Cardiovascular Disease: What the Primary Evidence Supports

The causal core is settled. Atherosclerotic disease is caused by cumulative exposure to apoB-containing lipoproteins, established by Mendelian randomization and trials, not mere association [1]. ApoB particle count is the primary driver, superior to LDL-C or particle size [2], lowering LDL cuts events proportionally [3], and Lp(a) is a genetic, causal, independent contributor [4].

PCSK9 is the cleanest confirmation. Gain-of-function mutations cause familial hypercholesterolemia [5]; loss-of-function lowers lifelong LDL and cuts coronary disease up to ~88% [6]; and two outcome trials confirm drugging it works, evolocumab [7] and alirocumab [8], both MACE HR 0.85.

Blood pressure is causal and dose-dependent. Each 10 mmHg lower systolic BP reduces major CV events ~20%, stroke ~27%, and all-cause mortality ~13% [9]; benefit holds in primary and secondary prevention with no reliable floor [10]; and targeting <120 vs <140 cut events ~25% and mortality ~27% in high-risk adults [11], at the cost of more hypotension/syncope/AKI.

Two drug stories are definitively negative or positive. Niacin, despite raising HDL, produced no CV benefit and net harm on a statin background [12, 13], with a vascular-inflammation mechanism via the terminal metabolite 4PY [14]. Conversely, semaglutide cut MACE ~20% in non-diabetic obese patients with CVD [15], moving GLP-1s from weight-loss to cardiovascular drugs.

Dietary fat, direction settled, magnitude contested. Replacing saturated fat with polyunsaturated fat reduces cardiovascular events (~17-30%) [16, 17], and higher blood linoleic acid tracks with lower CVD [18]. The magnitude, and whether saturated fat is a prime mover or a marker, remains contested (see Contested).

Measurement: what to trust. Coronary artery calcium predicts events across ethnicities [19] and a CAC of zero marks a low-risk state, though not an absolute free pass (smokers/diabetics retain risk) [20]. A low ankle-brachial index independently predicts mortality [21]. Carotid IMT is where the gate bites hardest: baseline CIMT is prognostic [22], but change in CIMT is not a valid surrogate, neither natural progression [23] nor drug-induced regression [24] tracks outcomes.

Where the Evidence Is Contested

The cardiovascular benefits of omega-3 fatty acids remain contested. The disagreement turns on which formulation is tested and at what dose. High-dose EPA alone reduced cardiovascular events significantly in REDUCE-IT [25] and JELIS [26]. Yet STRENGTH [27], which used a combination of EPA and DHA, found no such benefit. The low-dose approach fared no better. VITAL [28] found null results at 1 g, and a broad Cochrane review [29] found no reduction in all-cause mortality. Any straightforward endorsement is further complicated by Gencer [30], which identified a dose-dependent increase in atrial fibrillation risk. The question is therefore not whether omega-3s help. It is whether a particular form helps some patients while harming others, and no consensus has settled that.

The debate over saturated fat and heart disease is less about whether a relationship exists and more about how certain and how large that relationship is. The AHA treats the link as causal. A Cochrane analysis characterizes the evidence as weak and uncertain. The two sides disagree on the magnitude of the effect, not its direction. The field has thus not even agreed on how seriously to treat a harm that nearly everyone acknowledges in some form.

Two related disputes involve specific dietary fats. On seed oils and omega-6, a minority position holds that linoleic acid is uniquely harmful, while the mainstream literature treats it as neutral or protective [18]. On high LDL in people following ketogenic diets, the mainstream view holds that improved apoB is causally dangerous [1, 4]. Feldman argues instead that a distinct lean-mass hyper-responder phenotype, abbreviated LMHR, may not carry the same risk. The KETO-CTA trial [31] was designed to address this directly, but has been characterized as underpowered, leaving the question unresolved.

Two further controversies concern exercise and hormone therapy. On plaque, one position holds that the calcified plaque commonly found in endurance athletes is a benign adaptation. But the Master@Heart study [32] found that long-term athletes also accumulate more non-calcified plaque, the variety considered more vulnerable, which complicates the reassuring narrative. On hormone replacement therapy, the WHI trial [33] established a harm framing that shaped clinical practice for years. Proponents of the timing hypothesis counter by pointing to ELITE [34] and to evidence that transdermal delivery may be safer [35]. They argue that the WHI conclusions do not apply uniformly across all women, all ages of initiation, or all formulations.

References

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2. Marston et al. 2022, JAMA Cardiol — apoB primary risk driver · PubMed 34773460
3. CTT/Baigent 2010, Lancet — statin LDL-lowering meta-analysis · PubMed 21067804
4. Kamstrup et al. 2009, JAMA — genetic Lp(a) & MI (MR) · PubMed 19509380
5. Abifadel 2003, Nat Genet — PCSK9 gain-of-function FH (discovery) · PubMed 12730697
6. Cohen JC, Boerwinkle E, Mosley TH Jr, Hobbs HH. 2006 (NEJM) — ARIC study; 15yr prospective; n=3,363 Black + 9,524 White subjects; PCSK9 LOF… · PubMed 16554528
7. Sabatine MS et al. (FOURIER Steering Committee). 2017 (NEJM) — Phase 3 RCT; n=27,564; median 2.2yr; statin-background secondary-prevention… · PubMed 28304224
8. Schwartz 2018, NEJM — ODYSSEY OUTCOMES alirocumab (MACE HR 0.85) · PubMed 30403574
9. Ettehad 2016, Lancet — BP lowering per 10 mmHg SBP (613,815 participants) · PubMed 26724178
10. BPLTTC 2021, Lancet — BP lowering per 5 mmHg, IPD meta (344,716) · PubMed 33933205
11. SPRINT 2015, NEJM — intensive BP <120 cuts events + mortality (HR 0.75/0.73) · PubMed 26551272
12. HPS2-THRIVE 2014, NEJM — ER niacin, no CV benefit + harm · PubMed 25014686
13. AIM-HIGH 2011, NEJM (Boden) — niacin futility · PubMed 22085343
14. Ferrell et al. 2024, Nature Medicine — niacin 4PY & CVD · PubMed 38374343
15. Lincoff et al. 2023 (SELECT), NEJM — semaglutide & CV events · PubMed 37952131
16. Sacks et al. 2017, Circulation — AHA dietary fats advisory · PubMed 28620111
17. Hooper et al. 2020, Cochrane — reducing saturated fat · PubMed 32827219
18. Marklund et al. 2019, Circulation — linoleic acid biomarker & CVD · PubMed 30971107
19. Detrano 2008 MESA, NEJM — CAC predicts coronary events across ethnicities · PubMed 18367736
20. Blaha 2009, JACC Img — CAC=0 ~1% 10-yr mortality (but smokers/diabetics retain risk) · PubMed 19520338
21. ABI Collaboration/Fowkes 2008, JAMA — low ABI → mortality (n=48,294) · PubMed 18612117
22. Lorenz 2007, Circulation — baseline CIMT predicts MI/stroke · PubMed 17242284
23. Lorenz 2012 PROG-IMT, Lancet — CIMT progression does NOT predict events (refuted surrogate) · PubMed 22541275
24. Costanzo 2010, JACC — drug-induced CIMT regression doesn't track outcomes (refuted surrogate) · PubMed 21126642
25. REDUCE-IT (Bhatt 2019, NEJM) — EPA 4g, MACE ↓25% · PubMed 30415628
26. JELIS (Yokoyama 2007), Lancet — EPA 1.8g, coronary events · PubMed 17398308
27. STRENGTH (Nicholls 2020, JAMA) — EPA+DHA 4g null · PubMed 33190147
28. VITAL (Manson 2019, NEJM) — 1g omega-3, CV null · PubMed 30415637
29. Cochrane 2020 (Abdelhamid) — omega-3 CVD, ACM null · PubMed 30521670
30. Gencer 2021 (Circulation) — omega-3 & AFib meta
31. Soto-Mota/Budoff 2025, JACC Adv (KETO-CTA) — LMHR plaque
32. 36881712 (Master@Heart — contradicts the claim) · PubMed 36881712
33. WHI 2002 (Rossouw et al.), JAMA — estrogen + progestin · PubMed 12117397
34. Hodis et al. 2016 (ELITE), NEJM — early vs late estradiol · PubMed 27028912
35. Vinogradova et al. 2019, BMJ — HRT route & VTE · PubMed 30626577