Abstract
Background
The presence of large thrombus burden in patients presenting with acute myocardial infarction (AMI) is common and associated with poor prognosis. This study aimed to describe the feasibility and safety of the novel ‘mother-in-child’ thrombectomy (MCT) technique in patients presenting with AMI and large thrombus burden undergoing percutaneous coronary intervention (PCI).
Methods
We studied 13 patients presenting with AMI who underwent PCI with persistent large intracoronary thrombus after standard thrombectomy. The procedure was performed using a 5 F ‘Heartrail II-ST01’ catheter (Terumo Medical) into a 6 F guiding system. Angiographic assessment of thrombus burden and coronary flow was obtained at baseline, immediately after thrombectomy and at the end of the procedure.
Results
The mean age was 55.9 ± 13.0 years and involved mostly males (76.9%). All patients underwent PCI via radial approach. Following MCT Thrombolysis In Myocardial Infarction (TIMI) flow improved by 2 or more degrees in 11 patients (84.5%), while visible angiographic thrombus was reduced in 11 patients (84.5%). In the final angiogram, normal TIMI flow was restored in 11 patients (84.5%), with normal myocardial ‘blush’ in 7 patients (53.8%) and total clearance of a visible thrombus in 7 patients (53.8%). Overall, 6 patients received thrombectomy as ‘stand-alone’ procedure. All patients were discharged alive after a mean of 5.6 ± 2 days.
Conclusion
This initial report suggests that significant reduction in thrombus burden and improvement of the coronary flow can be safely achieved in patients presenting with AMI and large thrombus burden by using the novel MCT technique.
1
Introduction
Acute myocardial infarction (MI) is usually caused by the rupture or erosion of an atherosclerotic plaque and subsequent thrombosis resulting in partial or complete occlusion of a coronary artery . Primary percutaneous coronary intervention (PCI) is the preferred and more effective reperfusion strategy for acute MI . The presence of large thrombus burden in patients presenting with acute MI is common and associated with poor prognosis . PCIs in thrombus containing lesions are associated with a higher rates of peri-procedural MI, need for emergent coronary artery bypass grafting (CABG), and premature death compared with lesions without thrombus . In addition, patients with thrombotic lesions experience more distal embolization, slow flow and no-reflow during PCI, and prolonged ST-segment elevation and larger MI after PCI .
The routine use of manual thrombectomy during primary PCI has been associated with improved outcome as compared to standard PCI .The ‘mother-in-child’ technique has been anecdotally reported as an attractive approach to successfully extract large coronary thrombus . We have implemented the use of this technique to approach large burden thrombus lesions when standard thrombectomy catheters have failed to improve thrombus burden and coronary flow. In this initial clinical series we aimed to describe the feasibility, safety and initial clinical results of the novel ‘mother-in-child’ thrombectomy technique used in patients presenting with acute MI and large persistent thrombus burden undergoing PCI.
2
Methods
2.1
Study population
Between October 2010 and December 2011, n = 13 patients who presented with acute MI with large thrombus burden who underwent PCI using the ‘mother-in-child’ thrombectomy were retrospectively studied. Patients who presented with cardiogenic shock were excluded from this analysis. All patient had persistent intracoronary thrombus and reduced distal flow after standard thrombectomy by using either Export catheter (Medtronic Vascular, Santa Rosa, CA) or Fetch-2 catheter (Medrad Inc, Warrendale, PA). Angiographic assessment of the coronary thrombus burden and the coronary flow was assessed at baseline, immediately after thrombectomy and at the end of the procedure.
2.2
Percutaneous coronary intervention
PCI was performed according to guidelines current at the time of the procedure. In all cases, the interventional strategy was at the discretion of the responsible physician. Intra-procedural anticoagulation was ensured using unfractionated heparin to achieve an activated clotting time of > 250 s in all patients. All patients received an aspirin-loading dose of ≥ 100 mg and were encouraged to continue this regimen indefinitely. After a clopidogrel-loading dose of 600 mg, additional antiplatelet therapy with a 75-mg clopidogrel maintenance dose was instituted in all patients. Patients were advised to continue this regimen for ≥ 1 year. Stents, either bare-metal stent or drug-eluting stent use was at operator discretion.
2.3
Mother-in-child thrombectomy technique
The procedure was performed using a 5 F-‘Heartrial’ multipurpose guiding catheter (Terumo Medical, Somerset, NJ, USA) advanced into a 6 F-guiding system over a standard coronary wire before reaching the angiographic location of the thrombus (Moving Image 1 and 2). The 5 F-catheter was carefully advanced under vacuum (generated by a 20 cc syringe) until flow stop noted in the syringe followed by full pull back of the system ( Fig. 1 , Moving Image 3).
2.4
Definitions
MI was defined as the association of ≥ 1 clinical and ≥ 1 biological criteria: acute onset chest pain and/or typical modification on electrocardiogram (ST or T wave modification or new left bundle branch block) and an elevation of troponin value above the 99th percentile of the upper reference limit . Major bleeding was defined as a decrease in hematocrit of ≥ 15% and/or the occurrence of hemorrhagic stroke, based on the TIMI criteria . Chronic renal insufficiency was defined as the presence of previously documented renal failure and/or a baseline serum creatinine > 2.0 mg/dL.
2.5
Angiographic analysis
All angiograms were reviewed and analyzed “off-line” at each site. Coronary flow was graded using the TIMI flow scale, as defined by the Thrombolysis In Myocardial Infarction trial before intervention, immediately after thrombectomy, and at the end of the procedure. Thrombus burden using an analogue scale from 5 to 0 was determined at baseline, immediately after thrombectomy, and at the end of the procedure as previously described .
2.6
Statistical analysis
Continuous variables are expressed as mean ± standard deviation. Discrete variables are presented as absolute values and percentages. Differences in TIMI flow and thrombus burden before and after thrombectomy, and at the end of the procedure were evaluated by Chi-square test. Probability values < 0.05 (two-tailed) were considered significant.
2
Methods
2.1
Study population
Between October 2010 and December 2011, n = 13 patients who presented with acute MI with large thrombus burden who underwent PCI using the ‘mother-in-child’ thrombectomy were retrospectively studied. Patients who presented with cardiogenic shock were excluded from this analysis. All patient had persistent intracoronary thrombus and reduced distal flow after standard thrombectomy by using either Export catheter (Medtronic Vascular, Santa Rosa, CA) or Fetch-2 catheter (Medrad Inc, Warrendale, PA). Angiographic assessment of the coronary thrombus burden and the coronary flow was assessed at baseline, immediately after thrombectomy and at the end of the procedure.
2.2
Percutaneous coronary intervention
PCI was performed according to guidelines current at the time of the procedure. In all cases, the interventional strategy was at the discretion of the responsible physician. Intra-procedural anticoagulation was ensured using unfractionated heparin to achieve an activated clotting time of > 250 s in all patients. All patients received an aspirin-loading dose of ≥ 100 mg and were encouraged to continue this regimen indefinitely. After a clopidogrel-loading dose of 600 mg, additional antiplatelet therapy with a 75-mg clopidogrel maintenance dose was instituted in all patients. Patients were advised to continue this regimen for ≥ 1 year. Stents, either bare-metal stent or drug-eluting stent use was at operator discretion.
2.3
Mother-in-child thrombectomy technique
The procedure was performed using a 5 F-‘Heartrial’ multipurpose guiding catheter (Terumo Medical, Somerset, NJ, USA) advanced into a 6 F-guiding system over a standard coronary wire before reaching the angiographic location of the thrombus (Moving Image 1 and 2). The 5 F-catheter was carefully advanced under vacuum (generated by a 20 cc syringe) until flow stop noted in the syringe followed by full pull back of the system ( Fig. 1 , Moving Image 3).
2.4
Definitions
MI was defined as the association of ≥ 1 clinical and ≥ 1 biological criteria: acute onset chest pain and/or typical modification on electrocardiogram (ST or T wave modification or new left bundle branch block) and an elevation of troponin value above the 99th percentile of the upper reference limit . Major bleeding was defined as a decrease in hematocrit of ≥ 15% and/or the occurrence of hemorrhagic stroke, based on the TIMI criteria . Chronic renal insufficiency was defined as the presence of previously documented renal failure and/or a baseline serum creatinine > 2.0 mg/dL.
2.5
Angiographic analysis
All angiograms were reviewed and analyzed “off-line” at each site. Coronary flow was graded using the TIMI flow scale, as defined by the Thrombolysis In Myocardial Infarction trial before intervention, immediately after thrombectomy, and at the end of the procedure. Thrombus burden using an analogue scale from 5 to 0 was determined at baseline, immediately after thrombectomy, and at the end of the procedure as previously described .
2.6
Statistical analysis
Continuous variables are expressed as mean ± standard deviation. Discrete variables are presented as absolute values and percentages. Differences in TIMI flow and thrombus burden before and after thrombectomy, and at the end of the procedure were evaluated by Chi-square test. Probability values < 0.05 (two-tailed) were considered significant.
3
Results
The baseline clinical and laboratory characteristics are presented in Table 1 . Of the 13 studied patients, 11 patients presented with ST-elevation MI and 2 patients with non-ST elevation MI. The mean cohort age was 55.9 ± 13.0 years and involved mostly males (76.9%). The average time from ‘symptoms onset to case start’ was 6 h and 30 min. No patients developed post-procedural renal failure, while the mean hematocrit decrease was 5.6% ± 3.0% after PCI.
| n = 13 | |
|---|---|
| Clinical characteristics | |
| Age, years ± SD | 57.3 ± 13.5 |
| Male, n (%) | 10 (76.9) |
| Diabetes, n (%) | 1 (7.7) |
| Hypertension, n (%) | 8 (61.5) |
| Current smoking, n (%) | 4 (30.8) |
| Hypercholesterolemia, n (%) | 8 (61.5) |
| BMI, kg/m 2 ± SD | 28.4 ± 2.1 |
| Family history of CAD, n (%) | 4 (30.8) |
| Chronic renal failure (clearance < 60 mL/min), n (%) | 1 (7.7) |
| History of previous myocardial infarction, n (%) | 4 (30.8) |
| History of PCI, n (%) | 2 (15.4) |
| History of CHF, n (%) | 4 (30.8) |
| History of peripheral vascular disease, n (%) | 2 (15.4) |
| Left ventricular ejection fraction, % ± SD | 56.3 ± 8.7 |
| Laboratory characteristics | |
| Baseline creatinine, mg/dL | 0.90 ± 0.22 |
| Creatinine peak, mg/dL | 0.98 ± 0.32 |
| Baseline hematocrit, (%) | 41.5 ± 5.7 |
| Hematocrit nadir, (%) | 34.4 ± 5.5 |
| Baseline CPK, mg/dL | 1394.2 ± 2623.7 |
| CPK peak, mg/dL | 1972 ± 2388.6 |
| Baseline troponin, ng/dL | 10.0 ± 26.8 |
| Troponin peak, ng/dL | 40.4 ± 37.2 |
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