Knife Down

In this Q&A session, Dr. Lily Johnston dives into complex viewer questions regarding cardiovascular health and emerging medical research. She covers the impact of hormone therapies on LP(a), the nuances of managing cholesterol after a heart attack, and how to interpret advanced imaging like CIMT and Calcium Scores.

The episode concludes with a fascinating look at a novel, experimental microsurgical approach for Alzheimer’s disease being studied in China, which aims to improve the brain's waste clearance through lymphatic connections. Dr. Lily breaks down the mechanistic rationale, the early clinical data, and the significant physiological an...

Can you have a heart attack with “normal” labs and no warning signs? Or are we missing the warning signs because our thresholds are too late and our prevention model is too reactive?

Today I react to a fascinating video from Dr Brad Stanfield, BUT STICK AROUND because then we take a deep dive into the actual JACC paper behind the headline that “99% of people who had a heart attack had at least one warning sign beforehand.”

We break down:

* Why “normal” isn’t always optimal
* The difference between diagnosed risk factors vs actual expos...

Are omega-3s really the #1 supplement for heart disease prevention? In this reaction to Dr. Boz, I break down the nuance: atrial fibrillation risk, rancid oils, DHA vs EPA, heavy metal testing, delivery forms, omega level testing, and why small fatty fish may beat supplements for most people.

High Quality 3rd-party tested supplements at Fullscript (10% discount): https://us.fullscript.com/welcome/ljohnstonmd/store-start

Sign up for more information on my own practice here: https://corsighthealth.com/

Other tools for optimal health (note these are affiliate links):
Home BP Cuff: https://amzn.to/49...

A live, unfiltered Ask Me Anything on preventive cardiology and metabolic health — recorded on about three hours of sleep after a night in the OR, which tends to make me a little more candid than usual.

We cover the questions you actually ask: how plaque forms and how to stabilize it, what the "best" diet for cardiovascular health really is (spoiler: it depends on you), statins from every angle, Lp(a) and ApoB, the lean mass hyper-responder phenotype, GLP-1s and dementia risk, coronary CT angiograms and the AI tools reading them, carotid disease and how I th...

Peripheral artery disease Q&A — including one of the biggest mistakes people make when trying to “walk off” PAD symptoms.

In this video, we break down:
• Why erectile dysfunction is actually a sign of vascular disease
• What an ankle-brachial index (ABI) actually measures
• Normal ABI ranges and what abnormal results can mean
• Whether you should have vascular testing done at home or in a certified vascular lab
• The difference between artery disease and vein disease (including spider veins and varicose veins)
• PAD treatment options — from walking programs to procedures and surgery
• Recovery times...

Got APOE4? Here’s the exact prevention strategy I would use to protect my own brain if I carried this gene.

In this video, I walk through the major modifiable dementia risk factors identified by the Lancet Commission — and how I would actually approach them in real life as a vascular surgeon specializing in cardiometabolic prevention.

We cover:
* ApoB, vascular disease, and why “brain health” starts in the arteries
* What you can do NOW without any clinical support
* Blood pressure, insulin resistance, exercise, sleep, and inflammation
* Hearing loss, social isolation, alcohol, smoking...

What's the optimal ApoB level to reduce Alzheimer’s risk? Is lifestyle or genetics more important? And what does a pTau217 result actually mean for your brain health?

In this Brain Health Q&A, I answer your questions about ApoB, APOE2, dementia prevention, blood-based biomarkers, and what the science actually says right now.

Missed the first video? Check it out here: https://youtu.be/y8vkJE_Zy7A

Topics include:
• How low I think ApoB should ideally be for brain health (and what matters more!)
• How to think about lifestyle vs geneti...

If you've been told APOE4 means you're destined for Alzheimer's, the science says something very different.

As a vascular surgeon who has spent years treating the end-stages of preventable disease, I want to give you a clearer picture of what APOE4 actually does, and what it doesn't.

In this video, I break down:
- What the APOE4 gene is and how it affects your brain
- Why it raises Alzheimer's risk — but doesn't guarantee it
- The surprising evolutionary reason APOE4 exists in the first place
- What the science actually sa...

You asked 349 questions about my LDL video. I'm answering the ones that matter most — including who paid for the study.

Last week I broke down the LDL cholesterol trial. The comments flooded in — and several of you asked exactly the right questions. In this follow-up, I'm going through the most important ones as a vascular surgeon who's spent years treating the consequences of bad cardiovascular advice.

In this video:
🫘 Kidney function & muscle toxicity — one commenter raised a sharp mechanistic point worth spelling out: statins can cause muscle damage → muscle damage could reduce muscle mass → less muscle m...

Does lowering LDL cholesterol cause dementia? And how much dementia is actually “vascular” dementia versus Alzheimer’s disease?

In this video, I’m answering two viewer questions about dementia, vascular risk, statins, LDL cholesterol, and brain health. First, we look at the relative prevalence of vascular dementia compared with Alzheimer’s dementia — and why that distinction gets messy fast. Vascular dementia may be less common as a primary diagnosis, but vascular disease often contributes to cognitive decline even when the label is “Alzheimer’s.”

Then we spend most of the video on the bigger fear: whether lipid-lowe...

A common cholesterol drug might protect your brain from Alzheimer's — but I read the actual study, and there's a red flag nobody is talking about.

Nick Norwitz covered this story. I went further — I pulled the original paper published in Aging Biology and read every line. Here's what I found.Researchers ran a hypothesis-free screen of FDA-approved drugs to find compounds that could disrupt the 14-3-3/hexokinase protein interaction — a mechanism implicated in the protein aggregation that drives Alzheimer's disease and other dementias. 

Six drugs emerged from the screen. Ezetimibe was one of them, and it...

Is lower LDL cholesterol actually better for your heart? In this video, I break down the brand-new results from the EZ-Pave study to answer the question that keeps my patients up at night: How low should your cholesterol really go? 

As a vascular surgeon, I see the end-stage results of heart disease every day. 

We’ve heard the "lower is better" mantra for decades, but new research is finally providing the hard evidence we need to settle the debate. 

Study link: https://www.nejm.org/doi/full/10.1056/NEJMoa2600283 

We’re looking at how L...

I've seen daily aspirin save lives from heart attack — and cause fatal bleeds. As a vascular surgeon, here's my honest take on heart health.

The answer isn't yes or no — it depends entirely on who you are.

In this video I break down the three groups you need to know:

✅ Who SHOULD take daily aspirin — if you've already had a heart attack, stroke, or stent, aspirin for secondary prevention of heart disease is still one of the most evidence-backed interventions we have.

❌ Who SHOULD NOT — the 2022 USPSTF guidelines quietly changed the recommendati...

We hit all the high points today! Nutrition, exercise, lipids, dental health, hormones, and more. We had amazing participation and it was wonderful to have a chance to interact with everyone in real time. Thanks SO much for taking some of your precious weekend to talk cardiovascular health, heart scans, CAC scores, and all the other nerdy prevention things with me. Hope you enjoyed it! If you want me to do more of these in the future, please say so in the comments!

Water filters that remove microplastics:
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Plaque reversal is one of the most debated topics in preventive cardiology, so in this video I react to Dr. Kevin Ham’s CAST protocol for plaque reversal: Causes, Adding Cures, Strengthening the Body, and Training the Mind and Body.

Overall, I think this is a thoughtful framework and I agree with much of it. But as a vascular surgeon who treats advanced atherosclerosis, I also add some nuance around what “plaque reversal” really means, what may be missing from this conversation, and where I’d want more granularity in a real-world cardiovascular prevention plan.

We talk...

If you’ve had a positive calcium score (CAC score), you’ve probably asked the obvious next question: when should I repeat it?

In this video, I explain why I generally do not order another calcium score if the first one is positive—and what I prefer to use instead to follow atherosclerosis over time.

We walk through what a coronary artery calcium score actually measures, why it’s really just the tip of the iceberg, and why a higher repeat score does not necessarily mean your treatment failed. I also explain the difference between calcifie...

Joe Rogan got half a million people talking about what's happening inside their blood vessels. As a vascular surgeon, I've spent my career trying to do exactly that. So when a celebrity does it for me, I pay attention (and thank my lucky stars ;).

In the clip, Dr. Shauna Swan joins Joe Rogan to discuss the surprising hazards linked to everyday household products. In my reaction, I go through the actual studies behind the microplastics- and forever chemicals-cardiovascular disease conversation: what the data show, where the evidence is genuinely alarming, and where the certainty online is running...

SELECT trial explained: does semaglutide reduce cardiovascular risk because of weight loss, or is something else going on? In this video, I break down the SELECT trial and the follow-up analysis examining whether the cardiovascular benefit of semaglutide was directly mediated by weight loss. The answer matters, because the data suggest the reduction in major adverse cardiovascular events was not simply a function of people losing more weight.

I’m a board-certified vascular surgeon focused on cardiometabolic prevention, and in this video I walk through what the SELECT trial actually showed, what the subsequent analysis adds, and wh...

When people hear “poor circulation,” they often assume the answer is a procedure. Not so fast. In this episode of Knife Down, Dr. Jacqueline Majors and I talk about when opening a blocked artery helps, when it backfires, and why the real work of saving legs often starts long before the operating room.

We get into what patients with poor circulation, blocked leg arteries, leg pain with walking, smoking-related vascular disease, and diabetes actually need to know. We talk about when a procedure helps, when it can make things worse, why not every blockage should be opened, and...

Are supplements safe? Not automatically. In this video, I explain why supplements are really drugs, why the industry has so little oversight, which products worry me most, and how I think about using supplements more safely in real life.

I’m a board-certified vascular surgeon specializing in cardiometabolic prevention, and I do use supplements in practice — but in a targeted, evidence-informed way. Here I walk through the biggest myths about supplements, the real risks people ignore, the categories I side-eye hardest, and the framework I use to help patients choose products that are actually worth taking.

...

• Feeling “healthy” is not a screening test.
 
In this episode, Dr. Ford Brewer ( @DrFordBrewer ) tells the origin story: an ER doc who believed he was doing the right things—until he actually checked and found plaque. That discovery didn’t just change his health plan. It changed his entire job. He walked away from the adrenaline economy of emergency medicine and moved into cardiovascular prevention and teaching, because patching crises is not the same as stopping them.
 
We talk about:
• The moment “I’m fine” stopped being believable
• Why coronary heart (vessel!) disease continues to go undete...

Lp(a) Explained: The Genetic Cholesterol Most Doctors Don’t Check (And Why It Matters)

You can be fit, lift heavy, eat “clean,” and still have a hidden cardiovascular risk most standard cholesterol tests miss.

In this video, I break down lipoprotein(a), or Lp(a) — a genetically determined cholesterol particle that quietly raises the risk of heart attack, stroke, peripheral artery disease, and calcific aortic valve stenosis, even in people who look metabolically healthy.

You’ll learn:
 • What Lp(a) actually is (and why it’s different from LDL)
 • Why 1 in 5 people have e...

Dr. Lily Johnston is back to discuss why women are often underdiagnosed and undertreated for heart disease, highlighting often-overlooked risks in standard assessments. She addresses common menopause myths surrounding menopausal hormone therapy (HRT) and its impact on cardiovascular health. This discussion seeks to inform and reassure viewers about the latest research and recommendations for women's health and heart health, including a thorough cardiovascular risk assessment.

⸻

Find a menopause provider near you: 
https://www.directory.worldlinkmedical.com/
https://portal.menopause.org/NAMS/NAMS/Directory/Menopause-Practitioner.aspx

Sign up for more information on my...

Cholesterol isn’t the villain you were taught to fear — it’s the fuel. And in this video, I’m breaking down why fuel isn’t the same thing as fire, and why most people are fighting the wrong battle when it comes to heart disease.

If you’ve ever stared at your LDL number and wondered, “Is this actually going to kill me?” — this one’s for you.

Most people obsess over cutting down a few trees… while ignoring the raging sparks flying everywhere.

In this episode, we cover:
✔️ Why LDL/ApoB matters — but why it’...

What Is It Really Like Being On Call as a Surgeon? | Life, Death, Burnout & Decisions at 2AM

What does being on call as a surgeon actually mean—beyond the pager, the scrubs, and the stereotypes?

In this video, a board-certified vascular surgeon pulls back the curtain on life on call: the anxiety, the ethical decisions made at 2 a.m., the mistakes you never forget, and the rules that keep patients safe when you’re exhausted and human.

This isn’t a highlight reel. It’s an honest look at surgical call, decision-making under pressure...

Is it possible to fix a blocked artery without major open surgery? In this video, I explain the Detour procedure (Percutaneous Transmural Arterial Bypass)—a new, minimally invasive technique that routes blood flow around blockages to restore circulation. For patients with advanced peripheral artery disease (PAD), this innovation offers a powerful alternative to traditional leg bypass surgery.

DETOUR2 trial results: https://www.jvascsurg.org/article/S0741-5214(24)00307-0/fulltext

Sign up for more information on my own practice here: https://corsighthealth.com/

Other tools for optimal health (note these are affiliate links):
Ho...

In this video, I react to a recent post from Dr  @LeonidKimMD   a physician who shares evidence-based nutrition and lifestyle medicine content here on YouTube. His channel focuses on strategies for health, and this video discusses a meal pattern proposed to support cardiovascular health.

In this reaction, I walk through:
• What claims like “unclogging arteries” usually mean in physiologic terms
• Where diet and lifestyle can meaningfully improve vascular health
• Where expectations sometimes drift beyond what the data can support

My goal here isn’t to criticize or sensationalize, but to add clinical context and nu...

High Lp(a) cholesterol is common—and frustrating—because there’s no single drug that fixes it (yet).
In this video, I walk through how I manage elevated lipoprotein(a) today, using the tools we actually have: metabolic health optimization, LDL/ApoB lowering, statins, PCSK9 inhibitors, aspirin (in select patients), and menopausal hormone therapy where appropriate.

If you’ve been told your Lp(a) is high and then… nothing else, this video is about what does matter right now—and what doesn’t.

This is Part 2 of my Lp(a) series.
▶️ Part 1: What Lp(a) is, how to t...

Original video:
https://www.youtube.com/watch?v=mJLKTyKy-14&list=WL&index=31

We’ve been obsessed with this cholesterol number for decades — but what if we’ve been chasing the wrong thing this whole time?
In this video, I’m reacting to Physionic’s powerful “We Were Wrong” episode on cholesterol, where he argues that one widely celebrated marker has never actually been shown to be a therapeutic target in major trials.
We break down:
 • Why we’ve overvalued this marker, despite never having RCTs proving that raising it prevents heart disease
 • What the guidelines an...

In this video, we explore the exciting pipeline of drugs targeting lipoprotein a and its implications for cardiovascular disease prevention. We'll examine how these cholesterol drugs are designed to work, including those utilizing sirna technology, and discuss the reasons for both enthusiasm and caution regarding this medical breakthrough. This discussion aims to clarify the current landscape of new treatments and what questions still need answers.

Here’s what I cover:

- The strategy for lowering Lp(a): stop production vs block assembly (it’s basically all in the liver)
- The late-stage / headline agents and...

A subscriber asked about statins—so I made ChatGPT answer first… and then I fact-checked it as a vascular surgeon. We’re talking cholesterol, LDL, ApoB, plaque growth and plaque rupture, and what “prevention” actually means when the goal is avoiding the first heart attack (or the next one). We’ll cover when statins make sense, when they’re oversold, and why “my numbers are fine” doesn’t always mean your arteries are fine. This is AI in healthcare with a reality check.

For my more complete philosophy on the role of lipoproteins in plaque, please watch THIS video: https...

Sign up for more information on my own practice here: https://corsighthealth.com/

Wondering what a CIMT (carotid intima-media thickness) exam is actually like? In this quick “what to expect” walkthrough, I show you how the test works, what it feels like, how long it takes, and what the images can tell us about early plaque and cardiovascular risk.

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Apple Watch with slee...

In this research report deep dive, I walk through a randomized trial that asked a very specific, very modern question: can high-intensity interval training (HIIT) measurably change coronary atherosclerotic plaque—not just your VO₂ max?

We go line-by-line through the paper: who they enrolled, what the HIIT protocol actually was, how they measured plaque (and plaque type), what outcomes moved, what didn’t, and the limitations that matter before you turn “exercise is medicine” into a personality.

Also: this is ~40 minutes of dense research nerdery. So if you’re here for quick answers, you took a wrong turn...

Hypertension isn’t a mystery. It’s physics. And it’s quietly remodeling your arteries while you’re out here arguing with your salt shaker.

In this reaction to @DrAlexWibberly, I’m mostly nodding along—because he nails the big idea: blood pressure is a mechanical force + a hormonal system problem, not just “too much sodium.” We talk through the three levers that create blood pressure (cardiac output, blood volume, vascular resistance) and why the “salt is the villain” storyline is incomplete for a huge chunk of adults—especially anyone with insulin resistance / metabolic syndrome.

Then I add the vascula...

Which blood tests should you get? Most people get “standard labs” every year—but those basic tests often miss the early signs of heart disease, insulin resistance, kidney damage, and metabolic dysfunction.

In this video, vascular surgeon and metabolic health specialist Dr. Lily Johnston breaks down the essential lab tests every patient should know—PLUS the advanced labs she orders in her prevention-focused practice to detect problems before they lead to heart attack, stroke, dementia, kidney failure, or amputations.

Standard Labs You Already Get:
✅ Complete Blood Count (CBC)
✅ Basic Metabolic Panel (BMP)
✅ Lipid Panel (c...

Most women have been taught to fear menopausal hormone therapy.
Blood clots. Heart attacks. Strokes.
A generation of headlines convinced millions that estrogen was dangerous—even when the science didn’t actually say that.

As a vascular surgeon and metabolic health specialist, I spend my days treating the consequences of cardiovascular disease. And I can tell you this: women deserve far better information than they’ve been given.

I break down the three biggest myths about menopausal hormone therapy (MHT) and what the evidence actually shows when you look at timing, dose, delivery route...

In this video, I break down CAC (coronary artery calcium score), CIMT (carotid intima–media thickness), and CCTA (coronary CT angiography) — the three imaging tests that reveal your real cardiovascular risk. If you’ve ever been told your cholesterol is “fine” or “high” and you still don’t know what that means for you, this is the missing link.

Most people think cholesterol numbers (LDL, HDL, triglycerides) can predict heart attacks and strokes. They can’t — not on their own. What actually matters is whether you’re building plaque in your arteries. And the only way to know that is through i...

Most standard lab panels miss the early warning signs of heart disease, metabolic dysfunction, thyroid trouble, and chronic inflammation. In Part 2 of this series, I break down 5 more essential tests every patient should understand before symptoms show up.

In this video, we cover:
✅ Ferritin — why low or high iron can signal hidden disease
✅ ApoB — the most important cholesterol number (and why your doctor may not order it)
✅ Thyroid function tests — TSH, Free T4, and Free T3 (critical for energy, metabolism, and mood)
✅ STOP-BANG screening — the simplest way to detect sleep apnea, a massive and overlooked r...

What does a vascular surgeon really do?
Most people think it’s all about legs. It’s not. Your vascular system reaches every organ — your heart, brain, kidneys, gut...and even lower 🍆... — and when blood flow goes wrong, everything goes wrong with it.

In this video, I break down:
✅ What vascular surgeons actually treat (PAD, aneurysms, carotid disease, clots, strokes, ulcers, amputations)
✅ Why these problems are often preventable
✅ The common risk factors: diabetes, smoking, high blood pressure, high cholesterol
✅ The overlooked risk factors: inflammation, insulin resistance, hormones, genetics, lifestyle patterns
✅ How to lower your risk an...

My first job felt like cleaning up 20 years of bad decisions that looked like normal life. 

Metabolic disease doesn't announce itself—it compounds quietly while you're "fine" until your heart gives out or your brain shorts or you lose a limb. I was the last stop, and by then, I was just damage control with a scalpel.

It took me 2 years to realize I was fighting downstream from the actual war. So I pivoted to meet people where prevention still matters.

⚕️ What you'll learn:
The real timeline of metabolic disease (it starts way ear...