Impact of Platelet Function Test on Platelet Responsiveness and Clinical Outcome After Coronary Stent Implantation: Platelet Responsiveness and Clinical Outcome

BACKGROUND AND OBJECTIVES: The aim of this study was to confirm the predictive cut-off values for P2Y12 reaction units (PRU) and aspirin reaction units (ARU) and to evaluate the clinical impact of VerifyNow(R) assays. SUBJECTS AND METHODS: From November 2007 to October 2009, 186 eligible patients were prospectively recruited. Post-treatment platelet reactivity was measured by VerifyNow(R) assays within 12 to 24 hours after intervention, followed by standard dual maintenance dose therapy for 1 year. All patients had scheduled clinical follow-ups at 1, 3, 6, and 12 months. RESULTS: The rate of low responders to clopidogrel, aspirin, and both drugs were 41.4%, 10.2%, and 3.8%, respectively. The predictive factors for low responsiveness to clopidogrel (PRU > or =240) were female sex, age, and non-use of cilostazol medication in our univariate analysis and age > or =65 years and non-use cilostazol in the multivariate analysis. The predictors of low responsiveness to aspirin (ARU > or =550) were male sex and age in both univariate and multivariate analyses. There was no significant difference in the clinical event rate with a cut-off value of PRU > or =240 or ARU > or =550 for 30 days and 1-year (p>0.05). CONCLUSION: Hyporesponsiveness to antiplatelet agents (namely aspirin and clopidogrel) was identified in about half of the patients. The cut-off point of PRU > or =240 or ARU > or =550 did not confer predictive value for 30-day or 1-year clinical event rates in patients who had undergone coronary intervention with drug-eluting stents.

Determination of the Prevalence of Aspirin and Clopidogrel Resistances in Patients with Coronary Artery Disease by using Various Platelet-function Tests / 대한진단검사의학회지

BACKGROUND: Dual therapy with aspirin and clopidogrel has emerged as the gold standard therapy for patients treated with drug-eluting stents (DES). However, there is variability in patients' responses to this antiplatelet therapy, and some patients continue to show ischemic recurrences after therapy. The purpose of the study was to compare the simultaneously obtained results of various platelet-function tests for assessing the prevalence of antiplatelet resistance in coronary artery disease patients undergoing DES therapy. METHODS: A total of 66 patients were administered a loading dose of aspirin, clopidogrel, and cilostazol at least 12 hr before stenting. The results of VerifyNow (Accumetrics, USA), multiplate analyzer (Dynabyte Medical, Germany), and vasodilator-stimulated phosphoprotein/P2Y12 (Biocytex, France) assays were compared with those of light transmission aggregometry (LTA) analysis. RESULTS: The P2Y12 reaction units and P2Y12% inhibition values obtained using the VerifyNow assay showed strong correlation (r) with the results of the LTA analysis. All tests results showed low concordance in defining the antiplatelet resistance in patients, and the degrees of agreement were as follows: 0 for aspirin reaction units; 0.25, P2Y12% inhibition; 0, aspirin-sensitive patients' identification test; 0.21, ADPtest; and 0.14, platelet reactivity index, expressed as the kappa statistics. The prevalence of aspirin and clopidogrel resistances in patients resulted in remarkable variations, from 0% to 22.7% and from 9.1% to 48.5%, respectively. CONCLUSIONS: The clinical usefulness of the different assays for the correct classification of patients in terms of antiplatelet resistance remains unclear. Further studies are required to determine the best method for correlating the occurrences of adverse ischemic events.

High Plasma Levels of the B-type Natriuretic Peptide in Patients Without Heart Failure: Is There Clinical Significance?

We report a case of a 19-year-old female with an elevated plasma B-type natriuretic peptide (BNP) level, but without evidence of heart failure (HF). She presented with non-specific chest pain and a high level of the B-type natriuretic peptide, despite having unremarkable findings on physical examination, laboratory analysis, electrocardiogram, echocardiogram, chest X-ray, chest computed tomography, whole body scan, and coronary angiography. We attribute this finding to a genetic variation in the synthesis and cleavage of the natriuretic peptides.

Initial Experience of Retrograde Wire Approach in Coronary Chronic Total Occlusion Intervention

BACKGROUND AND OBJECTIVES: Retrograde wire approach has been emerged as a useful tool to enhance success rate in coronary chronic total occlusion (CTO) intervention. Therefore, we tried to report the initial experience of retrograde approach and its clinical implication on CTO intervention. SUBJECTS AND METHODS: From February 2007 to July 2008, retrograde approaches were performed in 28 patients with 31 CTO lesions out of 61patients. A hydrophilic coated guidewire was inserted by using microcatheter or over-the-wire (OTW) balloon through the collateral channel (septal or epicardial artery) via several strategies. RESULTS: Mean age of patients was 63.4+/-11.6 years. Male and female were 20 and 8 patients, respectively. The target artery with CTO lesions included the right coronary artery (45.2%), the left anterior descending artery (51.6%), and the left circumflex artery (3.2%). The mean length of CTO lesion was 18.4+/-16.4 mm. Overall technical success rate was 64.5%. The success rate of primary attempt was 78.9%, while the success rate of immediate and secondary attempt was 41.7%. Collateral channel dissections were observed in 3 patients and no patients among these patients developed cardiac tamponade. One patient had a silent non-Q wave myocardial infarction (MI) after the procedure. One failed patient died suddenly 3 days after the procedure. After percutaneous coronary intervention (PCI) procedure, no case was performed target vessel revascularization (TVR), urgent coronary artery bypass graft (CABG), and urgent PCI. CONCLUSION: Retrograde approach is an evolving technique to improve the success rate of CTO intervention. After the learning curve period, this technique could be the useful tool to enhance success rate in CTO intervention.

Clinical Effects of Additional Cilostazol Administration After Drug-Eluting Stent Insertion

BACKGROUND AND OBJECTIVES: Cilostazol, a selective inhibitor of phosphodiesterase III (PDE III), prevents inactivation of the intracellular second messenger cyclic adenosine monophosphate (cAMP) and irreversibly inhibits platelet aggregation and vasodilation. Hence, we performed this prospective randomized study to evaluate the clinical effects of additional cilostazol administration in patients receiving dual antiplatelet therapy after drug-eluting stent (DES) insertion. SUBJECTS AND METHODS: Between December 2003 and June 2006, we enrolled a total 603 consecutive patients who underwent successful percutaneous coronary intervention (PCI) with DES insertion at Dong-A University Hospital. Study patients received dual antiplatelet therapy (aspirin and clopidogrel, n=301) for at least six months or dual antiplatelet therapy (six months) combined with cilostazol medication for one month (triple therapy, n=302) after PCI. We investigated the incidence of major adverse cardiac events (MACE) at one month and six months after the initiation of medical therapy. MACE was defined as a composite of death, myocardial infarction (MI), stent thrombosis, and target lesion revascularization (TLR). Platelet function was evaluated in 66 patients (dual therapy group, n=40; triple therapy group, n=26) using a Chrono-Log platelet aggregometer and the VerifyNow P2Y12 assay system. RESULTS: The MACE rate was 0.66% in the triple therapy group (death only, 0.67%) and 1.67% in the dual therapy group (death, 0.67%; MI, 0.67%; stent thrombosis, 0.99%; TLR, 0.99%) at one month after PCI (p=0.087). At six months, there were no differences in the MACE rate between the two groups (triple group vs. dual group=2.65% vs. 3.99%, p=0.864). In laboratory tests, platelet aggregation induced by agonists of ADP (27.92+/-13.04% vs. 40.9+/-15.78%, p=0.0008), collagen (13.73+/-6.95% vs. 27.43+/-14.87%, p=0.03), and epinephrine (10.38+/-7.82% vs. 15.5+/-10.45%, p=0.0000) were lower in the triple therapy group versus the dual therapy group. However, platelet aggregation induced by agonists of arachidonic acid (3.23+/-1.07% vs. 3.78+/-2.12%, p=0.23) and ristocetin (29.19+/-35.55% vs. 44.78+/-32.65%, p=0.07) and aspirin reaction unit (412.96+/-96.25 vs. 427.93+/-76.24, p=0.48) measured by VerifyNow were not different in the triple group versus the dual group. CONCLUSION: Additional administration of cilostazol did not decrease the MACE rate when compared to dual therapy six months after PCI in patients with DES.

Comparison between the Portable Prothrombin Time Self Monitor CoaguChek XS and a Standard Laboratory Method, Sysmex CA-1500 for Monitoring Anticoagulant Therapy of Outpatients

BACKGROUND AND OBJECTIVES: Patients on oral anticoagulation therapy (OAT) require regular monitoring of the prothrombin time (PT) and dosage adjustment to prevent thromboembolic diseases without the risk of hemorrhage. Portable self PT monitors have been recently developed because the standard PT measurements are complicated and take considerable time. This study compared the International normalized ratio (INR) results that were obtained with using the CoaguChek XS device (Roche Diagnostic, Mannheim, Germany) with those obtained using a standard laboratory method Sysmex CA-1500 (Sysmex Corporation, Kobe, Japan) in the patients on OAT and also a healthy control group. SUBJECTS AND METHODS: 100 outpatients on OAT and 20 healthy controls were enrolled on a volunteer basis after providing informed consent at the Dong-A University Hospital. The outpatients and the healthy control group provided us the INR measurements with using both the CoaguChek XS and the Sysmex CA-1500. RESULTS: The coefficients of variation for CoaguChek XS and Sysmex CA-1500 were less than 10%. The PT (INR) results of CoaguChek XS and Sysmex CA-1500 were 2.0+/-0.7 and 2.2+/-0.7, respectively (p<0.001). There was a good correlation between CoaguChek XS and Sysmex CA-1500 (r=0.974, p<0.001). On the regression analysis, the slope of the regression line was 0.9197 and the y-intercept was 0.0058. On the Bland-Altman analysis, the INR mean difference (bias) between the two methods (CoaguChek XS INR-Sysmex CA-1500 INR) was -0.2 and the limit of agreement was +0.168~-0.568. CONCLUSION: The measurement with using CoaguChek XS has high repeatability, rapid availability and good accuracy that are comparable to the standard laboratory method. Therefore, CoaguChek XS can be a valuable tool for the self-monitoring of patients on OAT.