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.

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.

Lessons from the SYNTAX trial.

Despite the fact that CABG is the standard of care for patients with multivessel coronary arteries and/or left main stem stenosis, PCI has become a rival to CABG in patients with multivessel coronary artery disease or left main disease. However, the need for repeat revascularization, in-stent stenosis and thrombosis remain the achilis heal of PCI. SYNTAX trial randomized patients with left main disease and/or three-vessel disease to PCI with TAXus stent or CABG with the concept that PCI is not inferior to CABG. At 1 and 2 years follow up, MACCE was significantly increased in PCI patients mainly attributed to increased rate of repeat revascularization; however, stroke was significantly more with CABG. The composite safety endpoint of death/stroke/MI was comparable between the 2 groups. Therefore the criterion for non-inferiority was not met. What we learn from SYNTAX is that multi disciplinary team approach should be the standard of care when recommending treatment in more complex coronary artery disease. SYNTAX makes interventionists and surgeons come together, it may set the benchmark for MVD revascularization. PCI and CABG should be considered complementary rather than competitive revascularization strategies. There is no substitute for sound clinical judgment that takes into account the patient's overall clinical profile, functionality, co-morbidities, as well as the patient's coronary anatomy. The SYNTAX Score should be utilized to decide on treatment of patients with LM/MVD. Patients with low and intermediate score can be treated with PCI or CABG with equal results. Those with high score do better with CABG. SYNTAX trial showed that 66% of patients with 3VD or LMD are still best treated with CABG. In the remaining 1/3 of patients with low syntax score, PCI may be considered as an alternative to surgery. Finally, medical treatment should be optimized in patients going for CABG.