Between May 2006 and August 2008, all consecutive patients with STEMI referred to our hospital for primary or rescue PCI were enrolled. There were no exclusion criteria. Clinical and angiographic characteristics of all patients were prospectively collected. All patients signed a written informed consent prior to PCI procedure and agreed to be clinically followed. At the time of the study an IRB approval was not formally necessary for observational registries that use a CE-mark approved device.

Patients treated with primary PCI were pretreated with aspirin (300 mg), clopidogrel loading dose (300 mg) and unfractioned heparin adjusted to weight. The use of glycoprotein (GP) IIb/IIIa inhibitors was left at the discretion of the operators in case of significant thrombus, slow or non-reflow of thrombotic complications. PCI was performed according to conventional clinical practice. Manual TA; using the 6-French Pronto V3^® aspiration catheter (Vascular Solutions Inc, Minneapolis, MN) and the 6-French Export^® aspiration catheter (Medtronic, Minneapolis, MN), was performed according to the operator’s choice; and patients were thereafter classified in TA group and non-thrombus aspiration (NTA) group.

Manual TA technique was performed as follows. The aspiration was started 2-cm before the culprit lesion and the aspiration catheter was advanced very slowly, crossing the lesion with continuous aspiration. The catheter was removed under aspiration even into the guiding catheter, with generous backflow after retrieving the thrombectomy device. At least two or three passages were performed. Manual TA was especially considered, in case of high thrombus burden and initial slow thrombolysis in myocardial infarction (TIMI) flow.

Time to treatment was defined as time from symptom onset to initial intracoronary therapy by TA or balloon inflation of the infarct-related coronary artery[22].

TIMI flow grade was evaluated pre guide-wire and post-PCI[6].

No-reflow was defined as a TIMI flow grade < 2 in absence of coronary dissection, coronary hematoma, occlusive coronary thrombosis or epicardial spasm[10]. Thrombus embolization was defined as circumscribed filling defects and/or abrupt cut off of a vessel distal to the target lesion or in other coronary vessel on the angiogram after PCI[23]. Coronary dissection was defined by the presence of a curvilinear filling defect parallel to the vessel lumen, contrast medium outside of the vessel lumen persisting after passage of contrast medium, or a spiral-shaped filling defect partially or totally obstructing the coronary artery lumen[24].

ST was defined and categorized, according to Academic Research Consortium[25]. Angiographic success was defined as final TIMI flow equals 3 plus absence of any angiographic complication.

The angiographic assessment was performed by consensus of two independent experienced interventional cardiologists. The primary end-point of this study was the rate of angiographic success, as above defined. Secondary end-points included technical and clinical issues related to the procedure as the number of implanted stents, the rates of direct stenting and post-dilatation, the maximal diameter of the implanted stents, the total stented length segment, the final TIMI flow and the resolution of the ST-segment elevation after primary PCI.

A clinical follow-up up to 3 years was performed by a clinical visit or telephone interview. Clinical outcomes were evaluated by measuring the rate of the major adverse cardiac events (MACE) defined as the combination of cardiac death, myocardial infarction (MI) and need for cardiac artery by-pass grafting (CABG) and its individual components, as well as the rate of all-cause death, and the need for target vessel and non-target vessel PCI revascularization. MI was defined according to the World Health Organization extended definition[26].

Continuous variables were explored for normal distribution with the Kolmogorov-Smirnov test. Normally distributed variables were expressed as mean (1 standard deviation) and non-normally distributed variables were expressed as median (inter-quartile range) and were compared using t-student or with Mann-Whitney tests as appropriate. Categorical variables were expressed as count (percentage) and were compared using the χ² test.

In order to exclude confounding factors in primary end-point (angiographic success), multivariable logistic regression models were fitted to assess independent predictors. The following variables were tested for the predictors of the primary end-point: manual TA, age, gender, smoking history, prior MI, primary PCI, Killip class > I, initial TIMI flow = 0, use of GP IIb/IIIa inhibitors and the use of drug-eluting stents (DES). The result was reported as HR together with the 95%CI.

All P values were 2-tailed, with statistical significance set at a level of < 0.05. Statistical analyses were performed using SPSS Statistics 20.0 (SPSS Inc., Chicago, IL, United States).

A total of 542 patients were prospectively included during the recruitment period. Of them, 30 patients were not analyzable because impossibility to crossing the culprit lesion by the TA device and 56 patients because inability to analyze the angiographic data. The remaining 456 patients were finally studied and classified in TA (n = 156) and NTA groups (n = 300) (Figure 1).

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Figure 1 Study flowchart. STEMI: ST-segment elevation myocardial infarction; PCI: Percutaneous coronary intervention; TIMI: Thrombolysis in myocardial infarction.

Baseline characteristics are presented in the Table 1. TA group exhibited lower prevalence of dyslipidemia (19.2% vs 30.7%, P = 0.009) and multivessel disease (39.8% vs 54.7%, P = 0.003) in comparison with NTA group. Conversely, TA was more often used in primary PCI (73.1% vs 68.7%, P = 0.013), in presence of initial TIMI flow < 3 (P < 0.001), and with concomitant use of GP IIb/IIIa inhibitors (65.3% vs 50.6%, P = 0.012) in comparison with NTA group.

Main procedural results are presented in the Table 2. Patients included in TA group showed higher prevalence of angiographic success (78.8% vs 68%, P = 0.015) and better final TIMI flow (TIMI flow 3: 85.9% vs 78.3%, P = 0.04) in comparison with NTA group. Patients treated with TA received higher rate of direct stenting (58.7% vs 45.5%, P = 0.009), less number of stents implanted (1.3 ± 0.67 vs 1.5 ± 0.84, P = 0.009), with larger (3.17 ± 0.43 mm vs 2.93 ± 0.44 mm, P < 0.001) and shorter sizes (24.1 ± 11.8 mm vs 26.9 ± 15.7 mm, P = 0.038). The use of DES was lower in the TA group (DES; 11.3% vs 16.3%, P = 0.008). In multivariate analysis, TA was associated with angiographic success (HR = 2.3; 95%CI: 1.2-4.3) (Table 3).

In-hospital and long-term data are presented in the Table 4. No difference in major cardiac events was observed between groups during hospitalization. The only difference was a significantly higher CK peak [2563 (1284-4542) UI/L vs 1517 (744-3816) UI/L, P = 0.02] observed by the use of TA.

At three years clinical follow-up (36 ± 7 mo), no differences between manual TA and conventional PCI were observed in the rates of MACE (17.0% vs 21.6%, P = 0.25), all-cause death (17.0% vs 19.6%, P = 0.5), cardiac death (8.3% vs 7.9%, P = 0.83), MI (6.8% vs 10%, P = 0.27), need for CABG revascularization (1.4% vs 3.5%, P = 0.39), target vessel PCI revascularization (5.4% vs 8.9%, P = 0.2), and non-target vessel PCI revascularization (4.8% vs 5.7%, P = 0.68) and definite ST (1.4% vs 4.4%, P = 0.15).

According to clinical trials and real-world registries, our work confirms that manual TA is more often used in the presence of high thrombus burden, such as in patients with initial low TIMI flow (0-1) or primary PCI indication. This registry confirms as well that use of TA achieves better angiographic results than conventional PCI, with greater reduction in thrombus burden and higher rate of final TIMI flow 3. Of note is the recent article by Ahn et al[27] which showed that the addition of IIb/IIIa inhibitors (Abciximab) to manual TA improves the index of microcirculatory resistance and the microvascular obstruction assessed by cardiac magnetic resonance. This leads us to hypothesize that the optimal strategy to optimize myocardial perfusion would be the synergistic use of these two therapeutic options.

Moreover, it appeared that the use of TA allowed immediate good angiographic results before stent implantation, so that fewer, larger and shorter stents could be more often implanted. Previous clinical trials and real-world registries failed to show any differences in the length, diameter and number of implanted stents between patients treated with or without TA[6,7,10,20,28] except for one brief work[29] that demonstrated a higher stent diameter after manual TA, in STEMI patients treated with bare metal stents. Recently, the TASTE trial[21] also showed the need for fewer stents per procedure in manual TA group in comparison with conventional PCI. It is well known that intra-stent restenosis and ST are directly related to the characteristics of the stents[30,31]. Thus; optimizing on stent implantation using fewer stents and stents of larger diameter and smaller length, during STEMI could have long-term prognostic implications by reducing the intra-stent restenosis and ST.

Besides, in light of these results we might hypothesize that TA may be cost-saving. Therefore, further studies on cost-effectiveness implications by the use of manual TA in primary PCI are warranted.

This registry reflected real-world clinical practice in STEMI population as no exclusion criteria was applied. Additionally, both primary and rescue PCI patients were included.

Unlike other studies with strict inclusion criteria[6,10], this registry demonstrated no impact of TA on both short and long-term outcomes. In the TAPAS trial[5,6], only patients with primary PCI were included; in another real-world registry[10], only patients with primary PCI indication and TIMI flow 0-1 were included. Conversely, our clinical results are consistent with studies with broad inclusion criteria, such as the TASTE trial[21], that evaluated the primary end-point at short-term and with the largest published real-world registry in manual TA[20] that had a very extended follow-up. Both studies included patients with initial TIMI flow from 0 to 3 and rescue or primary PCI indication. Thus, differences in inclusion criteria and in follow-up periods between the various trials and inherent selection bias induced in clinical registries may explain the different impact of the TA on long-term outcome.

Furthermore, it is noteworthy that in our study MACE rate was numerically higher in NTA group, although it did not reach statistical significance, probably due to the small number of patients included in our registry.

Of note is that no difference in target-vessel revascularization or stent thrombosis was found between the two groups, despite implantation of larger and shorter stent in TA than NTA group: this finding may be explained by the higher rate of DES implanted in NTA group than TA group.

This interesting controversy will continue until the publication of the results of the TOTAL trial[32]. The TOTAL trial is a multicenter, prospective, open, international, randomized trial with blinded assessment of outcomes which will recruit 10700 STEMI patients to compare routine manual TA with the Export aspiration catheter vs conventional primary PCI alone. The primary outcome will be the composite of cardiovascular death, recurrent myocardial infarction, cardiogenic shock, or new or worsening New York Heart Association class IV heart failure up to 180 d.

First, this study is a non-randomized, prospective registry and there were differences in baseline clinical and angiographic characteristics that could lead to a worse baseline risk profile in NTA group. Second, the use of GP IIb/IIIa inhibitors was higher in the TA group and this difference could also affect angiographic results in this group. Third, in our study manual TA was only used in one third of cases, whereas current use of manual TA in recent all-comer RCT[33-35] is around two thirds of patients. This was related to the relatively lack of evidence of manual thrombectomy at the time of the recruitment of the registry. Fourth, the relative small number of patients included in our study could preclude any conclusions regarding clinical efficacy of TA.

In this all-comer registry, TA was able to optimize stent implantation technique, leading to the implantation of less number of stents per lesion of shorter lengths and larger sizes, and was associated with angiographic success following PCI for STEMI.

In ST-segment elevation myocardial infarction (STEMI) patients, manual thrombus aspiration (TA) is effective to reduce thrombus burden. Nevertheless, the effect on optimization of stent implantation has not been elucidated yet. Therefore, the objective of this study is to evaluate the impact of manual TA on acute angiographic success and stent implantation characteristics in a real-world STEMI.

Manual TA reduces thrombotic burden, receiving a recommendation class IIa during the performance of primary percutaneous coronary intervention. However, the TASTE trial, recently published, showing no impact of manual TA on 30-d mortality, has reopened the debate about the role of this technique in STEMI setting.

Thrombus embolization is detected up to 15% of STEMI population and is responsible for suboptimal myocardial reperfusion, leading to unfavorable clinical outcomes. Manual TA reduces thrombotic burden and receives a high recommendation during the performance of primary percutaneous coronary intervention. The TASTE trial, demonstrating absence of impact of manual TA on short-term mortality, has reopened the debate about the use of this technique in STEMI patients. In the present study the authors want to investigate, in a real-world STEMI population, the factors which can lead to the use of manual thrombectomy in STEMI and its impact on angiographic and stent implantation characteristics.

The study results suggest that manual TA during primary percutaneous coronary intervention is associated with a higher rate of angiographic success and optimization on stent implantation compared with conventional primary percutaneous coronary intervention, in a real-world population. However, it seems to have no impact on long-term clinical outcomes.

STEMI: It is a type of acute coronary syndromes, which occurs when a coronary artery becomes totally blocked by a blood clot, causing the heart muscle supplied by the artery to die; Primary percutaneous coronary intervention: It is a non-surgical procedure used to open the occluded coronary arteries during STEMIs; Manual TA device: It is a type of thrombectomy device, which comprises a monorail catheter with a central lumen connected proximally to a syringe for manual aspiration, designed to extract thrombotic material during percutaneous coronary intervention.

In this study, Diego et al reported that the thrombus aspiration therapy in patients with AMI were associated with high procedure success and contributed to optimize the implantation of stents. As a non-randomized, prospective registry study, it provide their some new insights about the use of thrombus aspiration in the real world.