Elevated HDL-C is associated with adverse cardiovascular events

Presented at the ESC congress 2018 by: Marc Allard-Ratick (Atlanta, US)

Introduction and methods

Low levels of high density lipoprotein cholesterol (HDL-c) are associated with an increased cardiovascular (CV) risk, however, efforts to increase HDL-c did not lead to a decrease in CV risk. On the other hand, recent data indicate that there is a U-shaped association between HDL-c levels and adverse CV events and all-cause mortality.

In this study, 5,291 adults with CV disease, included in the Emory Cardiovascular Biobank, were followed-up for a median of 4.5 years (IQR: 1.8-6.9). Participants were divided into five groups based on their HDL-c levels:

• <30 mg/dl (<0.78 mmol/L)
• 31-40 mg/dl (0.8-1mmol/L)
• 41-50 mg/dl (1.1-1-3 mmol/L)
• 51-60 mg/dl (1.3-1.5 mmol/L)
• >60 mg/dl (>1.5 mmol/L)

The primary outcomes were all-cause mortality and CV death or non-fatal myocardial infarction (MI).

Main results

• The average age of the study population was 63 years, and 35% were female.
• The median follow-up was 4.5 years, during which 13% of participants suffered an MI or died, due to CV causes.
• Participants with HDL-c between 41 and 60 mg/dl (1.1-1.6 mmol/L) had the lowest CV risk, whereas the risk increased with low levels (< 41 mg/dl [<1.1 mmol/L]), as well as with very high levels (>60 mg/dl[>1.6 mmol/L]). In the group with the highest HDL-c levels, the risk of CV death was almost two-fold, compared with those in the 41-50 mg/dl (1.1-1.2 mmol/L) group.

Conclusion

Very high levels of HDL-c were associated with increased risk of CV death.

Discussion

After the presentation it was discussed that HDL is a very complex and multifunctional molecule that has not been fully understood yet. The possible mechanisms explaining such results may be genetic differentiation or dysfunctional HDL molecules, which are impaired as quantity increases. Very high HDL-c levels impact 1-5% of the general population, mostly females.

- Our reporting is based on the information provided at the ESC congress -