Rule-out, or not, that is the heart of the question

A personal experience, and the could have been value of high sensitivity troponin in outcomes.

Oct 29, 2020 | Jitto Titus

It was just another day in Chennai, India, driving through the sea of vehicles when suddenly he felt some discomfort in his chest. As beads of sweat dripped down his brow, he clutched the steering wheel tighter. Noticing something amiss, his wife insisted on driving straight to the emergency department. Being inundated with patients with much more severe symptom presentations, the triage team anecdotally stratified him at a lower risk incorrectly in hindsight. Thankfully my father had a successful quadruple bypass surgery at another cardiac care hospital due to the providential insistence for a second opinion by my mother. Looking through this lens, I found this article by Chapman and Mills (Heart 2020;106:955-957) enlightening towards meeting a great need in clinical workflow.

Each year over 10 million patients visit  emergency departments with symptoms such as chest discomfort or angina that are indicative of myocardial infarction (MI) which is a blockage of blood flow to the heart. A little over a tenth of the patients are eventually diagnosed with MI. Until it becomes diagnostically apparent, all the patients are treated with the same urgency. Clearly, there is a problem begging for a solution. For the patients who are indeed suffering from an MI, the time to intervention is of utmost importance. The difference can be as significant as reversible vs irreversible heart damage. Patients for whom the symptoms are deemed to be non-cardiac related, undergo unnecessarily extended ED stays. Not to mention avoidable costs relating to central laboratory testing that were not designed as a quick rule-out tool.

Globally cardiac healthcare systems are recognizing an imminent need for a dependable early rule-out protocol, the downstream effects of which directly affect the well-being and outcome of patients. Firstly, a robust rule-out strategy allows for earlier risk stratification leading to earlier discharge and redirection of the low risk to outpatient clinics. Secondly, successful rule-out strategy permits effective allocation of resources to reach a cardiac diagnosis earlier leading to timely intervention that can significantly alter patient outcomes for the better. Both work towards economic savings with workflow efficiencies coupled with shorter length of stays.

Chapman and Mills posit a solution towards optimizing clinical workflow that comes in the form of high sensitivity Troponin measurements on patients presenting at the ED with MI symptoms with an onset or peak within the last 12 hours. A randomized controlled trial pooled from multiple healthcare systems looked at cTn values (assayed using 3 industry leaders) at 0h and 1h (<5ng/L cut-off) during the patients’ ED stay. Roche hs-cTnT assay identified 55% of patients as low risk, with a pooled sensitivity of 98.4% (100% NPV). The Abbott hs-cTnI assay identified 50% as low risk, with a sensitivity of 98.1% (100% NPV) and the Siemens hs-cTnI assay identified 51% of patients as low risk, with a sensitivity of 98.7% (100% NPV). That is a remarkable outcome for both the healthcare system and the patients.

I can’t help but wonder, if the first hospital my father visited had a robust rule-out strategy, maybe they would have not ruled-out, and could have intervened earlier. Maybe some of the myocardial damage could have been reversed and some of the complications of the surgery could have been avoided. Well, I can’t change the past, but I can make that experience count towards something.

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