For your stock standard NSTEMI, the go to drug of choice is enoxaparin – easy to administer, only twice a day, no ongoing APTT to continually monitor – and effective. Some people, particularly for a STEMI, prefer the old school unfractionated heparin – partly because of previous equivocal evidence, past experience, and because it can be monitored and you can be sure it’s working (remind anyone of the upcoming warfarin vs. the new anticoagulants?). The current ACC/AHA guidelines still have heparin as a class 1 recommendation – but how effective is it? This systematic review and meta-analysis from the BMJ compared the two.
Articles from as far back as 1996 were sourced, with just under 31,000 patients, and only studies using enoxaparin specifically were included (except one study). As you’d expect, the two major outcomes to look at were mortality and major bleeding, during PCI – and the outcome was in favour of enoxaparin. Looking at mortality, there was a 1.66% absolute risk reduction (translating to a relative risk reduction of 34%, and an NNT of 60), and if you look at the STEMI cohort specifically (about a 1/3 of all patients), the ARR goes to 2.91% (RRR 48%). For your average NSTEMI or just stable disease having a PCI, the enoxaparin vs. heparin choice made no difference when it came to mortality (maybe a small trend towards lower mortality with enoxaparin). But what about bleeding? Enoxaparin dropped the major bleeding rate by 1.2% (RRR 20%, NNT 83), and again, the results were even better in the STEMI cohort (ARR 1.9%, RRR 28%, NNT 53).
Why the difference? The authors postulate it might be related to the more stable/predictable pharmacokinetics of enoxaparin, and possibly due to some anti-inflammatory properties that enoxaparin has, not to mention the better bleeding profile.
I still have a few niggling questions on the inclusion and exclusion of studies into the group, and about the effect of enoxaparin vs. heparin together with other drugs used at the same time – but it’s still a great, practice changing article – read it here.
image | Genista
source | BMJ 2012;344:e553