No abstract

Background Dual antiplatelet therapy is recommended after coronary stenting to prevent thrombotic complications, yet the benefits and risks of treatment beyond 1 year are uncertain. Methods Subjects were enrolled after a drug-eluting coronary stent procedure. After 12 months of thienopyridine (clopidogrel bisulfate [Plavix] or prasugrel [Effient/Efient]) with aspirin, subjects were randomized to continued thienopyridine or placebo for another 18 months; all continued aspirin. The co-primary effectiveness end points were stent thrombosis and major adverse cardiovascular and cerebrovascular events (a composite of death, myocardial infarction, or stroke) at 12 to 30 months. The primary safety end point was moderate or severe bleeding. Results Subjects (N=9,961) were randomized to continued thienopyridine or placebo. Continued thienopyridine reduced stent thrombosis (0.4% vs. 1.4%, hazard ratio 0.29, 95% confidence interval [CI] 0.17-0.48, P<0.001) and major adverse cardiovascular and cerebrovascular events (4.3% vs. 5.9%, hazard ratio 0.71, 95% CI 0.59-0.85, P<0.001). Myocardial infarction was reduced (2.1% vs. 4.1%, hazard ratio 0.47, P<0.001). Rates of all-cause mortality in the continued thienopyridine and placebo groups were 2.0 and 1.5%, respectively (hazard ratio 1.36, 95% CI 1.00-1.85, P=0.052). Moderate or severe bleeding was increased with continued thienopyridine (2.5% vs. 1.6%, P=0.001). An elevated hazard for stent thrombosis and myocardial infarction was observed in both groups during the 3 months following thienopyridine discontinuation. Conclusion Dual antiplatelet therapy beyond one year after drug-eluting stent placement significantly reduced the risks of stent thrombosis and major adverse cardiovascular and cerebrovascular events compared with aspirin alone, but was associated with increased bleeding.

In this trial, LAA occlusion was noninferior to warfarin for ischemic stroke prevention or SE >7 days' post-procedure. Although noninferiority was not achieved for overall efficacy, event rates were low and numerically comparable in both arms. Procedural safety has significantly improved. This trial provides additional data that LAA occlusion is a reasonable alternative to warfarin therapy for stroke prevention in patients with NVAF who do not have an absolute contraindication to short-term warfarin therapy.

The crystal structure of nylon 6 (NH (CH2)5CO)p has been determined by interpretation of the x‐ray diffraction patterns given by drawn, rolled fibers. The determination was part of a program to investigate the relation between structure and physical properties, in particular melting point. Nylon 6 melts 50°C. lower than its isomer nylon 66 (NH (CH2)6NH·CO (CH2)4CO)p; it had been suggested that this was due to deficient hydrogen‐bond formation in nylon 6 crystallites. The unit cell contains eight chemical units (NH (CH2)5CO) and is monoclinic with a = 9.56 A., b = 17.24 A., c = 8.01 A., and β = 671/2°. Calculated density = 1.23. Observed density for a drawn monofilament = 1.16. The structure consists of planar chains of CH2 groups and amide groups tilted 7° from the (001) plane. Alternate chains in this plane are oppositely directed, an arrangement which allows all hydrogen bonds to be made perfectly. The hydrogen‐bonded sheets of atoms are packed in an “up‐and‐down” staggered configuration along the c‐axis. Distances between atoms in neighboring molecules are all normal van der Waals contact distances. It appears, from a general survey of polyamide melting points published elsewhere, that the determining factor is the number of CH2 groups between the amide “anchor points”—polymers with odd numbers of CH2 groups melt lower than those with even numbers. The present work shows that the odd number of CH2 groups in this polymer does not lead to deficient hydrogenbond formation, and that the lower melting point of nylon 6 as compared with nylon 66 must be ascribed to some other cause, possibly connected with the propagation of vibrations along odd‐numbered chain segments.

These 5-year outcomes of the PREVAIL trial, combined with the 5-year outcomes of the PROTECT AF trial, demonstrate that LAAC with Watchman provides stroke prevention in nonvalvular atrial fibrillation comparable to warfarin, with additional reductions in major bleeding, particularly hemorrhagic stroke, and mortality. (WATCHMAN Left Atrial Appendage System for Embolic Protection in Patients With Atrial Fibrillation; NCT00129545; and Evaluation of the WATCHMAN LAA Closure Device in Patients With Atrial Fibrillation Versus Long Term Warfarin Therapy; NCT01182441).