Coronary CT scans for the evaluation of chest pain illustrates the health care expenditure debate…

During residency, there was always a case of mis-diagnosed chest pain to discuss in conference.  Incorrectly sending a patient home and missing the diagnosis of cardiac chest pain was an infrequent but repetitively observed phenomenon.

So as to tread carefully with words, it is sufficient to say that even now, chest pain triage remains a vexing problem.

Chest pain diagnosis is like appendicitis: there are always small numbers of unusual cases in which an accurate diagnosis proves elusive.  In medicine, there is no such thing as perfection in diagnosis and no better example exists than chest pain.

Chest pain is ubiquitous -hundreds of patients per day from all walks of life with all manner of co-morbidities present daily to the ER.  The stories vary, ECG’s can be normal even in the face of a real heart attack and blood enzymes are often normal in the early phases.  Given the catastrophe of missing the diagnosis, many are working hard at a technological solution -the search for the ultimate adjudicator which provides a “yes” or “no” answer.

A recent study describes taking chest pain patients for CT scans of the chest to look for coronary calcium.   Calcium scores of zero are reassuring and confirm a low risk, thereby providing another tool for triage.

This proposed solution is emblematic of modern day medicine.  The CT scan attempts to mitigate clinical judgement by obtaining more objective data.  Present with chest pain and a nurse at the triage desk will just order a run through the CT scanner.

The problems with this strategy include…

CT scans are super expensive.  Whether they should be is another topic in itself.

Radiation dose.  CT scans emit much radiation -many times that of a CXR.  Cumulative radiation dose should not be understated and this risk is likely significant.

Embarrassment:  Ordering a coronary calcium score CT for the exclusion of cardiac disease seems embarrassing.  The doctor who employs common sense, including a careful history, a physical exam, an ECG, cardiac enzymes and in the worst case 4 hours of time for another blood test will triage patients equally well and with less cost and no radiation.

An older doctor must fight the urge to not dismiss new technology and act like the aged doctor who refuses to learn the new.  However, in the case of chest pain, a dose of common sense and trained observation is not yet replaceable by a big dose of radiation.

There are those who argue we doctors order too many tests and in cases like the CT scan replacing clinical skills, they are correct. It is clear that technology helps us much, but common sense and a mastery of the obvious still retains its value.

JMM

4 comments

  1. I thought you were going to mention the new study (out of South America, I think) that suggests a negative coronary calcium score misses a significant number of important coronary lesions.

    I believe it was covered in HeartWire.

    I've seen a number of patients with chest pain that, by history, seemed very unlikely to have coronary disease as the cause. Then the cath showed severe multivessel disease.

    -Steve

  2. Steve,

    Yes, I did see that study and indeed it does strengthen the argument against doing CT scans for chest pain. It was edited out in the interest of brevity and readability.

    It is also true and well validated that severe coronary disease can lie dormant for long periods and manifest little objective evidence. Lack of, or minimal symptoms despite severe coronary disease remains a striking phenomenon. The heart's "wiring" and perception of symptoms vary so greatly -an analogous example is evidenced by the disparate symptoms of my most commonly treated disease, atrial fibrillation.

    However in your case, you describe the "cath," and this illustrates my point that although CAD was unlikely your patients were triaged to cath and not home.

    In reviewing missed MI's, there is nearly always a clue, usually a significant one that was overlooked, perhaps just a subtle change on the ECG or a past historical item.

    In addition to sound clinical judgement, the simple ability to wait, and do a serial ECG or cardiac enzyme test over a period of a few hours greatly increases the likelihood of successful diagnosis and/or triage of chest pain.

    Thanks for the thoughtful commentary.

    JMM

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    Conclusion: MTWA ia an accurate NON-INVASIVE test to select ICD patients for primary prevention of arrhythmic events and sudden cardiac death. Even in our small cohort, a normal TWA test clearly identifies patients at low risk who have a good prognosis and are unlikely to benefit from primary prevention ICD implantationin in a long term follow-up…

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