Monday, February 9, 2015

Study group discussion: Why NSAIDs are avoided in MI, why aspirin is an exception

Why NSAIDs are not given in acute Myocardial Infarction?

I think it's because they're not strong enough and don't act fast enough. The pain relief lowers the stress on the heart.

NSAIDs hamper the process of scar formation after MI, there is chance of  wall rupture.

Steroids too.

Yes.

Isn't aspirin an NSAID? We give that in MI.

Yes, aspirin should be an NSAID. It's not a steroid, and it's anti-inflammatory.  So I don't see any reason why it wouldn't be one.
Edit, I just looked it up on the internet, and it's listed as one of the most common NSAIDs (along with ibuprofen and naproxen).

You give aspirin in antiagregation range. In order to help  dissolve the cloth and prevent new ones.

Well, I asked in reference to the comment on why NSAIDs should not be given in MI. But I read and found out that Aspirin is permitted as an exception.
None other NSAID should be given.
Aspirin is essential in the management of patients with suspected STEMI and is effective across the entire spectrum of acute coronary syndromes. Rapid inhibition of cyclooxygenase-1 in platelets followed by a reduction of thromboxane A2 levels is achieved by buccal absorption of a chewed 160–325-mg tablet in the Emergency Department. This measure should be followed by daily oral administration of aspirin in a dose of 75–162 mg.
Glucocorticoids and nonsteroidal anti-inflammatory agents, with the exception of aspirin, should be avoided in patients with STEMI. They can impair infarct healing and increase the risk of myocardial rupture, and their use may result in a larger infarct scar. In addition, they can increase coronary vascular resistance, thereby potentially reducing flow to ischemic myocardium.
Source: Harrison.

I think aspirin has a different mechanism to other NSAIDs. Aspirin, can worsen a bleed, for example, but is unlikely to be the direct cause of gi bleeding. I'm assuming it works differently with regards to myocardial repair too.

Non-selective NSAIDs enter the channels in both (cox1 and 2) enzymes and, except for aspirin, block them by binding with hydrogen bonds to an arginine halfway down. This reversibly inhibits the enzymes by preventing the access of arachidonic acid. Aspirin is unique in that it acetylates the enzymes (at serine 530) and is therefore irreversible.

I was taught that aspirin is the only NSAID you give in myocardial Infarction.
You have to give it as soon as possible because the latter you give, the benefit decreases.
That is why the first step in management of a patient with MI is aspirin (Not O2, not nitroglycerin, not beta blockers, not morphine) because aspirin has a time dependent mortality benefit.

Aspirin and clopidogrel!

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