Half of young adults with premature MI not identified by 2018 cholesterol guidelines
Performance of Guideline Recommendations for Prevention of Myocardial Infarction in Young AdultsLiterature - Zeitouni M, Nanna MG, Sun JL et al. - J Am Coll Cardiol. 2020 76(6):653-664. doi: 10.1016/j.jacc.2020.06.030
Introduction and methods
The 2018 American Heart Association (AHA) and American College of Cardiology (ACC) Multisociety Guideline on the Management of Blood Cholesterol provided updates for the risk assessment of patients eligible for statin prescription for primary prevention . Risk enhancers were included in the new criteria . The 2018 guideline also updated secondary prevention therapy, such as non-statin lipid lowering therapies as part of the treatment of patients with myocardial infarction (MI) and at the highest risk for recurrent ASCVD events .
The previous 2013 guideline for cholesterol management expanded statin therapy eligibility based upon a 10-year atherosclerotic cardiovascular disease (ASCVD) risk score [4-8]. However, this risk score calculator is heavily dependent upon age and is therefore often underestimating the risk for premature coronary artery disease (CAD) in young patients [3,9,10]. Young adults who develop CAD have high risk of poor outcomes by developing recurrent non-fatal and fatal CVD, emphasizing that early and adequate prevention are thus of paramount importance .
This study evaluated how the 2013 guidelines and updated 2018 guidelines on blood cholesterol management changes affected identification of young adults for preventative statin therapy who developed premature ischemic heart disease. The Duke Databank for Cardiovascular Disease (DDCD), a registry of patients who underwent cardiac catherization at Duke University Medical Center, Durham, NC, USA) was used and this study included patients (n=6,639) admitted from 1995 to 2012 for a first acute MI in combination with obstructive CAD (defined as a ≥50% diameter stenosis of the coronary artery). Individuals with previously documented stroke, MI, peripheral artery disease, or obstructive CAD were excluded. Also patients missing blood cholesterol values at the time of or within approximately 1 year of the index catheterization were excluded. The cohort was subsequently divided into the following age groups: <55 years of age (young, n=2,733), 55 to 65 years of age (middle-aged, n=2,324), and 66 to 75 years of age (old, n=1,582).
- Younger individuals had a lower 10-year ASCVD risk score (median 6.4%, IQR:3.7–10.4) calculated before their index MI compared with middle-aged (11.6%, IQR: 7.3–17.2) and older (19.6%, IQR: 13.4–28.4) patients (p<0.001). 10-year ASCVD risk score was calculated only among patients >40 years of age. Lifetime risk was higher in younger patients compared to middle-aged and older ones (33.9%, IQR: 29.2-39.6; 32.2%, IQR: 29.4-38.2; and 31.9%, IQR: 29.3-37.2, P<0.001, respectively)
- The 2018 guidelines identified less younger adults (<55 years of age) to meet a Class I and IIa recommendation for statin therapy before their first MI compared to the 2013 guidelines (2013: 56.7% and 2018: 46.4%; P<0.01). In contrast, 85.1% (2013) and 88.2% (2018) of the old adults (66-75 years of age) would be eligible for statin therapy when applying the guidelines. Even when including patients with borderline risk (ASCVD 5% to 7.5%) and a risk enhancer, the proportion of statin-eligible young patients (>55 years of age) increased by 6.2%.
- According to the 2018 guidelines, 28.3% of the younger patients met very high-risk criteria for intensive secondary prevention lipid-lowering therapy following their MI compared with 40.0% of middle-aged and 81.4% of older patients (P trend <0.001).
- During the 8 year follow-up, younger patients with very high-risk criteria were at higher risk of all-cause death, MI, or stroke compared with patients without very high-risk criteria (44.6% vs. 25.9%; HR 2.09, 95% CI: 1.82 to 2.41, P<0.001). These observations were consistent (P=0.53) among middle-aged patients (55 to 65 years of age: 48.1% vs. 28.5%; HR 1.97, 95% CI: 1.72 to 2.27, P<0.001) and old patients (66 to 75 years of age: 53.6% vs. 40.8%; HR 1.51, 95% CI: 1.23 to 1.84, P<0.001).
The current study provides important evidence that nearly half of young adults who experienced a MI were not eligible for primary prevention statin therapy using the updated 2018 cholesterol guidelines. And far fewer younger individuals would be eligible for the most intensive secondary prevention therapy post MI compared with older adults. A key factor accounting for this is that current risk scores are heavily based on age. Younger patients with very high-risk criteria are at increased risk of MACE and therefore subscription of lipid-lowering therapy in these patients is highly recommended.