Myocardial infarction may be an infectious disease

Here's a summary of the themes from the Hacker News discussion:

Nuance in Causation and Disease Etiology

A central theme is the complexity of disease causation, particularly in contrast to the original, potentially sensationalized, title. Many users emphasize that while infections can play a role in conditions previously thought to have other primary causes, this doesn't mean all cases are infectious or that the infectious agent is the sole cause.

• "The original title is 'Myocardial infarction may be an infectious disease' which appears to be clickbait, with the title posted here being much more accurate." - andy99
• "It's not even 'here's another way this can happen' - there's no real evidence that the bacteria are causing the heart disease." - lithocarpus
• "Of course it depends on fractions. You can develop cervical cancer via some other route, but the vast, vast majority of cervical cancers are caused by HPV infection." - tialaramex (used as an analogy)
• "Surely this? The number of ‘oh, it turned out to be more more complicated’ scenarios in medicine is high." - lostlogin
• "Peptic ulcers are another well-known case, in which most (though not all) instances can be traced to a Helicobacter pylori infection. Other causal factors include NSAID usage, stress, and diet." - dredmorbius

Correlation vs. Causation and Study Limitations

A significant portion of the discussion revolves around the interpretation of the study itself, with many users pointing out the difference between correlation and causation. Concerns were raised about the study's methodology, sample size, and the lack of baseline data.

• "This study shows a minor correlation in some bacterial DNA 'signatures' in arterial plaque in about 200 people (~40% had the correlated bacteria). The study only included tissues from people who died of heart disease or had surgery related to heart disease. There does not currently appear to be a strong baseline about how widespread this bacterial signature may exist in a broad population regardless of health." - duffpkg
• "So, one could make a similar article saying 'Myocardial infarction may be caused by sugar consumption' and support it by analyzing the recent diet of 200 people who died of heart disease and finding that 95% of them recently consumed a lot of sugar." - lithocarpus
• "This is a super common misconception, but a small p-value does not (necessarily) mean a strong correlation. It means high confidence that the correlation is non-zero." - teraflop (responding to user's interpretation of p-values in the study)
• "What Question Should Be Addressed Next? • Could a short-term antibiotics treatment given at the acute phase affect the outcome of myocardial infarction, and would it be possible to develop new diagnostic imaging and prevention methods for bacterial biofilm?" - DaveZale (quoting the study's own future questions)
• "I think the first question to be addressed should be, does the general population have similar prevalence of this bacteria? I didn't read the article but just based on the parent comment, it sounds like this baseline hasn't yet been established. It seems very wrong to start testing antibiotics without first establishing the baseline of whether everyone has this bacteria." - lithocarpus

Mechanisms of Heart Attack and Contributing Factors

Users delved into potential mechanisms for heart attacks, discussing how infectious agents might trigger events, as well as exploring other non-infectious causes. The role of inflammation was frequently mentioned.

• “Dormant bacteria within the biofilm remain[ing] shielded from both the patient’s immune system and antibiotics because they cannot penetrate the biofilm matrix” whose rupture “result[s] in thrombus formation and ultimately myocardial infarction” sounds like infection more than careless bacteria kicking up muck." - JumpCrisscross
• "Gaining a ton of body mass working out thickens the heart. It's necessary to push the blood into veins that get constricted, more and more with increased weight. In the epilogue, as you get older, optimal function fades. The thickened tissue isn't as elastic, compounding cardiac problems and sometimes causing infarction (also, not infectious related)." - Supermancho
• "In the context of the article, it's inflammation rupturing the 'fibrous cap' on plaque deposits leading to a heart attack, so I presume OP is talking about the inflammatory response to having the flu." - y1n0
• "Even temporary stress on the respiratory system can cause long-term damage to the brain, lungs, and heart. Because of Covid, we started to learn that an acute, severe infection can affect people much later." - smt88
• "The 'pantheon' of risk factors for heart disease are: hs-CRP (inflammation), ApoB, Lp(a), HbA1c, eGFR." - brandonb
• "The article mentions inflammation is a risk factor for heart attacks. In this study, the researchers designed a custom antibody that binds to oral bacteria. Then they used histological staining to identify specific biofilm structures inside the atherosclerotic tissue. Bacteria released from the biofilm were observed in heart attack cases, which gives us evidence that when the body's immune system responded to these bacteria, it triggered inflammation which ruptured cholesterol-laden plaque." - brandonb

Analogies to Other Diseases and Medical Discoveries

The discussion drew parallels with other well-established cases of infectious etiology for chronic diseases, providing context and illustrating how scientific understanding evolves.

• "Peptic ulcers are another well-known case, in which most (though not all) instances can be traced to a Helicobacter pylori infection." - dredmorbius
• "One of the rare examples of a mental health condition being virtually completely eliminated is that of General paresis of the insane, a symptom of late-stage syphilis." - dredmorbius
• "I think a better example is the very recent (i.e., in the 2000s) discovery of anti-NMDAR encephalitis which can very closely resemble schizophrenia." - ejstronge
• "It's been known for years that bad oral health leads to heart disease." - whatsupdog (referencing the link between oral health and heart disease)

Accessibility of Health Diagnostics and Healthcare Systems

A significant tangent emerged regarding the ease and cost of obtaining advanced diagnostic tests, contrasting healthcare systems in different countries, particularly the US and Canada.

• "Understanding this is a shameless plug, it's very cool this exists." - andy99 (referencing a direct-to-consumer lab testing service)
• "I live in Canada, despite being free this would be way more complicated to get. I don't want to be political, but just paying for this would be very appealing." - andy99
• "In the US you can buy 100+ tests from Quest Labs directly, the price even includes a discussion with MD about the results." - froglets
• "I'm in the US and our local hospital lab has 'test fair' week every year when anyone can roll up and get any test for a nominal payment (basic common tests). No doctor involved." - dboreham
• "This is very much not true. I just paid $12 to have a lipid test done. No doctor order or involvement at all." - burntsushi (refuting the idea that a doctor is always required in the US)
• "Lack of private medical care in general has played a big part in stopping me moving to Canada." - petesergeant
• "For example, one person got billed $1,338 for just an ApoB test when insurance denied coverage: [link]. Part of why we do cash pay (and pre-negotiated pricing with the labs) is that you avoid weird catastrophic scenarios like this." - brandonb

Future Research Avenues and Novel Treatments

The discussion touched upon potential future research and treatment modalities, including the use of antibiotics and other novel approaches.

• "Does this suggest that courses of antibiotics might reduce heart attack risk?" - A_D_E_P_T
• "Phages can penetrate biofilms. (They have practice.)" - JumpCrisscross
• "TFA says the biofilms protect the bacteria from antibiotics. Better approach is probably engineered antibodies or even a phage (engineered virus that attacks the bacteria)." - dreamcompiler
• "This has been suspected for decades." - jimbo808 (referencing an older study on bacteria and heart disease)