To begin, it is undeniable that in virtually any countries adult population, coronary artery disease is often grossly under diagnosed and treated. This particularly applies to certain ethnic groups particularly of South Asian (Indian) origin who have over recent years been shown as having a high incidence of coronary disease yet often undeclared by typical symptoms.
The medical culture has historically led us through a stepwise progression of focused diagnosis using a clinical algorithm beginning with symptoms and ending with angiographic study. However, it is sad but true that all too often the first presentation is with death and the first positive diagnosis is by autopsy.
Therefore, any tests that apply to the community to increase health professionals’ awareness of coronary disease, and which fast tracks past culturally historic thinking about diagnostic pathways to achieve more rapid diagnosis, must be to my mind, be welcomed.
Calcium scoring for coronary artery disease is one such test. It relies on CT imaging of the heart which detects focal Calcium deposits somewhere in the walls of the coronary arteries providing a numeric “score” ranked as a percentile against various known patient and normal populations. The score is then used to extrapolate to luminal coronary narrowings. The procedure has been enthusiastically embraced, mostly in the independent sectors, but this is not to say that the test is without its detractors and indeed some of the detractions are arguably fair. These concerns relate for example to the fair equitable access for populations dependent upon cost sensitive organisations who purchase their care be it in the UK primary care trusts, purchasing organisations elsewhere, or third party private insurers; the radiation dosage which might limit the applicability of longitudinal follow up to assess treatment strategies and, the validity of correlations between mural calcium and obstructive endoluminal arthosclerotic lipid disease.
My own personal algorithm for assessing patients who come to my consulting rooms or Hospital with a CT test result, (and at the present time the investigation is not particularly high on my radar), is to hope for a zero score. Zero scores are very predictive of very normal arterial anatomy. Of course if such a patient has, usually quite unlikely, a bunch of risk factors such as smoking, cholesterol and family history etc depending on age and gender a negative score does not necessarily demand that no statin agent is applied.
If I am presented with a patient at the other end of the spectrum with an extremely high score of above the 90 percentile of the published normal population for example, then notwithstanding the often completely irrelevant little diagrams that accompanies some reports (which seems to indicate that everyone seems to have entirely the same coronary anatomy i.e. shared dominant right circumflex and LAD with the calcium deposits illustrated as black lines imprinted on such an improbable likelihood) then I will first think of major risk factor modifications and I confess to whatever the cholesterol levels I will attack risk factors with gusto including statin agents.
For those patients with scores in the middle range, around the 50th percentile, again I would not accept the standard report of “almost certain obstructive coronary disease” that appears with the report, I would return to the principles of history and examination and would look towards aggressive control of the risk factors. Should the exercise test prove positive then this would probably lead to invasive diagnostic angiography.
In any patient or perhaps I should say person with elevated calcium scores we should turn to a properly conducted exercise test as a check. Exercise testing if properly conducted to maximum protocols with careful attention to blood pressure, heart rate responses and a sensible analysis of decent base lined ECG, remains the tool of choice and my view is a first stop assessment rather than a CT examination.
I don’t in this brief editorial mean to denigrate any of the scientific data whatsoever. I mean only to express as a rather old fashioned clinical cardiologist a simple personal view. However, I would have to say that in some examples of patients presenting with a high score, I have had patients despite a complete absence of symptoms and actually a negative exercise test, who have had critical coronary stenosis (it must be said that usually in relatively “ECG silent” areas of the heart.
So in summary, I welcome the procedure as a valid screen and if it were a test associated with less radiation and perhaps more diagnostic accuracy in the middle score ranges and if it were more generally available to populations often in the poorer social economical groups that could afford it, I would perhaps show a little more enthusiasm for its first line use. No doubt as more correlative data becomes available, these views might change.
