There are many ways to measure risk factors for having a heart attack, but since the 1950s the criteria used most by doctors to predict your likelihood to suffer a heart attack has been that HDL (“Healthy”) cholesterol predicts protection, and the LDL (“Lousy”) cholesterol predicts increased risk for heart attacks (Physiol Rev, 1954;34:589–607). An extensive review of the world’s literature demonstrates that this is not always true (Eur Heart J, 2023;44(16):1394-1407). For example, several studies show that high levels of HDL cholesterol may actually predict increased risk for a heart attack (Medscape Internal Medicine, July 27, 2018).
Now we know that:
• cholesterol particles are triglycerides and cholesterol molecules inside a large ball.
• there are many different types of HDL and LDL balls.
• HDL balls include Large Particle HDLs that help to prevent heart attacks, and Small Particle HDLs that do not help to prevent heart attacks.
• LDL balls include Small Particle LDLs that play a major role in heart attacks, and Large Particle LDLs that do not increase susceptibility to suffering a heart attack.
This means that having lots of Small Particle LDL increases risk for heart attacks, and Large Particle LDL may not be a major risk factor. Having lots of Large Particle HDL helps to prevent heart attacks and lots of Small Particle HDL may not help to prevent heart attacks.
High Levels of HDL (>100) Can Harm You
Having HDL levels of 60 to 90 mg/dL helps to prevent heart attacks (J Am Heart Assoc, 2014;3:e000519), but having higher levels offers no further reduction in heart attacks (J Am Heart Assoc, 2014;3:e000519). Having high HDL levels greater than 90 mg/dL is associated with increased dementia (Cardiovasc Res, 2022;118:1330–1343), and an increased death rate (Eur Heart J, 2017;38:2478–2486). HDL contains a lot of different particles that help to clear cholesterol from cells, but HDL also is an anti-oxidant, anti-inflammatory, and immune-regulator (Curr Med Chem, 2019;26:1644–1664). The ratio of large-to-small HDL is more dependable for assessing heart attack and diabetes risks (Clin Chem, 2011;57:392–410). It appears that the small and medium size HDL particles are associated with increased risk for heart attacks (J Clin Endocrinol Metab, 2020;105:e1657-e1666), but large HDL particles are not (Elife, 2021;10:e58361). Both very low and very high HDL levels are associated with an increased risk of infectious disease (Arterioscler Thromb Vasc Biol, 2020;40:267–278), autoimmune disease (Clin Chem, 2019;65:644–652), diabetes (Prog Lipid Res, 2018;71:54–690), cancer ( J Hematol Onco, 2020;13:129) and kidney failure (Arterioscler Thromb Vasc Biol, 2021;41:128–140). You can’t depend on drugs added to statins to raise a low HDL; drugs added to statins that increase blood levels of HDL levels have not been shown to help prevent heart attacks (N Engl J Med, 2011;365:2255–2267).
Physical Signs of Increased Heart Attack Risk
• Resting heart rate >70
• Family history of heart attacks
• High blood pressure (>120/80 at bedtime)
• Diabetes or prediabetes
• Being overweight or obese
• Storing excess fat in your belly
• Being physically inactive
• Family history of early heart disease
• History of preeclampsia during pregnancy
• Eating an unhealthful diet
Check your HDL and LDL Cholesterol Levels
You can find out your chances of suffering a heart attack by getting the blood tests for LDL and HDL cholesterol, non–HDL-cholesterol, and cholesterol particle size. Both a high (>90) and low HDL (<35) cholesterol are associated with increased risk. If any of these tests are abnormal, or you have other risk factors for a heart attack, your doctor can measure the amount of plaque in your arteries with either an ultrasound test of the arteries in your neck or a CT scan of the arteries in your heart.
Other Tests to Predict Risk for a Heart Attack
• Blood pressure >120/80 at bedtime, when blood pressure is lowest
• Triglycerides >150 – increased risk for diabetes
• Homocysteine >10 – vitamin deficiency or genetic
• Lp(a) >125 – blood test for a genetic clotting disorder
• NT-proBNP: BNP (brain natriuretic peptide) is a hormone released by your brain and heart when your heart muscle is stiff and cannot relax between beats
• CRP >1 – a measure of inflammation
• High sensitivity CRP – a measure of inflammation
• High sensitivity troponin T – a measure of heart muscle damage
• Carotid Intima-Media Thickness (CIMT) Test – Soundwaves measure plaques in the carotid arteries in your neck
• CT scan – shows plaques in your heart arteries
Whatever your test results, I believe that everyone should be on a heart attack prevention program. If you have significant plaques in your arteries, I recommend an immediate effort to reduce these plaques; they may be reversible with strict lifestyle changes. If you have one or more of the risk factors listed above, see if you can correct them with lifestyle changes. I believe that everyone should:
• lose weight if overweight (I recommend intermittent fasting) and avoiding sugar and refined carbohydrates)
• eat a healthful diet with plenty of vegetables, fruits, beans, nuts and other seeds
• avoid sugared drinks including fruit juices, sugar-added foods, red meat, processed meats and fried foods
• avoid smoking
• avoid taking in alcohol regularly or excessively
• keep hydroxy vitamin D levels above 30 ng/mL