Plasma eicosanoid profiling in the course of proprotein convertase subtilisin-kexin type 9 inhibition: insights from a metabolomic analysis

Background

Treatment with monoclonal antibodies targeting circulating proprotein convertase subtilisin-kexin type 9 (PCSK9) was found to reduce all-cause mortality in addition to cardiovascular events, suggesting pleiotropic effects. Eicosanoids are bioactive metabolites involved in cardiovascular disease and have not yet been studied in the course of PCSK9 inhibition.

Methods

In this prospective translational single-center study, plasma samples were collected from 64 patients before and after initiation of PCSK9 inhibitor treatment. Metabolomic analyses were performed using liquid chromatography coupled to high-resolution mass spectrometry.

Results

A total of 62 bioactive eicosanoids were detected. Among the metabolites, four were significantly decreased by PCSK9 inhibition after one month and remained stable after 6 months (figure): arachidonic acid (p=0.003), 12,13-DiHOME (p<0.001), 9-HpODE_9.91 (p=0.007) and HpODE_7.71 (p=0.011). Phospholipase A2 levels were reduced by 40% after 1 month (p=0.003) and by additional 50% after 6 months of treatment (p=0.015), but did not correlate with eicosanoids (p=0.057). The change in arachidonic acid levels resulted in a significant increase in the ratio of omega-3 to omega-6 polyunsaturated fatty acids (p=0.002).

Conclusion

PCSK9 inhibition leads to significant changes in the eicosanoid profile already after one month, in particular to a downregulation of arachidonic acid. This discovery complements the presumed pleiotropic effects of PCSK9 inhibition and may provide additional benefit in the treatment of atherosclerotic disease.

Funding Acknowledgement

Type of funding sources: None.

Monocyte subsets predict mortality after cardiac arrest

Background

After successful cardiopulmonary resuscitation with return of spontaneous circulation (ROSC), many patients show signs of an overactive immune activation. Monocytes are a heterogenous cell population that can be distinguished into three subsets.

Purpose

The aim of this prospective, observational study was to analyze whether monocyte subset distribution is associated with mortality at 6 months in patients after cardiac arrest.

Methods

We included 53 patients admitted to our medical ICU after cardiac arrest. Blood was taken on admission and monocyte subset distribution was analyzed by flow cytometry and distinguished into classical monocytes (CM; CD14++CD16-), intermediate monocytes (IM; CD14++CD16+CCR2+) and non-classical monocytes (NCM; CD14+CD16++CCR2-).

Results

Median age was 64.5 (IQR 49.8–74.3) years and 75.5% of patients were male. Mortality at 6 months was 50.9% and survival with good neurological outcome was 37.7%. Of interest, monocyte subset distribution upon admission to the ICU did not differ according to survival. However, patients that died within 6 months showed a strong increase in the pro-inflammatory subset of intermediate monocytes (8.3% (3.8–14.6)% vs. 4.1% (1.5–8.2)%; p=0.025), and a decrease of classical monocytes (87.5% (79.9–89.0)% vs. 90.8% (85.9–92.7)%; p=0.036) 72 hours after admission. In addition, intermediate monocytes were predictive of outcome independent of initial rhythm and time to ROSC and correlated with the CPC-score at 6 months (R=0.32; p=0.043).

Discussion

Monocyte subset distribution is associated with outcome in patients surviving a cardiac arrest. This suggests that activation of the innate immune system may play a significant role in patient outcome after cardiac arrest.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): FWF - Fonds zur Förderung der wissenschaftlichen Forschung

P4572Lipoprotein(a) is not associated with survival after acute coronary syndromes

Aims

Lipoprotein(a) [Lp(a)] is associated with coronary artery disease in population studies, however studies on its predictive value in patients with established cardiovascular disease, in particular after acute coronary syndromes (ACS), are conflicting. The aim of this study was to investigate whether Lp(a) is associated with survival after ACS.

Methods and results

We analyzed 4469 consecutive patients that underwent coronary angiography for ACS. Lp(a) measurement at time of ACS was available in 1245 patients and median follow-up for cardiovascular and total mortality was 5.0 (IQR 3.2–8.0) years. 655 (52.6%) presented with ST-segment elevation myocardial infarction (STEMI), 424 (34.1%) with Non-ST-segment elevation myocardial infarction (NSTEMI) and 166 (13.3%) underwent coronary angiography for unstable angina. Cardiovascular mortality was 9.1% and total mortality was 15.7%. Patients were stratified into four groups to their Lp(a) levels. (≤15 mg/dL, >15–30 mg/dL, >30–60 mg/dL, and >60 mg/dL). Multivessel disease was significantly more common in patients with Lp(a) >60 mg/dL (p<0.05). Increased levels of Lp(a) were not associated with cardiovascular mortality (HR compared with Lp(a) ≤15 mg/dL were 1.2, 1.2, and 1.0, respectively; p=0.69) and not with total mortality (HR compared with Lp(a) ≤15 mg/dL were 1.2, 1.2, and 1.2, respectively; p=0.46).

Central Figure

Conclusion

Lp(a) levels at time of ACS were neither associated with cardiovascular nor with total mortality. Although Lp(a) has been shown to be associated with incidence of coronary artery disease, this study does not support any role of Lp(a) as a risk factor after ACS. This should be taken into account for development of outcome studies for agents targeting Lp(a) plasma levels.