Summary
Background
In STEMI patients treated by primary PCI, damage of the microvascular circulation caused by distal embolization of thrombotic material affects the quality of myocardial reperfusion. Important controversies remain concerning the usefulness of the manual thrombectomy to improve myocardial perfusion. The aim of this study is to evaluate the impact of manual thrombectomy on ST resolution as a surrogate of reperfusion extent.
Methods
Two hundred and thirty-nine consecutive STEMI patients with an <12 hours onset of symptoms, were enrolled in an observational registry. Patients were divided into two cohorts according to the reperfusion strategy: manual thrombectomy before primary PCI ( n = 102) or conventional-PCI ( n = 137). The primary endpoint was the post procedural frequency of complete (>70%) resolution of ST segment elevation.
Results
A complete resolution of ST segment elevation occurred in 51.4% of patients in the thrombectomy group and in 35,6% of those in the conventional-PCI group ( P = 0.018). Thrombectomy strategy was associated with a lower use of stents. Multivariate analysis identified manual thrombectomy (HR = 2.08 IC 95% (1.01–4.26); P = 0.046), inferior location and short ischemic delay (<180 min) as independent predictors of ST resolution. The cumulative Kaplan-Meier estimate of MACE was not significantly different between the two groups at one, three years follow-up.
Conclusion
In STEMI patients, manual thrombectomy improves myocardial reperfusion as assessed by the percentage of ST segment resolution and a lower use of stents. However, in this cohort of limited size, this strategy did not translate into an improved cardiovascular outcome at one year follow-up.
Résumé
Introduction
Chez les patients traités par angioplastie primaire pour un syndrome coronaire aigu avec sus-décalage du segment ST, les dommages de la circulation microvasculaire, causés par l’embolisation distale de matériel thrombotique, affecte la qualité de la reperfusion myocardique. L’objectif de cette étude est d’évaluer l’impact de la thromboaspiration manuelle sur l’étendue de le reperfusion évaluée par la résolution du segment ST.
Méthodes
Deux cent trente-neuf patients consécutifs hospitalisés pour un syndrome coronaire aigu avec sus-décalage du segment ST ont été inclus dans un registre observationnel. Ces patients ont été subdivisés en 2 cohortes selon la stratégie de reperfusion usitée : thromboaspiration manuelle avant angioplastie primaire ( n = 102) ou angioplastie conventionelle ( n = 137). Le critère de jugement principal était le taux de résolution complète du segment ST (définie par une RST > 70 %) post procédural.
Résultats
Une résolution complète du segment ST a été observée chez 51,4 % des patients du groupe Thromboaspiration et 35,6 % des patients du groupe angioplastie conventionelle ( p = 0,018). La stratégie de thromboaspiration était associée à une moindre utilisation de stents. En analyse multivariée, la thromboaspiration manuelle, la localisation inférieure de l’infarctus et un délai court de reperfusion (< 180 min) sont apparus être des facteur prédictifs de résolution complète du segment ST. L’analyse de Kaplan Meier portant sur les évènements cardio-vasculaires adverses ne montrait pas de différences significatives entre les deux groupes pour un suivi de 1,3 ans.
Conclusion
Chez les patients se présentant pour un syndrome coronaire aigu avec sus-décalage du segment ST, la thromboaspiration manuelle entraîne une amélioration de la reperfusion myocardique attestée par une fréquence accrue de résolution complète du segment ST et une moindre utilisation de stents. Cependant, dans cette cohorte de taille limitée, cette stratégie ne s’est pas accompagnée d’une amélioration du pronostic cardiovasculaire à 1 an.
Introduction
Developments in ischemic myocardial reperfusion strategies have considerably improved the prognosis of patients presenting with acute ST-elevation myocardial infarction (STEMI). The main objective of reperfusion strategies in STEMI is to limit infarct size and improve outcomes. Primary percutaneous coronary intervention (primary PCI) is the reperfusion reference strategy for patients presenting with STEMI within 12 hours of symptom onset . Nevertheless, despite restoration of epicardial infarct related artery flow, damage of the microvascular circulation (microvascular obstruction) occurs in a sizeable portion of cases . Angioplasty can be complicated by spontaneous or procedural induced distal thrombotic material embolization that may alleviate the extent of myocardial reperfusion. Recent optical coherence tomography data have nicely demonstrated the huge amount of the atherothrombotic burden that follows stent implantation, with a residual thrombus being detected in 100% of cases. None surprisingly, important residual thrombotic burden was associated with angiographic no-flow, embolization distal occlusion and was evidenced as a strong predictor of ST resolution failure . The extent of these microvascular injuries is associated with worse clinical outcome . Preventing embolization theoretically should result in improved reperfusion success as measured electrocardiographically (increased ST-segment resolution [STR]), and clinically (enhanced survival free from MACE and heart failure events). In this occurrence, adjunctive devices have been developed to reduce the thrombus burden and to minimize the risk of fragmentation and embolization. In this view, manual thrombus aspiration systems appear to be an appealing issue. However, evidences supporting a systematic use of manual thrombectomy before primary PCI are still debated and were very recently challenged by the TASTE trial . Moreover, thrombus aspiration may not be a risk-free procedure. Systemic embolization can occur, and in a recent meta-analysis, thrombus aspiration was associated with a trend toward an increased rate of stroke . The aim of this study was to assess the impact of manual thrombus aspiration on myocardial reperfusion through ST-segment resolution assessment and new Q waves generation, in a cohort of STEMI patients undergoing primary PCI.
Methods
Study population
The data analyzed in this study were obtained from a single-centre cohort. In the institutional PCI database, we identified consecutive STEMI patients who underwent primary PCI, in the cardiology centre at University hospital of Strasbourg, France, between January 2009 and September 2011. Patients were eligible for inclusion if they presented ischemic chest pain within 12 hours of symptom onset, and a 2 mm ST elevation in the V1 to V3 leads or 1 mm ST elevation in the remaining leads. When thrombus aspiration was performed, only STEMI patients treated with 6F aspiration catheter (Export, Medtronic, Dancers, MA, USA) were included in the final study cohort. Exclusion criteria from the analysis were ischemic symptoms for >12 h, prehospital cardiac arrest, an ECG showing left bundle branch block or ventricular pacing, and patients already included in another STEMI research protocol. The primary PCI procedure and pharmacological treatment was performed according to the standard of care at the time of hospital admission. The choice to perform manual thrombus aspiration was at the discretion of the operator. Data including demographic, clinical, biological, angiographic and procedural characteristics were extracted from the PCI and the ICU databases. The study protocol complied with the tenets of the Declaration of Helsinki. Study was approved by our Institutional Review Board and all participants gave informed consent.
Electrocardiography
Analysis of ST-segment deviation was performed (in a blinded fashion according to use or not of manual thrombectomy) by comparing ECG obtained at time of first medical contact and ECG obtained 60 minutes after primary PCI. The following parameters were assessed (measured in millimeters): sum of ST-segment elevation in all 12 leads (cumulative ST elevation), and maximal ST elevation measured in the lead with the most prominent ST-segment deviation. A complete ST segment elevation resolution (complete STR) was defined when the regression of the sum of ST-segment elevation before and after PCI reached more then 70%.
Clinical outcomes
Follow up of the study cohort allowed to collect the following cardiac events.
Major adverse cardiac events (MACE), hospitalisation for acute heart failure. MACE was defined as a composite of all-cause death, recurrent myocardial infarction, and target vessel revascularization (TVR). Evidence of myocardial reinfarction was defined as chest pain or ECG changes accompanied by a reelevation in level (>3 times the upper limit of normal). Target vessel revascularization was defined as the need for new PCI or coronary artery bypass graft of the culprit vessel because of either symptom recurrence or a positive ischemic functional test at follow-up.
End points
The primary study end point was the extent of myocardial reperfusion assessed by the presence or not of complete ST-segment elevation resolution (STR > 70%), 60 minutes after PPCI, taking into account the sum of ST elevation in all 12 leads (cumulative ST elevation).
Secondary endpoints included the incidence of new Q waves generation, and the incidence of MACE (death, myocardial infarction, target vessel revascularisation), of hospitalisation for acute heart failure, and of a composite end point of MACE and hospitalisation for acute heart failure.
Statistical analysis
The normal distribution of the studied variables was tested using the D’agostino and Pearson omnibus normality test. Categorical variables were expressed as count and percentages. Continuous variables were reported as mean and SD for continuous, or as medians and interquartile ranges according to their distribution. Categorical variables were compared with Chi 2 test or Fisher’s exact test. Continuous variables were compared with the use of Mann-Whitney test. To determine the effect of thrombus aspiration on the primary outcome, logistic regression analysis was performed. Association between thrombus aspiration and occurrence of clinical outcomes was assessed by Kaplan Meier analysis and log rank test. All tests were 2-sided. A P value < 0.05 was considered significant. Calculations were performed using SPSS 13.0 for Windows (SPSS Inc., Chicago, IL, USA).
Results
Study population and baseline characteristics
The final study cohort comprised 239 patients who were treated with primary PCI and who did meet the inclusion and exclusion criteria between January 1, 2009 and September 30, 2011. Of these patients, 137 patients were treated with primary PCI (conventional PCI group) and 102 patients underwent adjunctive manual thrombus aspiration using a 6F export aspiration catheter before primary PCI (thrombectomy group). Baseline demographic and clinical characteristics are given in Table 1 . The percentage of obese patients (BMI > 30 kg/m 2 ) was higher in the conventional PCI group (27.3% vs. 15.9%, P = 0.042). Other demographic and clinical characteristics were similar in the two groups of patients.
| Conventional PCI ( n = 132) | Thrombectomy ( n = 107) | P | |
|---|---|---|---|
| Demographic | 98 (74.2) | 78 (72.9) | 0.88 |
| Male sex, n (%) | |||
| Age, year | 59.8 ± 13.5 | 62.8 ± 15.3 | 0.11 |
| Cardiovascular risk factor, n (%) | |||
| Current smoking | 76 (57.6) | 70 (65.4) | 0.23 |
| Diabetes mellitus | 24 (18.2) | 17 (15.9) | 0.73 |
| Hypertension | 63(47.7) | 43 (40.2) | 0.29 |
| Family history of CAD | 25 (18.9) | 20 (18.7) | 1 |
| Hypercholesterolemia | 58 (43.9) | 42 (39.3) | 0.51 |
| BMI > 30 kg/m 2 | 36 (27.3) | 17 (15.9) | 0.042 |
| Medical history, n (%) | |||
| STEMI | 8 (6.1) | 5 (4.7) | 0.77 |
| NSTEMI | 5 (3.8) | 3 (2.8) | 0.73 |
| PCI | 10 (7.6) | 7 (6.5) | 0.8 |
| CABG | 4 (3) | 2 (1.9) | 0.69 |
| Stroke | 5 (3.8) | 0 (0) | 0.06 |
| Chronic kidney disease | 6 (4.5) | 5 (4.7) | 1 |
| Clinical | |||
| Anterior STEMI | 59 (44.7) | 39 (36.4) | 0.3 |
| Systolic blood pressure, mmHg | 134.4 ± 23.9 | 132 ± 23.3 | 0.47 |
| Diastolic blood pressure, mmHg | 78.3 ± 13.4 | 77.2 ± 14.3 | 0.55 |
| Heart Rate, bpm | 76.8 ± 15.7 | 75.2 ± 16 | 0.46 |
| Killip class | |||
| 1 | 120 (90.9) | 90 (84.1) | 0.17 |
| 2 | 10 (7.6) | 11 (10.3) | |
| 3 | 0 (0) | 3 (2.8) | |
| 4 | 2 (1.5) | 3 (2.8) |
Angiographic and procedural data
Angiographic and procedural characteristics data are shown respectively in Tables 2 and 3 . Ischemic time (time delay between onset of symptoms and balloon inflation) did not significantly differ between the two groups. Initial TIMI flow were of grade 0 to 1 more frequently in the thrombus aspiration group (95.3% vs. 84.1%, P = 0.006). The percentage of direct stenting and the use of GPIIbIIIa antagonists was equivalent between groups. The rate of stent implantation was lower in the thromboaspiration group (89.7 vs. 100%; P < 0.001). In addition, the diameter of the stent was higher in the thromboaspiration group (3.5 vs. 2.7 mm, P = 0.005). Post procedural TIMI 2 to 3 flow grade was not significantly different between the two groups (conventional PCI group, 97.7%; thrombus aspiration group, 95.7%; P = 0.11).
| Conventional PCI ( n = 132) | Thrombectomy ( n = 107) | P | |
|---|---|---|---|
| Infarct related artery, n (%) | |||
| Left anterior descending artery | 59 (44.8) | 39 (36.4) | 0.35 |
| Left circumflex artery | 30 (22.7) | 28 (26.2) | 0.54 |
| Right coronary artery | 39 (29.5) | 39 (35.5) | 0.79 |
| Left main coronary artery | 4 (3) | 2 (1.9) | 0.69 |
| No of diseased vessel, n (%) | |||
| 1 | 63 (47.7) | 65 (60.7) | 0.051 |
| 2 | 37 (28) | 21 (19.7) | 0.17 |
| 3 | 32 (24.2) | 20 (18.7) | 0.34 |
| Initial TIMI flow | |||
| 0–1 | 111 (84.1) | 102 (95.3) | 0.006 |
| 2–3 | 21 (15.9) | 5 (4.7) | |
| Final TIMI flow | |||
| 0–1 | 3 (2.3) | 7 (6.7) | 0.11 |
| 2–3 | 129 (97.7) | 98 (93.3) |
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