Percutaneous coronary intervention in the setting of acute myocardial infarction is known to predict stent thrombosis (ST). This study aims to compare the ST rates across different coronary subsets. This was an observational cohort study from a large, single-center registry. Included were 12,198 consecutive patients who underwent percutaneous coronary intervention with stenting. Patients were categorized according to their clinical presentation: stable angina pectoris (SAP, n = 3,700), unstable angina pectoris (UAP, n = 2,845), non-ST-segment elevation myocardial infarction (NSTEMI, n = 4,083), and ST-segment elevation myocardial infarction (STEMI, n = 1,570). The study end points were ST rates at 1 year. Patients with STEMI were younger with a lower prevalence of cardiovascular risk factors, except for smoking. More type C lesions were treated in STEMI, whereas drug-eluting stents were used less frequently in patients with STEMI compared with the other groups. Definite ST at 1 year was highest in patients with STEMI (1.4%; vs SAP, 0.4%; UAP, 0.5%; NSTEMI, 0.5%; p <0.001). One-year definite/probable ST rates were SAP, 0.8%; UAP, 1.1%; NSTEMI, 1.4%; and STEMI, 3.2% (p <0.001). On multivariable analysis, STEMI independently predicts definite ST (hazards ratio [HR] 3.07, 95% confidence interval [CI] 1.32 to 7.10), whereas both STEMI (HR 3.36, 95% CI 1.84 to 6.12) and NSTEMI (HR 2.04, 95% CI 1.20 to 3.07) were independent predictors of definite/probable ST. Clopidogrel cessation was the strongest predictor of ST (definite ST, HR 17.00, 95% CI 7.54 to 38.31; definite/probable ST, HR 4.69, 95% CI 2.39 to 9.20). In conclusion, in patients who underwent percutaneous coronary intervention, the acuity of clinical presentation corresponds to an increase in ST incidence. Adherence to clopidogrel is critical to prevent ST in patients who underwent percutaneous coronary intervention, especially in STEMI.
Percutaneous coronary intervention with stent implantation has become the standard of care in coronary revascularization. Percutaneous coronary intervention reduces symptoms in patients with stable angina and may decrease morbidity and mortality in acute coronary syndromes. Stent thrombosis (ST) is a rare but devastating complication of stent implantation occurring in 0.5% to >2% of patients per year. ST events may lead to significant morbidity and mortality. In recent years, the medical community has begun to recognize the multifactorial nature of predisposing factors toward ST. These include treating high-risk patient subsets, treating complex lesions, suboptimal procedural techniques, device factors, and antiplatelet therapy noncompliance and resistance. Several registries have identified percutaneous coronary intervention in the setting of acute myocardial infarction in predicting ST. However, the association between the spectrum of clinical presentation and ST after percutaneous coronary intervention has not been well defined. Here we aim to compare the ST rates across the acuity of clinical presentation for percutaneous coronary intervention. In addition, we aim to identify whether acute myocardial infarction is an independent predictor of ST.
Methods
The present study included a cohort of consecutive patients who underwent percutaneous coronary intervention with stenting at MedStar Washington Hospital Center (Washington, DC) from January 2002 to December 2012 and had available 1-year follow-up information. Patients were categorized by their indication for percutaneous coronary intervention according to the clinical presentation: stable angina pectoris (SAP), unstable angina pectoris (UAP), non-ST-segment elevation myocardial infarction (NSTEMI), and ST-segment elevation myocardial infarction (STEMI). All patients provided written informed consent, and the study complied with the Declaration of Helsinki. The institutional review boards of the MedStar Washington Hospital Center and the MedStar Health Research Institute (Washington, DC) approved the present study.
Percutaneous coronary intervention was performed according to the guidelines present at the time of procedure. All patients received aspirin 325 mg before the procedure. The anticoagulation regimens were chosen at the operator’s discretion and included unfractionated heparin adjusted to a targeted activated clotting time or bivalirudin 0.75 mg/kg followed by an infusion of 1.75 mg/kg/hour for the duration of the procedure. The interventional strategy, together with the use of adjunct pharmacotherapy, devices, and choice of stents, was at the operator’s discretion. The need for thienopyridine loading and maintenance dosing was determined by the operator and/or managing physician. For this study, the type of thienopyridine prescribed is almost exclusively clopidogrel. About 12 months of clopidogrel therapy was recommended for patients receiving drug-eluting stents, as well as patients who presented with acute coronary syndrome regardless of stent type.
Clinical, procedural, and follow-up data were prospectively collected and stored in a central database. A dedicated data coordinating center performed all data management and analyses. Prespecified clinical and procedural data and in-hospital complications were obtained from hospital charts, which were reviewed by independent research personnel unaware of the study objectives. Clinical follow-up was performed by telephone contact or office visit at 30 days, 6 months, and 1 year by trained quality assurance nurses who worked exclusively with the database to determine postintervention clinical events. Primary source documents were obtained for all events and were adjudicated by physicians not involved in the procedures and who were unaware of the study objectives. The primary end points of the present study were ST rates at 1 year according to the Academic Research Consortium definitions of definite and probable. Clinical outcomes including death, myocardial infarction, and target lesion/vessel revascularizations were also analyzed across the groups. Multivariable analysis was performed to determine the independent predictors of definite and definite/probable ST. Antiplatelet therapy compliance at the time of ST was also reported.
SAP was defined as no change in frequency, duration, or intensity of angina in the 6 weeks before percutaneous coronary intervention. UAP was defined as angina of increasing frequency with less exertion or at rest/nocturnal and/or severe or prolonged episodes associated with electrocardiographic changes or evidence of ischemia, with negative biomarkers at the time of procedure. NSTEMI was defined as symptoms consistent with an acute coronary syndrome with positive biomarkers without ST-segment elevation on electrocardiogram. STEMI was defined as symptoms consistent with acute coronary syndrome, with chest pain lasting ≥30 minutes accompanied by ST-segment elevation ≥1 mm in ≥2 contiguous leads on a 12-lead electrocardiogram. Definite ST was defined as angiographic or pathological confirmation and ≥1 of the following: ischemic symptoms, ischemic electrocardiographic changes, and elevated cardiac biomarkers. Probable ST was defined as any unexplained death within 30 days or any MI with acute ischemia in the territory of stent without angiographic confirmation or other cause. Early ST was defined as occurring within the first 30 days of stent implantation. Late ST was defined as occurring between 31 days and 1 year of stent implantation. Death was defined as death from any cause, cardiac, and noncardiac. Myocardial infarction was defined as a total creatinine kinase of ≥2 times the upper limit of normal and/or creatine kinase-MB ≥20 ng/ml, together with symptoms and/or ischemic electrocardiographic changes. Target lesion revascularization was defined as any clinically driven repeat percutaneous coronary intervention or bypass grafting of the treated lesion, including in-stent and in-segments 5-mm proximal or distal to the initial stent edges. Target vessel revascularization was defined as any clinically driven percutaneous coronary intervention or bypass grafting of the target vessel.
All statistical analyses were performed using SAS version 9.2 (SAS Institute, Cary, North Carolina). Normally distributed continuous variables are presented as the mean ± SD. Variables not normally distributed are presented as the median ± interquartile range. Categorical variables are expressed as frequencies and percentages. Analyses of difference among the 4 groups were performed using analysis of variance for continuous variables and the chi-square or Fisher’s exact test for categorical variables. A multivariable Cox proportional hazard analysis was performed to determine predictors of definite and definite/probable ST at 1 year. Included were clinical and procedural variables of relevance to ST. Variables included in the model were clinical presentation (STEMI, NSTEMI, and UAP, using SAP as the reference), age, African-American race, chronic kidney disease, congestive heart failure, cardiogenic shock, American College of Cardiology/American Heart Association type C lesion, saphenous vein graft lesion, number of lesions treated, drug-eluting stent use, and intravascular ultrasound use. In addition, clopidogrel cessation status was entered into the model as a time-dependent covariate. The results are presented as adjusted hazard ratios with their 95% confidence intervals and p values. Cumulative incidences of ST events were calculated using the Kaplan-Meier method. The log-rank test was used to compare the differences in curves among groups. Values of p <0.05 were considered to be statistically significant.
Results
A total of 12,198 percutaneous coronary intervention patients were grouped according to their clinical presentation: SAP, n = 3,700; UAP, n = 2,845; NSTEMI, n = 4,083; and STEMI, n = 1,570 ( Figure 1 ). Baseline characteristics are listed in Table 1 . Compared with patients with SAP, UAP, and NSTEMI, the STEMI group was younger, had more African-Americans, and a lower frequency of cardiovascular risk factors, except for smoking. Left ventricular ejection fraction was lowest in patients with STEMI, with a higher incidence of periprocedural cardiogenic shock. Patients presenting with myocardial infarction had higher incidence of congestive heart failure.
| Variable | SAP (n = 3,700) | UAP (n = 2,845) | NSTEMI (n = 4,083) | STEMI (n = 1,570) | p Value |
|---|---|---|---|---|---|
| Age (yrs) | 66.1 ± 10.8 | 65.1 ± 11.5 | 65.7 ± 12.0 | 63.9 ± 13.2 | <0.001 |
| Men | 2,583 (69.9) | 1,838 (64.6) | 2,591 (63.5) | 1,033 (65.9) | <0.001 |
| European-American | 2,667 (72.1) | 1,861 (65.4) | 2,680 (65.6) | 959 (61.1) | <0.001 |
| African-American | 814 (22.0) | 758 (26.6) | 1,047 (25.6) | 482 (30.7) | <0.001 |
| Asian | 111 (3.0) | 88 (3.1) | 191 (4.7) | 49 (3.1) | <0.001 |
| Hispanic | 29 (0.8) | 27 (0.9) | 36 (0.9) | 26 (1.7) | 0.024 |
| Native American | 8 (0.2) | 8 (0.3) | 13 (0.3) | 2 (0.1) | 0.58 |
| Diabetes mellitus | 1,295 (35.3) | 1,065 (37.7) | 1,449 (35.8) | 443 (28.5) | <0.001 |
| Systemic hypertension ∗ | 3,150 (85.5) | 2,391 (84.4) | 3,488 (85.7) | 1,269 (81.3) | <0.001 |
| Hyperlipidemia | 3,244 (88.2) | 2,474 (87.4) | 3,516 (87.3) | 1,220 (78.6) | <0.001 |
| Current smoker | 578 (15.6) | 546 (19.2) | 798 (19.5) | 542 (34.5) | <0.001 |
| Family history of coronary artery disease | 1,936 (53.3) | 1,425 (51.4) | 2,049 (52.1) | 614 (40.4) | <0.001 |
| Chronic kidney disease | 433 (11.8) | 401 (14.2) | 642 (15.9) | 220 (14.1) | <0.001 |
| Dialysis patients | 87 (2.4) | 67 (2.4) | 122 (3.0) | 44 (2.8) | 0.29 |
| Peripheral vascular disease | 605 (16.4) | 452 (16.0) | 688 (17.2) | 168 (10.8) | <0.001 |
| Previous percutaneous coronary intervention | 888 (24.6) | 831 (30.5) | 1,126 (29.2) | 240 (16.0) | <0.001 |
| Previous coronary bypass surgery | 728 (19.8) | 629 (22.3) | 1,063 (26.3) | 165 (10.6) | <0.001 |
| Previous myocardial infarction | 720 (20.2) | 687 (25.2) | 1,033 (26.9) | 242 (15.6) | <0.001 |
| Previous congestive heart failure | 423 (11.8) | 372 (13.6) | 614 (15.9) | 191 (12.5) | <0.001 |
| Left ventricular ejection fraction | 50 ± 14 | 49 ± 16 | 47 ± 14 | 40 ± 15 | <0.001 |
| Periprocedural cardiogenic shock | 5 (0.1) | 4 (0.1) | 137 (3.4) | 268 (17.2) | <0.001 |
| Periprocedural congestive heart failure | 134 (3.7) | 151 (5.5) | 291 (7.5) | 100 (6.5) | <0.001 |
∗ History of systemic hypertension diagnosed and/or treated with medication or currently being treated with diet and/or medication by a physician.
Angiographic characteristics are listed in Table 2 . The most type C lesions were treated in the STEMI group. Drug-eluting stent use was lowest in STEMI (57.0%), followed by NSTEMI (64.6%), and was >76% in the SAP and UAP groups ( Figure 2 ). Most drug-eluting stents used were first-generation sirolimus- and paclitaxel-eluting stents (69.1% overall), whereas the rest were second-generation everolimus- and zotarolimus-eluting stents. Intravascular ultrasound use was high overall but lowest in the STEMI group. Aspiration thrombectomy was performed in approximately 1/3 of the patients in the STEMI group, which is much higher than in the other groups. There was greater use of heparin and glycoprotein IIb/IIIa receptor inhibitor use with NSTEMI and STEMI groups, and thienopyridine loading was >80% across the 4 groups. Angiographic success was high (>97%) across all groups.
| SAP (Patients, n = 3,700; Lesions, n = 6,163) | UAP (Patients, n = 2,845; Lesions, n = 4,667) | NSTEMI (Patients, n = 4,083; Lesions, n = 6,840) | STEMI (Patients, n = 1,570; Lesions, n = 2,422) | p Value | |
|---|---|---|---|---|---|
| Angiographic characteristics | |||||
| Target coronary vessel | |||||
| Left main | 110 (1.8) | 79 (1.7) | 142 (2.1) | 43 (1.8) | 0.43 |
| Left anterior descending | 2,363 (38.3) | 1,639 (35.1) | 2,364 (34.6) | 974 (40.2) | <0.001 |
| Left circumflex | 1,456 (23.6) | 1,110 (23.8) | 1,633 (23.9) | 465 (19.2) | <0.001 |
| Right | 1,844 (29.9) | 1,509 (32.3) | 1,999 (29.2) | 871 (36.0) | <0.001 |
| Venous graft | 348 (5.6) | 302 (6.5) | 641 (9.4) | 62 (2.6) | <0.001 |
| Internal mammary | 42 (0.7) | 28 (0.6) | 61 (0.9) | 7 (0.3) | <0.001 |
| In-stent restenosis lesion | 217 (3.5) | 276 (5.9) | 348 (5.1) | 40 (1.7) | <0.001 |
| ACC/AHA type C lesion | 1,777 (29.8) | 1,402 (31.6) | 1,903 (28.9) | 968 (40.8) | <0.001 |
| Number of diseased vessels | 1.8 ± 0.8 | 1.9 ± 0.8 | 1.9 ± 0.9 | 1.9 ± 0.8 | <0.001 |
| Procedural characteristics | |||||
| Number of treated lesions | 1.6 ± 1.9 | 1.6 ± 0.9 | 1.6 ± 0.9 | 1.5 ± 1.3 | <0.001 |
| Number of stents per patient | 1.4 ± 0.9 | 1.4 ± 1.0 | 1.4 ± 0.9 | 1.0 ± 1.0 | <0.001 |
| Bare metal stent | 1,305 (23.5) | 920 (22.0) | 2,114 (35.4) | 928 (43.1) | <0.001 |
| Drug-eluting stent | 4,248 (76.5) | 3,263 (78.0) | 3,856 (64.6) | 1,226 (57.0) | <0.001 |
| First-generation drug-eluting stent (% of drug-eluting stent) | 2,916 (68.6) | 2,054 (62.9) | 2,867 (74.4) | 869 (70.9) | <0.001 |
| Second-generation drug-eluting stent (% of drug-eluting stent) | 1,332 (31.4) | 1,209 (37.1) | 989 (25.6) | 357 (29.1) | <0.001 |
| Stent diameter, mm | 3.0 ± 0.9 | 3.0 ± 0.9 | 3.1 ± 1.4 | 3.2 ± 3.5 | <0.001 |
| Stent length, mm | 19.8 ± 7.1 | 19.6 ± 6.8 | 19.7 ± 6.3 | 20.2 ± 6.8 | <0.001 |
| Intravascular ultrasound | 4,104 (67.5) | 2,767 (60.8) | 3,844 (57.3) | 773 (32.2) | <0.001 |
| Intra-aortic balloon pump | 36 (1.0) | 59 (2.1) | 202 (5.0) | 330 (21.1) | <0.001 |
| Aspiration thrombectomy | 53 (1.4) | 73 (2.6) | 156 (3.8) | 509 (32.4) | <0.001 |
| Pharmacotherapy | |||||
| Preprocedural anticoagulation | 73 (2.0) | 291 (10.2) | 807 (19.8) | 959 (61.4) | <0.001 |
| Antiplatelet loading | 2,870 (85.7) | 2,192 (85.8) | 2,630 (83.8) | 1,298 (84.8) | <0.001 |
| Heparin | 596 (16.1) | 487 (17.1) | 1,107 (27.1) | 337 (21.5) | <0.001 |
| Bivalirudin | 2,955 (79.9) | 2,183 (76.7) | 2,586 (63.3) | 982 (62.5) | <0.001 |
| Glycoprotein IIb/IIIa receptor inhibitor | 286 (7.8) | 254 (9.0) | 714 (17.9) | 346 (22.1) | <0.001 |
| Procedural outcome | |||||
| Dissection | 38 (0.6) | 24 (0.6) | 49 (0.7) | 9 (0.4) | 0.23 |
| Abrupt closure | 17 (0.3) | 17 (0.4) | 28 (0.4) | 4 (0.2) | 0.24 |
| No reflow | 20 (0.3) | 13 (0.3) | 21 (0.3) | 20 (0.8) | 0.002 |
| Angiographic success | 5,953 (97.6) | 4,505 (97.9) | 6,549 (97.3) | 2,340 (97.0) | 0.07 |
| Procedure length (minutes) | 61.4 ± 34.8 | 60.2 ± 35.0 | 60.3 ± 41.7 | 56.4 ± 41.1 | <0.001 |
| Contrast used (ml) | 183 ± 88 | 178 ± 84 | 190 ± 113 | 177 ± 135 | <0.001 |
The ST and clinical outcomes are listed in Table 3 . Of 12,198 patients treated, definite ST occurred in 70 patients (0.6%), and definite/probable ST occurred in 169 patients (1.4%). At 1 year, patients with STEMI had the highest incidence of definite ST. The risk of definite/probable ST increases across the acuity of clinical presentation ( Figure 3 ). The cumulative event curves for definite and definite/probable ST are shown in Figure 4 . Most of the ST events occurred early ( Figure 5 ).
| SAP (n = 3,700) | UAP (n = 2,845) | NSTEMI (n = 4,083) | STEMI (n = 1,570) | p Value | |
|---|---|---|---|---|---|
| Definite ST | 14 (0.4) | 14 (0.5) | 20 (0.5) | 22 (1.4) | <0.001 |
| Early (≤30 days) | 10 (71.4) | 11 (78.6) | 13 (65.0) | 16 (72.7) | |
| Late (31 days to 1 year) | 4 (28.6) | 3 (21.4) | 7 (35.0) | 8 (36.4) | |
| Definite/probable ST | 29 (0.8) | 31 (1.1) | 59 (1.4) | 50 (3.2) | <0.001 |
| Early (≤30 days) | 17 (58.6) | 18 (58.1) | 35 (59.3) | 42 (84.0) | |
| Late (31 days to 1 year) | 12 (41.4) | 13 (41.9) | 24 (40.7) | 8 (16.0) | |
| Death | 128 (3.5) | 123 (4.3) | 351 (8.7) | 277 (17.8) | <0.001 |
| Myocardial infarction | 34 (0.9) | 51 (1.8) | 61 (1.6) | 33 (2.5) | <0.001 |
| Target lesion revascularization | 168 (4.6) | 153 (5.5) | 221 (5.7) | 68 (5.0) | 0.16 |
| Target vessel revascularization | 228 (6.3) | 245 (8.8) | 343 (8.8) | 118 (8.7) | <0.001 |
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