Platelet reactivity and mean platelet volume as risk markers of thrombogenesis in atrial fibrillation.

Atrial fibrillation (AF) is associated with increased risk of thromboembolic complications. One of the markers of the increased risk of hypercoagulable state is platelet hyperreactivity. The aim of the study was to assess impact of arrhythmia on platelet reactivity. METHODS: The study included 36 (mean age 48,3; range 21-60) male patients with lone atrial fibrillation, with exclusion of concomitant diseases known to trigger hypercoagulable state. The AF patients underwent cardioversion to restore sinus rhythm and were subsequently under observation for 1month. Echocardiography, ECG and blood collection was performed before cardioversion (T0) and 4weeks after successful cardioversion (T1). During the study period patients have been contacted and examined every week and 24h ECG monitoring was performed. Platelet reactivity was assessed based on changes of CD62 and CD42b expression on platelet surface after stimulation with thrombin. Also changes in MPV were assessed. RESULTS: In all patients sinus rhythm was maintained at the end of the study period, however in 14 patients recurrences of AF were observed, confirmed by 24h ECG monitoring (atrial fibrillation recurrence group - AFR) and 22 patients maintained sinus rhythm throughout the whole study period (SR group). Mean fluorescence intensity (MFI) of CD62 on thrombin stimulated platelets decreased significantly 4weeks after electrical cardioversion as compared to T0 (48.04±22.42 vs 41.47±16.03; p<0.01). Also MFI of CD42b on thrombin stimulated platelets decreased significantly 4weeks after electrical cardioversion as compared to T0 (22.16±10.82 vs 12.06±5.99; p<0.0001). Platelets reactivity estimated by CD 62 expression in SR group decreased significantly after 4weeks observation (58.01±15.26 vs 46.57±13.44; p<0.001) opposite to AFR group 35.66±21.87 vs 34.54±16.4; p-ns). Moreover there were significant differences between basal reactivity during AF between SR and AFR groups (58.01±15.26 vs 35.66±21.87; p-0.01). MFI of CD42b on thrombin stimulated platelets decreased significantly both in AFR and SR groups (22.05±11.36 vs 13.8±6.03; p<0.001 and 21.87±14.18 vs 10.04±5.09; p<0005). MPV decreased significantly 4weeks after electrical cardioversion as compared to T0 (8.81±0.19 vs 8.42±0.14; p<0.0001). CONCLUSION: The changes of platelet reactivity to thrombin observed after restoration of sinus rhythm in patients prove that arrhythmia intrinsically leads to increased reactivity of platelets.

[Homocystein serum levels and lipid parameters in children with atherosclerosis risk factors]. / Homocysteina i wybrane parametry przemiany lipidowej u dzieci z czynnikami ryzyka miazdzycy tetnic.

UNLABELLED: Atherosclerosis is a disease of adult patients, however, it begins in childhood and progresses from fatty streaks to raised lesions in arteries in adolescence and young adults. Clinical manifestation of atherosclerosis in adulthood depends on the risk factors such as: lipid disorders, obesity, hypertension, smoking habits and family history of CHD. High serum homocysteine concentration is increasingly recognised as a new risk factor for atherosclerosis and other vascular diseases. Atherogenic effect of homocystein is related to cytotoxin action on the endothelial cells and their function. The aim of this study was to estimate relations between the homocysteine serum concentration and the lipid levels in children with atherosclerosis risk factors. MATERIAL AND METHODS: The study was carried out on 48 children with atherosclerosis risk factors. The control group consisted of 25 healthy childrens. Total cholesterol (TC), Triglycerides (TG), HDL-C, LDL-C were determined by enzymatic method. Concentration of homocysteine was estimated by immunoenzymatic method (ELISA). RESULTS: Obesity, lipid disorders, and hypertension were the most frequent risk factors in the investigated children. Statistically significant higher concentration of TC, LDL-C, TG and lower HDL-C were observed in children with atherosclerosis risk factors. No significant differences in homocystein concentration were observed in the investigated groups, but homocystein concentration was significantly higher in group of children with atherosclerosis risk factors. CONCLUSION: We observed that increased number of the risk factors is followed by high homocystein concentration in the serum.