Predictive value of EBCT scanning.

To the Editor: Secci and colleagues are to be commended for the integrity required to question the accuracy of electron-beam CT (EBCT) scanning as a screening test for coronary disease,1 particularly when at least one member of the group had anticipated that the method would prove successful. However, their conclusion that the amount of coronary calcification fails to predict nonfatal myocardial infarction (MI) and coronary death is at odds with their own and other data and is probably the result of a critical flaw in the design of the South Bay Heart Watch. In the larger cohort of 1461 South Bay Heart Watch subjects, the risk of nonfatal myocardial infarction and coronary death has been proportional to the number of calcified coronary arteries as determined by fluoroscopy.2 The fact that there is a threshold for the detection of coronary calcification by any method (and, in the case of a method as insensitive as fluoroscopy, a rather high threshold3 ) implies first, that the greater the number of calcified vessels, the higher the coronary calcium score and second, that the sample of 326 high-risk subjects was too small to confirm what was already demonstrated in the larger study. Two other studies4 5 of EBCT scanning in less-selected populations have reported unprecedented accuracy of the EBCT-derived coronary calcium score in the prediction of nonfatal MI and coronary death. When pooled with data from the South Bay Heart Watch, these studies yield odds ratios of 4.7 to 9.5 for nonfatal MI and coronary death for subjects with calcium scores in the upper third versus the lower two thirds of the population ( P <0.001). These findings are consistent with autopsy evidence of calcification of the coronary arteries in victims of sudden cardiac death and fatal MI,6 as well as …