Author: Catherine Buckley MD
There are about 8 – 10 million ED visits with the chief complaint of chest pain per year in the US. (Owens et al.)10 billion dollars are spent on chest pain, 10% of which goes to the work up for ACS diagnosis. Yet somehow despite these millions we still miss 1-2% of MIs. Numbers! But lets talk about tools and then what to do once you’ve caught ACS based on a marvelous joint lecture by Drs Sprouse and Heinrich.
Decision tools
Inititally, per guidelines everyone who presented to the ED with chest pain needed to undergo provocative testing within 75 hours. So every one was either admitted or ensured follow up with cardiology. EVERYONE. Then TIMI came around.
The TIMI research showed that some people could be safely discharged without seeing cardiology with a low risk for an adverse event in the next thirty days. But the issue with TIMI was that only 5-10% of people met this low risk criteria. (Than et al.) So though sensitive, TIMI is not very specific.
Then along came the HEART score. 5 criteria are considered to give a score that is either high, moderate or low risk for adverse event in the next 6 weeks. The way that this score is written, anyone with a moderate or high risk needs provocative testing: so go on ahead and admit. I’d like to say that HEART is the best (mainly because the anagram actually makes sense) but it still has a 1.7% miss rate. ( People who are sent home with a low risk chest pain dx, who go on to have an adverse event in the next 6 weeks) (Six et al) SO Mahler et al, did one further step, adding a 3 hr repeat of EKG and troponin and further dropped the miss rate to .9%.
The Rush team has spent many a journal club night lost in the discussion of the use of these tools, clinical decision making, and comfort levels with risk for patients. And the nugget I’ve been able to take from this is: there is no right or wrong answer. You will have or develop your own decision making pattern and your own comfort levels. The important thing to remember is that there are tools to help you, but that even low risk patients do not have zero risk. So if this is a patient with poor follow up abilities or poor understanding of the risks of chest pain, then you should consider admission for further cardiac work up inpatient. AKA use the tools but don’t get sucked into check-boxing-bliss, every patient is different.
NSTEMI Tx
So let’s say that you were working up the HEART score, patiently waiting on your labs when suddenly, despite no EKG changes, the troponin returns elevated. You think that maybe this CKD patient just hasn’t excreted their trop. So you repeat the troponin in 2-3 hours and find a 20% increase. NSTEMI. Done. Great.
Remember MONAH B?
Good. Now forget her.
A lot of these treatments have been found to worsen outcomes. Let’s take a walk with old MONAH B for a bit.
Morphine: Back in the day with the CRUSADE initiative, morphine was actually found to increase mortality (Meine et al). The thought is that by covering up the pain, concerning changes in patient’s presentation were muted. Furthermore, Morphine has been found to decrease the efficacy of other meds that patient should be getting (i.e. Ticagrelor) So use your clinical decision, if patient’s pain is not improved with Nitro and they continue to have inexhaustible extreme pain- then you might need to treat.
Oxygen: Another no. It turns out that O2 has a paradoxical effect on the oxygenation of the heart, actually increasing coronary resistance, decreasing cardiac output and stroke volume and also causing reperfusion injury due to increase oxygen free radicals. In all good ol’ O2 has been shown to increase infarct size and possibly increase mortality risk. (Raut and Maheshwari) So, if they need it (i.e. Sats less than 90%) go ahead and give it- but be discerning because we may actually be doing harm here.
Nitroglycerin: Definitely. Give this. See if it helps with pain. Give .4mg every 5 min, or go ahead and start a drip (40mcg per minute) especially if there are signs of heart failure. But remember the contraindications — not in posterior MI, not if taking phsophodiesterace inhibitiors.
Aspirin: Yes. Do this. And add on Ticagrelor 180mg or Plavix for dual antiplatelet treatment.
Heparin: This one does need a little bit of conversation with your cardiologist. If this patient is not going to undergo PCI- give lovenox instead. This will likely vary hospital to hospital- definitely don’t hold up PCI for the heparin but patient does need it.
Beta-Blockers. Don’t give if bradycardia, CHF, reactive airway disease. But if there are no contraindications, go ahead with 25 mg oral metorprolol.
So change the mnemonic to ‘NAH (maybe B, O: sometimes M)’ ? Not quite as catchy I guess.
STEMI
We are going to avoid EKGs at this time because otherwise this post will never end.
But once you have a STEMI, follow your STEMI protocol at your hospital. Basically – send patient to the cath lab if they can get door to device time in 90 minutes. If you are working at a non-PCI center then your criteria changes slightly. If you can get them to a PCI hospital and to the device in less than 2 hours; then get that paperwork started and get them out of there! But if this is not practical, i.e. you do not have a nearby or reachable PCI center for whatever reason, then give the fibrinolytic agent within 30 minutes of arrival. But go ahead and start working on that transfer because you will need to transfer emergently if reperfusion fails. Even if your TPA does the trick – you get a few more hours leeway ( 3-24hrs for angiography and revascularization) – but you might as well get them out of your ED and over to where they ought to be sooner rather than later.
These patients will be discharged on a hefty bundle of meds including Beta blockers, Ace Inhibitor, Spirinolactone, high dose atorvastatin, dual anti-platelet therapy. As above, you will need to know the protocol of your hospital (or transfering hospital) and cardiology team to decide whether patient gets dual anti-platelet meds and/or heparin prior to, en route, or at the cath lab.
Don’t Forget
Females are more likely to present later, they have a longer door to balloon time and they are less likely to receive ASA. Minority patients and elderly patients are much more likely to delay pre-hospital care, which extends the average ambulance call time to 1.5hrs. Patients discharged with a missed MI/ ischemia are more likely to be younger, female, nonwhite. (Jones and Slovis.)
Why does this matter? Because this is part of our responsibility. We need to be aware of determinants that affect care of our patients, to acknowledge that we have underlying biases and blind spots toward ourselves and others that may be affecting their outcomes. I’m not going to be able to solve this problem with a blog post, but being aware and helping others be aware is at least a start. So remember: not every heart attack is an old man shoveling snow, so keep eyes open and your heart full (not of plaques.)
Citations
Jones, R. Slovis, C. Pitfalls in evaluating the low-risk chest pain patient. Emergency Medicine Clinicals North Am. 2010 28(1):183-201
Mahler, S. Riley, R. Hiestand, B. Russelg, G. Hoekstra, J. Lefebvre, C. Nicks, B. Cline, D. Askew, K. Elliot, S. Herrington, D. Burke, G. Miller, C. The HEART Pathway randomized trial: identifying emergency department patients with acute chest pain for early discharge.Circulation, Cardiology Quality and Outcomes. 2015; 8(2):195-203.
Meine, T. Roe, M. Chen, A. Patel, M. Washam, J. Ohman, E. Peacock, W. Pollack, C. Gibler, W. Peterson, E. Association of intravenous morphine use and outcomes in acute coronary syndromes: results from the CRUSADE Quality Improvement Initiative. American Heart Journal. 2005 Jun;149(6):1043-9.
Owens P, Barrett M, Gibson T, Andrews R, Weinick R, Mutter R. Emergency department care in the United States: a profile of national data sources. Annals Emergency Med. 2010; 56:150–165.
Raut, M. Maheshwari, A. Oxygen supplementation in acute myocardial infarction: To be or not to be? Annals of Cardiac Anaesthesia. 2016; 19(2):342-344.
Six, A. Backus, B. Kelder, J.Chest pain in the emergency room: value of the HEART score. Netherlands Heart Journal. 2008 Jun; 16(6): 191–196.
Than, M. Cullen, L. Reid, C. Lim, S. Aldous, S. Ardagh, M. Peacock, W. Parsonage, W. Ho, H. Ko, H. Kasliwal, R. Bansal, M. Soerianata, S. Hu, D. Ding, R. Hua, Q. Seok-Mon, K. Sritara, R. Chieu, T. Tsai, K. Chu, F. Chen, W. Chang, W. Flaws, D. George, P. Richards, A. A 2-h diagnostic protocol to assess patients with chest pain symptoms in the Asia-Pacific region (ASPECT): a prospective observational validation study. Lancet. 2011 26;377(9771):1077-84.
William Fiebig
Catherine Buckley