Estimating the magnitude of LDL-c reduction needed to overcome the increased risk of atherosclerotic cardiovascular events caused by Lp(a) – to guide clinical management

Presented at EAS 2022 by Brian Ference (Cambridge, UK)

Introduction and methods

Unfortunately, diet and exercise do not reduce Lp(a) levels, and there is no effective therapy to reduce Lp(a) at the moment. Therefore, guidelines recommend intensive risk factor modification among individuals with increased risk due to elevated Lp(a) levels. But this guidance is not specific enough, resulting in clinical inertia on measuring Lp(a) levels among clinicians.

Aim of the study

The primary objective was to quantify the amount of LDL-c lowering needed to overcome the increased risk caused by Lp(a) – depending on the age at which LDL-c lowering is initiated. The secondary objective was to provide clinical guidance about how elevated Lp(a) levels can be used to guide individual treatment decisions to reduce the risk of ASCVD events until potent Lp(a) lowering therapies will become available.

Methods

The study was designed as a naturally randomized trial of 445,765 participants that were enrolled in the UK Biobank. Each individual was naturally randomized to either average Lp(a), higher Lp(a), or both higher Lp(a) and lower LDL using genetic instruments.

Primary outcome

The primary outcome was lifetime risk of major coronary events (MCE – first occurrence of fatal or nonfatal MI or coronary revascularization) from 30-80 years.

Main results

• Lifetime risk of ASCVD was ~30-40% higher in those allocated to 123 nmol/L higher Lp(a) compared to those allocated to average Lp(a) levels at each age. This higher ASCVD risk was nearly completely attenuated in those allocated to 123 nmol/L higher Lp(a) AND 19.5 mg/dL (0.5 mmol/L) lower LDL-c, with superimposable Kaplan-Meier curves at all ages.
• The effect was almost identical in men and women.
• Individuals allocated to very high Lp(a) – 251 mmol/L higher – had a ~2-fold increased risk of an ASCVD event compared to those allocated to average Lp(a) levels at each age. This risk was nearly completely attenuated is individuals allocated to both 251 mmol/L higher Lp(a) and 36.1 mg/dL (0.8 mmol/L) lower LDL-c at all ages. These results suggest a dose-dependent relationship.
• The magnitude of LDL-c lowering that was needed to overcome the increased ASCVD risk caused by elevated Lp(a) depends on a person’s absolute Lp(a) level and the age that LDL-c lowering is initiated.
• Among those with very high Lp(a) levels of >200 nmol/L, the required additional LDL-c lowering needed to overcome ASCVD risk caused by Lp(a) was extremely high, around 1.5-2.0 mmol/L.

Conclusion

In this study, the quantification of additional LDL-c lowering that is needed to overcome the increased ASCVD risk caused by elevated Lp(a) levels was demonstrated. This provides a clear and directly actionable clinical guidance for how to use Lp(a) to individualize the prevention of ASCVD. The intensity of additional LDL-c lowering depends both on a individual’s absolute Lp(a) level and the age at which LDL-c lowering is started.

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