AT THE CLINIC ; ACCURACY OF 64-MSCT CORONARY ANGIOGRAM

I saw Mr HK about 6 weeks ago, when he came to see me for rather chest pains, which were not typical of angina pectoris. He had a 64-MSCT done in a popular Scan Center which showed that he had severe 3vd-CAD, with what appears to be a Left Main equivalent. He was also hypertensive. I did a submax stress ECG which was normal. I decided to treat him medically as an outpatient. After about 1 month of antiplatelet therapy and beta-blockers and antihypertensive therapy, he had less chest pains and I repeated a maximal stress ECG. This time, the stress ECG showed changes at stage 3 of the Bruce protocol. In view of this finding last week, I scheduled for him to have a coronary angiogram to day. The coronary angiogram showed minor CAD with good LV function. There was a 20-30% stenosis in the proximal segment ( after a segment of prox LAD ectasia ). There was also a 50% stenosis in the mid-RCA.
This has been our experience with the local 64-MSCT service. I find that the predictive value of the 64MSCT is about 50%. It usually over-estimate the stenosis. I feel a little guilty that I have now sunjected him to about 40msv ( equivalent to about 1,000 CXRs ) of radiation in 2 months. I felt that with his chest pains, I had to be quite sure that he does no have CAD that required myocardial revascularisation. I was quite certain, with my first stress ECG that he did not have unstable angina or critical 3VD.
I suppose I will add this case to my little collection of miss 64MSCT diagnosis. I look forward to our local cardiologist / radiologist, improving their experience at reporting 64MSCTs so that we can have a useful non-invasive tool. I have come to the conclusion, after seeing how the 64MSCT services have progress since 2005, that it will not be able to replace standard coronary angiogram, not for quite a few years to come. In fact, my gut impression is that, the 64MSCT has increase the need for coronary angiography. And there in lies the danger. The cardiologist who does a "checkup " 64 MSCT in an assymptomatic subject ( not even a patient, as the subject came for a checkup ). sees ( or oversees ) a lesion on the 64MSCT, convinces the patient that he has disease and schedules the coronary angiogram, by the same cardiologist, at 2pm in the afternoon. Sometimes they then see a sub-clinical lesion, and the subject ( assymptomatic ) gets a coronary angioplasty ( the oculo-stenotic-balloon reflex ). This is frightening, and I have seen patients where that has happened. When they come to see me for a second opinion, I always tell them what can I do. They already have everything done, and it is really no point crying over-spilt milk. I suppose the moral of the story is that when you consult a doctor for a non-emergency condition, and he suggest some invasive mode of therapy in a hurry, always ask for time to re-consider and if possible get a second opinion. Patients must wise up and be prepared to ask for second opinions and doctors must not deny patients the right to a second opinion.