Sunday, November 17, 2013

Low Risk Chest Pain and the Accelerated Protocols

This is a monster topic and the pain of our existence in the ED. We see CP patients left and right and some can represent a challenge to even the seasoned clinician. The crushing retro-sternal CP in a 66 y/o sweaty-obese-hypertensive-diabetic-smoker is the easy one, even the intern knows that patient is not going home b/c the probability of ACS is so high, that even normal tests are likely to be falsely negative. The 21 y/o with chest pain and large bruise after being hit with a baseball is going home b/c he doesn't have ACS. Those too are easy... the hard cases are the ones in between, when the story is not totally convincing, the exams is not helpful, the EKG is not conclusive and the patient may have some risk factors or positive family history. As the gate keepers and stewards of the health care system, we must move these patients through the department efficiently and effectively, without missing a single case. Right?

Multiple risk assessment tools have been developed to help us identify low risk CP patients who are safe for discharge and can be followed up as outpatient. Some of these score systems have been validated and the basic idea is to quickly identify patients who are a very low risk for adverse events in a short period of time (usually 2 hrs) instead of the usual 8-12 hr protocols. A key concept to understand is that we do not rule out ACS in the ED, a patient with 90% stenosis can graduated from the department with 3 sets of negative cardiac markers and non-diagnostic EKG's. So we re-stratify patients to a level of risk that is acceptable (and defendable) that will guide further management.

It is not my intention to write a meta-analysis given the heterogeneity of these individual studies in their methodology, protocols and type of biomarker used. But here is a quick summary of some of the main studies evaluating accelerated re-stratification protocols (Rajeev... I hope this answers your question)

The Lancet. March 2011 (http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2811%2960310-3/fulltext) was a prospective validation study of 3582 patient in Australasia using a TIMI score of 0 (http://www.mdcalc.com/timi-risk-score-for-uanstemi/), non-ischemic EKG, negative biomarkers at 0 and 2 hr time. If all of those criteria were fulfilled, these patients were considered safe for discharge. Out of the initial pool of patients, 352 met criteria for discharge and only 3 had a cardiovascular negative outcome within 30 days defined as AMI, need for revascularization or death. This gives a 99.3% sensitivity, a 99.1% NPV and specificity of only 11%.

JAMA, December 2011 (http://www.ncbi.nlm.nih.gov/pubmed/22203537?access_num=22203537&link_type=MED&dopt=Abstract) Another prospective study, done in Germany with 1818 subjects. This study used only highly sensitive troponin I (no scores and no EKG's) at 0, 3 and 6 hrs. At 3 hr, repeat negative troponins had a sensitivity of 98.2% and PPV of 95.8% for ACS, with the 6 hr marker not adding significant extra benefit, making the point that 3 hr markers are as good as the 6 hr.

Clinical Pathways in Cardiology. March 2013. This is an European journal (http://journals.lww.com/critpathcardio/Abstract/2013/03000/HEART_Score_to_Further_Risk_Stratify_Patients_With.1.aspx) and the authors here put forward a new HEART score (http://www.heartscore.nl/score/) applied to patients with an already low TIMI score (0-1) to further identify very low risk patients who are safe for discharge from the ED. This included 8815 enrolled, from which 485 had both a TIMI of 0 and HEART score of 0. From this subset none had a negative cardiovascular outcome at 30 days for a sensitivity of 100%.

JAMA, Internal Medicine. October 2013. (http://archinte.jamanetwork.com/article.aspx?articleID=1748796) This is a randomized, parallel comparison study with blinded outcomes comparing a 2-hr accelerated diagnostic protocol (ADP) including TIMI of 0, non-ischemic EKG and negative biomarkers at 0 and 2 hr, vs standard care (initial negative biomarkers, prolonged observation usually with admission to hospital and second biomarker at 6-12 hr after onset of symptoms). The ADP had 270 pt of which 52 were discharge following the protocol and the standard care group had 272 pt and 30 discharges. At 30 days none of the discharged patients in both groups reported a negative cardiovascular event, making the conclusion that accelerated protocols are as effective and more efficient than standard prolonged observation protocol.

So, now what do we do with this information? Are these accelerated protocols ready for clinical use in the ED? Well... sort of. The good news is that these studies were done in the ED with general population cohorts and not cardiology centers, they have excellent results which can be applied to general practice. The bad news is that the AHA and ACC have not yet come on record with an official opinion about these protocols. However, as more and more patients show up through our doors with CP's the need for more efficient and cost-effective disposition has become imperative. But don't be the odd ball of your group and start doing this alone, take this information and talk to your medical directors and come up with an agreement on how to use these protocols in your departments.


A heart ATTACK !!!







2 comments:

  1. Hi doc .thnks for going into details of this topic.
    I agree that extreme presentations are no brainer.
    But all these trials take and make prediction when timi score is 0.
    STOP.
    Lets answer the timi score NSTEMI question.
    Did you have CP in 24 hrs ? Answer is yes
    Age? More than 65
    Use of aspirin ? No
    Timi score is 3 .
    Now what?

    According to all these studies pt will fall in at least mod risk. When I know this pt most likely has no ACS . CP was muscular, he ran out of ASA, and he is 66.
    I am not trying to argue or prove these studies wrong ,just thy don't help me decide who should stay.

    I personally talk to pt, take him into confidence, make sure he is CP FREE,pt should look good and just calculate TIMI SCORE in occipital area..
    Edit and post if it makes sense to you.
    Thanks

    Rajeev Singh, MD

    ReplyDelete
    Replies
    1. Hi Rajeev!
      My take on this score system business is basically a way to codify what we are already doing. If your gestalt tells you the patient in front of you does not have ACS, it is nice to have a way to codify and standardize the approach for that low risk patient who is going home. But I completely agree with you, score systems on their own don't do much, they are useful only in the right patient. I think about this in the same way as I do with the low risk pulmonary embolism patient. My pre-test prob is low, then I apply PERC and if PERC negative, I am done, pt is very low risk for PE, bye bye. If my gestalt tells me low risk for ACS, then I apply TIMI, if TIMI is 0-1, the trops are negative, the EKG is non-ischemic and pt is pain free, bye bye.
      I guess your question is more related to the patient who you think is low risk and the TIMI is intermediate or high. I would say, don't use TIMI; get your trops, EKG, talk to your patient and engage him/her in the decision. Two years ago, David Newman in his podcast SMART-EM did a fantastic evidence based approach to the chest pain patient in the ED (http://smartem.org/podcasts/chest-pain-risk). The summary is this:
      - Patient < 40 y/o, who is low risk by gestalt, has non-ischemic EKG, negative trops and no hypotension, his risk for AMI is 1:500.
      - Same patient but age > 40, the risk goes to 1:250
      - Patient with moderate risk, with 2 or more risk factors (you are concerned this could be ACS), but EKG is non-ischemic and trops are negative, the risk is 1:125.
      So... in these group of patients in who I cannot use TIMI, I get all my other data and engage the patient in the decision of home vs admit based on the these probabilities and document the conversation. To my surprise more patients decide to go home than to be admitted, and that's OK as long as they understand that no one is 0 risk, they have good follow and they have a way back into the system if need be.

      Thanks for the comment Raj.

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