042: Real life dual antiplatelet therapy after NSTE-ACS in a Tunisian population: is there a need for 12 months of treatment?

AimEven if the recommended duration for dual antiplatelet therapy (DAT) after non ST elevation acute coronary syndromes (NSTE-ACS) is 12 months, evidence concerning the benefit of clopidogrel adjunction especially beyond 3 months remains poor. The aim of the study was to assess the effective clopidogrel intake and the incidence of a composite endpoint including all causes death and non fatal myocardial infarction in a Tunisian population after NSTE-ACS.MethodsWe included patients admitted for NSTE-ACS in our department between January 2010 and August 2011 for whom long term evaluation was possible. In-hospital deaths were excluded (including post operative deaths). By telephone follow up, we evaluated the effective DAT duration and the occurrence of all causes death and non-fatal myocardial infarction.ResultsOne hundred thirty patients were included. Mean (SD) follow up was 261 (99) days. DAT was effectively observed during 94(103 days (extremes ranging from 0 to 360 days). Angioplasty was performed in 51.5%, coronary artery bypass graft in 8.4% and medical therapy was considered in 40.1%. In 35 (26.9%) patients, aspirin was the only antiplatelet therapy taken after discharge although DAT was prescribed; 46.9% of the patients took the DAT for more than 3 months, and 23.1% for more than 6 months. The composite endpoint occurred in 6 (4.6%) patients: 2 deaths (both of cardiac causes) and 4 myocardial infarctions. Three of them were under DAT, and the 3 others remained event free during 7, 240 and 270 days after clopidogrel withdrawal. These findings suggest that DAT does not protect against death or myocardial infarction. The rebound phenomenon after clopidogrel withdrawal isn’t patent in our population.ConclusionIn the Tunisian context, DAT observance is poor after NSTE-ACS. Death and non fatal myocardial infarction don’t seem to be reduced by DAT and the rebound phenomenon after clopidogrel withdrawal isn’t patent. This may be in part attributed to the small sample of population and the predominantly low risk (as assessed by TIMI risk score), but larger studies are needed to strengthen the evidence for DAT after NSTE-ACS

Surface Finish and Residual Stresses Induced by Orthogonal Dry Machining of AA7075-T651

The surface finish was extensively studied in usual machining processes (turning, milling, and drilling). For these processes, the surface finish is strongly influenced by the cutting feed and the tool nose radius. However, a basic understanding of tool/surface finish interaction and residual stress generation has been lacking. This paper aims to investigate the surface finish and residual stresses under the orthogonal cutting since it can provide this information by avoiding the effect of the tool nose radius. The orthogonal machining of AA7075-T651 alloy through a series of cutting experiments was performed under dry conditions. Surface finish was studied using height and amplitude distribution roughness parameters. SEM and EDS were used to analyze surface damage and built-up edge (BUE) formation. An analysis of the surface topography showed that the surface roughness was sensitive to changes in cutting parameters. It was found that the formation of BUE and the interaction between the tool edge and the iron-rich intermetallic particles play a determinant role in controlling the surface finish during dry orthogonal machining of the AA7075-T651 alloy. Hoop stress was predominantly compressive on the surface and tended to be tensile with increased cutting speed. The reverse occurred for the surface axial stress. The smaller the cutting feed, the greater is the effect of cutting speed on both axial and hoop stresses. By controlling the cutting speed and feed, it is possible to generate a benchmark residual stress state and good surface finish using dry machining