TPA vs CALCIUM SCORE
Easy, faster and less expensive technique for carotid plaque area determination without the risk of radiation exposure if compared with coronary calcium score, and the patient cannot be exposed for a follow-up, while carotid plaque area can be the solution.
Carotid plaque area can identify any calcified and noncalcified atherosclerotic plaque with an axial resolution accuracy of <0.3 mm, it is a more sensitive test superior for recognizing earlier lesion formation than coronary calcium score, which relies on identifying only calcification in plaques that develop with the evolution of plaque over time.
Thus, from a clinical utility standpoint, a negative carotid plaque area test result is superior to a coronary calcium score of 0 in ruling out underlying CAD.
Using TPA first, it is likely, that risk is detected early, shortens the gap between detection of risk and treatment and can be managed with more accuracy in most subjects, since TPA rarely underestimates the extent of CAC. This finding is in very good agreement with a study entitled "High prevalence of ultrasound detected carotid atherosclerosis in subjects with low Framingham risk score: potential implications for screening for subclinical atherosclerosis" (1).
Further, TPA is also qualified to detect risk for ischemic stroke, which is far less documented for CAC. Moreover, TPA is far less costly to track coronary risk. Finally, with TPA, there is no radiation.
The Vascular Risk Foundation has a collection of 432 subjects, in whom both a coronary calcium score and TPA were measured. We found in 151 subjects without CAC (CAC=0) carotid plaque in 131 subjects, of whom 77 had a TPA > 25 mm2. In subjects with TPA=0, only 14 had CAC>0. In subjects with a high CAC score > 400 (N=54), only 2 had a TPA of zero, and N=46 had a TPA > 25 mm2. Therefore, TPA is a sensitive marker for CAC, whereas CAC is not sensitive enough for relevant amounts of TPA. Therefore, coronary artery calcifications CAC are a relatively late appearing marker of coronary risk in comparison to carotid total plaque area TPA, therefore CAC has a reduced detection and treatment gap in comparison to TPA (2).
1. J Am Soc Echocardiogr. 2010;23:809-815.
2. Romanens. M. Carotid Total Plaque Area is a sensitive marker for the presence and extent of Coronary Calcium (data on file Vascular Risk Foundation, Switzerland)..