Abstract
Background
Many studies have reported that low final thrombolysis in myocardial infarction (TIMI) flow and/or myocardial blush grade (MBG) are independent predictors of mortality in patients with ST-elevation myocardial infarction (STEMI). In addition, distal coronary embolization is a major pitfall of conventional percutaneous coronary intervention (PCI) in such a context.
Aim
This study aimed to assess the impact of thrombus aspiration (TA) use before primary PCI on final myocardial reperfusion in patients presenting with STEMI.
Methods
From January to December 2006, 100 patients presenting with STEMI in our catheterization laboratory were considered for the present study. During this time period, 50 patients underwent TA before primary PCI for treatment of STEMI and were then matched 1:1 to 50 controls who underwent conventional primary PCI for treatment of STEMI without TA. Patients of the control group were chosen after matching on age±3 years, sex, history of diabetes, and distribution of the infarct related coronary artery during the same period.
Results
Baseline clinical characteristics, initial TIMI flow and initial MBG of both groups were similar. There was a trend for a better final TIMI flow in the group with TA and the final MBG was significantly improved in the group with TA compared to the group without TA: final MBG of two or three in 70% versus 30% of the cases ( P =.001). In addition, direct stenting was significantly more often used in the TA group (92% versus 64%, P =.001). There were four patients with evident distal embolizations in the group without TA and none in the group with TA.
Conclusion
TA use before primary PCI for STEMI treatment resulted in improved final myocardial reperfusion. Of importance, TA use may have led to a better choice of the stent size and more frequent direct stenting. This benefit may directly improve patient outcomes.
1
Introduction
Percutaneous coronary intervention (PCI) is today the gold standard treatment for ST elevation myocardial infarction (STEMI) . Indeed, early effective myocardial reperfusion must be the principal objective in the management of such patients presenting with STEMI. Many studies have reported that low final thrombolysis in myocardial infarction (TIMI) flow and/or myocardial blush grade (MBG) that are perfect markers of myocardial reperfusion, are independent predictors of mortality in patients with myocardial infarction (MI) .
In addition, distal coronary embolization is a major pitfall of the conventional PCI technique and results in impaired myocardial reperfusion and increased infarct zones. This phenomenon results, in the end, in low ventricular function recovery and poor prognosis . Furthermore, large thrombus burden is rather the rule than the exception in the context of STEMI. Thrombus aspiration (TA) may reduce the risk of distal coronary embolization and may subsequently improve the prognosis of patients presenting with STEMI. The aim of the present study was to assess the impact of TA use before primary PCI on final myocardial reperfusion in the treatment of patients presenting with STEMI.
2
Methods
2.1
Population
Between January 2006 and December 2006, 100 patients presenting with STEMI in our catheterization laboratory were considered for the present study. During this period of time, 50 patients underwent TA before primary PCI for treatment of STEMI and were then matched 1:1 to 50 controls who underwent conventional primary PCI for treatment of STEMI without TA. Patients of the control group were chosen after matching on age±3 years, sex, history of diabetes and distribution of the infarct related coronary artery during the same period and fulfilling the inclusion criteria. Patients with pre-hospital thrombolysis, cardiogenic shock, stent thrombosis and culprit lesion localised on coronary artery bypass graft were excluded.
Baseline clinical and angiographic characteristics including cardiovascular risk factors, left ventricular ejection fraction (LVEF) assessed by trans-thoracic echocardiography immediately after PCI, infarct related coronary artery and pre and post-PCI MBG and TIMI flow were systematically indexed.
2.2
Percutaneous coronary intervention procedures
The device used for TA was the Export Medtronic 6F catheter. When used, TA was performed before PCI in all cases (at least two passes). PCI were performed in agreement with standard technique usually used in our catheterization laboratory . All patients were pre-treated with an intravenous bolus of 500 mg of aspirin and an intravenous bolus of heparin (50 IU/kg) or enoxaparin (0.05 mg/kg). They also received a 600mg loading dose of clopidogrel. The use of GpIIb-IIIa inhibitors was at the discretion of the physicians. Post-procedural treatment consisted of an association of unfractionated heparin (dose regimen 12 IU/kg per hour) or enoxaparin (dose regimen 0.1 mg/kg twice a day) in all patients for at least 72 h and dual antiplatelet therapy with aspirin 75 mg and clopidogrel 75 mg once daily.
2.3
Film review
All coronary angiogram were reviewed by two different cardiologists (AS and RB). The culprit lesion responsible for STEMI, initial MBG and TIMI flow, MBG and TIMI flow just after TA and final MBG and TIMI flow were analyzed. Evidence of complication related to TA use including distal embolization was systematically indexed.
2.4
Definitions
Final procedural success was defined as normal TIMI flow of 3 with a residual stenosis <30%. ST-segment regression was defined as a decrease in the ST-segment elevation more than 50% on the electrocardiogram performed after PCI compared to the one performed before PCI. In-hospital death was defined as all cause of death. In patients where recurrent MI was suspected from clinical signs or symptoms following the initial infarction, an immediate measurement of troponin and a second sample 6 h later were obtained. Inhospital recurrent MI was diagnosed if there was a ≥20% increase of the value in the second sample. Inhospital stent thrombosis was defined as any definite stent thrombosis according to the academic research consortium definition. Inhospital major bleeding was defined by the occurrence of a fatal haemorrhage and/or an intra cerebral haemorrhage and/or a need of transfusions and/or a decrease in the haemoglobin concentration of 5 g/dl or more or a 15% or greater decrease in hematocrit.
2.5
Statistical analysis
Continuous variables were expressed as mean±S.D., except for the delays that were expressed as median and interquartiles (25th–75th). Categorical variables were expressed as absolute number and percentages. Baseline characteristics between the two groups were compared by using the chi-square test or the Fisher’s Exact test for categorical variables and the Student’s unpaired t test for continuous variables as appropriate. Differences in MBG, TIMI flow and patient outcomes between the two groups were compared using the chi-square test. All statistical analyses were performed with the SPSS 13.0 for Windows software (Chicago, IL, USA). Statistical significance was assumed at P <.05.
2
Methods
2.1
Population
Between January 2006 and December 2006, 100 patients presenting with STEMI in our catheterization laboratory were considered for the present study. During this period of time, 50 patients underwent TA before primary PCI for treatment of STEMI and were then matched 1:1 to 50 controls who underwent conventional primary PCI for treatment of STEMI without TA. Patients of the control group were chosen after matching on age±3 years, sex, history of diabetes and distribution of the infarct related coronary artery during the same period and fulfilling the inclusion criteria. Patients with pre-hospital thrombolysis, cardiogenic shock, stent thrombosis and culprit lesion localised on coronary artery bypass graft were excluded.
Baseline clinical and angiographic characteristics including cardiovascular risk factors, left ventricular ejection fraction (LVEF) assessed by trans-thoracic echocardiography immediately after PCI, infarct related coronary artery and pre and post-PCI MBG and TIMI flow were systematically indexed.
2.2
Percutaneous coronary intervention procedures
The device used for TA was the Export Medtronic 6F catheter. When used, TA was performed before PCI in all cases (at least two passes). PCI were performed in agreement with standard technique usually used in our catheterization laboratory . All patients were pre-treated with an intravenous bolus of 500 mg of aspirin and an intravenous bolus of heparin (50 IU/kg) or enoxaparin (0.05 mg/kg). They also received a 600mg loading dose of clopidogrel. The use of GpIIb-IIIa inhibitors was at the discretion of the physicians. Post-procedural treatment consisted of an association of unfractionated heparin (dose regimen 12 IU/kg per hour) or enoxaparin (dose regimen 0.1 mg/kg twice a day) in all patients for at least 72 h and dual antiplatelet therapy with aspirin 75 mg and clopidogrel 75 mg once daily.
2.3
Film review
All coronary angiogram were reviewed by two different cardiologists (AS and RB). The culprit lesion responsible for STEMI, initial MBG and TIMI flow, MBG and TIMI flow just after TA and final MBG and TIMI flow were analyzed. Evidence of complication related to TA use including distal embolization was systematically indexed.
2.4
Definitions
Final procedural success was defined as normal TIMI flow of 3 with a residual stenosis <30%. ST-segment regression was defined as a decrease in the ST-segment elevation more than 50% on the electrocardiogram performed after PCI compared to the one performed before PCI. In-hospital death was defined as all cause of death. In patients where recurrent MI was suspected from clinical signs or symptoms following the initial infarction, an immediate measurement of troponin and a second sample 6 h later were obtained. Inhospital recurrent MI was diagnosed if there was a ≥20% increase of the value in the second sample. Inhospital stent thrombosis was defined as any definite stent thrombosis according to the academic research consortium definition. Inhospital major bleeding was defined by the occurrence of a fatal haemorrhage and/or an intra cerebral haemorrhage and/or a need of transfusions and/or a decrease in the haemoglobin concentration of 5 g/dl or more or a 15% or greater decrease in hematocrit.
2.5
Statistical analysis
Continuous variables were expressed as mean±S.D., except for the delays that were expressed as median and interquartiles (25th–75th). Categorical variables were expressed as absolute number and percentages. Baseline characteristics between the two groups were compared by using the chi-square test or the Fisher’s Exact test for categorical variables and the Student’s unpaired t test for continuous variables as appropriate. Differences in MBG, TIMI flow and patient outcomes between the two groups were compared using the chi-square test. All statistical analyses were performed with the SPSS 13.0 for Windows software (Chicago, IL, USA). Statistical significance was assumed at P <.05.
3
Results
3.1
Population
Patients of the control group (group without TA) were chosen after matching on age±3 years, sex, history of diabetes, and distribution of the infarct-related coronary artery during the same period of time.
Baseline clinical characteristics of both groups are summarized in Table 1 . The mean age was 56.2±8.1 years in the group with TA and 58.5±7.8 years in the group without TA ( P =ns). Altogether, 22% of the patients had history of diabetes in both groups. The rate of patients with initial LVEF <45% was similar in both groups: 56% in the group with TA versus 50% in the group without TA, P =ns. The elapsed period between symptom onset and PCI was <6 hours in 72% of the cases in the group with TA versus 70% in the group without TA ( P =ns), and the total ischaemic time was similar between both groups.
| Group TA ( n =50) | Group without TA ( n =50) | P | |
|---|---|---|---|
| Risk factors | |||
| Age, years | 56.2±8 | 58.5±8 | .464 |
| Sex male, n (%) | 10 (20) | 10 (20) | 1 |
| Diabetes mellitus, n (%) | 11 (22) | 11 (22) | 1 |
| Smoking history, n (%) | 43 (86) | 37 (74) | .211 |
| Hypertension, n (%) | 18 (36) | 27 (54) | .104 |
| Hypercholesterolemia, n (%) | 19 (38) | 19 (38) | 1 |
| Body mass index, kg/m 2 | 25.5±1.2 | 26.9±0.9 | .687 |
| Family history of CAD, n (%) | 12 (24) | 14 (28) | .820 |
| Renal failure (clearance <60 ml/kg), n (%) | 6 (12) | 5 (10) | .774 |
| LVEF <45%, n (%) | 28 (56) | 25 (50) | .689 |
| Total ischaemic time, min | 192±102 | 178±114 | .519 |
| Symptom onset <6 hours, n (%) | 36 (72) | 35 (70) | .994 |
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