Benefit and Risk of Prolonged Dual Antiplatelet Therapy After Percutaneous Coronary Intervention With Drug-Eluting Stents in Patients With Elevated Lipoprotein(a) Concentrations

Lipoprotein(a), platelet function and cardiovascular disease

Lipoprotein(a) (Lp(a)) is associated with atherothrombosis through several mechanisms, including putative antifibrinolytic properties. However, genetic association studies have not demonstrated an association between high plasma levels of Lp(a) and the risk of venous thromboembolism, and studies in patients with highly elevated Lp(a) levels have shown that Lp(a) lowering does not modify the clotting properties of plasma ex vivo. Lp(a) can interact with several platelet receptors, providing biological plausibility for a pro-aggregatory effect. Observational clinical studies suggest that elevated plasma Lp(a) concentrations are associated with worse long-term outcomes in patients undergoing revascularization. Furthermore, in these patients, those with elevated plasma Lp(a) levels derive more benefit from prolonged dual antiplatelet therapy than those with normal Lp(a) levels. The ASPREE trial in healthy older individuals treated with aspirin showed a reduction in ischaemic events in those who had a single-nucleotide polymorphism in LPA that is associated with elevated Lp(a) levels in plasma, without an increase in bleeding events. In this Review, we re-examine the role of Lp(a) in the regulation of platelet function and suggest areas of research to define further the clinical relevance to cardiovascular disease of the observed associations between Lp(a) and platelet function.

Aspirin and Cardiovascular Risk in Individuals With Elevated Lipoprotein(a): The Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Effective therapies for reducing cardiovascular disease (CVD) risk in people with elevated lipoprotein(a) are lacking, especially for primary prevention. Because of the potential association of lipoprotein(a) with thrombosis, we evaluated the relationship between aspirin use and CVD events in people with elevated lipoprotein(a).

METHODS AND RESULTS

We used data from the MESA (Multi-Ethnic Study of Atherosclerosis), a prospective cohort study of individuals free of baseline cardiovascular disease. Due to potential confounding by indication, we matched aspirin users to nonusers using a propensity score based on CVD risk factors. We then evaluated the association between aspirin use and coronary heart disease (CHD) events (CHD death, nonfatal myocardial infarction) stratified by baseline lipoprotein(a) level (threshold of 50 mg/dL) using Cox proportional hazards models with adjustment for CVD risk factors. After propensity matching, the study cohort included 2183 participants, including 1234 (57%) with baseline aspirin use and 423 (19%) with lipoprotein(a) >50 mg/dL. Participants with lipoprotein(a) >50 mg/dL had a higher burden of CVD risk factors, more frequent aspirin use (61.7% versus 55.3%, P=0.02), and higher rate of incident CHD events (13.7% versus 8.9%, P<0.01). Aspirin was associated with a significant reduction in CHD events among those with elevated lipoprotein(a) (hazard ratio, 0.54 [95% CI, 0.32-0.94]; P=0.03). Those with lipoprotein(a) >50 mg/dL and aspirin use had similar CHD risk as those with lipoprotein(a) ≤50 mg/dL regardless of aspirin use.

CONCLUSIONS

Aspirin use was associated with a significantly lower risk for CHD events in participants with lipoprotein(a) >50 mg/dL without baseline CVD. The results of this observational propensity-matched study require confirmation in studies with randomization of aspirin use.

Prolonged dual antiplatelet therapy in invasively treated acute coronary syndrome patients with different lipoprotein(a) concentrations

BACKGROUND

Lipoprotein(a) [Lp(a)] was positively associated with recurrent ischemic events in patients with acute coronary syndrome (ACS). This study was performed to investigate the effect of Lp(a) levels on outcomes of dual antiplatelet therapy (DAPT) > 1 year versus DAPT ≤ 1 year after percutaneous coronary intervention (PCI) in this population.

METHODS

A total of 4,357 ACS patients who were event-free at 1 year after PCI were selected from the Fuwai PCI Registry, and patients were stratified into four groups according to DAPT duration (≤ 1 year vs. > 1 year) and Lp(a) levels (≤ 30 mg/dL vs. > 30 mg/dL). The primary endpoint was major adverse cardiovascular and cerebrovascular event (MACCE), defined as a composite of cardiac death, myocardial infarction or stroke.

RESULTS

After 2.4-year follow-up, the incidence of MACCE (HRadjusted 0.284, 95% CI 0.115-0.700; HRIPTW 0.351, 95% CI 0.164-0.751) were significantly reduced in DAPT > 1 year group than that in DAPT ≤ 1 year group in individuals with elevated Lp(a) levels. However, in individuals with normal Lp(a) levels, no statistically difference was found between these two groups in terms of MACCE, although the risks of all-cause death and definite/probable stent thrombosis were lower in DAPT > 1 year group. Notably, the risk of clinically relevant bleeding did not statistically differ between these two groups in individuals with different Lp(a) levels.

CONCLUSIONS

This study firstly demonstrated that extended DAPT (> 1 year) was statistically associated with lower risk of ischemic events in ACS patients with elevated Lp(a) levels after PCI, whereas this association was not found in individuals with normal Lp(a) levels.

Australian Atherosclerosis Society Position Statement on Lipoprotein(a): Clinical and Implementation Recommendations

This position statement provides guidance to cardiologists and related specialists on the management of adult patients with elevated lipoprotein(a) [Lp(a)]. Elevated Lp(a) is an independent and causal risk factor for atherosclerotic cardiovascular disease (ASCVD) and calcific aortic valve disease (CAVD). While circulating Lp(a) levels are largely determined by ancestry, they are also influenced by ethnicity, hormones, renal function, and acute inflammatory events, such that measurement should be done after accounting for these factors. Further, circulating Lp(a) concentrations should be estimated using an apo(a)-isoform independent assay that employs appropriate calibrators and reports the results in molar units (nmol/L). Selective screening strategies of high-risk patients are recommended, but universal screening of the population is currently not advised. Testing for elevated Lp(a) is recommended in all patients with premature ASCVD and those considered to be at intermediate-to-high risk of ASCVD. Elevated Lp(a) should be employed to assess and stratify risk and to enable a decision on initiation or intensification of preventative treatments, such as cholesterol lowering therapy. In adult patients with elevated Lp(a) at intermediate-to-high risk of ASCVD, absolute risk should be reduced by addressing all modifiable behavioural, lifestyle, psychosocial and clinical risk factors, including maximising cholesterol-lowering with statin and ezetimibe and, where appropriate, PCSK9 inhibitors. Apheresis should be considered in patients with progressive ASCVD. New ribonucleic acid (RNA)-based therapies which directly lower Lp(a) are undergoing clinical trials.

Lipoprotein(a) in Youth and Prediction of Major Cardiovascular Outcomes in Adulthood

BACKGROUND

Elevated lipoprotein(a) [Lp(a)] is a common risk factor for cardiovascular disease outcomes with unknown mechanisms. We examined its potential role in identifying youths who are at increased risk of developing adult atherosclerotic cardiovascular disease (ASCVD).

METHODS

Lp(a) levels measured in youth 9 to 24 years of age were linked to adult ASCVD and carotid intima-media thickness in the YFS (Cardiovascular Risk in Young Finns Study), in which 95 of the original 3596 participants (2.7%) recruited as children have been diagnosed with ASCVD at a median of 47 years of age. Results observed in YFS were replicated with the use of data for White participants from the BHS (Bogalusa Heart Study). In BHS, 587 White individuals had data on youth Lp(a) (measured at 8-17 years of age) and information on adult events, including 15 cases and 572 noncases. Analyses were performed with the use of Cox proportional hazard regression.

RESULTS

In YFS, those who had been exposed to high Lp(a) level in youth [defined as Lp(a) ≥30 mg/dL] had ≈2 times greater risk of developing adult ASCVD compared with nonexposed individuals (hazard ratio, 2.0 [95% CI, 1.4-2.6]). Youth risk factors, including Lp(a), low-density lipoprotein cholesterol, body mass index, and smoking, were all independently associated with higher risk. In BHS, in an age- and sex-adjusted model, White individuals who had been exposed to high Lp(a) had 2.5 times greater risk (95% CI, 0.9-6.8) of developing adult ASCVD compared with nonexposed individuals. When also adjusted for low-density lipoprotein cholesterol and body mass index, the risk associated with high Lp(a) remained unchanged (hazard ratio, 2.4 [95% CI, 0.8-7.3]). In a multivariable model for pooled data, individuals exposed to high Lp(a) had 2.0 times greater risk (95% CI, 1.0-3.7) of developing adult ASCVD compared with nonexposed individuals. No association was detected between youth Lp(a) and adult carotid artery thickness in either cohort or pooled data.

CONCLUSIONS

Elevated Lp(a) level identified in youth is a risk factor for adult atherosclerotic cardiovascular outcomes but not for increased carotid intima-media thickness.