Red blood cell and platelet microparticles in myocardial infarction patients treated with primary angioplasty.

BACKGROUND: Red blood cell and platelet microparticles (RBCm and PLTm, respectively) have drawn research attention as to their potential prothrombotic and vasoconstrictive effects in experimental settings. However, the relevance of circulating microparticles in clinical settings is largely undetermined. METHODS: Circulating microparticles were quantified with a flow cytometric method in blood samples from consecutive STEMI patients after primary PCI. A matched cohort of healthy volunteers was used to derive reference values for comparison. STEMI patients were followed for 6 months for a composite clinical endpoint. RESULTS: Fifty-one STEMI patients (age 59.8 ± 8.8 years) and 50 controls (age 56.2 ± 9.2 years; p=0.155) were enrolled. RBCm concentration was 18,198 ± 6062/µl in the reference cohort versus 33,740 ± 21,169/µl in STEMI patients (p<0.001). RBCm count was not correlated to total RBCs (standardized beta 0.018; p=0.861). PLTm did not differ between groups (17,529 ± 16,292/µl in STEMI patients versus 14,372 ± 6211/µl in controls; p=0.203). RBCm c-statistic was 0.832 (95% confidence interval 0.720 to 0.944), while PLTm prognostic value was not statistically significant (c-statistic 0.614, 95% confidence interval 0.444 to 0.784). In the multivariate analysis, RBCm concentration was independently associated with the occurrence of the clinical endpoint, after adjustment for age, ejection fraction, serum creatinine and presence of diabetes (adjusted p=0.034). CONCLUSIONS: The present study demonstrates for the first time that erythrocyte microparticles are elevated in patients with STEMI treated with primary PCI, with levels approximately double those measured in a reference population of healthy volunteers, and their concentrations appear to be positively associated with adverse clinical events.

Radial artery flow-mediated dilation predicts arterial spasm during transradial coronary interventions.

BACKGROUND: Transradial coronary catheterization has emerged over the last years as a favorable catheterization practice, based on evidence that it is associated with less vascular complications and shorter hospital stays. However, access site crossover appears to be more frequent when the initial route is the transradial one, one of the main reasons being arterial spasm. We hypothesized that radial flow-mediated dilation (FMD) measurements could be used as a preprocedural method to assess the likelihood of arterial spasm. METHODS: The study population consisted of patients scheduled for transradial diagnostic catheterization in whom ad hoc percutaneous coronary intervention (PCI) was performed. FMD was measured 1-2 days before PCI. The primary endpoint of the study was operator-defined (operators were blinded as to the FMD results) radial artery spasm. RESULTS: A total of 172 patients (110 male, age 65.3 ± 9) were included. Radial artery spasm was recorded in 13 patients (7.6%). FMD showed a very significant univariate association with the occurrence of spasm (P < 0.001) and was the most important predictor of spasm in the multivariate logistic regression analysis (beta -3.15; P < 0.001), followed by baseline radial artery diameter (P = 0.04), the number of catheters used (P = 0.049) and the administered volume of contrast medium (P = 0.017). CONCLUSION: Preprocedural FMD is a significant predictor of arterial spasm before elective transradial PCI. It is a low cost, safe, and feasible noninvasive modality, whose results might be taken into account when deciding on the vascular access route for an elective procedure, the size of sheaths or catheters to be used or the intensity of antispasm medication.