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Implications of Coronary Artery Testing and Statin Use
Study Questions:
Does the presence or absence of coronary artery calcium assist in reclassifying patients who would be recommended for statin therapy using current American College of Cardiology (ACC)/American Heart Association (AHA) cholesterol guidelines?
Methods:
Data from MESA (Multi-Ethnic Study of Atherosclerosis), a longitudinal study of men and women (ages 45-84 years) were used for the present study. Participants had no clinical cardiovascular disease at baseline. For the present analysis, participants on lipid-lowering medication or with missing information on low-density lipoprotein (LDL) cholesterol or missing information that was required to calculate a 10-year risk for atherosclerotic cardiovascular disease (ASCVD) were excluded. Also excluded were those >75 years and those with an LDL cholesterol <70 mg/dl. Participants were grouped by those recommended for statin therapy per ACC/AHA guidelines, those considered for moderate-dose statin therapy (nondiabetic, LDL 70-189 mg/dl and atherosclerotic cardiovascular disease 10-year risk between 5% and 7.5%), and those not recommended for statin therapy. Coronary artery calcium (CAC) scores were assessed for each group, and event rates were calculated for the three groups by CAC = 0, CAC 1-100, and CAC >100.
Results:
A total of 4,758 MESA participants (mean age 59 ± 9 years, 47% males) were included in this analysis. Of these participants, 2,377 would be recommended for statin therapy according to current ACC/AHA guidelines, 589 would be considered for moderate disease statin therapy (nondiabetic, LDL 70-189 mg/dl, and ASCVD 10-year risk between 5% and 7.5%), and 1,792 would not be recommended for statin therapy. The proportion of participants with a CAC of 0 was 41.4% (978/2,377) of the statin-recommended group, 57.4% (338/589) of the statin-considered group, and 79.1% (1,417/1,792) not recommended for statins group. Over a median follow-up of 10.3 years, 247 participants were diagnosed with ASCVD and 155 had a hard coronary heart disease (CHD) event. In each group, CAC was associated with higher rates of ASCVD and CHD. Among those recommended for statin therapy and had a CAC = 0 had an ASCVD event rate of 5.2 (5.0-7.0) per 1,000 person-years, and those with a CAC >100 had an event rate of 15.4 (12.5-18.9) per 1,000 person-years. Among those considered for statin therapy, the ASCVD event rate was 1.5 (0.6-3.6) per 1,000 person-years for those with a CAC = 0 and 6.3 (2.4-16.8)/1,000 person-years for those with a CAC >100. Among those not recommended for statin therapy, the event rate was 1.3 (0.9-2.1)/1,000 person-years for those with a CAC = 0 and 2.7 (1.4-5.0)/1,000 person-years for those with a CAC >100.
Conclusions:
The investigators concluded that heterogeneity exists among those eligible for statin therapy by current ACC/AHA guidelines. The absence of CAC would reclassify approximately 50% of candidates not eligible for statin therapy.
Perspective:
These data suggest that CAC scores add value to the ASCVD 10-year score. However, it is clear that the opposite is true. Those defined as low risk by the ASCVD score and thus not recommended for statin therapy had a low event rate even with a CAC >100 compared to those with higher 10-year scores and CAC >100.
Keywords: Atherosclerosis, Cholesterol, Cholesterol, LDL, Coronary Artery Disease, Dyslipidemias, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Lipoproteins, LDL, Primary Prevention, Vascular Calcification
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