Manual catheter aspiration appears to be a useful adjunct to primary percutaneous coronary intervention (PCI) in ST-elevation myocardial infarction. We investigated effects of catheter aspiration during primary PCI in patients with different extents of coronary thrombus. The study included 46 patients with no or possible thrombus (thrombus scale [TS] grades 0 to 1) and 135 patients with angiographic evidence of obvious thrombus (TS grades 2 to 5). Reference vessel diameter, which was significantly larger in the group with TS grades 2 to 5 (3.4 vs 3.2 mm, p = 0.004), was the only independent predictor of angiographically visible thrombus (odds ratio 3.3, 95% confidence interval 1.3 to 8.7, p = 0.015, per millimeter increase). Aspiration catheter was successfully advanced across the lesion in 89% of patients with TS grades 0 to 1 and 96% of those with TS grades 2 to 5 (p = 0.115). Number of aspirations varied from 1 to 5 and was significantly larger in patients with TS grades 2 to 5. Visually observable aspirate was obtained in 90% of patients with TS grades 2 to 5 and in 67% of patients with TS grades 0 to 1 (p <0.001) with more patients with TS grades 2 to 5 having aspirate >5 mm in length (49% vs 11%, p <0.001). Final Thrombolysis In Myocardial Infarction grade 3 flow (89% vs 92%), residual TS (0.2 vs 0.1), frequency of distal embolization (2% vs 6%), and early complete ST resolution (65% vs 70%) were comparable between groups with TS grades 0 to 1 and 2 to 5. In conclusion, although the amount of aspirate is larger in patients with angiographically obvious thrombus, visually observable aspirate can be obtained in most patients without definite signs of thrombus. Extent of coronary thrombus does not influence primary PCI result if manual aspiration is used.
Manual catheter aspiration appears to be a useful adjunct to primary percutaneous coronary intervention (PCI) in ST-elevation myocardial infarction (STEMI). Aspiration before stenting has been shown to improve the angiographic result and clinical outcome of patients with STEMI. Therefore, manual aspiration has been upgraded from class IIb level B in European STEMI guidelines of 2008 to class IIa level A in recently published European revascularization guidelines. In the present study, we investigated effects of catheter aspiration in patients with STEMI and different sizes of coronary thrombus determined by coronary angiography. We investigated how often an aspirate visible to the eye can be obtained despite an absence of definite angiographic signs of coronary thrombus. We also hypothesized that presence of large thrombus does not compromise results of primary PCI if manual catheter aspiration is used as part of the intervention.
Methods
The study protocol was approved by the National Ethical Committee (No. 23/05/09). The study enrolled consecutive patients with STEMI undergoing primary PCI with manual catheter aspiration. Catheter aspiration was not attempted if the infarct-related artery had a diameter ≤2 mm and if significant tortuosity/calcification would not allow for nontraumatic passage of an aspiration catheter.
All interventions were performed by 1 of 2 experienced operators. After passing a guidewire, manual aspiration with a 6 Fr guiding catheter-compatible Diver (Invatec, Brescia, Italy), Export (Medtronic, Minneapolis, Minnesota), Pronto (Vascular Solutions, Inc., Minneapolis, Minnesota), or Quickcath (Travenol Laboratories, Inc., Baxter Healthcare Corporation, Deerfield, Illinois) was performed. Predilatation using a ≤2-mm balloon was used only if initial passage of aspiration catheter was not possible. Number of aspiration passes was left to the discretion of the operator. In general, aspiration passes were performed until visually observable aspirate was obtained in the syringe. After aspiration, direct stenting was the preferred strategy. Sizing of a stent was performed after intracoronary administration of nitroglycerin (100 to 200 μg). Predilatation after aspiration and before stenting was used if a distal vessel was not adequately visualized for safe stent placement.
Epicardial coronary flow was assessed by Thrombolysis In Myocardial Infarction (TIMI) classification. Thrombus burden in an infarct-related artery was estimated by coronary angiography using a TIMI thrombus scale (TS). Based on TS grade after passing a guidewire across the culprit lesion to distal vessel, patients were categorized as having no or possible thrombus (TS grades 0 to 1) or definite thrombus (TS grades 2 to 5). The 2 groups were compared in clinical parameters, angiographic characteristics, amount of aspirated material, and final angiographic result including TIMI flow in the infarct-related artery, frequency of distal embolization, and residual TS. Early ST-segment resolution was estimated as previously reported. Amount of aspirate obtained by catheter aspiration was graded as not visible to the eye, <5 mm in length, and >5 mm in length.
Numerical data are presented as mean ± SD or median with interquartile range and were analyzed by unpaired t test if normally distributed or by Mann–Whitney test if skewed. Categorical data are expressed as proportion and were analyzed by chi-square test. For post hoc comparison of categorical variables, Keppel modification of Bonferroni correction was used. Multiple logistic regression was used to analyze predictors of thrombus size at first coronary angiography. A p value <0.05 was considered statistically significant.
Results
The study included 46 patients with no or possible thrombus (TS grades 0 to 1) and 135 patients with obvious angiographic signs of thrombus (TS grades 2 to 5). The 2 groups were comparable in age, gender, and risk factors for coronary artery disease ( Table 1 ). There were also no significant differences in time delay between onset of symptoms and urgent coronary angiography and time delay between administration of antiaggregation therapy and coronary angiography between groups.
| Variable | Thrombus Scale 0–1 | Thrombus Scale 2–5 | p Value |
|---|---|---|---|
| (n = 46) | (n = 135) | ||
| Age (years) | 59 ± 13 | 63 ± 12 | 0.071 |
| Men | 36 (78%) | 89 (66%) | 0.118 |
| Hypertension | 26 (57%) | 87 (64%) | 0.338 |
| Diabetes mellitus | 8 (17%) | 31 (23%) | 0.427 |
| Hypercholesterolemia | 30 (65%) | 76 (56%) | 0.289 |
| Smoker | 18 (39%) | 49 (36%) | 0.664 |
| Onset of symptoms to coronary angiography (minutes) | 210 (127–304) | 168 (107–220) | 0.232 |
| Antiaggregation before coronary angiography | 0.924 | ||
| Aspirin + clopidogrel + heparin | 41 (89%) | 121 (90%) | |
| Glycoprotein Ilb/IIIa inhibitors | 5 (11%) | 14 (10%) | |
| Antiaggregation to coronary angiography (minutes) | 70 (49–102) | 62 (34–88) | 0.362 |
In patients with obvious thrombus (TS grades 2 to 5), the right coronary artery was more often (50% vs 28%) and the left circumflex artery less often (11% vs 24%) a culprit artery ( Table 2 ). Reference vessel diameter, which was significantly larger in the group with TS grades 2 to 5 (3.4 vs 3.2 mm), was the only independent predictor of angiographically visible thrombus (odds ratio 3.3, 95% confidence interval 1.3 to 8.7, p = 0.015, per millimeter increase). TIMI grade flow in the infarct-related artery at first coronary angiography and after passage of the guidewire was significantly greater in the group with TS grades 0 to 1 ( Figure 1 ). At the same time, TS grade was higher in the group with TS grades 2 to 5.
| Variable | Thrombus Scale 0–1 | Thrombus Scale 2–5 | p Value |
|---|---|---|---|
| (n = 46) | (n = 135) | ||
| Infarct-related coronary artery | 0.015 | ||
| Left anterior descending | 22 (48%) | 52 (39%) | 0.268 |
| Left circumflex | 11 (24%) | 15 (11%) | 0.033 |
| Right | 13 (28%) | 68 (50%) | 0.009 |
| Reference diameter (mm) | 3.2 ± 0.4 | 3.4 ± 0.4 | 0.004 |
| Predilatation before aspiration | 1 (2%) | 18 (13%) | 0.033 |
| Passage of aspiration catheter | 41 (89%) | 129 (96%) | 0.115 |
| Number of aspirations (range) | 1.3 ± 0.5 (1–2) | 1.8 ± 0.9 (1–5) | <0.001 |
| Amount of aspirate | <0.001 | ||
| Not visible | 15 (33%) | 14 (10%) | <0.001 |
| <5 mm | 26 (57%) | 55 (41%) | 0.063 |
| >5 mm | 5 (10%) | 66 (49%) | <0.001 |
| Final technique | |||
| Direct stenting | 37 (80%) | 95 (70%) | 0.185 |
| Stenting with predilatation | 8 (17%) | 31 (23%) | 0.427 |
| Only aspiration/balloon | 1 (2%) | 9 (7%) | 0.249 |
| Final Thrombolysis In Myocardial Infarction grade 3 flow | 41 (89%) | 124 (92%) | 0.574 |
| Residual thrombus scale grade | 0.2 ± 0.8 | 0.1 ± 0.5 | 0.294 |
| Distal embolization | 1 (2%) | 8 (6%) | 0.536 |
| Early ST-segment resolution | 0.737 | ||
| >70% | 30 (65%) | 95 (70%) | |
| 30–70% | 12 (26%) | 32 (24%) | |
| <30% | 4 (9%) | 8 (6%) |
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