CT CAC useful in identifying which patients may benefit from statin therapy: JAMA

Coronary artery calcium (CAC) scoring, also referred to as a coronary calcium scan, is a test that measures the quantity of calcium present in the walls of the heart's arteries. Calcium is an important mineral found mostly in one's bones and teeth. However, when calcium gets lodged into the arteries that supply the heart with oxygen and nutrients, it can disrupt normal circulation and one can experience a heart attack or a stroke. So, a coronary calcium scan is one way to predict someone's risk of developing a cardiovascular event, like a heart attack or stroke.

A study was conducted by Patel J et. al to investigate the association between risk-enhancing factors and incident atherosclerotic cardiovascular disease by CAC burden among those at intermediate risk of atherosclerotic cardiovascular disease.

The researchers conducted a multi-ethnic prospective cross-sectional study in the US. They selected a total of 16,888 participants and their baseline data was collected between July 15, 2000, to July 14, 2002, their follow-up for incident atherosclerotic cardiovascular disease (ASCVD) events were ascertained through August 20, 2015. Additionally, all the participants were aged 45 to 75 years with no clinical ASCVD or diabetes at baseline, were at intermediate risk of ASCVD (≥7.5% to <20.0%), and had a low-density lipoprotein cholesterol level of 70 to 189 mg/dL. The main outcome of this study was incident atherosclerotic cardiovascular disease over a median follow-up of 12.0 years.

The findings of the study are as follows:

· Among participants with CAC scores of 0, the presence of risk-enhancing factors was generally not associated with an overall ASCVD risk that was higher than the recommended treatment threshold for the initiation of statin therapy.

· 42.8% of the total participants had a CAC score of 0. Among those with 1 to 2 risk-enhancing factors vs those with 3 or more risk-enhancing factors, the prevalence of a CAC score of 0 was 45.7% vs 40.3%, respectively.

· Over after a median follow-up of 12 years, the unadjusted incidence rate of ASCVD among those with a CAC score of 0 was less than 7.5 events per 1000 person-years for all individual risk-enhancing factors (with the exception of the ankle-brachial index, for which the incidence rate was 10.4 events per 1000 person-years and combinations of risk-enhancing factors, including participants with 3 or more risk-enhancing factors.

· Although the individual and composite addition of risk-enhancing factors to the traditional risk factors was associated with improvement in the area under the receiver operating curve, the use of CAC scoring was associated with the greatest improvement in the C statistic (0.633 vs 0.678) for ASCVD events.

· For incident ASCVD, the net reclassification improvement for CAC was 0.067.

Thus, the researchers concluded that the usage of CAC scoring was linked with substantial improvements in the reclassification and discrimination of incident ASCVD. And the findings of this study bolster the use of CAC scoring simultaneous with the risk-enhancing factor assessment to more correctly classify individuals with an intermediate risk of ASCVD who might benefit from statin therapy.

Reference:

A study titled, "Assessment of Coronary Artery Calcium Scoring to Guide Statin Therapy Allocation According to Risk-Enhancing Factors: The Multi-Ethnic Study of Atherosclerosis" by Patel J et. al published in the JAMA Cardiol journal.

doi:10.1001/jamacardio.2021.2321