The long-term outcomes of patients with angiographically proved stent thrombosis (ST) are insufficiently known. The aim of this study was to evaluate the presentation and in-hospital and long-term outcomes of patients with angiographically proved ST as well as predictors of unfavorable clinical outcomes. One hundred six consecutive patients (mean age 69 ± 12 years, 85 men) presenting from 2003 to 2011 with 117 angiographically proved STs were included in the analysis. The time interval from initial stent implantation to ST, antiplatelet therapy at presentation, and the frequency and predictors of adverse events (death, myocardial infarction, and recurrent ST) during long-term follow-up (mean 65 ± 30 months) were evaluated. Eighty-six patients (80.9%) had early ST, 7 patients (6.6%) had late ST, and 13 patients (12.2%) had very late ST. Eighty-three patients (78.3%) were receiving dual-antiplatelet therapy at the time of ST. Eighty-three patients (78.3%) presented with ST-segment elevation myocardial infarctions, and 23 patients (21.6%) presented with other forms of acute coronary syndromes. Death rates during hospitalization, at 1 year, and at long-term follow-up were 17.9%, 23.8%, and 35.6%, respectively. The rates of recurrent definite ST during hospitalization, at 1 year, and at long-term follow-up were 7.5%, 9.9%, and 10.9%, respectively. Univariate predictors of the combined end point of death rate and definite recurrent ST were presentation with cardiogenic shock, left ventricular ejection fraction <30% at presentation, renal failure, discontinuation of clopidogrel administration at presentation, maximal creatine phosphokinase after ST, and Thrombolysis In Myocardial Infarction (TIMI) flow grade after intervention. Independent predictors of the primary end point at long-term follow-up remained cardiogenic shock (odds ratio [OR] 1.32, 95% confidence interval [CI] 1.08 to 1.63, p = 0.0069), renal failure (OR 1.26, 95% CI 1.01 to 1.57, p = 0.0425), and TIMI flow grade after intervention (OR 0.85, 95% CI 0.74 to 0.98, p = 0.0315). Current cigarette smoking was an independent predictor of repeat definite ST at long-term follow-up (OR 1.12, 95% CI 1.01 to 1.27, p = 0.0321). In conclusion, ST was associated with detrimental outcomes in the acute phase as well as the long-term phase. Recurrent ST was not infrequent.
Stent thrombosis (ST) occurs in 1% to 3% of patients after percutaneous coronary intervention (PCI). Although ST is a rare complication after PCI, it is associated with a death rate of 20% to 40% and myocardial infarction (MI) in up to 80% of patients. ST within the first year appears to occur with equal frequency after the implantation of bare-metal stents or drug-eluting stents, as long as patients with drug-eluting stents are treated with dual-antiplatelet therapy. Although ST-segment elevation MI (STEMI) is characterized by intraluminal thrombus, irrespective of whether the initial event is de novo or stent-related thrombosis, clinical outcomes are worse with ST. Emergency revascularization by PCI to restore vessel patency is the treatment of choice for STEMI as well as ST. Although risk factors for ST are well known, the prognosis of patients with ST as well as predictors of recurrent events are less well evaluated. In this single-center study, we evaluated the risk for recurrent events after first ST as well as risk factors for recurrent events.
Methods
This was a single-center retrospective study that included 106 consecutive patients with 117 angiographically proved STs. Patients presented with ST from January 2003 to March 2011. ST was defined according to the Academic Research Consortium criteria for definite ST. Definite ST was determined on the basis of clinical events and confirmed by coronary angiography. Angiographic criteria consisted of partial or complete occlusion within the previously implanted stent with evidence of fresh thrombus. ST was categorized according to the timing of the event as acute (occurrence within the first 24 hours after the index procedure), subacute (from 24 hours to 30 days), late (from 31 days to 1 year), or very late (>1 year after the index procedure).
Primary PCI was performed for all patients with STEMIs according to standard care. Heparin was administered during the procedure according to standard practice. All patients who had not taken aspirin before presentation received aspirin at a dose of 500 mg, followed by 100 mg/day. Patients were loaded if not previously taking clopidogrel with 300 or 600 mg before or immediately at the end of the procedure, followed by clopidogrel 75 mg/day for 9 to 12 months. The use of glycoprotein IIb/IIIa inhibitors and mechanical thrombus removal were left to the operator’s discretion.
Clinical follow-up was obtained by telephone interview for major adverse cardiac events, defined as death from any cause, MI, or need for target lesion revascularization. In addition, the occurrence of repeat definite ST was evaluated on the basis of hospital charts. Baseline clinical demographics, in-hospital complications, and the occurrence of death, MI, late recurrent coronary intervention, and repeat definite ST during follow-up were verified by independent hospital chart review and source documentation or the records of family physicians. In case neither patients nor relatives could be contacted and patients’ general physicians did not know about the patients’ outcomes, local population registries were contacted to obtain information about patients’ possible death or current locations.
The primary end point of the study was a composite of death and repeat definite ST. Secondary end points were major adverse cardiac events, all-cause death, target lesion revascularization, and definite repeat ST. Need for target lesion revascularization was determined on the basis of significant narrowing of the lumen within the stent or the lesion including 5 mm distal or proximal to the stent (>50% angiographic diameter stenosis) in the presence of symptoms or objective signs of ischemia. The diagnosis of MI required an elevation of creatine kinase levels to twice the upper limit of normal, together with an increase in creatine kinase-MB.
Statistical analysis was performed using SPSS version 17.0 (SPSS, Inc., Chicago, Illinois). Categorical data were compared using Pearson’s chi-square test and are presented as frequencies. Continuous data were compared using Student’s t test or analysis of variance as appropriate and are presented as mean ± SD. Cox proportional-hazards regression analysis was performed to identify univariate and multivariate predictors of death and repeat definite ST at follow-up after treatment of ST. Thus, all 106 patients were included in the analysis. Included variables were diabetes, vessel lesion location, stent length, stent diameter, initial stent type (drug-eluting stent or bare-metal stent), initial stent number, and initial stent length. Univariate predictors with p values <0.05 were included in the multivariate analysis. A p value <0.05 was considered statistically significant.
Results
Baseline clinical, angiographic, and procedural characteristics are listed in Tables 1 and 2 . During the study period, 106 patients with 117 angiographically proved STs were enrolled. Eleven patients (10.1%) had acute ST, 75 patients (70.8%) had subacute ST, 7 patients (6.6%) had late ST, and 13 patients (12.2%) had very late ST. In 36 patients (34.0%), ST was related to drug-eluting stents, and in 70 patients (66.0%), ST was related to bare-metal stents. In 10 patients with ST related to drug-eluting stents, ST occurred very late, whereas 3 of the 70 patients with ST related to bare-metal stents had very late ST (p = 0.0015). Twenty-three patients (21.7%) were not receiving clopidogrel at the time of ST, and 4 patients (3.8%) were not using aspirin. Eighty-three patients (78.3%) presented with STEMIs, and 23 patients (21.6%) presented with other forms of acute coronary syndromes (non-STEMI, unstable angina pectoris). Thirty patients (28.3%) presented with cardiogenic shock.
| Variable | All Patients (n = 106) | Event-Free Follow-Up (n = 56) | Event Follow-Up (n = 45) | p Value |
|---|---|---|---|---|
| Age (yrs) | 69.7 ± 11.6 | 69.8 ± 11.1 | 70.6 ± 11.6 | 0.7251 |
| Men | 85 (80.2%) | 46 (82.1%) | 36 (80%) | 0.9228 |
| Body mass index (kg/m 2 ) | 26.8 ± 4.5 | 27.1 ± 4.0 | 26.3 ± 5.3 | 0.3710 |
| Hypertension | 76 (71.6%) | 39 (69.6%) | 32 (71.1%) | 0.8716 |
| Current smokers | 55 (51.9%) | 29 (51.5%) | 22 (48.8%) | 0.9384 |
| Creatinine clearance <60 ml/min | 22 (20.8%) | 6 (10.7%) | 15 (33.3%) | 0.0118 |
| Diabetes mellitus | 32 (30.2%) | 14 (25.0%) | 18 (40%) | 0.1398 |
| Insulin dependent | 14 (13.2%) | 8 (14.3%) | 6 (13.3%) | 0.8305 |
| Coronary multivessel disease | 72 (67.9%) | 32 (57.1%) | 37 (82.2%) | 0.0230 |
| Previous MI | 44 (41.5%) | 23 (41.1%) | 17 (37.7%) | 0.8747 |
| Indication for index PCI | ||||
| Stable angina | 29 (27.4%) | 20 (35.7%) | 9 (20%) | 0.1701 |
| Unstable angina, non-STEMI | 31 (29.2%) | 13 (23.2%) | 17 (37.7%) | 0.2005 |
| STEMI | 46 (43.4%) | 23 (41.1%) | 19 (42.2%) | 0.9105 |
| Variable | All Patients (n = 106) | Event-Free Follow-Up (n = 56) | Event Follow-Up (n = 45) | p Value |
|---|---|---|---|---|
| Category of first ST at inclusion | ||||
| Acute | 11 (10.3%) | 6 (10.7%) | 5 (11.1%) | 0.8527 |
| Subacute | 75 (70.7%) | 41 (73.2%) | 32 (71.1%) | 0.9428 |
| Late | 7 (6.6%) | 3 (5.3%) | 3 (6.6%) | 0.9219 |
| Very late | 13 (12.3%) | 6 (10.7%) | 5 (11.1%) | 0.8802 |
| Use of clopidogrel at the time of ST | 83 (78.3%) | 41 (73.2%) | 38 (84.4%) | 0.2289 |
| Use of aspirin at the time of ST | 102 (96.2%) | 55 (98.2%) | 41 (91.1%) | 0.2288 |
| In-hospital occurrence of first ST | 50 (47.2%) | 25 (44.6%) | 24 (53.3%) | 0.5123 |
| Presentation | ||||
| STEMI | 83 (78.3%) | 42 (73.2%) | 37 (82.2%) | 0.3556 |
| Acute coronary syndromes | 23 (21.7%) | 15 (26.8%) | 8 (17.7%) | 0.3556 |
| Cardiogenic shock | 30 (28.3%) | 8 (14.3%) | 22 (48.8%) | 0.0000 |
| Peak creatinine phosphokinase after ST (U/L) | 1,981 ± 2,722 | 1,611 ± 1,728 | 2,622 ± 3,677 | 0.0707 |
| PCI-treated vessel | ||||
| Left anterior descending coronary artery | 66 (62.3%) | 37 (66.1%) | 27 (60.0%) | 0.8589 |
| Left circumflex coronary artery | 9 (8.4%) | 4 (7.1%) | 4 (6.8%) | 0.9978 |
| Right coronary artery | 32 (30.2%) | 16 (28.6%) | 14 (31.1%) | 0.8716 |
| Characteristics of previous stent implantation | ||||
| Bare-metal stent | 70 (66.0%) | 36 (62.0) | 33 (73.3) | 0.3232 |
| Drug-eluting stent | 36 (34.0%) | 22 (37.9) | 12 (26.6) | 0.3232 |
| Number of stents per patient | 1.56 ± 0.83 | 1.65 ± 0.90 | 1.46 ± 0.75 | 0.2647 |
| Total stent length (mm) | 24.2 ± 13.4 | 25.4 ± 14.6 | 22.2 ± 11.0 | 0.2458 |
| Diameter of stent (mm) | 2.96 ± 0.32 | 2.94 ± 0.33 | 3.00 ± 0.31 | 0.3689 |
| Characteristics of treatment of first ST | ||||
| Pre-PCI TIMI flow grade 0 or 1 | 93 (87.7%) | 50 (89.3%) | 41 (91.1%) | 0.8527 |
| Final post-PCI TIMI flow grade 3 | 89 (83.9%) | 54 (96.4%) | 31 (68.8%) | 0.0000 |
| Balloon angioplasty | 33 (31.1%) | 17 (30.3%) | 15 (33.3%) | 0.9729 |
| PCI with additional stent implantation | 73 (68.9%) | 40 (71.4%) | 30 (66.6%) | 0.9729 |
| Bare-metal stent | 56 (52.8%) | 29 (51.8%) | 25 (55.5%) | 0.8600 |
| Drug-eluting stent | 17 (16.0%) | 10 (17.9%) | 5 (11.1%) | 0.5572 |
| Aspiration catheter used | 16 (15.1%) | 11 (19.6%) | 4 (8.8%) | 0.2536 |
| Administration of glycoprotein IIb/IIIa therapy | 88 (83.0%) | 46 (82.1%) | 37 (82.2%) | 0.9228 |
| Left ventricular ejection fraction (%) | ||||
| <30 | 10 (9.4%) | 2 (3.6%) | 8 (17.7%) | 0.0379 |
| 30–45 | 35 (33.0%) | 16 (28.6%) | 17 (37.7%) | 0.4888 |
| >45 | 61 (57.5%) | 38 (67.9%) | 20 (44.4%) | 0.0323 |
Eighty-three patients with STEMIs underwent primary PCI, and 23 patients with other forms of acute coronary syndromes underwent emergency PCI within 24 hours. Thirty-three patients (31.1%) were treated only with balloon angioplasty, 73 patients (68.9%) were treated with balloon angioplasty followed by stent implantation (17 patients with drug-eluting stents and 56 patients with bare-metal stents). Sixteen patients (15.1%) were treated with thrombus aspiration during PCI. Two patients with ST underwent emergency coronary artery bypass grafting after PCI could not provide acceptable procedural results.
Clinical follow-up was obtained in 101 patients (95.3%). The median follow-up time was 64.5 ± 30.1 months.
In-hospital clinical event rates are listed in Table 3 . Nineteen patients (17.9%) died during hospitalization after ST, 18 patients from cardiac death and 1 from intracerebral bleeding.
| Variable | Patients With ST (n = 106) |
|---|---|
| In-hospital clinical events | |
| Primary end point | 24 (22.6%) |
| Death | 19 (17.9%) |
| Repeat definite ST | 8 (7.5%) |
| 1-yr clinical events | |
| Primary end point | 32 (31.6%) |
| Death | 24 (23.8%) |
| MI | 16 (15.8%) |
| Target vessel revascularization | 19 (18.8%) |
| Repeat definite ST | 10 (9.9%) |
| MACEs | 45 (44.6%) |
| Long-term clinical events | |
| Primary end point | 45 (44.6%) |
| Death | 36 (35.6%) |
| MI | 25 (24.7%) |
| Target vessel revascularization | 20 (19.8%) |
| Repeat definite ST | 11 (10.9%) |
| MACEs | 64 (63.4%) |
Univariate predictors of the combined end point of death and definite recurrent ST during hospitalization are listed in Table 4 . Cardiogenic shock (odds ratio [OR] 1.63, 95% confidence interval [CI] 1.38 to 1.91, p = 0.0000) and Thrombolysis In Myocardial Infarction (TIMI) flow grade after intervention (OR 0.87, 95% CI 0.79 to 0.97, p = 0.0122) remained independent predictors of the primary end point. Independent predictors of death during hospitalization were cardiogenic shock (OR 1.57, 95% CI 1.36 to 1.82, p = 0.0000) and TIMI flow grade (OR 0.85, 95% CI 0.78 to 0.93, p = 0.0007). The only independent predictor of recurrent definite ST during hospitalization was cardiogenic shock (OR 1.144, 95% CI 1.016 to 1.292, p = 0.0266).
| Variable | OR | 95% CI | p Value |
|---|---|---|---|
| In-hospital events | |||
| Presentation with cardiogenic shock | 2.19 | 2.14–2.24 | <0.0001 |
| LVEF <30% at presentation | 1.51 | 1.16–1.96 | 0.0023 |
| Discontinuation of clopidogrel use at presentation | 1.32 | 1.31–1.34 | <0.0001 |
| STEMI at presentation | 1.32 | 1.31–1.34 | <0.0001 |
| Maximum CPK after ST (per U/L) | 1.004 | 1.001–1.007 | 0.0030 |
| TIMI flow grade after intervention | 0.78 | 0.70–0.88 | <0.0001 |
| 1-yr events | |||
| Presentation with cardiogenic shock | 2.85 | 2.76–2.93 | <0.0001 |
| LVEF <30% at presentation | 1.53 | 1.14–2.06 | 0.0048 |
| Discontinuation of clopidogrel use at presentation | 1.46 | 1.44–1.47 | <0.0001 |
| STEMI at presentation | 1.46 | 1.44–1.47 | <0.0001 |
| Maximum CPK after ST (per U/L) | 1.004 | 1.001–1.007 | 0.0117 |
| TIMI flow grade after intervention | 0.76 | 0.67–0.86 | <0.0001 |
| Long-term events | |||
| Presentation with cardiogenic shock | 1.50 | 1.23–1.83 | <0.0001 |
| LVEF <30% at presentation | 1.50 | 1.09–2.06 | 0.0134 |
| Renal failure | 1.42 | 1.13–1.79 | 0.0033 |
| TIMI flow grade after intervention | 0.80 | 0.69–0.91 | 0.0019 |
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