​Studies have shown that one in five Singaporeans have one or more risk factors (the 'three highs') for cardiovascular disease. These risk factors can increase your risk for heart attack by more than three times.

By Dr Wang Luo-Kai, Associate Consultant, Department of Cardiology

Cardiovascular disease (CVD) is the top cause of mortality in Singapore, accounting for 31% of deaths locally in 20221. CVD is a spectrum of disease which covers four main areas: coronary artery disease, cerebrovascular disease, peripheral artery disease and aortic aneurysm.

Studies have shown that one in five Singaporeans has one or more risk factors for CVD, such as hypertension, high cholesterol, diabetes (commonly known as the ‘three highs’), smoking and obesity. In combination, these risk factors can increase your baseline risk for heart attack by more than three times. Hence, it is important to screen for ‘three highs’, adopt a healthy lifestyle and understand our individual risks for CVD.

The underlying cause of CVD is atherosclerosis, that is, accumulation of plaque in the arteries which causes narrowing and eventual end organ damage. When coronary arteries narrow over time due to atherosclerosis, they eventually struggle to supply blood to the heart, which may lead to ischaemic heart disease and even myocardial infarction, commonly known as heart attack.

An illustration of how the plaque builds up in the arteries over time, narrows and eventually cause a blockage, stopping blood supply to the heart.

Primary Prevention is the Best Defence

The best way to prevent heart attack, or CVD from happening is taking early primary prevention, that is to screen for hypertension, high cholesterol, diabetes, and obesity. Prior to taking preventive actions, it is important to be aware of

individual’s 10-year CVD risk. The Heart Disease Risk Calculator, available in the Health Buddy App, allows users to input parameters such as age, gender, race, smoking status, lipid and blood pressure profile, which will then generate an estimated 10-year CVD risk. There are three tiers of CVD risk classification in the calculator: Green for low to moderate risk, Amber for high risk, and Red for very high risk.

Screening recommendations based on Ministry of Health’s guidelines2.

Managing High Cholesterol

The estimated 10-year CVD risk provides useful indication in managing high cholesterol – the higher the CVD risk, the lower the target for low-density lipoprotein (LDL) or ‘bad’ cholesterol level.

Based on the heart disease risk calculator, for individuals who are in the low to moderate risk category, medications such as statins should be considered when LDL is persistently more than 4.1 mmol/L, and the LDL target should be less than 2.6 mmol/L. For those who are at high risk category, LDL target should be less than 1.8 mmol/L, and those at very high risk category should already be on medications, and the LDL target should be less than 1.4 mmol/L3. The general blood pressure target for persons with hypertension and less than 65 years old is around 130/80 mmHg. For persons aged above 65 years old, blood pressure target should be around 140/80 mmHg4.

Statins are the most common medication prescribed to reduce cholesterol. Statins help to slow down production of LDL and increase the ability to remove LDL in the liver. The anti-inflammatory properties also stabilise unstable plaque in heart arteries. Though there are known side effects such as muscle aches, they are considered rare (5%) and usually tolerated. Depending on one’s condition, side effects could be overcome by either lowering the dose or switching to another class of statins. Liver inflammation is the rarer type of side effects and can occur up to 1% of patients.

A new class of injectables have emerged in recent years which offer as alternatives to patients who are unable to achieve target LDL levels, and are statin-intolerant, or are not suitable for regular therapies. These injectables are usually reserved for patients who are at high risk or have established CVD. PCSK9 inhibitors are another class of drugs that can lower LDL. They are monoclonal antibodies which block the action of PCSK9 (the protein that degrades LDL receptor). This in turn increases LDL absorption from blood stream into liver cells. It is administered via subcutaneous injection once every two weeks. Inclisiran is another type of injectable which reduces upstream PCSK9 production, and in turn increases LDL absorption. Like PCSK9 inhibitors, it is also injected subcutaneously, but at a much lower frequency of once every six months.

Medications for Diabetes and CVD

Diabetes mellitus (DM) is a common condition in Singapore, affecting around 10% of our adult population. It is imperative for patients with both diabetes and CVD to be on diabetic medications with cardiovascular benefits. Metformin, a medicine used to treat diabetes, reduces liver production of glucose and increases the body’s sensitivity to insulin. It has been the mainstay of treatment of diabetes since the 1970s. It exerts cardiovascular benefits through improved blood vessel function, lipid control and weight loss. There are now newer glucose lowering medications which target numerous novel pathways to reduce cardiovascular and renal events in patients with diabetes.

Sodium-glucose co-transporter-2 (SGLT2) inhibitors, a type of oral medication used to treat type 2 diabetes, works by increasing glucose excretion through the urinary system. They exert cardiovascular benefits through improved blood pressure control, weight loss, and renal protection. Another class of medication to highlight is glucagon-like peptide 1 Receptor Agonist (GLP1- RA). They work by stimulating glucose dependent insulin release from pancreas, delaying gastric emptying and exerts cardiovascular benefit via blood pressure control, improve blood vessel function, reduction in inflammation and weight loss5. These two new classes of medications have robust data on CV benefits and has currently Class 1 indications for initiation for patients with diabetes and CVD6.

More Tools to Assess CVD Risk: Coronary Artery Calcium Score (CACS)

Calcium score interpretation7.

CACS is a measure of the amount of calcified plaque (calcium) in the walls of the arteries of the heart (blood vessels). A build-up of plaque can cause these arteries to become narrow, reducing the amount of blood, oxygen and nutrients to reach the heart. The calcium score is computed based on volume and density of the calcium deposits. The higher the score, the higher the CVD risk. It is measured through a non-invasive computed tomography (CT) scan of the heart and is currently the most widely adopted non-traditional CVD risk marker, due to its high sensitivity for atherosclerosis. CACS is utilised when there is a need to further refine the management of asymptomatic patients who are considered to be at moderate risk, to help determine whether to start medications such as statins and/or aspirin initiation7. CACS is not suitable for patients who are considered low risk, high risk or very high risk.

The decision to start medications is a shared one by both physician and the patient, after a thorough risk and benefit discussion.

Remember the ‘ABCDE’ for Primary Prevention

Adapted from the 2019 ACC guidelines8.

A: Assess 10-year CVD Risk. Consider aspirin for selective high risk patients

B: Broad target for blood pressure is 130/80 for hypertensive patients < 65 years old

C: Cholesterol management involves CVD risk assessment, lifestyle modification and calcium score in moderate risk patients. Patients should stop smoking altogether.

D: Diabetic patients with CVD should be on SGLT2 Inhibitors, GLP1-RA or metformin. A heart-healthy diet should focus on vegetables, fruits, nuts, legumes, fish and wholegrains.

E: Exercise for at least 150 minutes a week of moderateintensity physical activity.

If we can do these ABCDEs well, we will have a very good chance of keeping heart attacks at bay!

1. https://www.moh.gov.sg/resources-statistics/singapore-health-facts/principal-causes-of-death
2. Report of the Screening Test Review Committee. Academy of Medicine, Singapore. March 2019
3. Mach F, Baigent C, Catapano AL et al. , 2019 ESC/EAS Guidelines for the management of dyslipidaemias: lipid modification to reduce cardiovascular risk: The Task Force for the management of dyslipidaemias of the European Society of Cardiology (ESC) and European Atherosclerosis Society (EAS). European Heart Journal, Volume 41, Issue 1, 1 January 2020, Pages 111–188.
4. Williams B , Mancia G, Spiering W at al.2018 ESC/ESH Clinical Practice Guidelines for the Management of Arterial Hypertension. The Task Force for the management of arterial hypertension of the European Society of Cardiology (ESC) and the European Society of Hypertension (ESH). European Heart Journal, Volume 39, Issue 33, 01 September 2018, Pages 3021–3104.
5. Wilcox T , Block CD , Schwartzbard AZ et al. Diabetic Agents, From Metformin to SGLT2 Inhibitors and GLP1 Receptor Agonists: JACC Focus Seminar. J Am Coll Cardiol. 2020 Apr, 75 (16) 1956–1974 
6. Marx N, Federici M, Schütt K et al. 2023 ESC Guidelines for the management of cardiovascular disease in patients with diabetes: Developed by the task force on the management of cardiovascular disease in patients with diabetes of the European Society of Cardiology (ESC). European Heart Journal, Volume 44, Issue 39, 14 October 2023, Pages 4043–4140.
7. Hecht H, Blaha MJ, Berman DS et al. Clinical indications for coronary artery calcium scoring in asymptomatic patients: Expert consensus statement from the Society of Cardiovascular Computed Tomography. Journal of Cardiovascular Computed Tomography 11 (2017) 157e168.
8. Alfaddagh A,Kelly Arps K,Blumenthal RS et al. The ABCs of Primary Cardiovascular Prevention: 2019 Update. American College of Cardiology Expert Analysis. 21 March 2019.

This article is from Murmurs Issue 46. Click here to read other articles or issues.