Measurement of plasma lipids in patients admitted with acute myocardial infarction or unstable angina pectoris

Differences between repeated lipid profile measurements in a tertiary hospital over a short time period

BACKGROUND

Measurement of the plasma lipid profile, mainly low-density lipoprotein cholesterol (LDL-C), is widely used in the management of hospitalized patients as part of their cardiometabolic risk assessment. In common practice, LDL-C is calculated indirectly by the Friedewald equation. For many years, fasting of 8-14 h is needed to obtain an accurate lipid profile measurement, although recent guidelines do not necessitate it. The aim of this study was to find patients with two consecutive LDL-C measurements taken over a short time period on the same admission to see if a significant difference exists and to suggest reasons that may explain it. We also aim to define whether the difference between LDL-C calculated by the Friedewald equation is diminished while using the newer Martin/Hopkins, de Cordova or Sampson/NIH equations.

METHODS

This was a retrospective cohort study performed in one medical center in Israel. In a five-year time period, 772 patients with two repeated LDL-C measurements taken on the same admission were found. The median time gap between tests was 2 days. Correlations between laboratory results and LDL-C measurements were determined.

RESULTS

A total of 414 patients (53.6%) had a difference greater than the acceptable total error of 8.9% in LDL-C calculation using the Friedewald equation, with a mean 25.8% difference between the two tests. Newer LDL-C calculations showed less diversity. Non-HDL-C was found as the only variable with a major correlation with LDL-C results in all equations. A weaker correlation was found with HDL-C. Triglycerides showed an even weaker correlation, and glucose differences had no correlation with LDL-C differences.

CONCLUSIONS

Repeated LDL-C measurements can vary widely, even during a short period of hospitalization. In this study, more than half of the patients had a significant difference between their consecutive LDL-C results. This wide difference between two consecutive tests was diminished using newer calculations, yet not well explained. The fasting state likely has no effect on LDL-C levels. The results of this study might emphasize that many factors influence LDL-C calculation, especially in the disease state. Further research is needed, especially in looking for a more accurate LDL-C calculation from existing formulas.

Pharmacological rationale for the very early treatment of acute coronary syndrome with monoclonal antibodies anti-PCSK9

Immediate and aggressive lipid lowering therapies after acute coronary syndromes (ACS) and percutaneous coronary interventions (PCI) are supported by the ESC/EAS dyslipidemia guidelines, recommending the initiation of high-intensity statin therapy within the first 1-4 days of hospitalization. However, whether non statin lipid-lowering agents, added to statin treatment, could produce a further reduction in the risk of major adverse cardiovascular events (MACE) is still unknown. Thus, the efficacy of early treatment post-ACS with monoclonal antibodies (mAbs) anti PCSK9, evolocumab and alirocumab, is under investigation. The rationale to explore the rapid and aggressive pharmacological intervention with PCSK9 mAbs is supported by at least five confirmatory data in ACS: 1) circulating PCSK9 levels are raised during ACS 2) PCSK9 may stimulate platelet reactivity, this last being pivotal in the recurrence of ischemic events; 3) PCSK9 is associated with intraplaque inflammation, macrophage activation and endothelial dysfunction; 4) PCSK9 concentrations are associated with inflammation in the acute phase of ACS; and 5) statins raise PCSK9 levels promptly and, at times, dramatically. In this scenario, appropriate pharmacodynamic characteristics of anti PCSK9 therapies are a prerequisite for an effective response. Monoclonal antibodies act on circulating PCSK9 with a direct and rapid binding by blocking the interaction with the low-density lipoprotein receptor (LDLR). Evolocumab and alirocumab show a very rapid (within 4 h) and effective suppression of circulating unbound PCSK9 (- 95 % ÷ - 97 %). This inhibition results in a significant reduction of LDL-cholesterol (LDL-C) after 48 h (- 35 %) post injection with a full effect after 7-10 days (55-75 %). The complete and swift inhibitory action by evolocumab and alirocumab could have a potential clinical impact in ACS patients, also considering their potential inhibition of PCSK9 within the atherosclerotic plaque. Thus, administration of evolocumab or alirocumab is effective in lowering LDL-C levels in ACS, although the efficacy to prevent further cardiovascular (CV) events is still undetermined. The answer to this question will be provided by the ongoing clinical trials with evolocumab and alirocumab in ACS. In the present review we will discuss the pharmacological and biological rationale supporting the potential use of PCSK9 mAbs in ACS patients and the emerging evidence of evolocumab and alirocumab treatment in this clinical setting.

Lipid levels achieved after a first myocardial infarction and the prediction of recurrent atherosclerotic cardiovascular disease

BACKGROUND

Low density lipoprotein cholesterol (LDL-C) goals post-myocardial infarction (MI) are debated, and the significance of achieved blood lipid levels for predicting a first recurrent atherosclerotic cardiovascular disease (rASCVD) event post-MI is unclear.

METHODS

This was a cohort study on first-ever MI survivors aged ≤76 years attending 4-14 week revisits throughout Sweden 2005-2013. Personal-level data was collected from SWEDEHEART and linked national registries. Exposures were quintiles of LDL-C, high density lipoprotein cholesterol (HDL-C), total cholesterol (TC), and triglycerides (TGs) at the revisit. Group level associations with rASCVD (nonfatal MI or coronary heart disease death or fatal or nonfatal ischemic stroke) were estimated in Cox regression models. Predictive capacity was estimated by differences in C-statistic, integrated discriminatory improvement, and net reclassification improvement when adding each blood lipid to a validated risk prediction model.

RESULTS

25,643 patients, 96.9% on statin therapy, were followed during a mean of 4.1 years. rASCVD occurred in 2173 patients (8.5%). For LDL-C and TC, moderate associations with rASCVD were observed only in the 5th vs. the lowest (referent) quintiles. For TGs and HDL-C increased risks were observed in quintiles 3-5 vs. the lowest. Minor predictive improvements were observed when lipid fractions were added to the risk model but the discrimination overall was poor (C-statistics <0.6).

CONCLUSIONS

Our data question the importance of LDL-C levels achieved at first revisit post-MI for decisions on continued treatment intensity considering the weak association with rASCVD observed in this post-MI cohort.

Lipid Biomarkers for Risk Assessment in Acute Coronary Syndromes

PURPOSE OF REVIEW

The objective of this review was to summarize evidence gathered for the prognostic value of routine and novel blood lipids and lipoproteins measured in patients with acute coronary syndromes (ACS).

RECENT FINDINGS

Data supports clear association with risk and actionable value for non-high-density lipoprotein (Non-HDL) cholesterol and plasma ceramides in a setting of ACS. The prognostic value and clinical actionability of apolipoprotein B (apoB) and lipoprotein(a) [Lp(a)] in ACS have not been thoroughly tested, while the data for omega-3 fatty acids and oxidized low-density lipoprotein (Ox-LDL) are either untested or more varied. Measuring basic lipids, which should include Non-HDL cholesterol, at the time of presentation for ACS is guideline mandated. Plasma ceramides also provide useful information to guide both treatment decisions and follow-up. Additional studies targeting ACS patients are necessary for apoB, Lp(a), omega-3 fatty acids, and Ox-LDL.

Change in serum lipids after acute coronary syndromes: secondary analysis of SPACE ROCKET study data and a comparative literature review

BACKGROUND

It has long been an accepted belief that serum cholesterol significantly falls after myocardial infarction and that a return to pre-event levels takes approximately 3 months. The magnitude and clinical significance of this fall has recently been challenged.

METHODS

In the Secondary Prevention of Acute Coronary Events-Reduction Of Cholesterol to Key European Targets (SPACE ROCKET) trial, we measured serum lipids of individuals on day 1 and between days 2 and 4 after acute myocardial infarction (AMI). Second, we performed a thorough literature review and compared all studies reporting data on absolute changes in lipids immediately after AMI, using weighted means.

RESULTS

Of 1263 SPACE ROCKET participants, 128 had paired lipid measurements where both samples had been measured using identical methods at baseline and on days 2-4 after AMI. The mean lowering in total cholesterol between day 1 and day 2-4 was 0.71 mmol/L (95% CI 0.58-0.84; P < 0.0001) and in triglycerides was 0.10 mmol/L (-0.14-0.33; P = 0.405). A total of 25 papers showing absolute lipid changes post-AMI were identified. The combined data demonstrated a mean fall in total cholesterol of 9% to 11% from baseline over days 3-14 post-AMI, whereas for triglycerides, there was a rise of 18% from baseline to between day 9 and 12 weeks.

CONCLUSIONS

After a secondary analysis of SPACE ROCKET data and a comparison of previously published data, we report a 10% fall in total cholesterol after AMI-a difference that is of high clinical significance. Consequently, measurement of serum lipids in patients with AMI should be performed within the first hours after presentation.

Repeated serum lipid measurements during the peri-hospitalization period

The early treatment of hyperlipidemia in hospitalized patients confers potential benefit, yet total cholesterol is known to vary with acute illness, often delaying treatment decisions. A prospective study was conducted of 61 patients (mean age 57 years; 49% women) admitted to an acute care community hospital with various diagnoses with random nonfasting lipid profile measurements at admission, followed by second fasting lipid profile measurements on day 3 of hospitalization or upon discharge (whichever occurred first), and final fasting lipid profile measurements 4 weeks after discharge. All individual values of the lipid profile decreases at discharge, whereas the ratios of total cholesterol to high-density lipoprotein (HDL) and of low-density lipoprotein (LDL) to HDL did not change significantly. The 95% confidence interval around the total cholesterol/HDL ratio for each patient was within the same National Cholesterol Education Program Adult Treatment Panel III treatment recommendation category 42.6% of the time, whereas corresponding intervals for total cholesterol and LDL were within a single treatment category only 6.6% of the time. The total cholesterol/HDL ratio was significantly more consistent with regard to treatment implications than LDL or total cholesterol (p <0.0001). In conclusion, serum lipid values vary significantly during and after a hospital stay, whereas the ratio of total cholesterol to HDL remains relatively stable. This ratio may therefore serve as a more reliable basis for early treatment decisions in dyslipidemia.

Minimally modified electronegative LDL and its autoantibodies in acute and chronic coronary syndromes

OBJECTIVES

To determine the minimally modified electronegative LDL (LDL-) and its autoantibodies in coronary syndromes.

DESIGN AND METHODS

LDL(-) and its autoantibodies were determined by ELISA in patients with acute (ACS, unstable angina; AMI, acute myocardial infarction) and chronic coronary syndromes (stable angina, SA) and compared to subjects without coronary disease (controls). Results are expressed as median of LDL- (microg/mL) and anti-LDL(-) IgG (OD405 nm).

RESULTS

The concentrations of LDL(-) were higher in patients with coronary disease (ACS: 40.7 microg/mL; SA: 35.0 microg/mL) as compared to controls (21.6 microg/mL). The highest LDL- concentrations were found in patients with AMI (41.8 microg/mL). Anti-LDL(-) IgG was elevated in ACS (1.143) in relation to CCS (0.527) and controls (0.467). A positive correlation was observed between anti-LDL- IgG and CRP levels (r = 0.34, p <0.01) in the studied groups.

CONCLUSIONS

LDL(-) and anti-LDL(-) autoantibodies may be useful markers to follow patients with high risk for coronary events.

The evaluation and management of dyslipidemia and impaired glucose metabolism during acute coronary syndromes

Dyslipidemia and hyperglycemia are common among patients presenting with acute coronary syndromes (ACS), and patients with ACS and metabolic disorders are at increased risk for worse outcomes. Although guidelines for the diagnosis and management of dyslipidemia, diabetes, and the metabolic syndrome have been published, these guidelines have not specifically focused on the ACS patient population. Recent observational registries and clinical trials have advanced the appreciation of these disorders in ACS populations and data from these studies support aggressive efforts to diagnose and treat dyslipidemia and hyperglycemia in patients admitted for ACS.

Preventing a second stroke in the young

In the United States, more than 220,000 adults under the age of 45 have had a stroke. Secondary stroke prevention is critical in this population because of the potential impact of a second stroke on productivity and future quality of life. In addition to conventional stroke risk factors, younger patients have special risk factors inherent to genetic and environmental elements, such as the use of illicit drugs and cardiac abnormalities; in women, risk factors include pregnancy, migraine, and the use of oral contraceptives.