ELECTRON BEAM CT MEASUREMENT OF CORONARY ARTERY CALCIUM ALLOWS INDIVIDUAL RISK ASSESSMENT OF CHD IN UK DIABETIC PATIENTS
PJ Jenkins1, T McArthur2, C Salek2, M Tighe2 & SJ Howling2
Current guidelines advocate the use of statins in all patients with diabetes for primary prevention of CHD, regardless of cholesterol levels. Measurement of coronary artery calcium score (CACS) in diabetic patients is reported to offer a superior prognostic assessment of an individual's risk of cardiovascular disease than the Framingham Risk assessment. To date, there have been no studies of CACS in the UK diabetic population.
Patients and Methods
A total of 2756 patients had CACS assessment of whom 1957 were male. Analysis was restricted to the 1571 male subjects who had no cardiovascular symptoms, of whom 84 had diabetes. CACS was performed on a GE C300 Electron Beam CT (EBCT) scanner using a standard method with coronary calcium deposition scored according to Agatston, and categorised as Group 1 = 0; 2 = 1-10; 3 = 11-100; 4 = 101-400; 5 = >400.
Overall, the prevalence of elevated CACS was significantly greater in diabetic subjects than non-diabetic subjects: Group 4, 34.5% vs 13.1%, p<0.0001; Group 5, 28.6% vs 11.6%, p<0.0001. However, 23.9% of diabetics were in Group 1 or 2, indicative of none or very mild cardiovascular disease. Categorising by total cholesterol levels revealed that of diabetic subjects with a level <5.2 mmol/l, 20.9% were in Group 1 or 2, 16.7% in Group 3, and 62.5% in Groups 4 or 5. For cholesterol levels between 5.2 and 6.5 mmol/l, 31.8% of patients were in Groups 1 and 2, 9.4% in Group 3 and 59.4% in Groups 4 or 5.
Asymptomatic UK male diabetics have a high prevalence of significant coronary atherosclerosis. However, the significant proportion of subjects with none or mild CHD suggests that statin therapy may not be appropriate for all patients but reserved for those in whom EBCT has demonstrated an increased individual cardiovascular risk.