Implications of Coronary Artery Testing and Statin Use
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?
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.
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.
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.
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.
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