Abstract
Background Elevated lipoprotein(a) is a well-established risk factor for atherosclerotic vascular disease but is not measured in routine clinical care. Screening of high lipoprotein(a) in individuals with moderate elevations of low-density lipoprotein cholesterol (LDL-C) may identify individuals at high risk of cardiovascular disease. Methods and Results We examined 2606 Framingham Offspring participants (median age, 54 years; 45% men) prospectively with a median follow-up of 15 years (n=392 incident cardiovascular events). Individuals with higher (≥100 nmol/L) versus lower lipoprotein(a) were divided into groups based on LDL-C <135 mg/dL versus ≥135 mg/dL. In Cox models, after adjustment for known risk factors, high lipoprotein(a) (≥100 nmol/L) and LDL-C ≥135 mg/dL were each significant predictors of cardiovascular disease (LDL-C ≥135 mg/dL: hazard ratio [HR], 1.34; 95% CI, 1.09-1.64; P=0.006; high lipoprotein (a): HR, 1.31; 95% CI, 1.03-1.66; P=0.026). Across the groups of high/low lipoprotein (a) and LDL-C ≥135 mg/dL or <135 mg/dL, the absolute cardiovascular disease risks at 15 years were 22.6% (high lipoprotein(a)/LDL-C ≥135 mg/dL, n=248), 17.3% (low lipoprotein(a)/LDL-C ≥135 mg/dL, n=758), 12.7% (high lipoprotein(a)/LDL-C <135 mg/dL, n=275) and 11.5% (low lipoprotein(a)/LDL-C <135 mg/dL, n=1328, reference group). Among individuals with LDL-C ≥135 mg/dL, those with high lipoprotein(a) had a 43% higher risk (HR, 1.43; 95% CI, 1.05-1.97; P=0.02). Presence of high lipoprotein(a) with moderate LDL-C levels (135-159 mg/dL) yielded absolute risks equivalent to those with LDL-C ≥160 mg/dL (23.5%, 95% CI, 17.4%-31.3%; and 20.7%, 95% CI, 16.8%-25.3%, respectively). Conclusions Concomitant elevation of LDL-C ≥135 mg/dL and lipoprotein(a) ≥100 nmol/L is associated with a high absolute risk of incident cardiovascular disease. lipoprotein(a) measurement in individuals with moderate elevations in LDL-C, who do not otherwise meet criteria for statins, may identify individuals at high cardiovascular risk.