We evaluated a hypothesis that thrombus aspiration with distal protection is superior to simple thrombus aspiration in patients treated with primary percutaneous coronary intervention (PCI). A total of 176 consecutive patients with ST-segment elevation myocardial infarction were enrolled in this study and assigned to either the thrombus aspiration group (A, n = 104) or the thrombus aspiration with distal protection group using a filter device system (A + DP, n = 72). We compared the angiographic reperfusion grade, left ventricular (LV) function, and clinical outcomes between the 2 groups. There were no significant differences in age, gender distribution, the onset-to-reperfusion time, the peak levels of creatine kinase, or 6-month mortality between the 2 groups. The rate of achieving a Thrombolysis In Myocardial Infarction flow grade of 3 and a myocardial blush grade of 3 was higher in the A + DP group than in the A group. Among the patients who underwent follow-up catheterization 6 months after PCI (A, n = 62; A + DP, n = 52), there were no significant differences in the LV end-diastolic volume index, LV end-systolic volume index, or LV ejection fraction between the 2 groups at the time of PCI or 6 months after PCI. In conclusion, thrombus aspiration with distal protection may be more effective in initially restoring the coronary blood flow than thrombus aspiration alone, although it may not be superior to thrombus aspiration in preventing LV remodeling or preserving the LV function in patients with ST-segment elevation myocardial infarction.
A recent large prospective randomized trial demonstrated superior coronary reperfusion and clinical outcomes after primary percutaneous coronary intervention (PCI) with thrombus aspiration than after conventional PCI in patients with acute ST-segment elevation myocardial infarction (STEMI). In contrast, the beneficial effects of distal protection in primary PCI remain controversial although there are some favorable subgroups. The EMARALD study, for the Enhanced Myocardial Efficacy and Recovery by Aspiration of Liberated Debris Investigaors, a prospective randomized controlled trial of patients with STEMI treated with balloon occlusion and the aspiration distal microcirculatory protection system versus angioplasty without distal protection, did not demonstrate an improved microvascular flow, greater reperfusion success, a reduced infarct size, or enhanced event-free survival. The effectiveness of using a more feasible device, such as a filter-protection system, in achieving myocardial reperfusion, however, remains unknown. We evaluated the hypothesis that thrombus aspiration with distal protection using a filter device is superior to simple thrombus aspiration in patients treated with primary PCI.
Methods
This is a retrospective observational study of patients who were indicated for primary PCI because of acute ST-segment elevation myocardial infarction (STEMI). STEMI was defined as persistent chest pain lasting for ≥30 minutes associated with new ST-segment elevation in ≥2 contiguous leads with a cut-off point of ≥0.2 mV. Myocardial damage was confirmed by an elevation of the levels of creatine kinase-MB (greater than or equal to twofold the upper limit of the normal range) or troponin-T during the patient’s clinical course. Coronary angiography revealed at least 1 culprit lesion defined as an occluded coronary artery or an artery with 90% to 99% stenosis based on a visual estimate and the angiographic appearance of the thrombus. A total of 176 consecutive patients with STEMI were assigned to either the conventional thrombus aspiration group (A, n = 104) or the thrombus aspiration with distal protection using a filter device system group (Filtrap, NIPRO, Osaka, Japan; A + DP, n = 72) based on the operator’s decision and anatomical accessibility; that is, vessels were not tortuous and the diameter of ≥3 mm. Patients with a culprit lesion in the left main trunk and/or cardiogenic shock were excluded. Patients with autoimmune or inflammatory diseases (including patients treated with steroids and/or nonsteroidal anti-inflammatory drugs), active infections, malignant diseases, or liver cirrhosis were also excluded.
The patients underwent coronary angiography and primary PCI according to standard techniques using a femoral or radial/brachial approach, followed by the intra-arterial administration of 100 IU/kg of heparin. In the PCI in distal protection group (A + DP, n = 72), the distal protection procedure was similarly performed as previously reported by Maier et al. We crossed the culprit lesion with a filter device system (Filtrap) after crossing the lesion with a conventional guidewire. After crossing the culprit lesion, the filter device was inflated for distal protection of the culprit artery. A 6F Eliminate aspiration catheter (Clinical Supply Co. Ltd., Gifu, Japan) was inserted over the guidewire and 2 to 3 passages of aspiration with a syringe through continuous aspiration from the distal end at the site of the filter to the upper border of the culprit lesion was performed. Subsequently, PCI was carried out after predilatation using a slightly undersized balloon when necessary for stent delivery, followed by single or multiple stenting. After this procedure, the filter device was deflated and retrieved. In the patients in the thrombus aspiration alone group (A: n = 104), this step was followed by advancing the 6F Eliminate aspiration catheter into the target coronary segment during continuous aspiration. In all patients, after restoration of the anterograde coronary flow, the same doses of intracoronary nitrates were administered to both groups to ensure maximal epicardial vasodilation to determine the size and length of the stent and to facilitate stent placement. All placed stents were bare-metal stents. Some patients underwent pulse infusion thrombolysis when the target lesion was angiographically rich in thrombi. When a Thrombolysis In Myocardial Infarction (TIMI) flow grade of 2 or 3 was achieved, no further PCI was performed.
All patients were administered pharmacologic treatment before PCI including the administration of aspirin (100 mg), heparin (5,000 IU), and clopidogrel (a loading dose of 300 mg). The standard therapy after PCI included aspirin, clopidogrel, β blockers, lipid-lowering agents, and angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, according to current guidelines.
Blood tests were performed on admission under fasting or casual conditions. The blood samples were obtained on admission and every 8 hours serially for 3 days in both groups.
Written informed consent for cardiac catheterization and data utilization was obtained from each patient, and the study protocol conformed to the ethical guidelines of the 1975 Declaration of Helsinki, as reflected in a priori approval by our institution’s Human Research Committee.
The primary end points were the postprocedural frequency of a myocardial blush grade (MBG) of 2 or 3 as previously defined by Van’t Hof et al and that of a TIMI flow grade of 2 or 3 as previously described. Angiographic evidence of thrombi was assessed according to the criteria summarized by Mabin et al.
The secondary end points were changes in the left ventricular (LV) function and volume between the time of primary PCI and 6 months after PCI, as assessed with biplane left ventriculography. The LV end-diastolic volume and LV end-systolic volume were measured using biplane left ventriculography, and the LV ejection fraction (LVEF) was calculated according to the Simpson method. Because the body surface area was generally larger for men than for women, the LV volume was indexed to the body surface area for comparisons between the 2 groups. The data obtained from the coronary angiograms were analyzed at an independent core laboratory. The final angiographic reperfusion grades were assessed by the third individual who was blinded to the treatment strategy. The coronary angiograms were analyzed in 2 selected views, the right anterior oblique view and left anterior oblique view.
Because the continuous parameters in the present study were found to show a non-normal distribution, the data are expressed as the median (interquartile range) for continuous variables and as numbers and percentages for categorical variables. We therefore performed the statistical analysis using the nonparametric method. Comparisons of continuous variables between the 2 groups were performed using the Mann-Whitney test or Wilcoxon signed-rank test. The chi-square test or Fisher’s exact test were used to compare categorical variables. A 2-tailed p value of <0.05 was considered to be statistically significant. All statistical analyses were performed using the GraphPad Prism 5.0 (GraphPad Software Inc., San Diego, California) software packages.
Results
The initial TIMI flow grades were 0 in 85 (82%) of group A and 56 (78%) of group A + DP and 1 in 19 (18%) of group A and 16 (22%) of group A + DP, respectively (p >0.05). It took 5 minutes to complete thrombus aspiration maneuver in average and 8 minutes in average to place the filter device.
The baseline characteristics of the patients are summarized in Table 1 . There were no significant differences in age, the distribution of gender, coronary risk factors, or the renal function.
| Variables | A (n = 104) | A + DP (n = 72) | p |
|---|---|---|---|
| Age (yrs) | 67 (56–79) | 66 (57–77) | 0.4878 |
| Men | 79 (76) | 58 (81) | 0.5803 |
| Hypertension | 49 (47) | 42 (58) | 0.1682 |
| Diabetes mellitus | 42 (40) | 20 (28) | 0.1085 |
| Dyslipidemia ∗ | 51 (49) | 31 (43) | 0.4469 |
| Smoker | 40 (39) | 23 (32) | 0.4256 |
| Estimated glomerular filtration rate (ml/min/1.73 m 2 ) | 70.5 (58.3–88.3) | 75.0 (60.3–91.3) | 0.2275 |
∗ Dyslipidemia was defined as low-density lipoprotein cholesterol levels of ≥140 mg/dl, high-density lipoprotein cholesterol levels of <40 mg/dl, and triglyceride levels of ≥150 mg/dl.
The results of cardiac catheterization and PCI are summarized in Table 2 . There were also no significant differences in the distribution of the culprit lesions, the number of diseased vessels, the PCI procedures, or the rate of use of assist devices. In addition, the onset-to-reperfusion time did not differ between the 2 groups. The initial rate of achieving TIMI flow grade of 3 and MBG of 3 was significantly higher in the A + DP group than in the A group ( Table 3 ).
| Variables | A (n = 104) | A + DP (n = 72) | p |
|---|---|---|---|
| Culprit coronary artery | 0.5941 | ||
| Left anterior descending | 42 (40) | 28 (39) | |
| Left circumflex | 18 (17) | 9 (13) | |
| Right | 44 (43) | 35 (48) | |
| Number of narrowed coronary arteries | 0.9828 | ||
| 1 | 56 (54) | 38 (53) | |
| 2 | 29 (28) | 21 (29) | |
| 3 | 19 (18) | 13 (18) | |
| PCI procedure | 0.058 | ||
| Stent | 77 (74) | 50 (70) | |
| Percutaneous old balloon angioplasty | 14 (13) | 17 (23) | |
| Pulse infusion thrombolysis | 6 (6) | 5 (7) | |
| Aspiration alone | 7 (7) | 0 (0) | |
| Intra-aortic balloon pump | 0.1038 | ||
| + | 12 (12) | 3 (4) | |
| − | 92 (88) | 69 (96) |
| A | A + DP | p | |
|---|---|---|---|
| Time from onset to recanalization (h) | 5.0 (3.0–8.5) | 4.0 (3.0–6.0) | 0.1994 |
| TIMI flow grade | 0.0049 | ||
| 0 | 2 (2) | 0 (0) | |
| 1 | 2 (2) | 1 (2) | |
| 2 | 23 (22) | 3 (4) | |
| 3 | 77 (74) | 68 (94) | |
| MBG | 0.0186 | ||
| 0 | 14 (13) | 1 (1) | |
| 1 | 9 (9) | 3 (4) | |
| 2 | 7 (7) | 5 (7) | |
| 3 | 74 (71) | 63 (88) | |
| Peak creatine kinase (IU/L) | 2,834 (1,496–4,496) | 3,520 (1,994–5,228) | 0.1999 |
| Peak white blood cell (per mm 3 ) | 12,450 (10,100–15,230) | 12,050 (10,030–15,180) | 0.6277 |
| Peak C-reactive protein (mg/dl) | 8.33 (5.51–13.97) | 6.4 (3.71–10.12) | 0.0072 |
| Brain natriuretic peptide (pg/ml) | 86.5 (32.5–201.5) | 68 (33–130) | 0.4004 |
The blood chemistry data were obtained on admission and every 8 hours serially for 3 days in the 2 groups. There were no significant differences in the levels of peak creatine kinase, peak white blood cells, or baseline brain natriuretic peptide, whereas the peak C-reactive protein levels were higher in the A group than in the A + DP group ( Table 3 ).
There were no significant differences in LV end-diastolic volume index, LV end-systolic volume index, or LVEF between the 2 groups at the time of PCI ( Table 4 ). The medications administered after PCI were similar between the 2 groups except aspirin and statins ( Table 5 ). Aspirin was more prescribed in group A, and statins were prescribed more in A + DP group. There were no significant differences in LV end-diastolic volume index, LV end-systolic volume index, or LVEF between the 2 groups 6 months after PCI, and there were no significant changes in LV end-systolic volume index or LVEF in either group, whereas LV diastolic volume index was significantly larger in the A + DP group at 6 months after PCI than at the time of primary PCI ( Table 4 ). Among the patients who underwent follow-up catheterization 6 months after PCI with a similar follow-up rate, the 6-month mortality was not significantly different between the 2 groups under similar post-PCI medications ( Table 5 ).
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