Clopidogrel use in children

Neonatal Myocardial Infarction: A Proposed Algorithm for Coronary Arterial Thrombus Management

BACKGROUND

Neonatal myocardial infarction is rare and is associated with a high mortality of 40% to 50%. We report our experience with neonatal myocardial infarction, including presentation, management, outcomes, and our current patient management algorithm.

METHODS

We reviewed all infants admitted with a diagnosis of coronary artery thrombosis, coronary ischemia, or myocardial infarction between January 2015 and May 2021.

RESULTS

We identified 21 patients (median age, 1 [interquartile range (IQR), 0.25-9.00] day; weight, 3.2 [IQR, 2.9-3.7] kg). Presentation included respiratory distress (16), shock (3), and murmur (2). Regional wall motion abnormalities by echocardiogram were a key criterion for diagnosis and were present in all 21 with varying degrees of depressed left ventricular function (severe [8], moderate [6], mild [2], and low normal [5]). Ejection fraction ranged from 20% to 54% (median, 43% [IQR, 34%-51%]). Mitral regurgitation was present in 19 (90%), left atrial dilation in 15 (71%), and pulmonary hypertension in 18 (86%). ECG was abnormal in 19 (90%). Median troponin I was 0.18 (IQR, 0.12-0.56) ng/mL. Median BNP (B-type natriuretic peptide) was 2100 (IQR, 924-2325) pg/mL. Seventeen had documented coronary thrombosis by cardiac catheterization. Seventeen (81%) were treated with intracoronary tPA (tissue-type plasminogen activator) followed by systemic heparin, AT (antithrombin), and intravenous nitroglycerin, and 4 (19%) were treated with systemic heparin, AT, and intravenous nitroglycerin alone. Nineteen of 21 recovered. One died (also had infradiaphragmatic total anomalous pulmonary venous return). One patient required a ventricular assist device and later underwent heart transplant; this patient was diagnosed late at 5 weeks of age and did not respond to tPA. Nineteen of 21 (90%) regained normal left ventricular function (ejection fraction, 60%-74%; mean, 65% [IQR, 61%-67%]) at latest follow-up (median, 6.8 [IQR, 3.58-14.72] months). Two of 21 (10%) had residual trivial mitral regurgitation. After analysis of these results, we present our current algorithm, which developed and matured over time, to manage neonatal myocardial infarction.

CONCLUSIONS

We experienced a lower mortality rate for infants with neonatal infarction than that reported in the literature. We propose a post hoc algorithm that may lead to improvement in patient outcomes following coronary artery thrombus.

Covered Stent Treatment of an Extracranial Internal Carotid Artery Pseudoaneurysm in a Three Year Old Child with 12 Years of Follow Up: A Case Report

Introduction

Extracranial internal carotid artery (ICA) pseudoaneurysms in children, although uncommon, are life threatening. Covered stents are a good alternative treatment, as they avoid the risk of open surgery and preserve the ICA. Until recently, long term outcomes were unknown.

Report

A three year old boy was hospitalised with an enlarged swelling on the left side of his neck and severe respiratory distress. He had been treated a month prior for a left deep cervical abscess, with bacteriological culture positive for Staphylococcus aureus. Computed tomography angiography (CTA) revealed a large pseudoaneurysm originating from the left ICA, approximately 2 cm above the bifurcation. A balloon expanded covered stent (Jostent Graftmaster; Abbott Vascular, Redwood City, CA, USA) was deployed via a left femoral approach, after selective angiography, to seal the carotid rupture without incident. Control angiography revealed immediate exclusion of the pseudoaneurysm and patent ICA. The bacteriological culture of the residual haematoma was negative. The child was discharged with full recovery and without neurological sequelae, under platelet anti-aggregation. He has been followed up and has remained asymptomatic for 12 years, with CTA confirmed ICA patency, without deformation or evidence of significant restenosis.

Discussion

This is the first report of the long term outcome of a covered stent in a child treated at three years of age, with a 12 year follow up. The good performance of the covered stent in this case reinforces its adoption as a first line option in the treatment of extracranial ICA pseudoaneurysms in children.

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Endovascular treatment is the first choice for carotid pseudoaneurysms in children.

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Covered stents can be an effective and safe option.

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Uneventful long term outcomes.

Vasodilator-Stimulated Phosphoprotein to Monitor Clopidogrel Posology in a 7-Year-Old Child Stented for a Post-Traumatic Intracranial Internal Carotid Artery Aneurysm

Many pediatric medical protocols or drug posology like biantiplatelet therapy are extrapolated from adult care. This association could be indicated in specific pediatric situations such as ischemic stroke, some cardiac conditions, or to control post stent thrombosis/stenosis. If acetylsalicylic acid is commonly used, few data are available about optimal management of clopidogrel in children. We describe the case of a 7-year-old girl admitted to pediatric intensive care unit who undergoes a transitory hemiparesis after a bicycle accident. Brain magnetic resonance imaging reveals a subarachnoid hemorrhage and a wide right Sylvian arachnoid cyst. Hemorrhage predominated at the level of the optochiasmatic cistern, close to the right internal carotid artery. At the same level, angiography revealed a small aneurysm of the internal carotid artery supposed to be a postfalse traumatic aneurysm. The deployment treated this aneurysm of a flow diverter. The treatment was performed under continuous systemic heparin therapy associated with intravenous acetylsalicylic acid, and Clopidogrel was administered immediately after the procedure. An oral bi antiplatelet treatment was initiated the day 2 with acetylsalicylic acid and clopidogrel (1 mg/kg/day). To monitor clopidogrel posology, a vasodilator-stimulated phosphoprotein [VASP]) was performed. The final VASP assay result was 20% for a clopidogrel posology at 0.5 mg/kg/day. Blood pressure and neurological examination were normal during all the hospitalization. VASP assay can be used in children to define the optimal posology of clopidogrel. Further studies are required to determine an optimal initial posology.

Management of idiopathic intracranial hypertension in children utilizing venous sinus stenting

BACKGROUND

Venous sinus stenting (VSS) is an accepted and minimally invasive treatment for adult idiopathic intracranial hypertension (IIH) associated with lateral sinus stenosis (LSS). The efficacy and safety of venous sinus stenting (VSS) in children with IIH has not been established.

METHODS

This is a retrospective analysis of IIH patients 18 years of age or younger with LSS treated with VSS at our institution. Included patients have fulminant disease course or are refractory or intolerant to medical management.

RESULTS

Eight patients were identified; 4 males and 4 females. Mean age is 13.4 years (range 4-18). All patients had severe headaches, 5 had blurred vision, 3 had diplopia and 3 had pulsatile tinnitus. Papilledema was present in 4 patients. Three patients had prior surgical procedures. Four patients were intolerant to medical management, 3 were refractory and 1 had fulminant course. Cerebral venography demonstrated severe stenosis of the dominant sinus in 6 patients and of bilateral co-dominant sinuses in 2 patients. Six patients had intrinsic stenosis and 2 had extrinsic stenosis. Venous sinus stenting (VSS) resulted in improvement of symptoms, papilledema and normalization of CSF opening pressure in 7 patients. No immediate complications were observed. Mean follow-up period is 21 months (range 6-42). Two patients required re-stenting; one responded well and the other had persistent symptoms and underwent subsequent surgical procedures of CSF diversion, suboccipital decompression and duraplasty which were also ineffective.

CONCLUSION

VSS may provide a viable option for pediatric IIH patients who are intolerant to medication, have failed conservative management or prior surgical interventions, or present with fulminant disease.

Pipeline-assisted coil embolization of a large middle cerebral artery pseudoaneurysm in a 9-month-old infant: experience from the youngest flow diversion case

Intracranial aneurysms in the pediatric population are rare entities. The authors recently treated a 9-month-old infant with a 19-mm recurrent, previously ruptured, and coil-embolized left middle cerebral artery (MCA) pseudoaneurysm, which was treated definitively with single-stage Pipeline-assisted coil embolization. The patient was 5 months old when she underwent resection of a left temporal Grade 1 desmoplastic infantile ganglioglioma at an outside institution, which was complicated by left MCA injury with a resultant 9-mm left M1 pseudoaneurysm. Within a month, the patient had two aneurysmal rupture events and underwent emergency craniectomy for decompression and evacuation of subdural hematoma. The pseudoaneurysm initially underwent coil embolization; however, follow-up MR angiography (MRA) revealed aneurysm recanalization with saccular enlargement to 19 mm. The patient underwent successful flow diversion-assisted coil embolization at 9 months of age. At 7 months after the procedure, follow-up MRA showed complete aneurysm occlusion without evidence of in-stent thrombosis or stenosis. Experience with flow diverters in the pediatric population is still in its early phases, with the youngest reported patient being 22 months old. In this paper the authors report the first case of such a technique in an infant, whom they believe to be the youngest patient to undergo cerebral flow diversion treatment.

[What is the optimal dose of clopidogrel in pediatric patients?]

INTRODUCTION

The aim of this study was to collect retrospective data on the prescription of clopidogrel, describe the conditions of its use in the paediatric population of a tertiary referral hospital, and evaluate its use based on the current scientific evidence.

PATIENTS AND METHODS

We conducted a retrospective, observational and descriptive study between March 2010 and March 2017. We included all patients under the age of 18 who were discharged from our hospital for home treatment with clopidogrel within the study period. We collected data on the following: demographic data, diagnosis, indication for clopidogrel, start and end date of treatment, presence or absence of concomitant treatment with acetylsalicylic acid or other antiplatelet or anticoagulant drugs, concomitant treatment with proton pump inhibitors, effectiveness, and adverse effects.

RESULTS

The study included a total of 11 patients (45% male). The mean age was 3.1 years (range, 1 month-8 years). The prescribed dose of clopidogrel was 0.2mg/kg/day in all patients, and 10/11 patients received concomitant treatment with acetylsalicylic acid with the purpose of optimising antiplatelet therapy. None of the children received concomitant treatment with anticoagulants, and only one of them received treatment with a proton pump inhibitor. We did not find evidence of haemorrhagic complications or other adverse effects associated with clopidogrel.

CONCLUSION

Based on our experience, a clopidogrel dose of 0.2mg/kg/day is a safe and effective treatment, regardless of the patient's age. The good tolerance observed in our study could be related to the adjustment of the optimal dose with the aim of achieving platelet aggregation without increasing the risk of adverse effects.

Migraine Symptoms Related to the Percutaneous Closure of An Ostium Secundum Atrial Septal Defect: Report of Four Paediatric Cases and Review of the Literature

Several publications have recently suggested that atrial septal defect may be associated with the physiopathology of headache with migraine-type characteristics. We describe four previously asymptomatic paediatric patients with atrial septal defect who underwent percutaneous Amplatzer septal occluder device implantation and who subsequently developed symptoms compatible with migraine headache. The cases had normal echocardiograms after the intervention and a benign course with headache improvement after several weeks or months. There are paediatric patients with atrial septal defect who may dramatically develop migraine symptoms with or without aura following percutaneous correction of their defect. Large paediatric studies are needed to offer accurate prognoses for children and their families. The possibility of using clopidogrel to treat this type of headache is subject to debate.

Pediatric Cardiac Intensive Care Society 2014 Consensus Statement: Pharmacotherapies in Cardiac Critical Care Anticoagulation and Thrombolysis

OBJECTIVE

Thrombotic complications are increasingly being recognized as a significant cause of morbidity and mortality in pediatric and congenital heart disease. The objective of this article is to review the medications currently available to prevent and treat such complications.

DATA SOURCES

Online searches were conducted using PubMed.

STUDY SELECTION

Studies were selected for inclusion based on their scientific merit and applicability to the pediatric cardiac population.

DATA EXTRACTION

Pertinent information from each selected study or scientific review was extracted for inclusion.

DATA SYNTHESIS

Four classes of medications were identified as potentially beneficial in this patient group: anticoagulants, antiplatelet agents, thrombolytic agents, and novel oral anticoagulants. Data on each class of medication were synthesized into the follow sections: mechanism of action, pharmacokinetics, dosing, monitoring, reversal, considerations for use, and evidence to support.

CONCLUSIONS

Anticoagulants, antiplatelet agents, and thrombolytic agents are routinely used successfully in the pediatric patient with heart disease for the prevention and treatment of a wide range of thrombotic complications. Although the novel oral anticoagulants have been approved for a limited number of indications in adults, studies on the safety and efficacy of these agents in children are pending.

Efficacy and safety of clopidogrel in children with diarrhea associated hemolytic uremic syndrome

INTRODUCTION

Hemolytic uremic syndrome is a thrombotic microangiopathy. Clopidogrel, a recently developed platelet aggregation inhibitor, has not been previously reported as a treatment for this illness. Our study's objective was to explore the efficacy and safety of clopidogrel in children with diarrhea associated hemolytic uremic syndrome.

MATERIALS AND METHODS

We performed a retrospective chart review of all children (≤ 18 years) hospitalized with diarrhea associated hemolytic uremic syndrome. Outcomes in clopidogrel treated children were described. In subgroup analysis, outcomes were compared to those untreated with platelet aggregation inhibitors.

RESULTS

Of 72 children with diarrhea associated hemolytic uremic syndrome, 88% were treated with platelet aggregation inhibitors (clopidogrel 56%, sulfinpyrazone 19%, dipyridamole 13%). The median age of clopidogrel treated children was 5 years; 40% were male. Initial median hemoglobin, platelet count, and serum creatinine were 10.1g/dL, 53 × 10(3)/μL, and 2.3mg/dL respectively. Clopidogrel (median dose 1mg/kg/d) was given for a median of 4 days (range 1-15). Other therapies included erythropoietin (98%), red blood cell transfusions (80%), diuretics (58%), anti-hypertensive agents (45%), and dialysis (33%). The median hospital length of stay was 9 days (range 3-26). Three children had bleeding complications (epistaxis/hematemesis). The risk of chronic kidney disease was 5% and death 2.5%. In subgroup analysis, median duration of dialysis was 11 days in thirteen clopidogrel treated children compared to 21 days in five untreated patients (P=0.04).

CONCLUSIONS

Children with diarrhea associated hemolytic uremic syndrome treated with clopidogrel have outcomes comparable to untreated patients. Bleeding complications may occur.

Pharmacogenomics of cardiovascular drugs and adverse effects in pediatrics

Individual response to medication is highly variable. For many drugs, a substantial proportion of patients show suboptimal response at standard doses, whereas others experience adverse drug reactions (ADRs). Pharmacogenomics aims to identify genetic factors underlying this variability in drug response, providing solutions to improve drug efficacy and safety. We review recent advances in pharmacogenomics of cardiovascular drugs and cardiovascular ADRs, including warfarin, clopidogrel, β-blockers, renin-angiotensin-aldosterone system inhibitors, drug-induced long QT syndrome, and anthracycline-induced cardiotoxicity. We particularly focus on the applicability of pharmacogenomic findings to pediatric patients in whom developmental changes in body size and organ function may affect drug pharmacokinetics and pharmacodynamics. Solid evidence supports the importance of gene variants in CYP2C9 and VKORC1 for warfarin dosing and in CYP2C19 for clopidogrel response in adult patients. For the other cardiovascular drugs or cardiovascular ADRs, further studies are needed to replicate or clarify genetic associations before considering uptake of pharmacogenetic testing in clinical practice. With the exception of warfarin and anthracycline-induced cardiotoxicity, there is lack of pharmacogenomic studies on cardiovascular drug response or ADRs aimed specifically at children or adolescents. The first pediatric warfarin pharmacogenomic study indeed indicates differences from adults, pointing out the importance and need for pediatric-focused pharmacogenomic studies.

Significant increase in clopidogrel use across U.S. children's hospitals

The primary aim of this study was to describe the use of the antiplatelet agent clopidogrel in pediatric tertiary care hospitals and to evaluate how it has changed over time. This retrospective cohort study of pediatric inpatients from 2000 to 2009 used the Pediatric Health Information System database (PHIS) which contains data from 42 U.S. tertiary care children's hospitals. Pharmacy billing codes were used to identify hospital admissions during which clopidogrel was administered. Patient demographics and concurrent use of other anticoagulant and antiplatelet drugs were collected. The International Classification of Diseases, ninth edition (ICD-9) codes were used to categorize admissions by potential indications for antiplatelet drugs and to identify bleeding and thrombotic events. From 2001 to 2009, clopidogrel use increased 15-fold, from 6 to 89.5 per 100,000 admissions. Patients with cardiac disease accounted for the largest proportion (75%), followed by stroke (9.4%) and Kawasaki disease (6.1%). Among those with cardiac disease, hypoplastic left heart syndrome (38%) and pulmonary artery anomalies (37%) were the most common. Aspirin was used concurrently during 52% of the admissions, enoxaparin during 9%, and warfarin during 5%. The use of clopidogrel is increasing rapidly among children with cardiovascular diseases. This population has a high risk of bleeding, thrombosis, and mortality. It therefore is imperative that future studies continue to evaluate the safety and efficacy of clopidogrel for these children.

Kawasaki disease

Kawasaki disease is an acute vasculitis of childhood, complicated by coronary artery aneurysms in up to 25% of affected children. High-dose intravenous immunoglobulin (IVIG) administered in the acute phase of Kawasaki disease leads to a fivefold reduction in the prevalence of coronary aneurysms. When fever persists, a second IVIG infusion should be administered. Rescue therapies for IVIG-resistant Kawasaki disease include pulsed-dose methylprednisolone or other steroid regimens, as well as infliximab, a tumor necrosis factor-alpha antagonist. Aspirin is used initially in an anti-inflammatory dosage, then at a low dosage until approximately 6 weeks after illness onset. Patients with coronary aneurysms require chronic antithrombotic therapy. For small aneurysms, aspirin alone is sufficient. For larger aneurysms, agents added to aspirin include clopidogrel and, for giant aneurysms, warfarin or low molecular weight heparin. Long-term management is tailored to the degree of coronary artery involvement. Evidence-based data to guide indications for transcatheter and surgical intervention are limited.

Stability of an extemporaneously prepared clopidogrel oral suspension

PURPOSE

The stability of an extemporaneously prepared clopidogrel oral suspension was studied. Methods Clopidogrel oral suspension (5 mg/mL) was prepared using clopidogrel bisulfate tablets, Ora-Plus, and Ora-Sweet. Six 2-oz samples were prepared; three were stored at room temperature and three under refrigeration. One milliliter was withdrawn from each sample, diluted to 10 mL with methanol, and exposed to high-frequency sound waves in a water bath to ensure complete dissolution of clopidogrel. A 300-microL sample was then withdrawn, diluted with mobile phase to an expected concentration of 15 microg/mL, and assayed in duplicate using high- performance liquid chromatography immediately after preparation and at 7, 14, 28, and 60 days. The stability of the clopidogrel suspension was determined by calculating the percentage of the initial concentration remaining on each test day. Stability was defined as retention of at least 90% of the initial concentration.

RESULTS

At least 97% of the initial clopidogrel concentration remained throughout the 60-day study period, regardless of storage conditions. There were no detectable changes in color, odor, taste, or pH and no visible microbial growth in any sample. The preparation was palatable, with a slightly gritty consistency and a slightly bitter aftertaste; the bitterness intensified slightly between 28 and 60 days but remained fairly mild.

CONCLUSION

Extemporaneously compounded suspensions of clopidogrel, 5 mg/mL, in a 1:1 mixture of Ora-Plus and Ora-Sweet were stable for at least 60 days when stored in amber plastic bottles at room temperature and under refrigeration.

Antiplatelet therapy in pediatric cardiovascular patients

Platelets play a critical role in normal physiologic processes such as hemostasis, wound healing, inflammation, and innate immunity. However, they also play a role in the pathologic process of thrombosis. Although antiplatelet therapy is most commonly used to prevent thrombotic events for adults with atherosclerotic vascular disease, children with certain types of congenital heart disease, stroke, and Kawasaki disease also are at risk for thrombosis and may benefit from antiplatelet therapy. Unfortunately, very little data on the efficacy and safety of antiplatelet therapy for pediatric patients are available. As a consequence, consistent clinical practice among pediatric practitioners is lacking. Furthermore, much of what is practiced results from extrapolation from adult studies, which may be problematic because many aspects of platelet biology differ between children and adults. This review discusses aspects of antiplatelet therapy for pediatric patients.

Gastrointestinal bleed with clopidogrel and aspirin

Anti-platelet drugs have been used to prevent thrombosis of systemic to pulmonary artery shunts. Aspirin has traditionally been used. Clopidogrel is being studied as an alternative and in combination with aspirin for shunt patients. We report a near fatal gastro-intestinal bleed in a patient with shunt and on aspirin and clopidogrel. This combination has been known to produce similar bleeds. The authors recommend caution in combining them. Prospective studies currently underway should evaluate this aspect of the antiplatelet drugs.

Clopidogrel in a pediatric population: prescribing practice and outcomes from a single center

BACKGROUND

This study aimed to provide descriptive information about off-label treatment practice with clopidogrel in a pediatric population.

METHODS

Patients less than 18 years of age prescribed clopidogrel between March 2002 and August 2005 were retrospectively identified at Children's Hospital, Boston. Data from the time of first documented clopidogrel use to the most recent follow-up assessment were collected. Adverse events were classified according to seriousness and relationship to clopidogrel.

RESULTS

Of the 90 patients in the study, 53% were boys. The median age of the patients was 6.7 years, and their median weight was 23.6 kg at first clopidogrel use. Prescriptions were predominantly for cardiac indications (96%), with a few for neurologic indications (4%). Common cardiac indications were history of thrombosis involving a conduit or shunt, abnormal vasculature with potential for low flow, and device placement. The median total dose was 1.3 mg/kg/day, and the duration of therapy varied from less than 1 day to 4 years (median, 45 days). Three patients experienced minor bleeding, all of whom were receiving concomitant acetylsalicylic acid. Another patient experienced catastrophic bleeding after vessel tear during catheterization. One patient with a fenestrated Fontan and poor ventricular function had baffle thrombosis and subsequent stroke while receiving clopidogrel and acetylsalicylic acid.

CONCLUSIONS

Clopidogrel was prescribed most often to prevent thrombosis in patients with cardiac disease. Patients with neurologic conditions also were treated. Bruising and bleeding events occurred rarely.

Combination thrombolytic and anti-platelet therapies in an infant with incomplete kawasaki disease and coronary aneurysms

A 3-month-old infant was transferred to our facility with persistent fever and concerns for septic shock. A 2-D echocardiogram revealed multiple coronary aneurysms and axillary and coronary artery thrombi, and a diagnosis of incomplete Kawasaki disease (KD) was established. Aggressive therapies including intravenous immunoglobulins, enoxaparin, abciximab, aspirin, and alteplase were used to decrease the size of the coronary aneurysms and inhibit further thrombus formation. After minimal change in the size of coronary aneurysms and in thrombus formation, clopidogrel was added. Approximately 2 weeks after initiation of these therapies, a decrease in the coronary aneurysm size was noted with no signs of thrombus. This case documents successful use of thrombolytic and combination anti-platelet agents (i.e., clopidogrel, abciximab, and aspirin) in an infant with KD and cardiovascular sequelae.

Safety and efficacy of clopidogrel in children with heart disease

OBJECTIVE

To evaluate the efficiency and safety of clopidogrel treatment in children with heart disease.

STUDY DESIGN

We conducted single center retrospective chart review of children with heart disease at the University Hospital, Leuven, Belgium, in whom clopidogrel was used. The indication, dosage, duration of therapy, and adverse events were examined. Clinical efficacy was defined by an absence of thrombotic events.

RESULTS

46 children were identified. The mean age of first clopidogrel dose was 4.9 +/- 4.1 years. The study dosage ranged from 0.1 to 0.7 mg/kg/day clopidogrel. Almost all patients received concomitant aspirin therapy. No thrombotic events developed. Skin bruising developed in almost every patient, suggesting that clopidogrel has an anti-platelet effect. 2 patients who were treated with concomitant warfarin had bleeding complications (severe epistaxis and gastrointestinal bleeding). Hematological abnormalities were documented in 1 patient who received clopidogrel for 1 year; they reversed with medication cessation.

CONCLUSION

Clopidogrel therapy in a pediatric population appears to be relatively safe and effective; however, randomized, controlled prospective studies are needed to determine the true efficacy and safety of clopidogrel in children.

Dosing of Clopidogrel for Platelet Inhibition in Infants and Young Children

Background— Infants and young children with certain types of heart disease are at increased risk for thromboses. Clopidogrel 75 mg/d is used in adults to prevent thrombotic events. The dose to achieve similar platelet inhibition in children is unknown. The objectives of the present study were (1) to determine the dose of clopidogrel needed in infants and young children to achieve a mean 30% to 50% inhibition of 5-μmol/L ADP–induced platelet aggregation (ie, inhibition similar to that observed with 75 mg in adults) and (2) to assess the safety and tolerability of clopidogrel in infants and young children.

Methods and Results— We performed a prospective, multicenter, randomized, placebo-controlled trial evaluating the pharmacodynamics of clopidogrel in children (0 to 24 months) with a cardiac condition at risk for arterial thrombosis. Patients were randomized to clopidogrel versus placebo in a 3:1 ratio in 4 sequential groups (0.01, 0.10, 0.20, and 0.15 mg/kg) for ≥7 and ≤28 days. Platelet aggregation was assessed at baseline and steady state by light-transmission aggregometry. Of 116 patients enrolled, 92 (50% neonates, 50% infants/toddlers) were randomized, and 73 completed the study. A total of 79% of the randomized and treated patients were taking aspirin. Compared with placebo, clopidogrel 0.20 mg · kg −1 · d −1 resulted in a mean 49.3% (95% confidence interval 25.7% to 72.8%) inhibition of the maximum extent of platelet aggregation and a mean 43.9% (95% confidence interval 18.6% to 69.2%) inhibition of the rate of platelet aggregation. There was marked interpatient variability in the degree of platelet aggregation inhibition within each treatment-dose group and age group. No serious bleeding events occurred.

Conclusions— Clopidogrel 0.20 mg · kg −1 · d −1 in children 0 to 24 months of age achieves a platelet inhibition level similar to that in adults taking 75 mg/d. Clopidogrel is well tolerated in infants and young children at this dose.

Elevated Risk of Thrombosis in Neonates Undergoing Initial Palliative Cardiac Surgery

BACKGROUND

Thrombotic events cause significant morbidity and mortality in children who undergo surgery for complex congenital cardiac disease. We prospectively evaluated the incidence of thrombosis and examined preoperative and postoperative laboratory tests of coagulation and inflammation in neonates experiencing initial surgical palliation for variations of single ventricle physiology.

METHODS

Neonates (<30 days) requiring initial surgical palliation were studied. All subjects received aspirin from postoperative day 1 onward. Thromboses were diagnosed by serial transthoracic echocardiograms, vascular imaging, and interstage cardiac catheterizations according to predefined criteria.

RESULTS

Twenty-two neonates, age 1 to 11 days (mean 4 +/- 2.5) were studied. Follow-up ranged from three hours to 18 months (median, 212 days). Eight infants died. Four of the 14 subjects who survived (28%), and one of the eight who died (12.5%), had evidence of thrombosis identified over a range of four hours to nine months postoperatively (median 14 days). When compared with reference values established in healthy children, preoperative subject hematocrit (Hct), platelet count, factors II, V, VII, VIII, and X, antithrombin, protein C, and soluble CD40 ligand measures were significantly lower, and the prothrombin time and partial thromboplastin time were significantly higher. Postoperative C reactive protein (CRP) was significantly higher, and Hct and platelet count significantly lower, than preoperative values. Thrombotic events were significantly related to high preoperative CRP (p = 0.02).

CONCLUSION

Thrombotic complications occur frequently in neonates undergoing initial palliative surgery, suggesting that aspirin therapy alone may constitute inadequate protection. Elevated preoperative CRP appears to be associated with increased thrombotic risk.