Peter Attia MD229 ‒ Understanding cardiovascular disease risk, cholesterol, and apoB
CHAPTERS
- 0:11 – 2:39
Introduction to the Compilation Episode
Peter Attia explains that this special episode compiles clips from earlier episodes and AMAs on ASCVD, cholesterol, and apoB. He describes the order of the clips and asks listeners for feedback on the format.
- •Compilation of clips from previous episodes and AMAs
- •Focus on ASCVD, cholesterol, and apoB
- •Clips are ordered for best listening, with commentary between them
- •Listeners can find past episodes to revisit
- •Feedback on the format is requested
- 2:39 – 4:38
Why ASCVD Matters: The Only Inevitable Disease
Attia argues that atherosclerosis is the one inevitable disease of our species, and that we have strong tools to mitigate it. Hypertension and lipid abnormalities are named as the two biggest less-clear behavioral risk factors, setting aside smoking.
- •Everybody dies with atherosclerosis if they live long enough
- •Cancer and dementia do not appear inevitable in the same way
- •Effective tools exist to mitigate the disease
- •Hypertension and lipid abnormalities are the two biggest risk factors after smoking
- 4:38 – 8:09
Is ASCVD Just a Disease of Old Age?
Attia recounts a pathology lecture in which the most common first presentation of a heart attack was sudden death. He then uses age-distribution data to show that many first events occur before 65, with women lagging men by about a decade.
- •Over 50% of first heart attacks were fatal, a figure now somewhat lower
- •Over half of men with a cardiac event have it before 65
- •About one-third of women have their first event before 65
- •Disease takes a long time to develop, which matters for prevention
- 8:09 – 13:47
What ASCVD Is and What Cholesterol Does
Attia defines ASCVD as buildup of sterols in the artery wall, progressing from fatty streaks to plaques and reduced blood flow. He then explains that cholesterol is essential for cell membranes, hormones, and bile acids, and that dietary cholesterol has little relation to blood cholesterol.
- •ASCVD is defined by cholesterol deposition in the artery wall
- •Fatty streaks consolidate into plaques that reduce blood flow
- •Cholesterol is essential for cell membranes, hormones, and bile acids
- •Most dietary cholesterol is excreted, not absorbed
- •Circulating cholesterol is mostly made by the body and moved by lipoproteins
- 13:47 – 16:02
Atherosclerosis Already Present in Young Autopsies
Attia describes autopsy images in a pathology textbook showing atherosclerosis in people who died young from other causes. This explained his professor's statement about first heart attacks being fatal.
- •Textbook autopsies showed coronary arteries of people in their 20s and 30s
- •Oxidized apoB-bearing particles were already engulfed by macrophages
- •Plaque that ruptures may not yet be present but the disease is
- 16:02 – 23:05
Flaws of 10-Year Risk and the Causal Benefit Model
Allan Sniderman argues that 10-year risk calculators are driven mostly by age and sex and make prevention of premature disease nearly impossible. He proposes a causal benefit model that uses apoB or non-HDL to project risk over 20 to 30 years.
- •Risk calculators are driven mainly by age and sex
- •Event rates are low under 60 but absolute numbers are high because there are more people
- •Disease advances for decades before 10-year risk crosses treatment thresholds
- •A causal benefit model projects lifetime-scale risk from apoB or non-HDL
- •It can show how much is lost by starting treatment later
- 23:05 – 35:54
Cholesterol 101: Lipoproteins and Why "Good" and "Bad" Cholesterol Are Wrong
Attia gives a TLDR on lipids, explaining why cholesterol must be carried in lipoproteins and distinguishing apoB and apoA families. He argues the cholesterol in HDL and LDL is identical, so labeling it good or bad is erroneous, and that apoB is his preferred risk measure.
- •Cholesterol is hydrophobic and travels inside lipoproteins
- •ApoB defines VLDL, IDL, LDL, and Lp(a); apoA defines HDL
- •HDL-C level doesn't reveal HDL function
- •LDL-C, HDL-C, and particle counts are distinct lab metrics
- •ApoB captures total atherogenic particle burden
- 35:54 – 39:42
Limits of the Standard Lipid Panel and Triglycerides
Sniderman explains that LDL-C is usually calculated, with multiple methods, and that particle number is a better indicator of risk. He argues that triglycerides matter because of the particle count, and that apoB can identify conditions like remnant type III dyslipoproteinemia that the standard panel misses.
- •LDL-C is almost always a calculation with at least eight methods
- •Direct LDL-C assays haven't been shown more accurate for disease
- •Particle number is a more accurate index of risk than LDL-C
- •High triglycerides signal more particles; triglyceride itself isn't shown to be atherogenic
- •ApoB helps diagnose remnant type III dyslipoproteinemia
- 39:42 – 48:58
Mendelian Randomization and the Causal Case for apoB
Attia and Sniderman explain how Mendelian randomization gets closer to causality than observational cohorts because genes are fixed at conception. They discuss how it shows apoB subsumes triglycerides, LDL-C, and HDL-C, that HDL is not causal, and why methods can mislead along linked metabolic chains.
- •Prospective cohorts show association but are confounded by later changes
- •Genes are fixed, so Mendelian randomization reduces confounding
- •Studies suggest apoB includes the information in triglycerides, LDL-C, and HDL-C
- •HDL-raising trials and MR don't support HDL as causal
- •MR can mislead with linked variables like triglycerides
- 48:58 – 58:15
Hypertension, Endothelium, and apoB Over Time
Sniderman shares his speculation that hypertension reflects loss of elasticity in the proximal aorta, and that higher pressure drives particles into the wall. They discuss how stable apoB is from age 35, changes at menopause, and rising coronary disease despite statins.
- •Sniderman says the pathophysiology of hypertension is not well understood and offers his own bet about the proximal aorta
- •Hypertension may act as a driving force pushing particles into the wall
- •ApoB high at 35 tends to stay high
- •ApoB rises with menopause, but data are limited
- •LDL-C-based treatment may under-diagnose metabolic patients with discordant apoB
- 58:15 – 1:02:54
Exceptions and Particle Quality with Tom Dayspring
Attia raises a patient with very high apoB and a zero calcium score. Tom Dayspring responds that atherosclerosis is multifactorial, so particle number, endothelial function, and particle quality all matter.
- •Not every person with high apoB develops atherosclerosis, much as not all smokers get lung cancer
- •Risk must be individualized
- •Particle quality, including proteins and lipidome, may matter
- •Other injuries to the endothelium should be examined even after apoB is lowered
- 1:02:54 – 1:10:48
How Low Can apoB Go? Plasma vs. Body Cholesterol
Attia and Dayspring discuss the dose-response of lowering apoB, noting that lower is better with no signal of harm from current drugs. They explain that plasma lipoproteins hold only a small fraction of body cholesterol, so lowering them does not deprive cells.
- •Guidelines suggest a 50% initial reduction yields most benefit
- •Dayspring cites apoB under 50 mg/dL as a physiologic target, similar to newborns
- •No signal of harm from currently approved drugs
- •Most cholesterol is in cells and red blood cells, not lipoproteins
- •Brain cholesterol is a separate system
- 1:10:48 – 1:18:53
Attia's Stance: Treat Early and Aggressively
Attia explains that he has become more aggressive on the timing and magnitude of apoB reduction. He lays out a thought experiment about lowering apoB in the 20s and proposes a practical ceiling of 60 mg/dL by the late 30s or early 40s.
- •Smoking, hypertension, and excess apoB-containing lipoproteins are the big three modifiable causes
- •ApoB of 30 to 40 mg/dL is the level in children and is not shown to be harmful
- •Waiting for a positive calcium score is too late given how long benefit takes
- •Thought experiment: lowering apoB to 20-30 in the 20s might eliminate ASCVD
- •Practical target: an apoB ceiling of 60, roughly the 5th percentile
