BACKGROUND: Patients with low-density lipoprotein cholesterol (LDL-C) ≥190 mg/dL are at high risk of atherosclerotic cardiovascular disease events. Treatment guidelines recommend intensive treatment in these patients. Variation in the use of lipid-lowering therapies (LLTs) in these patients in a national sample of cardiology practices is not known. METHODS AND RESULTS: Using data from the American College of Cardiology National Cardiovascular Data Registry-Practice Innovation and Clinical Excellence registry, we assessed the proportion of patients with LDL-C ≥190 mg/dL (n=49 447) receiving statin, high-intensity statin, LLT associated with ≥50% LDL-C lowering, ezetimibe, or a PCSK9 (proprotein convertase subtilisin/kexin type 9) inhibitor between January 2013 and December 2016. We assessed practice-level rates and variation in LLT use using median rate ratio (MRR) adjusted for patient and practice characteristics. MRRs represent the likelihood that 2 random practices would differ in treatment of identical patients with LDL-C ≥190 mg/dL. The proportion of patients receiving a statin, high-intensity statin, LLT associated with ≥50% LDL-C reduction, ezetimibe, or PCSK9 inhibitor were 58.5%, 31.9%, 34.6%, 8.5%, and 1.5%, respectively. Median practice-level rates and adjusted MRR for statin (56% [interquartile range, 47.3%-64.8%]; MRR, 1.20 [95% confidence interval [CI], 1.17-1.23]), high-intensity statin (30.2% [interquartile range, 12.1%-41.1%]; MRR, 2.31 [95% CI, 2.12-2.51]), LLT with ≥50% LDL-C lowering (31.8% [interquartile range, 15.3%-45.5%]; MRR, 2.12 [95% CI, 1.95-2.28]), ezetimibe (5.8% [interquartile range, 2.8%-9.8%]; MRR, 2.42 [95% CI, 2.21-2.63]), and PCSK9 inhibitors (0.16% [interquartile range, 0%-1.9%]; MRR, 2.38 [95% CI, 2.04-2.72]) indicated significant gaps and >200% variation in receipt of several of these medications for patients across practices. Among those without concomitant atherosclerotic cardiovascular disease, even larger treatment gaps were noted (proportion of patients on a statin, high-intensity statin, LLT with ≥50% LDL-C reduction, ezetimibe, or PCSK9 inhibitor were 50.8%, 25.25%, 26.8%, 4.9%, and 0.74%, respectively). CONCLUSIONS: Evidence-based LLT use remains low among patients with elevated LDL-C with significant variation in care. System-level interventions are needed to address these gaps and reduce variation in care of these high-risk patients.