Objective

Lipoprotein(a) (Lp(a)) is an important genetically determined risk factor for atherosclerotic vascular disease (ASCVD). With the development of Lp(a)-lowering therapies, this study sought to characterise patterns of Lp(a) levels in a global ASCVD population and identify racial, ethnic, regional and gender differences.

Methods

A multicentre cross-sectional epidemiological study to estimate the prevalence of elevated Lp(a) in patients with a history of myocardial infarction, ischaemic stroke or peripheral artery disease conducted at 949 sites in 48 countries in North America, Europe, Asia, South America, South Africa and Australia between April 2019 and July 2021. Low-density lipoprotein cholesterol (LDL-C) and Lp(a) levels were measured either as mass (mg/dL) or molar concentration (nmol/L).

Results

Of 48 135 enrolled patients, 13.9% had prior measurements of Lp(a). Mean age was 62.6 (SD 10.1) years and 25.9% were female. Median Lp(a) was 18.0 mg/dL (IQR 7.9-57.1) or 42.0 nmol/L (IQR 15.0-155.4). Median LDL-C was 77 mg/dL (IQR 58.4-101.0). Lp(a) in women was higher, 22.8 (IQR 9.0-73.0) mg/dL, than in men, 17.0 (IQR 7.1-52.2) mg/dL, p<0.001. Black patients had Lp(a) levels approximately threefold higher than white, Hispanic or Asian patients. Younger patients also had higher levels. 27.9% of patients had Lp(a) levels >50 mg/dL, 20.7% had levels >70 mg/dL, 12.9% were >90 mg/dL and 26.0% of patients exceeded 150 nmol/L.

Conclusions

Globally, Lp(a) is measured in a small minority of patients with ASCVD and is highest in black, younger and female patients. More than 25% of patients had levels exceeding the established threshold for increased cardiovascular risk, approximately 50 mg/dL or 125 nmol/L.

Trial registration number

Adipocytes increase energy expenditure in response to prolonged sympathetic activation via persistent expression of uncoupling protein 1 (UCP1)^1,2. Here we report that the regulation of glycogen metabolism by catecholamines is critical for UCP1 expression. Chronic β-adrenergic activation leads to increased glycogen accumulation in adipocytes expressing UCP1. Adipocyte-specific deletion of a scaffolding protein, protein targeting to glycogen (PTG), reduces glycogen levels in beige adipocytes, attenuating UCP1 expression and responsiveness to cold or β-adrenergic receptor-stimulated weight loss in obese mice. Unexpectedly, we observed that glycogen synthesis and degradation are increased in response to catecholamines, and that glycogen turnover is required to produce reactive oxygen species leading to the activation of p38 MAPK, which drives UCP1 expression. Thus, glycogen has a key regulatory role in adipocytes, linking glucose metabolism to thermogenesis.