When Does Primary Prevention Encroach on Secondary Prevention?

The risk of incident atherosclerotic cardiovascular disease (ASCVD) in primary prevention is typically lower than in secondary prevention. However, there is a spectrum of risk among individuals undergoing primary prevention with the risk in some individuals approaching those of secondary prevention. We review the clinical conditions wherein the risk in primary prevention is similar to that observed in secondary prevention.

Among individuals without established ASCVD, coronary artery calcium (CAC) scores ≥ 300 AU are associated with ASCVD event rates similar to secondary prevention populations. CAC score ≥ 1,000 AU are associated with an ASCVD risk seen in very high-risk secondary prevention populations. Interpretation of these observations must however consider differences in the risk reduction strategies.

Current guidelines dichotomize ASCVD prevention into primary and secondary prevention, but certain primary prevention patients have an ASCVD risk equivalent to that of secondary prevention populations. Identifying higher risk primary prevention populations will allow for better risk mitigation strategies.