Abstract
Background
Manual coronary thrombus aspiration was associated with improved outcomes of ST-elevation myocardial infarction (STEMI) patients. We aimed to evaluate the outcome of aspiration in a “real-world” setting of primary percutaneous coronary intervention (PPCI).
Methods and materials
We analyzed the outcome of STEMI patients who underwent PPCI (initial Thrombolysis in Myocardial Infarction flow grade 0/1), comparing patients who underwent aspiration (ASP) to those who had standard (STD) therapy. Various subgroups outcomes were further analyzed. Clinical end points included mortality and major adverse cardiovascular events (MACE) at 30 days and at 1 year.
Results
One thousand thirty-five consecutive patients were included: 189 (18.26%) with ASP and 846 (81.74%) with STD. ASP patients were younger (58±12 vs. 61±13, P <.05) and had higher incidence of direct stenting compared to STD patients (34% vs. 16.7%, P <.05). No significant differences were noted in the outcome of ASP vs. STD at 30 days (mortality rate 4.2% vs. 4.5%, P =.9; MACE 6.9% vs. 9.8%, P =.2) and at 1 year (mortality rate 8.0% vs. 8.3%, P =.9; MACE 20.0% vs. 22.3%, P =.5). A significant advantage in favor of ASP was evident in patients with proximal culprit lesions, anterior infarcts, and right ventricular involvement.
Conclusions
Although this was largely a negative study, when STEMI involved a large jeopardized myocardium, aspiration was associated with sustained improved clinical outcomes.
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Introduction
Primary percutaneous coronary intervention (PPCI) is considered to be the established treatment strategy for acute ST-elevation myocardial infarction (STEMI) . However, “normally” appearing angiographic flow in the culprit epicardial artery is not always indicative of optimal perfusion in the distal coronary microvasculature. It is estimated that suboptimal myocardial blush, which in turn translates into poor short- and long-term clinical outcomes, is encountered in about two thirds of STEMI patients . Suboptimal restoration of the microvasculature perfusion is related to embolized material, primarily thrombus and plaque debris.
Prospective randomized clinical trials provide ample evidence of both the angiographic and clinical benefits of manual thrombus aspiration, leading to a class IIa recommendation for its use in the STEMI guidelines . We sought to assess the angiographic and clinical outcome of manual aspiration thrombectomy in the “real world” of PPCI practice with the intent of identifying subgroups of patients who benefit most from this adjunct catheter-based technical maneuver.
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Materials and methods
From January 2001 to July 2010, consecutive patients who presented with STEMI and underwent PPCI at our medical center were prospectively observed and registered in a certified database. Acute STEMI was defined as the presence of typical chest pain and accompanying symptoms lasting <12 hours in the presence of an ST-segment elevation of >1 mm in two contiguous leads or new or presumably new left branch bundle block on electrocardiogram (ECG) in association with an increase in cardiac enzymes (troponin I or T) above the upper limit. This registry was approved by the institutional review board of our hospital. We collected demographic, clinical, angiographic, and procedural data together with routine follow-up of STEMI patients with an initial Thrombolysis in Myocardial Infarction (TIMI) flow of 0–1 which was reported as the relevant subgroup for which aspiration is beneficial . Excluded from the present analysis were patients who presented with cardiogenic shock [these high-risk patients were excluded from most previous trials including the Thrombus Aspiration during Percutaneous coronary intervention in Acute myocardial infarction Study (TAPAS)] and those who presented 12 hours after the onset of chest pain or had an initial TIMI flow >1. The characteristics and outcomes of patients who had undergone manual thrombectomy at the operator’s discretion, using either Export (Medtronic, Inc., Minneapolis, MN, USA) or Pronto (Vascular Solutions, Minneapolis, MN, USA) catheters, were compared with those of patients who had not undergone manual thrombectomy. The outcome measures included were all-cause mortality, reinfarction, target vessel revascularization (TVR), stent thrombosis (defined as probable or according to Academic Research Consortium (ARC) definitions), unplanned coronary bypass surgery (CABG) or PCI, and hierarchical major adverse cardiovascular events (MACE) consisting of all-cause mortality, reinfarction, TVR, and unplanned CABG. For the identification of patients who may benefit from aspiration more than others, we compared the outcome of the following subgroups: age>65 years, gender, concurrent treatment with glycoprotein IIb–IIIa receptor antagonists, anterior location of MI, right ventricle (RV) involvement, proximal lesion (as defined in the SYNTAX (Synergy between PCI with TAXUS drug-eluting stent and Cardiac Surgery) trial ), and “ischemic time” (defined time from beginning of chest pain).
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Materials and methods
From January 2001 to July 2010, consecutive patients who presented with STEMI and underwent PPCI at our medical center were prospectively observed and registered in a certified database. Acute STEMI was defined as the presence of typical chest pain and accompanying symptoms lasting <12 hours in the presence of an ST-segment elevation of >1 mm in two contiguous leads or new or presumably new left branch bundle block on electrocardiogram (ECG) in association with an increase in cardiac enzymes (troponin I or T) above the upper limit. This registry was approved by the institutional review board of our hospital. We collected demographic, clinical, angiographic, and procedural data together with routine follow-up of STEMI patients with an initial Thrombolysis in Myocardial Infarction (TIMI) flow of 0–1 which was reported as the relevant subgroup for which aspiration is beneficial . Excluded from the present analysis were patients who presented with cardiogenic shock [these high-risk patients were excluded from most previous trials including the Thrombus Aspiration during Percutaneous coronary intervention in Acute myocardial infarction Study (TAPAS)] and those who presented 12 hours after the onset of chest pain or had an initial TIMI flow >1. The characteristics and outcomes of patients who had undergone manual thrombectomy at the operator’s discretion, using either Export (Medtronic, Inc., Minneapolis, MN, USA) or Pronto (Vascular Solutions, Minneapolis, MN, USA) catheters, were compared with those of patients who had not undergone manual thrombectomy. The outcome measures included were all-cause mortality, reinfarction, target vessel revascularization (TVR), stent thrombosis (defined as probable or according to Academic Research Consortium (ARC) definitions), unplanned coronary bypass surgery (CABG) or PCI, and hierarchical major adverse cardiovascular events (MACE) consisting of all-cause mortality, reinfarction, TVR, and unplanned CABG. For the identification of patients who may benefit from aspiration more than others, we compared the outcome of the following subgroups: age>65 years, gender, concurrent treatment with glycoprotein IIb–IIIa receptor antagonists, anterior location of MI, right ventricle (RV) involvement, proximal lesion (as defined in the SYNTAX (Synergy between PCI with TAXUS drug-eluting stent and Cardiac Surgery) trial ), and “ischemic time” (defined time from beginning of chest pain).
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Statistical methods
The data are presented as mean±standard deviation or as percentage for continuous or categorical variables, respectively. χ 2 and Fisher’s Exact Tests were used for analysis of categorical variables when appropriate. The Student’s t test was used for analysis of continuous variables. Statistical analysis was performed using “Statistica” software (StatSoft, Tulsa, OK, USA), and P <.05 was considered significant for all analyses. Due to the nonrandomized study design, we used propensity-score (PS) analytical methods . PS scores were calculated for each patient based on a number of prespecified clinical, angiographic and procedural variables: age, year of PCI, gender, diabetes mellitus, previous MI, prior CABG, aspirin and clopidogrel pretreatment, renal failure, coronary calcification, thrombus, lesion length, and vessel diameter.
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Results
The original cohort of STEMI patients (excluding patients in cardiogenic shock) included 1621 patients who underwent PPCI, of which a total of 1035 consecutive patients who met the inclusion criteria of initial TIMI 0–1 were included in the present analysis. A total of 189 patients (18.26%) underwent aspiration thrombectomy (ASP group), while 846 (81.74%) had standard PCI with stent implantation preceded in most cases by balloon dilatation (STD group). It should be noted that rate of aspiration was 6% prior to TAPAS trial publication as compared to 48% after the trial was published ( P <.05). The baseline characteristics are presented in Table 1 . Compared to the STD group, the ASP group patients were younger, had lower rate of renal failure, and had a trend for lower rate of final TIMI flow grade 0–1, albeit they had higher rates of prior CABG. These patients were also more likely to be treated with glycoprotein IIb–IIIa antagonists and with intracoronary nitroprusside. Angiographic visible thrombus was less frequently observed in the STD group, and so was the use of direct stenting. No difference was noted in the final myocardial blush score. All the other parameters were not significantly different between the groups, including ejection fraction <40%. Due to the limited number of patients in the ASP group, PS matching was not possible. However, multivariate models adjusting for PS and Cadillac Score were created for 1-year mortality. After accounting for variable baseline risk profiles between the two groups using multivariate and PS techniques, aspiration use was not an independent predictor of all-cause mortality at 1 year [adjusted odds ration(aOR) 0.4, 95% confidence interval (CI) 0.1–3, P =.4]. In fact, CADILAC Score was the only independent predictor of mortality (aOR=1.4, 95% CI 1.3–1.6, P <.05) after risk adjustment.
| Variable | Total ( n =1035) | Aspiration ( n =189) | Standard PCI ( n =846) | P value |
|---|---|---|---|---|
| Age | 60.5±12.7 | 58±12 | 61±13 | <.05 |
| Male | 189 (18.3%) | 26 (13.8%) | 163 (19.3%) | .08 |
| Diabetes (%) | 26 | 23 | 27 | .3 |
| HTN (%) | 50 | 52 | 49 | .5 |
| Hyperlipidemia(%) | 48 | 54 | 47 | .09 |
| Renal failure GFR<60(%) | 13.9 | 7.5 | 15.4 | <.05 |
| Killip Class>1 (%) | 14 | 11 | 14 | .5 |
| Anterior wall MI (%) | 44 | 44.4 | 44 | .7 |
| IV IIb–IIIa use (%) | 74 | 81 | 72.5 | <.05 |
| Distal embolization (%) | 11 | 12.2 | 11 | .6 |
| Thrombus observed (%) | 91 | 98 | 89 | <.05 |
| IC nitroprusside (%) | 16 | 26 | 13 | <.05 |
| Time from chest pain to ER (h) | 2.5 [1.5–4] | 3 [1.5–4] | 2 [1.5–4] | .2 |
| Time from ER to PCI (h) | 1 [1–2] | 1 [0.5–1.5] | 1 [1–2] | .05 |
| Direct stenting (%) | 20 | 34 | 16.7 | <.05 |
| No-reflow phenomenon (%) | 6.6 | 4.8 | 7.0 | .2 |
| Final MBG 2/3 (%) | 85 | 88 | 84 | .6 |
| Final TIMI 0–1 (%) | 6.4 | 2.6 | 7.2 | .07 |
| Final TIMI 3 (%) | 93.6 | 97.4 | 92.8 | .07 |
| Prior CABG (%) | 2.7 | 5.3 | 2.1 | <.05 |
| 2 or 3 VD (%) | 57 | 60 | 57 | .4 |
| EF<40% (%) | 44.5 | 40 | 44 | .6 |
| CADILAC Score | 4.4±3.6 | 4.2±3.5 | 4.4±1.2 | .5 |
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