Potential use of coronary artery calcium progression to guide the management of patients at risk for coronary artery disease events.

Subclinical coronary artery disease (CAD) is widespread and under-diagnosed. Preventive efforts are required to reduce the burden of this disease and its complications. Imaging of coronary artery calcium (CAC) with cardiac computed tomography is highly specific for the diagnosis of subclinical CAD and can also facilitate treatment decisions in preventive cardiology. Indeed, CAC testing has been recommended by the American Heart Association for asymptomatic patients at intermediate risk for future cardiac events (as defined by clinical risk factors) to refine existing risk estimates. However, the optimal follow-up of those patients who have already undergone CAC testing remains unclear, particularly with regards to repeat CAC testing. The existing literature points to two major considerations for the use of CAC progression in the management of subclinical CAD. On one hand, CAC progression has been used as a surrogate marker to test the efficacy of cardiac preventive medications in halting or regressing CAD. To date, study results have been mostly disappointing and CAC progression appears resistant to medications such as statins. On the other hand, however, CAC progression has potential as a clinical indicator of underlying CAD activity. This may facilitate optimization or up-titration of preventive medications by using CAC progression as a marker of subclinical disease activity. We believe that the data, thus far, argues against the use of a CAC progression as a clinical surrogate marker of preventive therapy efficacy. Further studies with non-statin medications and with concomitant outcome data are needed. However, CAC progression has potential for monitoring subclinical CAD in some patients and may facilitate treatment decisions. In this review we will provide recommendations for repeat CAC testing and discuss when repeat CAC testing may be helpful to assess coronary artery disease progression.