Question explored with the scientific record
Is cholesterol really the cause of heart attacks
Cholesterol is a real causal driver of heart attacks, but "LDL is the cause" oversells it: apoB-carrying particles, remnants, Lp(a), inflammation, and clotting all share the blame.
The strongest causal evidence here is genetic. People carrying a PCSK9 loss-of-function mutation have lifelong lower LDL and lower heart attack risk, and the instrumental-variable analysis estimated a causal risk ratio of 0.26 for MI per standard-deviation drop in LDL [3]. That is causation, not just correlation. Drug trials back it: adding ezetimibe to a statin after a heart attack cut LDL another 24% and produced a 2% absolute reduction in cardiovascular events over six years [8], and evolocumab reduced MI and mortality in the FOURIER trial of 27,564 patients [7].
But the picture is not "LDL alone." ApoB (the protein on all artery-penetrating particles) predicts MI better than LDL does [2], and the apoB/apoA-I ratio beat the standard cholesterol ratio in one case-control study [10]. Remnant cholesterol explains more of the apoB-linked risk for peripheral disease and shares MI risk with LDL [11], and in the Copenhagen general population remnant cholesterol tracked all-cause mortality more strongly than LDL did [4]. Lp(a) raises MI risk even when LDL is normal [1], and independently predicts early heart attack [9]. Meanwhile, the actual event is a rupture: the rupture sites in fatal MI are dominated by inflammatory cells regardless of plaque type [5], and low or zero coronary calcium did not exclude fatal infarction in 5 of 36 autopsy cases [6]. Cholesterol loads the gun; inflammation and clotting pull the trigger.
| Marker | What the evidence shows |
|---|---|
| LDL (genetic PCSK9) | Causal; lower LDL, ~74% lower MI risk ratio per SD [3] |
| ApoB / apoB:apoA-I | Predicts MI better than LDL [2][10] |
| Remnant cholesterol | Stronger mortality signal than LDL [4]; shares MI risk [11] |
| Lp(a) | Independent risk even with normal LDL [1][9] |
| Inflammation | Dominant at every rupture site [5] |
My call: LDL cholesterol is genuinely causal for heart attacks, but it is one of several apoB-related and inflammatory drivers, and treating it as the single cause is marketing-grade oversimplification. Confidence: high on causality, moderate on the exact share LDL deserves versus remnants and Lp(a).
Sources used 11
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Elevated lipoprotein (a) levels are associated with the acute myocardial infarction in patients with normal low-density lipoprotein cholesterol levels
Elevated lipoprotein(a) levels are associated with increased acute myocardial infarction risk in Chinese adults with normal LDL-C, especially among men and older individuals.
DOI: 10.1042/bsr20182096 -
Improving Prediction of Ischemic Cardiovascular Disease in the General Population Using Apolipoprotein B
In a prospective Danish general-population cohort (The Copenhagen City Heart Study, n=9231; 8-year follow-up), apolipoprotein B (apoB) predicted ischemic cardiovascular events, including ischemic heart disease and myocardial infarction, better than LDL cholesterol and added pred…
DOI: 10.1161/01.ATV.0000255580.73689.8e -
PCSK9 R46L Loss-of-Function Mutation Reduces Lipoprotein(a), LDL Cholesterol, and Risk of Aortic Valve Stenosis
In Danish cohort studies, PCSK9 R46L loss-of-function carriers had lower lipoprotein(a) and LDL cholesterol and reduced odds of aortic valve stenosis and myocardial infarction.
DOI: 10.1210/jc.2016-1206 -
Extreme Nonfasting Remnant Cholesterol vs Extreme LDL Cholesterol as Contributors to Cardiovascular Disease and All-Cause Mortality in 90000 Individuals from the General Population
In the Copenhagen General Population Study, higher nonfasting remnant cholesterol and LDL cholesterol were associated with increased risks of IHD and MI, but remnant cholesterol was more strongly associated with all-cause mortality than LDL cholesterol.
DOI: 10.1373/clinchem.2014.234146 -
Site of intimal rupture or erosion of thrombosed coronary atherosclerotic plaques is characterized by an inflammatory process irrespective of the dominant plaque morphology.
This study investigates the role of inflammation in the rupture of atherosclerotic plaques in patients who died from acute myocardial infarction, revealing that the immediate sites of rupture are consistently characterized by an inflammatory process regardless of the plaque morp…
DOI: 10.1161/01.cir.89.1.36 -
Postmortem coronary artery calcium score in cases of myocardial infarction
In 36 autopsy-proven myocardial infarction deaths, postmortem CACS increased with age and was significantly higher in ruptured than eroded fatal plaques; zero or low CACS did not exclude fatal ACAD.
DOI: 10.1007/s00414-021-02586-z -
Cardiovascular Outcomes of PCSK9 Inhibitors: With Special Emphasis on Its Effect beyond LDL-Cholesterol Lowering
This narrative review concludes that PCSK9 inhibitors markedly lower LDL-C and reduce cardiovascular events in high-risk patients, with apparent safety and possible pleiotropic benefits, though long-term outcome data were still pending.
DOI: 10.1155/2018/3179201 -
Cholesterol-lowering drugs: Focus on Ezetimibe: Cholesterol-lowering drugs: Focus on ezetimibe
Ezetimibe, alone or added to statins or other lipid-lowering drugs, lowers LDL-C and, with statins after ACS, reduces cardiovascular events.
DOI: 10.56095/eaj.v1i1.8 -
Lipoprotein(a) is an independent risk factor for myocardial infarction at a young age
In a case-control study of 509 young male myocardial infarction survivors and 1053 controls, elevated lipoprotein(a) was independently associated with early myocardial infarction and was not correlated with other lipid risk factors, apo E polymorphism, or age.
DOI: 10.1093/clinchem/36.1.20 -
The correlation of apolipoprotein B, apolipoprotein B/apolipoprotein A-I ratio and lipoprotein(a) with myocardial infarction
apoB, Lp(a), and the apoB/apoA-I ratio are independent predictors of myocardial infarction risk; the apoB/apoA-I ratio shows the strongest association and predictive performance relative to traditional lipid markers.
DOI: 10.2478/s11536-008-0057-3 -
Remnant cholesterol, not LDL cholesterol, explains peripheral artery disease risk conferred by apolipoprotein B: a cohort study
In two large cohorts, remnant cholesterol, rather than LDL cholesterol, explains most of the peripheral artery disease (PAD) risk conferred by apolipoprotein B–containing lipoproteins, with remnants driving PAD risk while both remnants and LDL contribute to myocardial infarction…
DOI: 10.1093/eurheartj/ehae666.2272