Renal function assessed using cystatin C and antiplatelet efficacy of clopidogrel assessed using the vasodilator-stimulated phosphoprotein index in patients having percutaneous coronary intervention.

Renal dysfunction is a strong independent predictor of stent thrombosis. The aim of the present study was to evaluate the strength and direction of the association between kidney function and clopidogrel efficacy. The study group consisted of consecutive patients (n = 275) who underwent stent implantation. Drug efficacy was measured using the vasodilator-stimulated phosphoprotein (VASP) index 20 ± 4 hours after clopidogrel 600 mg. Nonresponse was defined as an VASP index ≥50%. Renal function was determined using serum cystatin C. The upper reference levels are 1.12 mg/L for ≤65 years of age and 1.21 mg/L for >65 years of age. Estimated glomerular filtration was calculated using cystatin C. The median value of cystatin C was 1.16 mg/L (twenty-fifth and seventy-fifth percentiles 0.96 and 1.43); 47.63% of the study population had cystatin C above reference levels and 33.1% of patients were nonresponders to clopidogrel. No correlation was found between clopidogrel efficacy assessed with the VASP index and kidney function assessed with cystatin C (Spearman r = -0.070, p = 0.248). Based on cystatin C the proportion of nonresponders to clopidogrel was 34.4% versus 31.9% (p = 0.702) in patients with impaired renal function compared to normal renal function, respectively. The proportion of clopidogrel nonresponders did not differ (p = 0.902) among groups with normal (28.8%), mildly impaired (34.8%), moderately impaired (32.9%), and severely impaired (34.8%) renal function. In conclusion, renal function assessed by cystatin C does not predict clopidogrel efficacy. Renal dysfunction is a complex entity and its significant relation to stent thrombosis cannot be explained simply by a decrease in clopidogrel efficacy.

Primary angioplasty in acute myocardial infarction with right bundle branch block: should new onset right bundle branch block be added to future guidelines as an indication for reperfusion therapy?

AIMS: The current guidelines recommend reperfusion therapy in acute myocardial infarction (AMI) with ST-segment elevation or left bundle branch block (LBBB). Surprisingly, the right bundle branch block (RBBB) is not listed as an indication for reperfusion therapy. This study analysed patients with AMI presenting with RBBB [with or without left anterior hemiblock (LAH) or left posterior hemiblock (LPH)] and compared them with those presenting with LBBB or with other electrocardiographic (ECG) patterns. The aim was to describe angiographic patterns and primary angioplasty use in AMI patients with RBBB. METHODS AND RESULTS: A cohort of 6742 patients with AMI admitted to eight participating hospitals was analysed. Baseline clinical characteristics, ECG patterns, coronary angiographic, and echocardiographic data were correlated with the reperfusion therapies used and with in-hospital outcomes. Right bundle branch block was present in 6.3% of AMI patients: 2.8% had RBBB alone, 3.2% had RBBB + LAH, and 0.3% had RBBB + LPH. TIMI flow 0 in the infarct-related artery was present in 51.7% of RBBB patients vs. 39.4% of LBBB patients (P = 0.023). Primary percutaneous coronary intervention (PCI) was performed in 80.1% of RBBB patients vs. 68.3% of LBBB patients (P< 0.001). In-hospital mortality of RBBB patients was similar to LBBB (14.3 vs. 13.1%, P = 0.661). Patients with new or presumably new blocks had the highest (LBBB 15.8% and RBBB 15.4%) incidence of cardiogenic shock from all ECG subgroups. Percutaneous coronary intervention was done more frequently (84.8%) in patients with new or presumably new RBBB when compared with other patients with blocks (old RBBB 66.0%, old LBBB 62.3%, new or presumably new LBBB 73.0%). In-hospital mortality was highest (18.8%) among patients presenting with new or presumably new RBBB, followed by new or presumably new LBBB (13.2%), old LBBB (10.1%), and old RBBB (6.4%). Among 35 patients with acute left main coronary artery occlusion, 26% presented with RBBB (mostly with LAH) on the admission ECG. CONCLUSION: Acute myocardial infarction with RBBB is frequently caused by the complete occlusion of the infarct-related artery and is more frequently treated with primary PCI when compared with AMI + LBBB. In-hospital mortality of patients with AMI and RBBB is highest from all ECG presentations of AMI. Restoration of coronary flow by primary PCI may lead to resolution of the conduction delay on the discharge ECG. Right bundle branch block should strongly be considered for listing in future guidelines as a standard indication for reperfusion therapy, in the same way as LBBB.

Platelet gene polymorphisms and risk of bleeding in patients undergoing elective coronary angiography: a genetic substudy of the PRAGUE-8 trial.

AIM: Utilization of cardiac catheterization has increased dramatically over time. Bleeding is a major prognostic predictor after percutaneous coronary catheterization procedures. This study aimed to assess the impact of eight polymorphisms of genes encoding platelet receptors and enzymes on the risk of bleeding in patients undergoing elective coronary angiography (CAG). METHODS: Polymorphisms of platelet receptors, GP Ia (807C>T, rs1126643), GP VI (13254T>C, rs1613662), GP IIIa (HPA-1, rs5918), PAR-1 (IVS-14A>T, rs168753), P2Y(12) (34C>T, rs6785930 and H1/H2 haplotype, rs2046934), and genetic variations of the gene coding for cyclooxygenase-1 (COX-1) (-842A>G, rs10306114 and 50C>T, rs3842787) were studied. The frequencies of gene polymorphisms carriers were investigated in 696 patients undergoing elective CAG because of suspected or proven stable coronary artery disease. Genotyping was done using PCR, followed by melting curve analysis with specific fluorescent hybridization probes. RESULTS: In patients undergoing elective CAG (without ad hoc percutaneous coronary intervention (PCI) and without clopidogrel pretreatment) a significant association was found between bleeding risk and variations in the gene coding for COX-1 (-842A>G and 50C>T) (both p=0.013). Six other investigated polymorphisms did not show any influence on bleeding complications. After controlling for potential bleeding confounders, the association between COX-1 gene polymorphisms (-842A>G and 50C>T) and bleeding risk remained statistically significant (both odds ratios 12.1, p=0.012). CONCLUSION: Cyclooxygenase-1 -842G and 50T alleles significantly contribute to the risk of bleeding complications in patients undergoing elective CAG. Genetic testing is able to influence the safety of diagnostic cardiac catheterization in large numbers of low risk patients with borderline indications.