In a November 2020 editorial in the Journal of The American College of Cardiology, Khurram Nasir, MD, MPH, chief of the division of cardiovascular disease prevention and wellness at Houston Methodist, and his editorial colleagues make the argument that a coronary artery calcium (CAC) score should be “part of the early diagnostic workup of patients suspected of coronary artery disease (CAD).”

The absence of CAC, known as the power of zero, is shown to indicate low risk of obstructive disease and favorable long-term prognosis in patients with stable chest pain. CAC scans are also readily available at low cost.

The authors cite the PROMISE trial, which shows that pre-test probability (PTP) scores using the current methodology overestimate risk of obstructive CAD, resulting in a low incidence of ischemia or obstructive CAD on noninvasive imaging.

Further, a new study in the same issue of JACC helps substantiate the predictive value of CAC using a large cohort of 41,177 symptomatic patients from the Western Denmark Heart Registry. This study compared a risk-factor weighted PTP model, based on age, sex, typical presenting symptoms and cardiac risk factors, with a CAC-score weighted PTP model. The CAC weighted model substantially improved the predictive performance.

In context of multiple studies published on this topic, Nasir et al encourage their peers to accept the power of zero and include it as a sentinel part of the upcoming chest pain guidelines. For more in-depth analysis, see the editorial in JACC.