BACKGROUND: Low-density lipoprotein cholesterol (LDL-C) is an important causal risk factor for atherosclerotic cardiovascular disease (ASCVD). However, a sizable proportion of middle-aged individuals with elevated LDL-C level have not developed coronary atherosclerosis as assessed by coronary artery calcification (CAC). Whether presence of CAC modifies the association of LDL-C with ASCVD risk is unknown. We evaluated the association of LDL-C with future ASCVD events in patients with and without CAC. METHODS: The study included 23 132 consecutive symptomatic patients evaluated for coronary artery disease using coronary computed tomography angiography (CTA) from the Western Denmark Heart Registry, a seminational, multicenter-based registry with longitudinal registration of patient and procedure data. We assessed the association of LDL-C level obtained before CTA with ASCVD (myocardial infarction and ischemic stroke) events occurring during follow-up stratified by CAC>0 versus CAC=0 using Cox regression models adjusted for baseline characteristics. Outcomes were identified through linkage among national registries covering all hospitals in Denmark. We replicated our results in the National Heart, Lung, and Blood Institute –funded Multi-Ethnic Study of Atherosclerosis. RESULTS: During a median follow-up of 4.3 years, 552 patients experienced a first ASCVD event. In the overall population, LDL-C (per 38.7 mg/dL increase) was associated with ASCVD events occurring during follow-up (adjusted hazard ratio [aHR], 1.14 [95% CI, 1.04–1.24]). When stratified by the presence or absence of baseline CAC, LDL-C was only associated with ASCVD in the 10 792/23 132 patients (47%) with CAC>0 (aHR, 1.18 [95% CI, 1.06–1.31]); no association was observed among the 12 340/23 132 patients (53%) with CAC=0 (aHR, 1.02 [95% CI, 0.87–1.18]). Similarly, a very high LDL-C level ( > 193 mg/dL) versus LDL-C <116 mg/dL was associated with ASCVD in patients with CAC>0 (aHR, 2.42 [95% CI, 1.59–3.67]) but not in those without CAC (aHR, 0.92 [0.48–1.79]). In patients with CAC=0, diabetes, current smoking, and low high-density lipoprotein cholesterol levels were associated with future ASCVD events. The principal findings were replicated in the Multi-Ethnic Study of Atherosclerosis. CONCLUSIONS: LDL-C appears to be almost exclusively associated with ASCVD events over ≈5 years of follow-up in middle-aged individuals with versus without evidence of coronary atherosclerosis. This information is valuable for individualized risk assessment among middle-aged people with or without coronary atherosclerosis.