By Graham Walker, MD

The second year of medical school can be summarized in one word: mnemonics. The first year felt like drinking from a garden hose, but the second was definitely drinking from a fire hose. I vaguely remember coming up with some of the most esoteric and random ways to recall the different types of parasitic worms, but nowadays there’s only a few I still recall: MUDPILES for metabolic acidosis, AEIOU-TIPS for altered mental status, and, of course, MONA for acute coronary syndromes.

MONA was queen. Nothing summed up the medical student’s experience of knowing how to “save a life” more than giving a patient the right medicines for a heart attack, and damn if I wasn’t going to make sure all my patients got their Morphine, Oxygen, Nitrates, and Aspirin.

But unfortunately, my dear colleagues, MONA is on her deathbed, comfort care only, and we may be left with only the tried and true aspirin very soon. Let me tell you why.

Morphine: Moribund

Our tried and true friend may have its days numbered for acute coronary syndromes. You may have learned about coronary vasodilation and decreased oxygen demand with morphine, but when you look at actual outcomes, the data aren’t so peachy any more. Some even worry that morphine is just masking ongoing pain.

n The CRUSADE registry compared patients receiving morphine with those not receiving morphine, and suggested a higher adjusted risk of death even when doing their best to match these patients, but this was not randomized or blinded. (Am Heart J 2005;149[6]:1043; http://1.usa.gov/1GUelQn .)

n Morphine seems to have drug-drug interactions with several of the antiplatelet agents, slowing their time of onset or concentration. (J Am Coll Cardiol 2014;63[7]:630, http://1.usa.gov/1KtIsWs ; J Am Coll Cardiol 2015;65(10_S), http://bit.ly/1MREe8D ; Circulation 2013;128:A11449, http://bit.ly/1U25tBp .)

n When you look at STEMI patients’ hearts post-PCI via MRI and compare those who received morphine with those who did not, morphine was an independent risk factor for bigger infarct size and lower salvageable myocardium. (Clin Res Cardiol 2015 Mar 1. [Epub ahead of print]; http://bit.ly/1VIRSRc .)

Some experts are now recommending avoiding morphine if and when possible and really trying to control symptoms with nitrates, only recommending morphine for refractory or severe chest pain. Let’s be clear: No one is saying active chest pain is OK. The goal is still to find ways to make patients chest-pain-free. But if there are alternative ways to make a patient chest-pain-free, they may be preferred. (Eur Heart J Acute Cardiovasc Care 2015 Apr 22 [Epub ahead of print]; http://bit.ly/1JKuKZF .)

O 2 : Not for You

I know, it’s heresy, but let’s at least start with this reminder: Oxygen is a drug. Our bodies are adapted to about 21 percent of the stuff in the air. James Roberts, MD, reported on this in February’s issue of EMN ( http://bit.ly/1Jnjqbd ) so I won’t steal his fantastic thunder, but take a look at the AVOID trial, which randomized 441 STEMI patients to oxygen versus no oxygen if you weren’t hypoxic, keeping everything else the same. CK levels were higher and infarct size was larger in those getting oxygen. There were also more repeat MIs and arrhythmias in those receiving oxygen, but there was a trend toward lower mortality if you received oxygen as well.

I don’t know that any guideline body has officially made up its mind about what to do with these data, but it’s worth knowing about. (Interestingly, this has been looked at in stroke, and no benefit was seen to supplemental O 2 , either.) (“SO 2 S: No Benefit of Routine Oxygen in Acute Stroke,” Medscape; http://wb.md/1LNx6eM .)

Nitrates: No Mortality Benefit

This is probably the topic we know the most about: Nitrates don’t change outcome. GISSI-3 looked at nitrates in the early 1990s along with lisinopril, and showed no mortality benefit, and barring the contraindications we all know about as emergency physicians (inferior and especially right-sided MIs causing profound hypotension, for example), nitrates haven’t come up in the literature as potentially harmful ,just not beneficial. (Lancet 1994;343[8906]:1115; http://1.usa.gov/1D1SMm1 .)

Aspirin: Amen!

Salicylic acid is our savior, luckily. Morphine, oxygen, and nitrates have started to show their wear with age, but aspirin’s still got it. Aspirin reduces your patients’ risk of death (NNT for STEMI: 42 [treat 42 people, save one life), and it’s dirt cheap. Remember to crush it or have patients chew it to get a more rapid onset. (Lancet 1988;2[8607]:349; http://1.usa.gov/1D1SH1P .)