Coronary artery calcium may indicate risk of cardiovascular disease

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1. This study found that coronary artery calcium density was inversely related to risk of coronary heart disease (myocardial infarction, resuscitated cardiac arrest, or coronary heart disease death) and cardiovascular disease (hard cardiovascular disease, stroke, stroke death). 

2. The addition of coronary artery calcium density in a risk scoring system resulted in significantly improved risk prediction. 

Evidence Rating Level: 2 (Good)           

Study Rundown: Computed tomography (CT) scanning can be used to assess coronary artery calcium. The Agatston score is the method currently used to score the amount of calcium in the coronary arteries, and this metric has been shown to predict cardiovascular disease.  This score, however, does not account for the density of calcium in atherosclerotic plaques even though it is hypothesized that higher densities are associated with lower cardiovascular risk.  This study followed 3,394 male and female participants from the Multi-Ethnic Study of Atherosclerosis (MESA) for a median of 7.6 years.  The natural logarithm of coronary artery calcium volume had an association with incident coronary heart disease and cardiovascular disease.  The coronary artery calcium density, however, was inversely correlated with coronary heart disease and cardiovascular disease risk.  The authors subsequently found that coronary artery calcium density improved risk prediction using a risk prediction model.

Major strengths of this study include the large sample size and diversity of the population studied.  Limitations of the study include a relatively short follow up time of 7.6 years and the fact that outcomes like angina and need for cardiac revascularization were not included in the model.  While this study identifies an important relationship, further studies will be required before coronary artery calcium density can be incorporated into risk prediction models used in clinical practice.

Click to read the study in JAMA

Relevant Reading: Comparison of Novel Risk Markers for Improvement in Cardiovascular Risk Assessment in Intermediate-Risk Individuals

In-Depth [prospective cohort study]: This study followed 3,394 men and women from the Multi-Ethnic Study of Atherosclerosis (MESA) for a median of 7.6 years after a CT scan to assess coronary artery calcium for one of two types of cardiac endpoints: coronary heart disease (myocardial infarction, cardiac arrest with resuscitation, or coronary heart disease death) and cardiovascular disease (hard cardiovascular disease, stroke, or stroke death. The natural logarithm of coronary artery calcium was independently associated with an increased risk of coronary heart disease (HR 1.81, 95% CI 1.47-2.23 per standard deviation increase) and an increased risk of cardiovascular disease (HR 1.68, 95% CI 1.42-1.98 per standard deviation increas. Area under the receiver operating curve analysis also showed that the addition of coronary artery calcium density to risk prediction models for coronary heart disease and cardiovascular disease resulted in significant improvement.

By Jeffrey Cohen and Rif Rahman

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