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Dive into the research topics where Pieter J. Vlaar is active.

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Featured researches published by Pieter J. Vlaar.


The New England Journal of Medicine | 2008

Thrombus aspiration during primary percutaneous coronary intervention.

Tone Svilaas; Pieter J. Vlaar; Iwan C. C. van der Horst; Gilles Diercks; Bart J. G. L. de Smet; Ad F.M. van den Heuvel; Rutger L. Anthonio; Gillian A.J. Jessurun; Eng-Shiong Tan; Albert J. H. Suurmeijer; Felix Zijlstra

BACKGROUND Primary percutaneous coronary intervention (PCI) is effective in opening the infarct-related artery in patients with myocardial infarction with ST-segment elevation. However, the embolization of atherothrombotic debris induces microvascular obstruction and diminishes myocardial reperfusion. METHODS We performed a randomized trial assessing whether manual aspiration was superior to conventional treatment during primary PCI. A total of 1071 patients were randomly assigned to the thrombus-aspiration group or the conventional-PCI group before undergoing coronary angiography. Aspiration was considered to be successful if there was histopathological evidence of atherothrombotic material. We assessed angiographic and electrocardiographic signs of myocardial reperfusion, as well as clinical outcome. The primary end point was a myocardial blush grade of 0 or 1 (defined as absent or minimal myocardial reperfusion, respectively). RESULTS A myocardial blush grade of 0 or 1 occurred in 17.1% of the patients in the thrombus-aspiration group and in 26.3% of those in the conventional-PCI group (P<0.001). Complete resolution of ST-segment elevation occurred in 56.6% and 44.2% of patients, respectively (P<0.001). The benefit did not show heterogeneity among the baseline levels of the prespecified covariates. At 30 days, the rate of death in patients with a myocardial blush grade of 0 or 1, 2, and 3 was 5.2%, 2.9%, and 1.0%, respectively (P=0.003), and the rate of adverse events was 14.1%, 8.8%, and 4.2%, respectively (P<0.001). Histopathological examination confirmed successful aspiration in 72.9% of patients. CONCLUSIONS Thrombus aspiration is applicable in a large majority of patients with myocardial infarction with ST-segment elevation, and it results in better reperfusion and clinical outcomes than conventional PCI, irrespective of clinical and angiographic characteristics at baseline. (Current Controlled Trials number, ISRCTN16716833.)


Journal of the American College of Cardiology | 2011

Culprit Vessel Only Versus Multivessel and Staged Percutaneous Coronary Intervention for Multivessel Disease in Patients Presenting With ST-Segment Elevation Myocardial Infarction : A Pairwise and Network Meta-Analysis

Pieter J. Vlaar; Karim D. Mahmoud; David R. Holmes; Gert van Valkenhoef; Hans L. Hillege; Iwan C. C. van der Horst; Felix Zijlstra; Bart J. G. L. de Smet

OBJECTIVES The purposes of this study were to investigate whether, in patients with ST-segment elevation myocardial infarction (STEMI) and multivessel disease (MVD), percutaneous coronary intervention (PCI) should be confined to the culprit or also nonculprit vessels and, when performing PCI for nonculprit vessels, whether it should take place during primary PCI or staged procedures. BACKGROUND A significant percentage of STEMI patients have MVD. However, the best PCI strategy for nonculprit vessel lesions is unknown. METHODS Pairwise and network meta-analyses were performed on 3 PCI strategies for MVD in STEMI patients: 1) culprit vessel only PCI strategy (culprit PCI), defined as PCI confined to culprit vessel lesions only; 2) multivessel PCI strategy (MV-PCI), defined as PCI of culprit vessel as well as ≥1 nonculprit vessel lesions; and 3) staged PCI strategy (staged PCI), defined as PCI confined to culprit vessel, after which ≥1 nonculprit vessel lesions are treated during staged procedures. Prospective and retrospective studies were included when research subjects were patients with STEMI and MVD undergoing PCI. The primary endpoint was short-term mortality. RESULTS Four prospective and 14 retrospective studies involving 40,280 patients were included. Pairwise meta-analyses demonstrated that staged PCI was associated with lower short- and long-term mortality as compared with culprit PCI and MV-PCI and that MV-PCI was associated with highest mortality rates at both short- and long-term follow-up. In network analyses, staged PCI was also consistently associated with lower mortality. CONCLUSIONS This meta-analysis supports current guidelines discouraging performance of multivessel primary PCI for STEMI. When significant nonculprit vessel lesions are suitable for PCI, they should only be treated during staged procedures.


Journal of the American College of Cardiology | 2011

Clinical ResearchInterventional CardiologyCulprit Vessel Only Versus Multivessel and Staged Percutaneous Coronary Intervention for Multivessel Disease in Patients Presenting With ST-Segment Elevation Myocardial Infarction: A Pairwise and Network Meta-Analysis

Pieter J. Vlaar; Karim D. Mahmoud; David R. Holmes; Gert van Valkenhoef; Hans L. Hillege; Iwan C. C. van der Horst; Felix Zijlstra; Bart J. G. L. de Smet

OBJECTIVES The purposes of this study were to investigate whether, in patients with ST-segment elevation myocardial infarction (STEMI) and multivessel disease (MVD), percutaneous coronary intervention (PCI) should be confined to the culprit or also nonculprit vessels and, when performing PCI for nonculprit vessels, whether it should take place during primary PCI or staged procedures. BACKGROUND A significant percentage of STEMI patients have MVD. However, the best PCI strategy for nonculprit vessel lesions is unknown. METHODS Pairwise and network meta-analyses were performed on 3 PCI strategies for MVD in STEMI patients: 1) culprit vessel only PCI strategy (culprit PCI), defined as PCI confined to culprit vessel lesions only; 2) multivessel PCI strategy (MV-PCI), defined as PCI of culprit vessel as well as ≥1 nonculprit vessel lesions; and 3) staged PCI strategy (staged PCI), defined as PCI confined to culprit vessel, after which ≥1 nonculprit vessel lesions are treated during staged procedures. Prospective and retrospective studies were included when research subjects were patients with STEMI and MVD undergoing PCI. The primary endpoint was short-term mortality. RESULTS Four prospective and 14 retrospective studies involving 40,280 patients were included. Pairwise meta-analyses demonstrated that staged PCI was associated with lower short- and long-term mortality as compared with culprit PCI and MV-PCI and that MV-PCI was associated with highest mortality rates at both short- and long-term follow-up. In network analyses, staged PCI was also consistently associated with lower mortality. CONCLUSIONS This meta-analysis supports current guidelines discouraging performance of multivessel primary PCI for STEMI. When significant nonculprit vessel lesions are suitable for PCI, they should only be treated during staged procedures.


European Heart Journal | 2008

Incidence and clinical consequences of distal embolization on the coronary angiogram after percutaneous coronary intervention for ST-elevation myocardial infarction

Marieke L. Fokkema; Pieter J. Vlaar; Tone Svilaas; Mathijs Vogelzang; Diny Amo; Gilles Diercks; Albert J. H. Suurmeijer; Felix Zijlstra

AIMS We investigated the incidence and sequelae of angiographically visible distal embolization (AVDE) after primary percutaneous coronary intervention (PCI) in ST-elevation myocardial infarction patients treated with aspirin, heparin, clopidogrel, and glycoprotein-IIb/IIIa inhibitors. METHODS AND RESULTS As part of TAPAS, AVDE was a predefined secondary endpoint. We compared angiographic and clinical characteristics, and outcomes of patients with and without AVDE after PCI. AVDE was present on 6.3% of 883 post-procedural angiograms. Angiographically visible distal embolization was associated with significantly worse outcomes, as expressed by lower myocardial blush grade, impaired ST-segment resolution, and higher enzyme levels (all P </= 0.001). Mortality 1 year after PCI was 4 of 56 (7.1%) in patients with AVDE and 43 of 827 (5.2%) in patients without AVDE (P= ns), re-infarction occurred in 5 of 56 (8.9%), and 25 of 827 (3.0%) patients (P = 0.018). The thrombus aspirate more often contained erythrocytes in patients with AVDE than in patients without AVDE (50.0% vs. 15.7%, P < 0.001), and the size of the aspirated thrombus was larger in patients with AVDE (P = 0.002). CONCLUSION In patients with triple anti-platelet therapy, the incidence of AVDE after PCI is low, compared with previous reports. Nevertheless, AVDE is associated with impaired myocardial reperfusion and poor outcome. Thrombus composition and size are related to AVDE after PCI.


Circulation | 2008

Impact of Pretreatment With Clopidogrel on Initial Patency and Outcome in Patients Treated With Primary Percutaneous Coronary Intervention for ST-Segment Elevation Myocardial Infarction. A Systematic Review

Pieter J. Vlaar; Tone Svilaas; Kevin Damman; Bart J. G. L. de Smet; Jan G.P. Tijssen; Hans L. Hillege; Felix Zijlstra

Background— The main goal of the initial treatment of ST-segment elevation myocardial infarction is prompt reperfusion of the infarct-related artery. The value of pretreatment with clopidogrel before primary percutaneous coronary intervention is currently unclear. Methods and Results— Studies were retrieved through MEDLINE and Cochrane Controlled Trials Register searches over the past 20 years. Two authors independently performed the study selection and data extraction. Randomized controlled studies were included when the research subjects were unselected patients with ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention. Pilot trials, studies that enrolled patients undergoing rescue percutaneous coronary intervention, and studies with angiographic assessment not performed by a core laboratory or 2 blinded investigators were excluded. Thirty-eight treatment groups, including 8429 patients, were included. Initial patency was higher in treatment groups in which patients received pretreatment with clopidogrel (34.3%; 95% confidence interval, 32.9 to 35.8) compared with those in which patients did not receive clopidogrel before initial coronary angiography (25.8%; 95% confidence interval, 24.5 to 27.1). In multivariate-weighted logistic regression analysis, pretreatment with clopidogrel was an independent predictor of early reperfusion (odds ratio, 1.51; 95% confidence interval, 1.31 to 1.74; P<0.0001) and improved clinical outcome. Conclusions— Initial patency and clinical outcome were improved in treatment groups that received pretreatment with clopidogrel. These results in patients undergoing primary percutaneous coronary intervention are in line with the experience of pretreatment with clopidogrel in elective patients, non–ST-elevation coronary syndromes, and thrombolytic studies.


Circulation-cardiovascular Interventions | 2009

Effect of High-Dose Intracoronary Adenosine Administration During Primary Percutaneous Coronary Intervention in Acute Myocardial Infarction A Randomized Controlled Trial

Marieke L. Fokkema; Pieter J. Vlaar; Mathijs Vogelzang; Youlan L. Gu; Marthe A. Kampinga; Bart J. G. L. de Smet; Gillian A.J. Jessurun; Rutger L. Anthonio; Ad F.M. van den Heuvel; Eng-Shiong Tan; Felix Zijlstra

BACKGROUND Coronary microvascular dysfunction is frequently seen in patients with ST-elevation myocardial infarction after primary percutaneous coronary intervention. Previous studies have suggested that the administration of intravenous adenosine resulted in an improvement of myocardial perfusion and a reduction in infarct size. Intracoronary adenosine (bolus of 30 to 60 microg) is a guideline-recommended therapy to improve myocardial reperfusion. The effect of intracoronary adenosine during primary percutaneous coronary intervention has not been investigated in a large randomized trial. METHODS AND RESULTS Patients presenting with acute ST-elevation myocardial infarction were randomized to 2 bolus injections of intracoronary adenosine (2 x 120 microg in 20 mL NaCl) or placebo (2 x 20 mL NaCl). The first bolus injection was given after thrombus aspiration and the second after stenting of the infarct-related artery. The primary end point was the incidence of residual ST-segment deviation <0.2 mV, 30 to 60 minutes after percutaneous coronary intervention. Secondary end points were ST-segment elevation resolution, myocardial blush grade, Thrombolysis in Myocardial Infarction flow on the angiogram after percutaneous coronary intervention, enzymatic infarct size, and clinical outcome at 30 days. A total of 448 patients were randomized to intracoronary adenosine (N=226) or placebo (N=222). The incidence of residual ST-segment deviation <0.2 mV did not differ between patients randomized to adenosine or placebo (46.2% versus 52.2%, P=NS). In addition, there were no significant differences in secondary outcome measures. CONCLUSIONS In this randomized placebo controlled trial enrolling 448 patients with ST-elevation myocardial infarction, administration of intracoronary adenosine after thrombus aspiration and after stenting of the infarct-related artery did not result in improved myocardial perfusion.


Circulation-cardiovascular Interventions | 2009

Effect of High-Dose Intracoronary Adenosine Administration During Primary Percutaneous Coronary Intervention in Acute Myocardial InfarctionCLINICAL PERSPECTIVE

Marieke L. Fokkema; Pieter J. Vlaar; Mathijs Vogelzang; Youlan L. Gu; Marthe A. Kampinga; Bart J. G. L. de Smet; Gillian A.J. Jessurun; Rutger L. Anthonio; Ad F.M. van den Heuvel; Eng-Shiong Tan; Felix Zijlstra

BACKGROUND Coronary microvascular dysfunction is frequently seen in patients with ST-elevation myocardial infarction after primary percutaneous coronary intervention. Previous studies have suggested that the administration of intravenous adenosine resulted in an improvement of myocardial perfusion and a reduction in infarct size. Intracoronary adenosine (bolus of 30 to 60 microg) is a guideline-recommended therapy to improve myocardial reperfusion. The effect of intracoronary adenosine during primary percutaneous coronary intervention has not been investigated in a large randomized trial. METHODS AND RESULTS Patients presenting with acute ST-elevation myocardial infarction were randomized to 2 bolus injections of intracoronary adenosine (2 x 120 microg in 20 mL NaCl) or placebo (2 x 20 mL NaCl). The first bolus injection was given after thrombus aspiration and the second after stenting of the infarct-related artery. The primary end point was the incidence of residual ST-segment deviation <0.2 mV, 30 to 60 minutes after percutaneous coronary intervention. Secondary end points were ST-segment elevation resolution, myocardial blush grade, Thrombolysis in Myocardial Infarction flow on the angiogram after percutaneous coronary intervention, enzymatic infarct size, and clinical outcome at 30 days. A total of 448 patients were randomized to intracoronary adenosine (N=226) or placebo (N=222). The incidence of residual ST-segment deviation <0.2 mV did not differ between patients randomized to adenosine or placebo (46.2% versus 52.2%, P=NS). In addition, there were no significant differences in secondary outcome measures. CONCLUSIONS In this randomized placebo controlled trial enrolling 448 patients with ST-elevation myocardial infarction, administration of intracoronary adenosine after thrombus aspiration and after stenting of the infarct-related artery did not result in improved myocardial perfusion.


American Journal of Cardiology | 2011

Usefulness of Thrombus Aspiration for the Treatment of Coronary Stent Thrombosis

Karim D. Mahmoud; Pieter J. Vlaar; Ad F.M. van den Heuvel; Hans L. Hillege; Felix Zijlstra; Bart J. G. L. de Smet

Current treatment for coronary stent thrombosis (ST) often lacks satisfactory results and clinical outcome is poor. We investigated the impact of manual thrombus aspiration during percutaneous coronary intervention (PCI) on myocardial reperfusion and clinical outcome in patients with angiographically proved ST. We interrogated our PCI registry for patients with a first stent placement from January 2002 through May 2010 who had undergone an emergency repeated PCI procedure and systematically reviewed coronary angiograms and hospital records for evidence of ST. We identified 113 patients with ST. Thrombus aspiration was used in 51 patients and 62 patients received conventional PCI. Histopathologic analysis of thrombus aspirates was performed in 6 patients. Use of thrombus aspiration predicted postprocedure Thrombolysis In Myocardial Infarction grade 3 flow (odds ratio 3.16, 95% confidence interval 1.22 to 8.17, p = 0.018) and myocardial blush grade 2/3 (odds ratio 3.20, 95% confidence interval 1.20 to 8.55, p = 0.020) after multivariable adjustment with bootstrap model selection. Distal embolization was lower in the thrombus aspiration group compared to the conventional PCI group (14% vs 37%, p = 0.017). In most patients, aspirated thrombus was large and contained platelet and erythrocyte components at histopathologic analysis. Mortality in the thrombus aspiration group and conventional PCI group was 9.8% versus 16% at 30 days (p = 0.351) and 12% versus 21% at 1 year (p = 0.220), respectively. In conclusion, use of manual thrombus aspiration in patients with ST was associated with greater epicardial and microvascular myocardial reperfusion. In addition, mortality was lower in patients treated with thrombus aspiration, although not statistically significant.


Netherlands Heart Journal | 2009

Thrombus Aspiration during Percutaneous coronary intervention in Acute non-ST-elevation myocardial infarction Study (TAPAS II)-Study design.

Marthe Kampinga; Pieter J. Vlaar; Marieke L. Fokkema; Youlan Gu; Felix Zijlstra

Background and Objective. The Thrombus Aspiration during Percutaneous coronary intervention in Acute myocardial infarction Study (TAPAS) has shown that thrombus aspiration improves myocardial perfusion and clinical outcome compared with conventional primary percutaneous coronary intervention (PCI) in patients with ST-segment-elevation myocardial infarction. Impaired myocardial perfusion due to spontaneous or angioplasty-induced embolisation of atherothrombotic material also occurs in patients with non-ST-elevation myocardial infarction (NSTEMI). The aim of this study is to determine whether thrombus aspiration before stent implantation will result in improved myocardial perfusion in patients with NSTEMI compared with conventional PCI.Study design. The study is a single-centre, prospective, randomised trial with blinded evaluation of endpoints. The planned inclusion is 540 patients with acute NSTEMI who are candidates for urgent PCI. Patients are randomised to treatment with manual thrombus aspiration or to conventional PCI. The primary endpoint is the incidence of myocardial blush grade 3 after PCI. Secondary endpoints are coronary angiographic, histopathological, enzymatic, electrocardiographic and clinical outcomes including major adverse events at 30 days and one year.Implications. If thrombus aspiration leads to significant improvement of myocardial perfusion in patients with acute NSTEMI it may become part of the standard interventional approach. (Neth Heart J 2009;17:409–13.)


Eurointervention | 2011

Operator dependence of outcome after primary percutaneous coronary intervention

Pieter J. Vlaar; Bart J. G. L. de Smet; Ad F.M. van den Heuvel; Rutger L. Anthonio; Gillian A.J. Jessurun; Eng-Shiong Tan; Hans L. Hillege; Felix Zijlstra

AIMS Primary percutaneous coronary intervention (PCI) is a widely practised therapeutic procedure to treat ST-elevation myocardial infarction (STEMI). However, a significant proportion of patients undergoing primary PCI suffers from adverse events, such as incomplete myocardial reperfusion. It is currently unknown to which degree these adverse events are operator related. METHODS AND RESULTS We investigated inter-operator variation using objective safety and efficacy endpoints during primary PCI for STEMI. All PCIs were performed by six experienced interventional cardiologists as part of a randomised single centre trial. The primary endpoint of this study was optimal myocardial reperfusion (myocardial blush grade 3 [MBG]). All 1,071 patients enrolled in the Thrombus Aspiration during Percutaneous coronary intervention in Acute myocardial infarction Study (TAPAS) were included in this analysis. In the six operator groups, the rate of the primary endpoint MBG 3 ranged between 29.2% and 55.5%. The variable for operators remained significantly associated with MBG 3 after adjustment for baseline and procedural differences. There were no statistical differences observed with regard to safety endpoints. CONCLUSIONS This study illustrates the observation that even in a controlled setting significant inter-operator variation may exist in the efficacy of primary PCI. This study supports the routine collection of high-quality datasets to evaluate and improve individual operator competence and skills.

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Felix Zijlstra

Erasmus University Rotterdam

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Bart J. G. L. de Smet

University Medical Center Groningen

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Marieke L. Fokkema

University Medical Center Groningen

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Tone Svilaas

University Medical Center Groningen

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Ad F.M. van den Heuvel

University Medical Center Groningen

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Mathijs Vogelzang

University Medical Center Groningen

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Eng-Shiong Tan

University Medical Center Groningen

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Rutger L. Anthonio

University Medical Center Groningen

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Hans L. Hillege

University Medical Center Groningen

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