the previous 12 hours) who had undergone successful rescue PCI with implantation of DESs (n = 134; 85 sirolimus stents and 49 paclitaxel stents) or BMSs (n = 177) from May 2003 to September 2008. The diagnosis of AMI was established on the basis of typical chest pain lasting >30 minutes, unrelieved by sublingual nitrates, associated with ST-segment elevation (>1 mV in >2 limb leads or >0.2 mV in >2 contiguous precordial leads) or new-onset left bundle branch block on the surface electrocardiogram. Failed thrombolysis was defined by a second 12-lead electrocardiogram, obtained 60 minutes after the onset of fibrinolytic therapy, showing failure of ST-segment elevation in the worst lead to have resolved by 50% compared to the findings from the baseline electrocardiogram and the absence of chest pain relief. The stent type was selected at the discretion of the operator.
All patients were pretreated with aspirin and a loading dose of clopidogrel 300 mg. All patients were given aspirin (100 mg) indefinitely and clopidogrel 75 mg/day for ≥6 to 12 months. Glycoprotein IIb/IIIa inhibitors were administrated at the discretion of the operator.
The exclusion criteria were AMI due to left main coronary artery (8 patients) or venous graft disease (2 patients), Thrombolysis In Myocardial Infarction flow grade of 1 or 0 after stent implantation (2 patients, 1 with a DES and 1 with a BMS). The follow-up protocol included evaluation at hospital discharge and a clinical visit at 1, 6, and 12 months. A stress test was scheduled at 11 months. Only patients with evidence of spontaneous or inducible ischemia, unstable angina, or AMI underwent repeat coronary angiography.
Angiographic analysis was done on end-diastolic frames demonstrating the stenosis at its more severe view. The view with the least foreshortening was selected for analysis. A computer assisted automated algorithm (CAAS II; Pie Medical Imaging, Maastricht, The Netherlands) and standard morphologic criteria were used for the analysis of the entire treated segment. The reference lumen diameter before and after stent implantation, the minimal lumen diameter, and the percentage of residual stenosis were calculated. The lesion length was measured after vessel recanalization. Successful PCI was defined as a final Thrombolysis In Myocardial Infarction flow grade of 2 or 3 and residual stenosis of <30% by visual estimation after stent implantation.
The end point of the study was the incidence of major adverse cardiac events (MACE), defined as a composite of death, recurrent AMI, and target vessel revascularization, at 1 year of follow-up. Recurrent AMI was diagnosed in the presence of new pathologic Q waves on the electrocardiogram or an increase in creatine kinase of more than twice the upper limit of normal. Target vessel revascularization was defined as any repeat revascularization of the infarct-related artery, and target lesion revascularization was defined as any repeat revascularization involving the stent or within 5 mm of the proximal or distal stent edge, in the presence of evidence of spontaneous or inducible ischemia.
The data are presented as the mean ± SD or numbers (percentages). Comparisons between groups were performed using the 2-tailed t test for continuous data and the chi-square test or Fisher’s exact test (when appropriate) for categorical data. The Cox proportional hazards model was used to determine the independent correlates of the composite end point. Event-free from MACE survival curves were developed using the Kaplan-Meier method and compared using the log-rank test. To compensate for the nonrandomized design of our study, we used propensity score methods. The individual propensity scores, defined as the conditional probability of obtaining a DES instead of a BMS, were estimated using forward stepwise multiple logistic regression models according to the baseline covariates listed in Tables 1 through 3 , with the exception of the predictors of the composite primary end point. Adjusted relative risks were estimated from models in which the propensity score and the stent group were entered as covariates. The analyses were performed using the S-PLUS statistical package (Insightful, Seattle, Washington). Statistical significance was accepted at p <0.05.
| Variable | DES (n = 134) | BMS (n = 177) | p Value |
|---|---|---|---|
| Age (years) | 58 ± 11 | 59 ± 12 | 0.19 |
| Women | 15 (11%) | 24 (13%) | 0.53 |
| Previous myocardial infarction | 4 (3%) | 7 (4%) | 0.64 |
| Previous coronary artery bypass surgery | 0 | 1 (1%) | 0.38 |
| Previous percutaneous coronary intervention | 5 (4%) | 6 (3%) | 0.87 |
| Diabetes mellitus | 24 (18%) | 32 (18%) | 0.97 |
| Arterial hypertension ⁎ | 59 (44%) | 102 (57%) | 0.02 |
| Hypercholesterolemia † | 49 (36%) | 79 (44%) | 0.15 |
| Current smoker | 65 (48%) | 99 (56%) | 0.19 |
| Ejection fraction (%) | 48 ± 8 | 48 ± 8 | 0.99 |
| Infarct location | 0.0007 | ||
| Anterior | 90 (67%) | 87 (49%) | |
| Inferior | 30 (22%) | 76 (43%) | |
| Inferolateral | 14 (10%) | 14 (8%) | |
| Thrombolytic agent | 0.66 | ||
| Streptokinase | 0 | 1 (1%) | |
| Alteplase | 66 (49%) | 89 (50%) | |
| Reteplase | 68 (51%) | 87 (49%) | |
| Cardiogenic shock ‡ | 2 (1%) | 4 (2%) | 0.62 |
| Pain to angioplasty time (hours) | 7 ± 4 | 7 ± 4 | 0.74 |
| Pain to thrombolysis time (hours) | 3 ± 2 | 3 ± 2 | 0.79 |
| Creatine kinase-MB peak (IU/L) | 215 ± 187 | 192 ± 160 | 0.11 |
⁎ Defined as systolic blood pressure >140 mm Hg, diastolic blood pressure >90 mm Hg, or use of blood pressure-lowering agents.
† Defined as total cholesterol >230 mg/dl or use of lipid-lowering agent.
‡ Defined as blood pressure <100 mm Hg, pulse >100 beats/min, and the patient cool, clammy, or requiring inotropes, intra-aortic balloon pump, or cardiopulmonary support to assist circulation.
| Variable | DES (n = 134) | BMS (n = 177) | p Value |
|---|---|---|---|
| Target vessel | 0.001 | ||
| Left anterior descending | 90 (67%) | 87 (49%) | |
| Circumflex | 13 (10%) | 15 (8%) | |
| Right | 31 (23%) | 75 (42%) | |
| Treated coronary segment | 0.03 | ||
| Ostial | 6 (4%) | 7 (4%) | |
| Proximal | 58 (42%) | 70 (39%) | |
| Middle | 62 (46%) | 70 (39%) | |
| Distal | 8 (6%) | 30 (17%) | |
| Narrowed arteries (n) | 0.27 | ||
| 1 | 99 (74%) | 116 (65%) | |
| 2 | 26 (19%) | 47 (26%) | |
| 3 | 9 (7%) | 14 (8%) | |
| Treated vessels (n) | 0.59 | ||
| 1 | 120 (89%) | 159 (90%) | |
| 2 | 14 (10%) | 18 (10%) | |
| 3 | 0 | 0 | |
| Preintervention Thrombolysis In Myocardial Infarction flow grade | 0.34 | ||
| 0 | 57 (42%) | 70 (39%) | |
| 1 | 9 (7%) | 16 (9%) | |
| 2 | 16 (12%) | 32 (18%) | |
| 3 | 52 (39%) | 59 (33%) | |
| Intra-aortic balloon pump | 0 | 2 (1%) | 0.21 |
| Glycoprotein IIb/IIIa inhibitor therapy | 75 (56%) | 86 (49%) | 0.53 |
| Thrombus aspiration | 19 (14%) | 32 (18%) | 0.35 |
| Direct stenting | 82 (61%) | 125 (70%) | 0.08 |
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