Endothelial Microparticles as Potential Biomarkers of Endothelial Dysfunction

Endothelial microparticles (EMP) have a promising role as a diagnostic and prognostic tool in the assessment of endothelial function. This study compares the levels of EMP in hypercholesterolaemia patients before and after treatment with statins and correlates it with the current method of assessing endothelial function using pulse wave analysis.

The current available methods to assess endothelial function are tedious and not suitable to be applied clinically. Detecting EMP levels are simpler as it only involves routine blood taking which is better tolerated by patients.

Outcome from this study will contribute to finding a potential diagnostic, prognostic and treatment assessment tool that is suitable to be used clinically. This will have a large impact in the management of cardiovascular-related disease that is prevalent worldwide and increasing in the developed countries.

General study objective

To evaluate EMP as a simple diagnostic tool in assessing endothelial function in hypercholesterolaemic patients.

Specific objectives:

1. To compare the levels of EMP ( Cluster of differentiation (CD)144, CD62e and CD31+/42-) in hypercholesterolaemics before and after statin.
2. To correlate the levels of EMP with the assessment of endothelial function using pulse wave analysis (PWA) in hypercholesterolaemics before and after statin.

Research design

It is a clinical cohort study involving newly diagnosed hypercholesterolemic patients before and after intervention with statin.

Sampling method and subject recruitment Consecutive sampling of sampling frame will be applied due to limited number of sample who could fulfill the criteria within the planned data collection period.

Data collection method

Screening

Before acceptance into the study, all potential subjects will undergo a screening procedure. A signed written informed consent will be obtained from the subjects before screening procedure is performed. The screening procedure will include detailed history taking on medical history, physical examination and 5 ml venous blood sampling for fasting lipid profile (FLP) from the antecubital vein.

Clinical study session

Once the FLP results are obtained, appointment to attend the clinical study sessions will be arranged with the eligible subjects who fulfil the criteria.

Newly diagnosed hypercholesterolaemia patients recruited will undergo clinical study.

First visit

The first visit will involve blood taking for baseline values, assessment with SphygmoCor and consultation by the treating physician.

During the first visit, 10 ml of venous blood will be withdrawn from the antecubital vein followed by the assessment of endothelial function, augmentation index (AI) and central arterial pressure (CAP) using SphygmoCor.

Venous blood is needed for baseline full blood count (FBC), renal function test (RFT), liver function test (LFT), fasting blood sugar (FBS), high sensitivity C-reactive protein (hs-CRP) and EMP.

Assessment of endothelial function, AI and CAP using SphygmoCor .

Physician consultation

During the first visit, all patients will be seen by the treating physician (a Family Medicine Specialist) at the outpatient clinic (KRK) and advised for therapeutic life style changes (TLC) as recommended by the Malaysian Clinical Practice Guideline (CPG) for Hyperlipidaemia (2011). Patients will be on TLC for a minimum duration of 6 weeks before the next visit.

Second visit

The second visit will only involve blood taking for FLP (5 ml blood) after at least 6 weeks duration of TLC.

Third visit

Once the FLP results are obtained (in approximately a week), patients will then be seen by the treating physician in the clinic.

Patients who do not achieve the targeted LDL level after TLC and indicated for treatment will be prescribed with statin by the attending physician.

Patients who achieve the targeted LDL level after TLC will continue TLC and will be excluded from the study

Fourth visit

The fourth visit will be arranged with the patients 3 months later. 10 ml of blood will be withdrawn for EMP quantification, FLP, hs-CRP and LFT. This will be followed by the assessments of endothelial function, AI and CAP as explained above.

Fourth visit marks the end of the Study 2. Thereafter, patients will continue their treatment at the KRK.

The study duration for each subject will be approximately 5 months.

Patients that miss follow-up or not compliant to the medication prescribed will be excluded from the study analysis. However, this will not compromise the treatment received by patients as they will continue to be treated in KRK.

Eligibility Criteria:
Inclusion Criteria:

1. Hypercholesterolaemia: ( LDL \>4.1 mmol/l)
2. Age 35 years and above
3. Agreeable to the treatment with statin if indicated

Exclusion Criteria:

1. Pregnancy and breast feeding
2. Serious medical illness eg kidney failure, liver failure, stroke and malignancy.
3. Arrythmias
4. Contraindicated to statin