Prevalence and risk factors of clopidogrel non-response among Saudi patients undergoing coronary angiography.

OBJECTIVES: To estimate the prevalence of clopidogrel non-response and identify its risk factors among Saudi patients.  METHODS: This cross-sectional study was conducted at Prince Sultan Cardiac Center, Riyadh, Kingdom of Saudi Arabia between January and June 2013, to assess the degree of platelet inhibition using the VerifyNow assay (Accumetrics, San Diego, CA, USA) after receiving clopidogrel standard loading dose. Clopidogrel resistance was defined as ≤15% platelet inhibition or greater than 213 P2Y12 reaction units (PRU).  RESULTS: Three hundred and four patients were included in the study. The mean age was 60.3 ± 11.4 years, and 73% were males. Clopidogrel doses were 300 mg (57%), 600 mg (27%), and 75 mg (16%). All patients used aspirin (81 mg in 94%). Approximately 66% (200/304) showed in vitro clopidogrel non-response, 54% had low platelet inhibitions, and 61% had high post-loading PRU. Using multivariate regression analysis that included all significant characteristics; only diabetes (odds ratio [OR]: 2.36, 95% confidence interval [CI]: 1.30-4.27, p=0.005) and higher preloading PRU (OR: 2.39, 95% CI: 1.40-4.11, p=0.002) remained significantly associated with higher clopidogrel non-response while myocardial infarction (OR: 0.34, 95% CI: 0.15-0.81, p=0.014) remained significantly associated with lower clopidogrel non-response. The associations of morbid obesity and diuretics use with higher clopidogrel non-response were slightly attenuated.   CONCLUSION: Our findings indicate a high rate of clopidogrel in-vitro non-response among Saudi patients undergoing coronary angiography.

Predictors of radial artery size in patients undergoing cardiac catheterization: insights from the Good Radial Artery Size Prediction (GRASP) study.

BACKGROUND: Radial artery occlusion occurs after transradial cardiac catheterization or percutaneous coronary intervention. Although use of a sheath larger than the artery is a risk factor for radial artery occlusion, radial artery size is not routinely measured. We aimed to identify bedside predictors of radial artery diameter. METHODS: Using ultrasound, we prospectively measured radial, ulnar, and brachial artery diameters of 130 patients who presented for elective percutaneous coronary intervention or diagnostic angiography. Using prespecified candidate variables we used multivariable linear regression to identify predictors of radial artery diameter. RESULTS: Mean internal diameters of the right radial, ulnar, and brachial arteries were 2.44 ± 0.60, 2.14 ± 0.53, and 4.50 ± 0.88 mm, respectively. Results for the left arm were similar. The right radial artery was larger in men than in women (2.59 vs 1.91 mm; P < 0.001) and smaller in patients of South Asian descent (2.00 vs 2.52 mm; P < 0.001). Radial artery diameter correlated with wrist circumference (r(2) = 0.26; P < 0.001) and shoe size (r(2) = 0.25; P < 0.001) and weakly correlated with height (r(2) = 0.14; P < 0.001), weight (r(2) = 0.18; P < 0.001), body mass index (r(2) = 0.07; P = 0.002), and body surface area (r(2) = 0.22; P < 0.001). The independent predictors of a larger radial artery were wrist circumference (r(2) = 0.26; P < 0.001), male sex (r(2) = 0.06; P < 0.001), and non-South Asian ancestry (r(2) = 0.05; P = 0.006; final model r(2) = 0.37; P < 0.001). A risk score using these variables predicted radial artery diameter (c-statistic, 0.71). CONCLUSIONS: Wrist circumference, male sex, and non-South Asian ancestry are independent predictors of increased radial artery diameter. A risk score using these variables can identify patients with small radial arteries.

Efficacy of a single dose intravenous heparin in reducing sheath-thrombus formation during diagnostic angiography: A randomized controlled trial.

BACKGROUND: Femoral arterial sheath thrombosis and distal embolization are well-recognized complications of cardiac catheterization but the occlusion is extremely rare. Heparinized saline flushes are used during diagnostic coronary angiography to prevent thrombus formation within the sheath lumen. However, the use of prophylactic intravenous heparin following the femoral arterial sheath insertion is controversial. The aim of this study is to evaluate the effectiveness of 2000 units of intravenous heparin bolus in comparison to a saline placebo on the thrombus formation within the arterial sheath during the diagnostic coronary angiography. METHODS: Eligible patients were randomized to receive either a study drug or placebo at the time of femoral sheath insertion. The sheath was aspirated and flushed for any presence of thrombus after each catheter exchange and at the end of the procedure. Five milliliters of blood were extracted and visualized on clean gauze followed by a saline flush. The primary end-point was the effectiveness of the study drug on reducing the incidence of sheath-thrombus formation. RESULTS: Three hundred and twenty patients were randomized into two arms. Three hundred and four patients were analyzed: 147 patients in heparin arm and 157 patients in placebo arm after exclusion of 13 patients in heparin arm and three in placebo arm because of incomplete reports. The baseline characteristics were similar and sheath-thrombi formation was observed in 20% of the total cohort. Of the heparin arm, 12% (19 patients) developed sheath-thrombus formation, whereas 26% (42 patients) in the placebo arm, p-value = 0.002. An adjusted logistic regression model showed that the only predictor for the sheath-thrombus formation was the study drug (i.e. heparin). The odds ratio of developing a thrombus in the control arm was 2.5 (95% CI: 1.4-4.5, p = 0.003). There were no bleeding events observed. CONCLUSION: The risk of thrombus formation is significant and intravenous heparin significantly reduced thrombus formation during diagnostic coronary angiography, with no excess bleeding events.