Performance of Guideline Recommendations for Prevention of Myocardial Infarction in Young Adults

Background: The 2018 cholesterol guidelines of the American Heart Association and the American College of Cardiology (AHA/ACC) changed 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitor (statin) eligibility criteria for primary prevention to include multiple risk enhancers and novel intensive lipid-lowering therapies for secondary prevention.

Objectives: This study sought to determine how guideline changes affected identification for preventive therapy in young adults with premature myocardial infarction (MI).

Methods: The study identified adults presenting with first MI at Duke University Medical Center in Durham, North Carolina. Statin therapy eligibility was determined using the 2013 ACC/AHA and 2018 AHA/ACC guidelines criteria. The study also determined potential eligibility for intensive lipid-lowering therapies (very high risk) under the 2018 AHA/ACC guidelines, by assessing the composite of all-cause death, recurrent MI, or stroke rates in adults considered "very high risk" versus not.

Results: Among 6,639 patients with MI, 41% were <55 years of age ("younger"), 35% were 55 to 65 years of age ("middle-aged"), and 24% were 66 to 75 years of age ("older"). Younger adults were more frequently smokers (52% vs. 38% vs. 22%, respectively) and obese (42% vs. 34% vs. 31%, respectively), with metabolic syndrome (21% vs. 19% vs. 17%, respectively) and higher low-density lipoprotein cholesterol (117 vs. 107 vs. 103 mg/dl, respectively) (p trend <0.01 for all). Pre-MI, fewer younger adults met guideline indications for 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitor (statin) therapy than middle-aged and older adults. The 2018 guideline identified fewer younger adults eligible for statin therapy at the time of their MI than the 2013 guideline (46.4% vs. 56.7%; p < 0.01). Younger patients less frequently met very high-risk criteria for intensive secondary prevention lipid-lowering therapy (28.3% vs. 40.0% vs. 81.4%, respectively; p < 0.01). Over a median 8 years of follow-up, very high-risk criteria were associated with increased risk of major adverse cardiovascular events in individuals <55 years of age (hazard ratio: 2.09; 95% confidence interval: 1.82 to 2.41; p < 0.001), as was the case in older age groups (p interaction = 0.54).

Conclusions: Most younger patients with premature MI are not identified as statin candidates before their event on the basis of the 2018 guidelines, and most patients with premature MI are not recommended for intensive post-MI lipid management.