To explore (i) in what proportion and direction coronary artery calcium (CAC) score reclassifies coronary risk in asymptomatic diabetic patients at high a priori coronary risk, and (ii) whether screening for asymptomatic myocardial ischemia / coronary stenosis only in patients at very high coronary risk - whether a priori or combined with those reclassified at very high risk according to their CAC score - has good sensitivity to detect these conditions.

We retrospectively selected 377 asymptomatic primary prevention diabetic patients at high or very high a priori coronary risk according to national guidelines. All had their CAC score measured and underwent stress myocardial scintigraphy to detect myocardial ischemia. Those identified with ischemia then had a coronary angiography to identify coronary stenoses.

Of the selected patients, 242 and 135 patients had a high and very high a priori coronary risk, respectively. After taking into account their CAC score, the former were reclassified into three risk categories: moderate (n=159, 66%), high (n=38) and very high (45 patients) risk.

Myocardial ischemia was identified in 35 patients and coronary stenoses in 14 of the latter. Had a stress scintigraphy been performed only in the 135 patients at very high risk a priori, 18 patients would have been detected with ischemia (sensitivity 51%), and 9 with coronary stenoses (sensitivity 64%). Had a scintigraphy also been performed on the 45 patients at very high risk after CAC-reclassification, an additional 7 and 5 patients with ischemia and coronary stenoses, respectively, would have been identified.

Following national guidelines, 66% of our population of asymptomatic diabetic persons at high a priori coronary risk were reclassified into the moderate risk category, translating into less stringent goals for risk factor control. Eighteen percent were reclassified into the very high-risk category, leading to 100% detection sensitivity for patients with ischemia and coronary stenoses.