Abstract 5753: The Warranty Period of a Zero Calcium Score: 5-Year Serial Follow-Up of 422 Individuals by Non-Contrast Computed Tomography
Presence and severity of coronary artery calcium (CAC) by Agatston scoring is a well established index for stratification of cardiovascular prognosis. Absence of CAC is associated with excellent clinical prognosis. To date, for patients with baseline absence of CAC, rates of conversion to positive CAC (i.e., CAC>0) and severity of CAC at the time of conversion is unknown. 9,838 asymptomatic individuals underwent CAC screening with multidetector row or electron-beam computed tomography. Within this cohort, 422 asymptomatic subjects (mean age 48.8±8.9 yrs; 52.1% male, 9% diabetes; 46.0% hypertension, 66% dyslipidemia, 32% smoker) with an initial baseline CAC Agatston score of zero agreed to undergo annual CAC screening for five consecutive years or until conversion to a positive CAC. 106 patients (25.1%) converted from no CAC to a positive CAC within the 5-year follow-up period (mean conversion time 4.08±1.10 yrs). No subject exhibited CAC conversion within the first year. Rates of CAC conversion were low in year 2 (2/422, 0.5%) and year 3 (5/420, 1.1%). No differences were noted for time to CAC conversion in patients with or without diabetes, hypertension, dyslipidemia, or tobacco use (p=NS for all). Similarly, time to CAC conversion was similar among male and female subjects (p=NS). However, subjects with diabetes (p=0.001), hypertension (p=0.02) and tobacco use (p<0.0001) were more likely to transition from absence to presence of CAC during the entire study period, compared to non-diabetic, normotensive and non-smoking subjects. Furthermore, for subjects who exhibited conversion from absence to presence of CAC, Agatston CAC scores at the time of conversion were higher for diabetic (33.0 vs. 16.0, p=0.005) and hypertensive (24.3 vs. 12.4, p=0.001) subjects, compared to their non-diabetic and normotensive counterparts. In subjects with baseline absence of CAC, rates of conversion to positive CAC scores is low during five-year follow-up with rare conversion in the first three years. Conversion rates and severity of CAC at time of conversion is highest amongst individuals with diabetes, hypertension and tobacco use.