‘Til Now, I Always Got By On My Own/The HEART of the Matter
- Dr. Zak Flaming
- May 18, 2021
- 5 min read
Working in the emergency department gives me two recurring thoughts on a shiftly basis:
1) These new residents know nothing about “boomer” music, which I attribute to the fact that I keep getting older and they stay the same age. I had to explain who FLEETWOOD MAC was the other day. I informed them the song Higher Love by Kygo is sampling Steve Winwood’s self-titled track. This of course made me think of Don Henley’s Heart of the Matter, which leads to my 2nd recurring thought:
2) The HEART score (1)
The last data I checked lists chest pain as one of the most common complaints in the ED, at ~5.4% of all ED presentations (2). We think about myocardial ischemia with a variety of complaints, not just chest pain. Additionally, we parrot the statement that “missed MI is the most common reason for a lawsuit from the ED.” It is actually the second most commonly missed diagnosis in the ED resulting in a lawsuit, right after fracture (3). The percent of lawsuits it represents? 5% (3). It turns out we only miss about 2% of ACS (4) which has led to people thinking that we are dangerously close to the “acceptable miss rate” as determined by ACEP (5). However, not all of these missed MIs have chest pain, and it is estimated that we only miss about 0.6% of MIs in patients with chest pain (6). Regardless, we deal with chest pain every day, and likely apply or at least consider the HEART score similarly, so I figured it would be good to learn the nuances of it beyond what MD Calc shows us.
The HEART score was designed by doctors in the Netherlands in 2008. This underwent external validation and was turned into the HEART pathway by Dr. S Mahler in 2015. Since then it has gone through numerous validations which have all reiterated its utility (6). It has received nearly unanimous support and has even found its way into ACEP clinical policies (7), so it’s safe to say it is considered the standard of care at this point. I’m not here to prove to you whether or not the HEART pathway is scientifically sound, I’m here to dive into the individual components.
Each part of the 5-question score is trichotomous, and three of the sections should be relatively straightforward, so this should be easier than some tests (I’m looking at you Wells’, for asking if I think PE is the most likely diagnosis).
History
We have ideas in our head about “classic” symptoms, but fortunately, this score was designed with specific criteria to define the suspiciousness of the history, which simplifies the most subjective component of the score. It was also designed before more mixed/novel evidence (8,9) suggesting we re-evaluate our historical components came out.
The following 7 characteristics were recorded:
Retrosternal pain
Pressure radiation to jaw, left shoulder, or arms
Duration of 5 to 15 min
Initiation by exercise, cold, or emotion
Perspiration, nausea, or vomiting
Reaction to nitrates within minutes
Patient recognizes symptoms (previous symptoms of MI)
If a patient had “primarily specific elements” it was classified as highly suspicious (10). If there were both nonspecific and suspicious elements, it was classified as moderately suspicious. In the absence of specific elements it was considered nonspecific.
Main talking points here: the consideration of age, past medical history, and sex do NOT factor into these elements, and therefore applying abdominal pain as an MI “mimic” is already going outside the evidence and validation of this score.
ECG:
A normal ECG is defined by Minnesota criteria, which is a 9 page document (11). Needless to say, I didn’t memorize this (and neither should you). It should just serve to remind you that to get 0 points, you need a pretty boring ECG.
An ECG worthy of 1 point is defined as having unchanged, known repolarization disorders or those from a pacemaker, repolarization disorders suggesting use of digoxin, LBBB, typical changes suggesting LVH, or nonspecific repolarization disturbances without significant ST-segment depression.
To bring home the 2-point trophy an ECG needs significant ST-segment elevation or depression in the absence of a bundle branch block, digoxin, or LVH.
Surprises here: ECG discoveries have been disseminated at an accelerating pace, especially to recently educated physicians, and there are a number of concerning findings that I don’t feel are adequately credited here. Wellens’ syndrome often lacks ST-segment elevation but represents a critical finding (12). Hyperacute T waves are difficult to objectively define, but represent a highly concerning ECG.
Age:
I think we’ve all got this one
Risk Factors:
Surprisingly hard to find the exact criteria (13), and not always replicated identically on validation trials, but a point is given if a patient has any of the following: obesity, hypercholesterolemia, diagnosed and/or treated hypertension, currently treated DM, active smoker (define as having any cigarettes in the past 3 months), or positive family history defined as mother, father, or sibling having cardiovascular disease.
2 points are given if a patient has at least 3 of these risk factors, or if a patient has a diagnosis of atherosclerotic disease as defined by peripheral arterial disease, or prior MI, stroke, or PCI.
Note that all family history of CAD is included, meaning an 84 yo grandparent with a silent MI gets you just as much credit as a dad getting a CABG at 37. Secondly, several risk factors may be unidentified (physicians are pretty bad at recognizing obesity (14)) and won’t be made in the ED, like hypercholesterolemia.
Troponin:
0 points are award for a troponin level <0.04 ng/mL, while 1 point was given for a value >.04 up to .12, and 2 points were given to a value of 0.12 ng/mL or higher. A standard troponin I assay was used (NOT a high sensitivity troponin).
The sum of these scores yields a HEART score, which will stratify patients into low risk (0-3 points), moderate risk (4-6 points), or high risk (>7 points). This provides you with a 1.6%, 20.3%, and 72.7% chance of major adverse cardiac events within 6 weeks, defined as STEMI, NSTEMI, USA, PCI, CABG, significant stenosis (>50%) treated conservatively, or death due to any cause.
The HEART Pathway utilizes this data to recommend a repeat troponin at 3 hours with discharge home with outpatient follow up. Now the AHA states “It is reasonable for patients with possible ACS who have normal serial ECGs and cardiac troponins to have a treadmill ECG (Level of Evidence: A), stress myocardial perfusion imaging, or stress echocardiography before discharge or within 72 hours after discharge. (Level of Evidence: B) (5)” However, ACEP says “do not routinely use further diagnostic testing (coronary CT angiography, stress testing, myocardial perfusion imaging) prior to discharge in low-risk patients in whom acute myocardial infarction has been ruled out to reduce 30-day major adverse cardiac events (Level B Recommendations) and “arrange follow-up in 1 to 2 weeks for low-risk patients in whom myocardial infarction has been ruled out. If no follow-up is available, consider further testing or observation prior to discharge (Consensus recommendation) (7)”.
Many iterations of the HEART pathway have been worked on, now getting to the modified HEART pathway which includes a 2h troponin, if high-sensitivity assays are used. This knocks more time off a patient’s ED stay, which ultimately improves their care. Although validated, it is not the standard of care in the US to get just a single high sensitivity troponin (16). In the future I would love to see a way to incorporate results from prior cardiology stress testing, as this seems to be one of the most significant components to the story in the eyes of some.
This review illuminated many definitions and misapplications of the HEART score for me, so hopefully it serves to help others adhere to the specific information for which the HEART score provides EBM.
References
1) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2442661/
2) (https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2294235)
3) https://onlinelibrary.wiley.com/doi/full/10.1111/j.1553-2712.2010.00729.x)
10) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2442661/
13) https://pubmed.ncbi.nlm.nih.gov/20802272/
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