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Carlos Macaya

Publications and source records attributed to Carlos Macaya.

At least 73 records · Page 4Linked to original sources
PubMed2005

[Usefulness of parametric imaging-based quantitative myocardial contrast echocardiography in predicting the functional recovery of akinetic segments following primary angioplasty in acute myocardial infarction patients].

INTRODUCTION AND OBJECTIVES: Myocardial contrast echocardiography (MCE) is useful for predicting the functional recovery of akinetic segments in patients undergoing primary angioplasty after acute myocardial infraction (AMI). Recently, parametric imaging-based quantitative MCE has been developed for measuring perfusion. Our aims were: a) to measure perfusion in akinetic myocardial segments in patients undergoing primary angioplasty using parametric imaging-based quantitative MCE; and b) to assess the usefulness of these measurements in predicting functional recovery of these segments. PATIENTS AND METHOD: The study group comprised 49 consecutive patients undergoing primary angioplasty. Both MCE and standard echocardiography were performed between 2 and 5 days after AMI. Six months later, additional standard echocardiography and coronary angiography were performed. Perfusion was quantified independently off-line from parametric images. RESULTS: The patients' mean age was 62.3+/-14.5 years (39 men; 79.2%). Some 170 akinetic segments were detected. Of these, 105 (62.1%) recovered function. The quantitative MCE parameter that best predicted functional recovery was myocardial blood flow velocity (beta): the area under the receiver operating characteristic (ROC) curve was 0.96 (95% CI, 0.92-0.99). For a cut-off point of 31 dB/s, the sensitivity was 87.62%, the specificity was 95.31%, the positive predictive value was 96.8%, and the negative predictive value was 82.43%. These results were better than those obtained using qualitative methods for assessing myocardial perfusion. CONCLUSIONS: Perfusion measurement by parametric imaging-based quantitative MCE is useful for predicting the functional recovery of akinetic segments in patients undergoing primary angioplasty after AMI. The technique provides superior information to older qualitative methods.

Aged↗
PubMed2005

Infective endocarditis: mid-term prognosis in patients with good in-hospital outcome.

BACKGROUND AND AIM OF THE STUDY: The study aim was to analyze the mid-term prognosis of infective endocarditis (IE) in patients managed with medical therapy during the in-hospital phase and who had a good initial outcome. Comparison was made with the prognosis of patients treated surgically during this period. METHODS: A total of 151 patients diagnosed with IE was studied, and in-hospital outcome, clinical characteristics and mid-term follow up data were analyzed. The main end-point was a composite of death and need for surgical repair. RESULTS: Among 151 patients, 84 (56%) underwent surgery or died during the in-hospital phase, while 67 patients (44%) received medical treatment and were discharged clinically stable with a final diagnosis of healed infective endocarditis. A better baseline profile was seen in the medically treated group, but outcome in this group showed extensive mid-term morbidity/mortality. In total, 52.2% of patients underwent surgery to correct complications and 60% died as a consequence of the disease. The event-free survival rate was 20% at five years. CONCLUSION: Despite a favorable in-hospital clinical course and successful medical treatment, patients with IE are at risk of late complications that result in a need for surgical repair, or in death. A close follow up should be made in order to treat late complications.

Aneurysm, False↗
PubMed2005

Prognostic significance of ischemic mitral regurgitation after non-Q-wave acute myocardial infarction.

BACKGROUND AND AIM OF THE STUDY: The development of mitral regurgitation (MR) soon after acute myocardial infarction (AMI) is a recognized and frequent complication. Its negative impact on survival has been observed after Q-wave AMI, even when of a mild degree, and independently of left ventricular systolic function. Few data exist regarding MR after non-Q-wave AMI (nQ AMI), however. Hence, the study aim was to investigate the incidence, clinical predictors and prognostic implications of MR in the setting of nQ AMI. METHODS AND RESULTS: A total of 99 consecutive patients (37 men, 62 women; mean age 72 +/- 13 years) who suffered a nQ AMI was studied. All patients underwent echocardiography during the first week after the nQ AMI. MR was detected in 34 patients (17 men, 17 women; mean age 76 +/- 10 years). Events during follow up were coded as death, AMI, unstable angina, or heart failure. The in-hospital outcome was not significantly different between patients with and without MR. The mean follow up period was 663 +/- 574 days. In the univariate analysis, freedom from hospital survival was significantly greater in patients without MR. However, multivariate analysis showed that MR was not an independent predictor of cardiovascular hospitalization or death. CONCLUSION: The incidence of MR is high among patients with nQ AMI but, unlike results found with Q-wave AMI, its presence does not add any prognostic significance to other known negative factors in the setting of nQ AMI.

Aged↗
PubMed2004

Prognostic influence of mitral regurgitation prior to a first myocardial infarction.

AIMS: Mitral regurgitation (MR) following an acute myocardial infarction (AMI) confers an adverse prognosis during long-term follow-up. There are no studies evaluating the influence of pre-AMI MR in the short- and long-term prognosis of such patients. Our aim was to assess the prognostic value of pre-AMI MR in the short- and long-term follow-up of patients who suffered a first AMI and to assess its influence on left ventricular haemodynamics. METHODS AND RESULTS: Sixty-eight consecutive patients with a first AMI and an echocardiographic study before AMI (<3 months) were included in the study. The pre-AMI echo was performed for various reasons. Of these 68 patients, 42 had pre-AMI MR (Group 1) and 26 showed no pre-AMI MR (Group 2). The presence of degenerative changes at the level of the mitral valve was confirmed in all cases. Patients with any other cause of MR were excluded. Clinical and echocardiographic variables for both phases (pre-AMI and post-AMI) were analysed and patients were followed up. Mean age was 75.5+/-9.5 years; there were 38 males (55.9%). There were no statistical differences in baseline clinical variables between the groups, except for the presence of pre-AMI atrial fibrillation, which was more frequent in Group 1 (21.4 vs. 0%; P = 0.01). After AMI, only end-diastolic left ventricular diameter was significantly larger in Group 1 (54.9 +/- 4.7 vs. 48.1 +/- 5.6 mm; P < 0.001). During long-term follow-up, median survival times were 912 days (interquartile range: 690 days) in Group 1 and 1423 days (interquartile range: 520 days) in Group 2 (Log-rank P = 0.02). The multivariable analysis showed that the presence of pre-AMI MR relates to a statistically significant relationship with a worse post-AMI evolution [relative risk (95% confidence interval): 3.8 (1.1-13.1); P = 0.037]. CONCLUSION: The present study shows that the presence of pre-AMI MR is an independent prognostic marker among those patients suffering a first AMI.

Aged↗
PubMed2004

Proteomic analysis of plasma from patients during an acute coronary syndrome.

OBJECTIVES: The aim of this study was to analyze modifications in the plasma protein map during an acute coronary syndrome (ACS) using proteomics. BACKGROUND: Proteomics is a new technology that allows the detection and identification of several proteins at a given time in a sample. METHODS: Plasma from 19 patients, 11 with acute myocardial infarction (AMI) and 8 with unstable angina (UA), was investigated. The control group included nine age-matched volunteers. RESULTS: In two-dimensional electrophoresis using a pH range of 4 to 7, constant differences were found in at least four different areas within the plasma protein map. In area 1, we identified the presence of seven alpha(1)-antitrypsin (AAT) isoforms in plasma from control subjects. alpha(1)-antitrypsin isoform 1 was undetectable in plasma from UA and AMI patients. The AAT isoforms 5, 6, and 7 were reduced in plasma from AMI patients when compared with UA patients. Three fibrinogen gamma chain isoforms were identified in area 2. Fibrinogen gamma chain isoforms 1 and 2 were increased in AMI patients with respect to UA patients. Five apolipoprotein A-I isoforms were identified in area 3. All of them were reduced in plasma from AMI patients with respect to UA patients. In area 4, the gamma-immunoglobulin heavy chains were detected and were found increased in plasma from ACS patients. CONCLUSIONS: Plasma proteomic analysis makes it possible to develop a map of the protein isoforms that are expressed in plasma during an ACS.

Acute Disease↗
PubMed2004

Effectiveness of percutaneous coronary interventions in nonagenarians.

Data on percutaneous coronary intervention (PCI) in nonagenarians are very scarce. The investigators present a series of 26 nonagenarians who underwent PCI (29 lesions, 1.1 +/- 0.3 per patient). Most (96%) had acute coronary syndrome at presentation, 27% underwent primary PCI for acute myocardial infarctions, and 54% had multivessel disease. Angiographically successful results were obtained in 24 patients (92%), and coronary stents were used in 81%. Five patients (19%) died during hospitalization. In-hospital mortality was significantly greater in patients with Killip class III or IV at presentation (100% vs 9%, p = 0.001), in those in whom the procedure was a primary PCI for acute myocardial infarction (57% vs 5%, p = 0.010), and in the presence of angiographic failure (100% vs 13%, p = 0.031). In-hospital mortality was 0% after excluding patients in cardiogenic shock and those with primary PCI. Thus, most nonagenarians who undergo PCI have a high-risk profile. However, PCI achieves a successful angiographic result in most patients. Mortality is high but concentrated in patients in cardiogenic shock and with primary angioplasty as PCI.

Aged↗
PubMed2004

Intracoronary brachytherapy after stenting de novo lesions in diabetic patients: results of a randomized intravascular ultrasound study.

OBJECTIVES: We studied the efficacy of intracoronary brachytherapy (ICB) after successful coronary stenting in diabetic patients with de novo lesions. BACKGROUND: Intracoronary brachytherapy has proven effective in preventing recurrences in patients with in-stent restenosis. However, the role of ICB for the treatment of de novo coronary stenoses remains controversial. METHODS: Ninety-two patients were randomized to either ICB or no radiation after stenting. Primary end points were in-stent mean neointimal area (primary end point of efficacy) and minimal luminal area of the entire vessel segment (primary end point of effectiveness), as assessed by intravascular ultrasound at six-month follow-up. Quantitative coronary angiography analysis was performed at the target, injured, irradiated, and entire vessel segments. RESULTS: At follow-up, the in-stent mean neointimal area was 52% smaller in the ICB group (p < 0.0001). However, there was no difference in the minimal luminal area of the vessel segment (4.5 +/- 2.4 mm2 vs. 4.4 +/- 2.1 mm2). Restenosis rates increased progressively by the analyzed segment in the ICB group: target (7.1% vs. 20.9%, p = 0.07), injured (9.5% vs. 20.9%, p = NS), irradiated (14.3% vs. 20.9%, p = NS), and vessel segment (23.8% vs. 25.6%, p = NS). At one year, 1 cardiac death, 6 myocardial infarctions (MIs) (3 due to late stent thrombosis), and 10 target vessel revascularizations (TVRs) (6 due to the edge effect) occurred in the ICB group, whereas in the nonradiation group, there were 11 TVRs and no deaths or MIs. CONCLUSIONS: Intracoronary brachytherapy significantly inhibited in-stent neointimal hyperplasia after stenting in diabetic patients. However, clinically this was counteracted by the occurrence of the edge effect and late stent thrombosis.

Aged↗
PubMed2004

Direct stenting versus direct stenting followed by centered beta-radiation with intravascular ultrasound-guided dosimetry and long-term anti-platelet treatment: results of a randomized trial: Beta-Radiation Investigation with Direct Stenting and Galileo in Europe (BRIDGE).

OBJECTIVES: We sought to assess the efficacy of vascular brachytherapy (VBT) combined with stenting for the primary prevention of restenosis. BACKGROUND: Intravascular brachytherapy after stent implantation for de novo lesions has been abandoned for the present. We revisited this procedure by optimizing all procedural steps-the use of glycoprotein IIb/IIa blockers, direct stenting, adequate radiation coverage, avoidance of edge damage, source centering, intravascular ultrasound-guided dosimetry, and continuation of a dual anti-platelet regimen for one year. METHODS: The Beta-Radiation Investigation with Direct stenting and Galileo in Europe (BRIDGE) study is a multicenter, randomized controlled trial evaluating the long-term efficacy of VBT with P-32 (20 Gy at 1 mm in the coronary wall) after direct stenting. The primary end point was angiographic intra-stent late loss; secondary end points were six months binary restenosis and neo-intimal hyperplasia. Patients (n = 112) with de novo lesions (2.5 to 4.0 mm in diameter up to 15 mm long) were randomized to either VBT or no-VBT. RESULTS: At six months, intra-stent loss was 0.43 and 0.84 mm (p < 0.001) in the irradiated and control groups, respectively. Intra-stent neo-intimal volume was reduced from 36 mm3 to 10 mm3. However, in the irradiated group there were six late occlusions as well as eight restenoses outside the stented and peri-stented area at the fall-off dose edges of the irradiated area. Accordingly, the target vessel revascularization and major adverse cardiac and cerebrovascular events rates at one year in the VBT group (20.4% and 25.9%, respectively) were higher than in the control group (12.1% and 17.2%, respectively). CONCLUSIONS: Despite the optimization of pre-, peri-, and post-procedural factors and despite the relative efficacy of the brachytherapy for the prevention of the intra-stent neo-intimal hyperplasia, the clinical outcome of the irradiated group was less favorable than that of the control group.

Aged↗
PubMed2004

Coronary stenting versus balloon angioplasty in small vessels: a meta-analysis from 11 randomized studies.

OBJECTIVES: A meta-analysis of 11 randomized trials was done to compare stenting versus balloon angioplasty (BA) in small coronary vessels. BACKGROUND: Randomized studies on coronary stenting (CS) in small vessels have yielded controversial results. METHODS: Eleven randomized trials on CS versus BA in small vessels, including angiographic re-evaluation at six months, were analyzed. RESULTS: The BeStent (Medtronic Instent, Minneapolis, Minnesota) was used in four studies, the Multi-Link (Guidant, Advanced Cardiovascular Systems Inc., Santa Clara, California) in three trials, and the NIR (Boston Scientific Corp., Boston, Massachusetts), JoStent (Jomed International AB, Helsingborg, Sweden), Tenax (Biotronik, Berlin, Germany), and BioDivysio (Abbott Vascular Devices, Redwood City, California) in the remaining four trials. Overall, 3,541 patients were included (1,672 allocated to BA and 1,869 to stent). The rate of cross-over from balloon to stent in the pooled population was 19%, and unsuccessful stent deployment occurred in 2% of the patients allocated to stent. The pooled rates of restenosis were 25.8% and 34.2% in patients allocated to stent and balloon, respectively (p = 0.003) (risk ratio [RR] 0.77; 95% confidence interval [CI] 0.65 to 0.92). A smaller reference vessel diameter at baseline was associated with a higher risk reduction in the restenosis rate (y = -3.551 + 1.826 [x]; p = 0.012). Patients allocated to stent had lower rates of major adverse cardiac events (15.0% vs. 21.8%, p = 0.002; RR 0.70; 95% CI 0.57 to 0.87) and new target vessel revascularizations (12.5% vs. 17.0%, p = 0.004; RR 0.75, 95% CI 0.61 to 0.91). CONCLUSIONS: Elective stenting is superior to provisional stenting in small coronary arteries. This benefit is more evident in smaller coronary arteries.

Angioplasty, Balloon↗
PubMed2004

Real-time three-dimensional echocardiography for rheumatic mitral valve stenosis evaluation: an accurate and novel approach.

OBJECTIVES: Our aim was to assess which echo-Doppler method has the best agreement with the mitral valve area (MVA) invasively evaluated by the Gorlin's formula. We also evaluated the feasibility and reproducibility of real-time three-dimensional echocardiography (RT3D) for the estimation of MVA and the Wilkins score in patients with rheumatic mitral stenosis (RMVS). BACKGROUND: Real-time three-dimensional echocardiography is a novel technique that allows us to visualize the mitral valvular anatomy in any desired plane orientation. The usefulness and accuracy of this technique for evaluating RMVS has not been established. METHODS: We studied a series of consecutive patients with RMVS from two tertiary care hospitals. Mitral valvular area was determined by conventional echo-Doppler methods and by RT3D, and their results were compared with those obtained invasively. Real-time three-dimensional echocardiography planimetry and mitral score were measured by two independent observers and then repeated by one of them. RESULTS: Eighty patients with RMVS comprised our study group (76 women; 50.6 +/- 13.9 years). Compared with all other echo-Doppler methods, RT3D had the best agreement with the invasively determined MVA (average difference between both methods and limits of agreement: 0.08 cm(2) [-0.48 to 0.6]). Interobserver variability was as good for RT3D (intraclass correlation coefficient [ICC] = 0.90) as for pressure half-time (PHT) (ICC = 0.95). For PHT and RT3D, the intraobserver variability was similar (ICC 0.92 and 0.96, respectively). Real-time three-dimensional echocardiography valvular score evaluation showed a better interobserver agreement with RT3D than with 2D echocardiography. CONCLUSIONS: Real-time three-dimensional echocardiography is a feasible, accurate, and highly reproducible technique for assessing MVA in patients with RMVS. Real-time three-dimensional echocardiography has the best agreement with invasive methods.

Echocardiography, Three-Dimensional↗
PubMed2004

Differences in regional systolic and diastolic function by Doppler tissue imaging in patients with hypertrophic cardiomyopathy and hypertrophy caused by hypertension.

OBJECTIVE: Doppler tissue (DT) velocity abnormalities have been described in patients with pathologic left ventricular hypertrophy (LVH). Impaired myocardial function has been suggested as a primary disorder in hypertrophic cardiomyopathy (HCM) and differences in DT parameters have been reported to be distinguishable from other LVH causes. We evaluated DT differences for patients with LVH caused by hypertension and patients with HCM, assessing regional systolic and diastolic function. METHODS: A total of 62 participants were studied: 21 with HCM; 22 with LVH secondary to hypertension; and 19 control subjects. DT was used to record mitral annulobasal segment motion in the longitudinal axis. Systolic and diastolic velocities were measured at lateral and septal sites, and well-known ratios were obtained for diastolic assessment. A new global function index (GFI) that evaluates both systole and diastole was also calculated (GFI = [Emi/E(DT)]/S(DT) [s x cm(-1)], where mi is mitral inflow, E is E wave, and S is systolic wave). RESULTS: Comparison showed significant differences in all parameters evaluated at the septal-basal segment and a GFI value of 1.77 showed 85% sensitivity and 75% specificity for detecting HCM when interventricular septum thickness was increased. CONCLUSIONS: In the presence of unexplained LVH, markedly decreased DT velocities at basal septum efficiently detect myocardial dysfunction at this segment, and a calculated GFI > 1.77 strongly supports the diagnosis of HCM.

Cardiomyopathy, Hypertrophic↗
PubMed2004

High clopidogrel loading dose during coronary stenting: effects on drug response and interindividual variability.

AIM: To assess platelet inhibitory effects, interindividual variability in platelet inhibition as well as response to a 600 mg, compared to a standard 300 mg, clopidogrel loading dose (LD) after coronary stenting METHODS AND RESULTS: Platelet function profiles were assessed in 50 patients undergoing coronary stenting receiving either a 300 mg (n=27) or 600 mg clopidogrel LD. ADP (6 microM) and collagen (6 microg/mL) induced platelet aggregation, as well as ADP (2 microM) induced glycoprotein (GP) IIb/IIIa activation and P-selectin expression were assessed at baseline and 4, 24, and 48 h following clopidogrel front-loading. A more intense and rapid inhibition of platelet activation (both GP IIb/IIIa activation and P-selectin expression) were achieved using a 600 mg, compared to a 300 mg, LD throughout the entire 48 hours (p<0.001). Although there were no differences in platelet aggregation, overall a 600 mg LD increased the number of clopidogrel responders and this was also achieved earlier compared to a 300 mg LD. A 600 mg LD did not reduce interindividual variability of platelet response. CONCLUSION: The use of a 600 mg clopidogrel LD in patients undergoing coronary stenting optimises platelet inhibitory effects early after intervention and may provide a more effective protection against early thrombotic complications.

Blood Platelets↗
PubMed2004

Non-invasive assessment of mitral valve area during percutaneous balloon mitral valvuloplasty: role of real-time 3D echocardiography.

BACKGROUND: In the last decade, multiple studies depicted discrepancies between mitral valvular orifice area (MVA) measurements obtained with the pressure half-time (PHT) method and invasive methods during the immediate post-percutaneous mitral valvuloplasty (PMV) period. Our aim was to assess the accuracy of Real-Time 3D echo (RT3D) to measure the MVA in the immediate post-PMV period. The invasively determined MVA was used as the gold standard. METHODS AND RESULTS: We studied 29 patients with rheumatic mitral stenosis from two centres (27 women; mean age 48.2+/-11.3 years), all of which had underwent PMV. MVA was calculated before and after PMV using the PHT method, 2D echo planimetry, RT3D echo planimetry and invasive determination (Gorlin's method). The RT3D MVA assessment showed a better agreement with the invasively derived MVA before and in the immediate post-PMV period (Bland-Altman analysis: Average difference between both methods and limits of agreement: 0.01 (-0.31 to 0.33) cm(2) and -0.12 (-0.71 to 0.47) cm(2)) before and immediately after the PMV, respectively. CONCLUSIONS: RT3D is a feasible and accurate technique for measuring MVA in patients with RMVS. It has the best agreement with the invasively determined MVA, particularly in the immediate post-PMV period.

Adult↗
PubMed2004

Identifying patients without favourable long-term outcome among those with medically stabilized unstable angina and a negative dipyridamole stress echocardiogram.

AIMS: Patients with medically stabilized unstable angina and a negative stress echocardiogram have a favourable outcome as a whole. This study sought to identify which subsets of patients are associated with serious events at long-term within this population. METHODS AND RESULTS: We studied and followed-up 128 patients (mean 2.2 +/- 1.3 years) with medically stabilized unstable angina and a negative dipyridamole stress echocardiogram. Cumulative survival rates were 98.2 +/- 1.3%, 96.0 +/- 2.2% and 93.2 +/- 3.2%, at 1, 2 and 4 years, respectively. Freedom from events (death, myocardial infarction, and revascularization) were 98.2 +/- 1.3%, 96.0 +/- 2.2% and 86.3 +/- 6.0%, at 1, 2, and 4 years, respectively. Cumulative mortality rate was higher in men (3.6 +/- 2.5%, 8.5 +/- 4.1%, and 12.2 +/- 5.4% at 1, 2, and 4 years, vs. 0% at the end of the follow-up in women; p = 0.034), and in those with previous myocardial infarction (4.3 +/- 4.3%, 9.1 +/- 6.2%, and 18.2 +/- 2.3% at 1, 2 and 4 years, vs. 1.1 +/- 1.1%, 2.9 +/- 2.1%, and 2.9 +/- 2.1% in those without previous myocardial infarction, respectively; p = 0.047). CONCLUSION: Among patients with medically stabilized unstable angina and a negative dipyridamole stress echocardiogram, male gender and previous myocardial infarction are associated with a non-favourable outcome.

Adult↗
PubMed2004

PlA polymorphism and platelet reactivity following clopidogrel loading dose in patients undergoing coronary stent implantation.

The PlA polymorphism (Leu33Pro) of the platelet glycoprotein (GP) IIIa gene has been suggested to play an important role in coronary thrombosis. In vitro studies have shown differences for this polymorphism in platelet sensitivity towards antiplatelet drugs (aspirin and abciximab), suggesting a pharmacogenetic modulation. The aim of the study was to assess the modulatory effect of the PlA polymorphism on clopidogrel-induced antiplatelet effects in 38 patients undergoing coronary stent implantation receiving a 300 mg clopidogrel loading-dose. Platelet reactivity was assessed as GPIIb/IIIa activation and P-selectin expression in platelets stimulated with 2 micromol/l adenosine diphosphate using whole blood flow cytometry. The distribution of the homozygous PlA1/A1 and heterozygous PlA1/A2 genotypes were 74 and 26%, respectively. PlA2 carriers had a higher degree of GPIIb/IIIa activation (P = 0.05) and P-selectin expression (P = 0.02) during the overall study time course and a lower antiplatelet effect to a 300 mg clopidogrel loading-dose up to 24 h following intervention (P < 0.05). In conclusion, the Pl polymorphism of the GPIIIa gene modulates platelet reactivity towards clopidogrel front loading in patients undergoing coronary stenting. This suggests the need for individualized antithrombotic regimens to optimally inhibit platelet reactivity.

Abciximab↗
PubMed2004

807 C/T Polymorphism of the glycoprotein Ia gene and pharmacogenetic modulation of platelet response to dual antiplatelet treatment.

Glycoprotein (GP) Ia/IIa is a major platelet-collagen receptor playing a key role in thrombosis following collagen exposure. The 807 C/T polymorphism of the GP Ia gene (ITGA2) has been associated with platelet GP Ia/IIa receptor expression, having T-allele carriers, increased receptor density and thrombotic risk. The aim of the study was to assess the role of the 807 C/T polymorphism on modulating platelet function in patients undergoing coronary stenting receiving a 300 mg clopidogrel loading dose. Platelet aggregation was assessed in 44 patients by light transmittance aggregometry following adenosine diphosphate and collagen stimuli at baseline, and 10 min, 4 h and 24 h after clopidogrel front loading. The T allele was found in 73% of patients. Clopidogrel reduced adenosine diphosphate-induced platelet aggregation (P < 0.01), which was similar in carriers and non-carriers of the T allele throughout the study (P = 0.73). Clopidogrel reduced collagen-induced platelet aggregation only in non-carriers of the T allele (P = 0.03), which resulted in an increase in T allele carriers during the overall study (P = 0.04). In conclusion, the T allele of the GP Ia gene modulates platelet aggregation and clopidogrel antiplatelet effects, suggesting an enhanced reactivity to fibrillar collagens (exposed during coronary stenting) in T allele carriers and might contribute to an increased thrombotic risk in these patients.

Adenosine Diphosphate↗