This is probably going to get a lot of press, unfortunately. PR
medpagetoday.com/clinical-c...?
On the page there are a couple of links to the full study which can be downloaded.
Lots of shortcomings to the whole study.
Conclusion
Ongoing and incident L-T4 treatment in patients with HF was associated with an increased risk of all-cause mortality, cardiovascular death, and MACE. Increased risk of MI was observed for ongoing treatment, and reduced risk was observed for incident treatment.
I dint really understand the study. It says that a group of people were left untreated and I wondered if those people had thyroid disease or whether the compare was people with thyroid disease who were being treated and those with no thyroid disease. I am not sure what they meant by incidental treatment. I dont belive it anyway and feel glad it is not going to be published, there is enough hysteria about thyroid treatment given people heart problems already.
It has been published. I couldn’t get through to the full paper but from the summary it’s saying there is an increased risk for those with heart failure being treated with T4 at the start of the study or initiated during their study for most heart failure except myocardial infarction. Basically saying negative effects of introducing t4 long term after diagnosis of heart failure?
"Basically saying negative effects of introducing t4 long term after diagnosis of heart failure."
I haven't read it yet but did they compare those people with others who had heart failure but not on T4? Either way it could be the heart failure that's the problem - the patients were prescribed meds AFTER being diagnosed.
Perhaps they were poor converters and would have done okay if treated with T3 instead... 🤸🏿♀️🥛
On the contrary. This is good news.
I had heart failure when taking t4, but after switching to t3 it had resolved.
I think everyone struggling with t4 treatment should demand and echocardiogram.
So long as they read the paper and not just the headline.
Could I ask if you take T4 and T3 to help your situation please.
Thanks
This is interesting. I was on Levothyroxine for 11 years. Last year I collapsed after weeks of feeling extremely tired. My heart rate in ambulance was 43. Later on admission to hospital my T3 was low 3.9 and my T4 was high 15.5 After months I changed to combination T4, T3 and started to feel better. I didn’t have any previous T3 results to go off as my GP never tests T3. However on NDT my T3 was good 5.0 But my T4 poor 6.5.
I then went to see a private Endocrinologist who said I need to revert back to T4 only. Since then I’ve suffered high blood pressure and feeling a lot worse.
Tomorrow I’m seeing a cardiologist. And today I will be getting my first blood results after being on Levothyroxine T4 only after 7 weeks. I’m interested to see my T3 result! Is the lack maybe causing my collapsing and high blood pressure I wonder. I shall digest this article before I see my cardiologist tomorrow.
Thank you for this article and this very important site with such helpful people.
Clearly you should be treated with what works best for you. Ask for evidence of the endo what he’s trying to protect you from by insisting on t4. (And I mean the research not the platitudes). Should get more sense from the cardiologist.
Demand an echocardiogram......my ejection fraction was 38%
Improved to 55% after t3 only
WOW ! What a Great Turn around . Kudos for You . I too had many symptoms on T4 only after my TT . Adding just a tiny dose of NDT for my T3 mix with my T4 made a huge difference and resolved my symptoms .
My Endocrinologist called me unexpectedly this afternoon. After I told him my test results being on T4 only he said he is writing to my GP today requesting to put me in T3 also.
I’m not sure what my GP may respond with. He said if my GP refused that he can get me T3 from Germany. I feel relieved. It’s tsken a year of hell. I lost my brilliant job too. Just wanted to share with you. 👍😀
I'm so sorry you have lost your job. That must be quite devastating.
I'm also sorry that you have had a year of hell.
I've had 6 months of hell. That's too long.
I'm fed up of bloody stupid thyroid and I'm fed up of the ups and downs of incomplete care.
It's poor as ...
They should treat you better.
If I were a teacher .... D-
I'm hoping my endocrinologist at Charing cross has read this........I know he reads this site.........so I'll say hello ☺
I know a number of doctors read and we must have quite a number of doctor members. But good to know of at least one endocrinologist.
🙊🙊🙊
It is a shame they did not do a comparable group taking T3. I am just concerned it will be seen as a reason not to offer any treatment at all especially as it seems a cohort in the group did better on no treatment. I think there has been a sudy recently. Not sure where I saw it showing low T3 and heart problems.
Mandy you seem very negative.
No treatment at all is ridiculous......even manslaughter lol
Low T3 and heart problems is mentioned in this study - you would think that would give every reason for doctors to check T3 along with TSH and T4 and also to see if people are poor converters and then to treat with T3 where necessary.
Altho I've never looked into it, in passing I've heard quite a few mentions of T3 bring used to treat heart problems ( prescribed by cardiologists), but this is the first time I've ever heard of T4.
I think I am misunderstanding the study. But it did seem to have a cohort of untreated people. I have a headache I might be getting it all wrong.
Interesting. Well I would certainly say that talking T4 increases heart and blood-pressure problems. Were these patients all Hypothyroid or had other conditions? But the question is why? Because they are not taking enough, taking too much or need T3?
Absolutely!! Not enough information about other factors influencing heart health or other thyroid factors to draw any worthwhile conclusions. But some Endos will try to use it.
That's the problem with studies - the researchers go in with pre-conceived ideas!
The main thing reading this paper is the authors admission that they cannot prove causality and cannot say whether thyroid failure itself or thyroid hormone replacement is the linking factor. Nor of course can they avoid the possibility that diagnosing by TSH and FT4 alone is not optimally treating some (or maybe many) patients. If FT3, as we know, is lower on average on T4 only treatment COMPARED WITH HEALTH, this (unmeasured) parameter could be the cause - ie inadequate treatment using the wrong parameters to control.
There is also the question of dosage, and did the doctors prescribing for these patients test their T3 levels or just TSH? We know the answer. This study just gives rise to questions.
its another study where something is associated with another thing but there is no direct causation.
i like the analogy of "it was found that of those civil servants who had heart attacks 75% of them wore bowler hats. We therefore recommend that civil servants do not wear bowler hats".
In any case, the courts and Good Medical Practice say that the doctor should explain the risks and benefits of ALL treatment options. The patient then weighs them up and makes a decision. (NB the doctor can't act on your behalf unless you lack the capacity to make decisions). When you make a decision, you can consider non medical factors such as your need to earn money or care for a relative.
So in this case, the following conversation may apply:
Doctor: I'm reducing your dose of LT4 because this new study says there are risks to heart health from using LT4.
Patient: Please quantify the risk to me personally so I can make an informed decision about my own health.
D: I'm afraid I can't do that, because I haven't assessed your heart health or any other factors that may influence your personal heart health - but for a Danish population with heart failure the Incident Rate Ratios for all-cause mortality was 1.25, cardiovascular death 1.23 and MACE 1.26.
P: Oh, so what is my personal Incident Rate Ratio for those incidents?
D: I'm afraid I don't know yours but I do know the average of 15,567 Danish people.
P: Did the study show that LT4 directly caused Heart Failure in those Danish people who already has heart problems?
D: Err no.
P: Hmm. I do know that without LT4, I actually do experience fatigue, brain fog, irritability, high blood pressure low pulse rate, and weight gain. I am unable to do my work and look after my 3 children. I do know that with LT4 those signs and symptoms actually are mitigated so that I can do my job and look after my three children. I actually do get my life back on LT4. Its not a theoretical risk that it happens, it actually does happen and is happening now, in the present. You are wanting me to give up my life for a theoretical risk of heart failure in the future, which has not been proved to be directly caused by LT4?
D; Err yes.
P: i'm sorry doctor, but in line with the General Medical Council's Code of Practice Consent: patients and doctors making decision together, I have weighed up the risks and benefits of reducing my LT4 dose and I chose to maintain my dose as it is.
D: I can see that you have the mental capacity to make decisions about your health, you have information about your own condition and you have listened to what I have said about the risk of treatment by LT4. You have considered your own knowledge of your condition and other non medical factors. I can see that you have weighed up the risks and benefits of the options I have put to you and your own options. I can see that you have chosen to remain on your current dose. I respect your decision and I will leave the dose as it is.
The conversation could go on to consider measuring T3 and the use of T3 instead of T4 but that would take a LONG time to write
T4 won't give you heart failure......this study is only reflects on the treatment of t4 if you already have heart failure.
I didn't know I had heart failure when I commenced t4. It was only when I became more hypo trying to reduce my tsh, that I felt my heart was suffering from some insufficiency, which I then pleaded to see a cardiologist to perform an echocardiogram, which consequently showed I indeed was suffering from heart failure.
Only reducing my t4 and letting my tsh rise, did I get any relief. T3 corrected this as confirmed by another echocardiogram some months later.
Obviously there is some underlying cause, of which I'm not sure.
But a private test done by genova many months before my cardiology appointment, showed that my selenium levels were undetectable, which possibly and more than likely, drastically affected the deiodinaise enzymes that convert t4 to t3.
Well that's one of my theories anyway.
Many people are fine taking t4.
If you don't have heart failure, this study is irrelevant to you.
I am wondering though if others who struggle with t4 have some degree of heart failure.
I find you story interesting. It is becoming more and more clear to me that patients, GPs and Endos should prioritise T3 as the hormone for health
I personally don't think that such studies contribute anything of value. This one studies people who already have had Heart Failure and unsurprisingly discovers that people with heart failure are more likely to have heart problems in the future. It also discovers that people who are already ill are more likely to be ill in the future. It discovers that people over 70 are more likely than not to be dead in 5 years time.
it then sees how many of those patients were taking LT4. I didn't see an average dose but I'm at work and cant take so much time over it, so we cant even associate an average dose to a heart event. And importantly for Uk members, it didn't find out what the patients wishes were - to take LT4 with the unfounded theoretical risk of heart problems in the future or to run the risk of hypothyroidism and a risk of heart problems by NOT taking LT4.
T3sortedme posted a study to show that Low T3 is A Strong Prognostic Predictor of Death in Patients With Heart Disease and concluded Low-T3 syndrome is a strong predictor of death in cardiac patients and might be directly implicated in the
poor prognosis of cardiac patients
So T3sortedme basically posted an identical study.
Did you read any of the study?
You seem to be very confused.
It contributes a lot of value to people who have heart failure with low t3 who are taking t4!
The risk is obvious.......if you are taking t4 with a respectable tsh but have low t3 plus heart failure ......your mortality rate is high.
The choice is stark.....add some t3.
You are baffling 😣
I am one of the lucky ones over 70's and taking NDT
"Only reducing my t4 and letting my tsh rise, did I get any relief. T3 corrected this as confirmed by another echocardiogram some months later."
Did you have more hypo symptoms when you reduced T4 and your TSH rose?
When you say, "I am wondering though if others who struggle with t4 have some degree of heart failure." do you mean you think they may have problems with T4 because of underlying, undiagnosed heart failure? (don't know how to put quoted text in bold.)
I did as my thyroid failed, dreadful angina where I though I might drop down dead - it worsen on t4 and has improved on NDT, but I now have blood pressure it could be hereditary (a few relative have died suddenly of heart attacks) or a consequence of the hypothyroidism/lack of T3...or both.
Thank you holyshedballs! I find your posts really useful to keep reminding us what our rights are! It is slowly slowly sinking into my brain and I hope to have a conversation similar to this imaginary patient with my doctor one day 
From the study itself
(It is possible ) "that patients treated with levothyroxine may have an overall inferior medical condition than those not treated and that these unmeasured cofounders bias our findings. Especially, the fact that some HF patients treated with L-T4
may have a mild “low-T3 syndrome” with a simultaneous increase in TSH and therefore may have a worse clinical condition than those not treated with L-T4 (43). Another interpretation of our results is that the elevated risk of death and adverse cardiovascular death is due to thyroid dysfunction rather than levothyroxine treatment. Due to the limitations inherent to the
observational study design this cannot be refuted, albeit in a prior study by our group, no risk of increased mortality was found in patients with low thyroid function substituted with levothyroxine compared to euthyroid individuals".
and
"It is generally not possible based on observational data alone, to draw
conclusions on causality".
See also this revent study:
USA study of cardiac patients in journal shows low T3 caused death in heart patients (nearly 5x higher than normal)
ahajournals.org/doi/full/10...
Thanks for the link. Cardiology seems on the right track. Now if they will just do a study treating patients with low T3 and see what the results are. PR
I have not read the article yet but I have been on T4 all my life and later T3 too!
I did have heart failure nearly five years ago, but I also had complications due to respiratory problems and pneumonia at the time, which evidently caused the heart failure. I also do suffer with oedema which was brought on by mismanagement of my meds by a GP and then the respiratory problems followed.
I think what I find alarming about these articles is that they are scare mongering and they will always say T3 and T4 can cause heart problems, but what they don't tell you, is that if they are taken in excess then of course they will like any drug. Also that some people who DO NOT have a thyroid condition take the meds as slimming agents and body beautiful supplements and in excess, so obviously they are going to have problems. You don't need a medical degree to work that out!
The NHS will say T3 is bad for you and hide behind the "bad for the heart" study, but basically it is all down to cost of the drug to the NHS and greedy pharmaceutical companies.
I have had several echo cardiograms and my heart is strong and healthy as it can be.
At the end of the day, we want quality of life. Ignore these articles as sometimes they are not worth the paper they are written on.
Take care everyone
So, if I understand this correctly...
A total of 224,670 patients were diagnosed with HF (mean age 70.7 [SD±14.7], 53% male).
These patients all had heart failure, and weren't young.
6,560 patients were treated with L-T4 at baseline, 9,007 patients initiated L-T4 during follow-up, and 209,103 patients did not receive L-T4.
6,560 patients were already hypothyroid at the start of the study. A further 9,007 patients were found to be hypothyroid during the study.
Following up all these patients - those with "just" heart failure and those with heart failure and hypothyroidism showed that there was a greater risk of death in the HF + hypo group than there was in the HF group.
The researchers conclude that treating hypothyroidism with levothyroxine increases the risk of death in patients with HF.
What ?!!?
Why couldn't they have concluded that suffering HF + Hypothyroidism is more likely to kill you than HF alone? Or to put it another way... Suffering two diseases/conditions that adversely affect the heart is more likely to kill you than suffering from just one.
I really, really want to say "Well, Duh!", but I probably missed something in my reading of the paper.
I agree humanbean, the misinformation does not make sense.
Changing the topic slightly, The other night I was watch a program about how four celebrities did a 21 day regime of eating junk food - as if anyone would do that in reality?? But hey ho - one of the contestants, then was told he had a sleep problem and was diagnosed with Sleep apnoea and it was alleged that his sleep apnoea was caused because of his junk food addiction - I took great offence at that, because it is not true. Obviously life style choices can contribute to our health problems, but not always the case. I have sleep apnoea as well as thyroid and I do not eat junk food. So I bet because of the program, a lot of people with the condition and/or thyroid conditions, will be judged and labelled.
There is a lot of misinformation out there, no wonder people are alarmed. 
Patient blaming is absolutely standard behaviour for the medical profession, the government, and the media. None of them can resist doing it.
I know, I was once told by a respiratory nurse "That I should take responsibility for my actions" - If I had had the strength at the time, I think I would have clouted her! I don't smoke, rarely drink, almost certainly never eat fast/junk food although partial to an occasional fish and chips. 
But due to mismanagement of my meds, I now have a weight problem with oedema, but that is my fault! ??
That's horrendous!
Arghhhh. Why do they say such stupid things? Supportive? No. Helpful? No. Got any evidence to back that up? No. Know the patient? No.
Making huge, great assumptions? Yes
Should be,
how can we support you to self manage and self care? Have you got any questions? Do you understand the medicine and treatment protocol?
Is there anything else I can do to help you? Is there anything you dont understand?
Exactly Hpbr!
At this present time, I am being body shamed too because of my BMI (ha ha) is not in "normal" range. I will no doubt be told to lose weight at my next Consultant appointment, but I think the most frustrating thing is, they never read their notes. If they did read the notes, they will see that I am trying to lose despite the obstacles in my way, I certainly don't want to live like this??
It is when they sit there nodding their heads with the silly patronising smile, I get annoyed. (did I say that out loud)
As sad as it sounds, I am glad it is just not me that goes through this, as I was beginning to think it was. Just not fair on any of us.
Take care
It is out of order 😬 I’d loose my temper - how can medical “professionals” lack such basic knowledge of metabolism and thyroid hormones? It is not rocket science even I understand it, it is so blindingly obvious.
I remember my dad told me the hygienist he saw told my dad he was not cleaning his teeth correctly so he asked the hygienist how many other 85 year old did she deal with who still had all their own teeth! None. That shut her up.
Good on your dad! Also very true what he said as well! People can be so judgemental and patronising. Lets hope she learnt to kerb her judgements before opening her mouth lol x
Looks like this was another ALL MALE study? I hate it when that happens....
Actually the majority was women.....Doh!
57 years on Levo (branded and generic) with 50mg Atenolol. Past ECG’s show no heart problems. Only issue since 2010 is mismanagement by Diabetes docs masquerading as Thyroid specialists. Managed to right myself once already and now working on it again. Luckily no heart problems since all-clear on last ECG in January 2018. So far, so good then!
I was thinking that rather than not give patients an increase in Levo when TSH is 'in range'; but the people still being ill; because 'TSH too low can cause heart problems,' it would be far better to give an increase and keep a check on heart function. I realise this would cost money so it's not likely to be done 
Funny you should say that AnneEvo -
When they started messing me around, I was told (never forgotten these words), "Too much thyroxine is bad for the heart, as it can cause heart problems, BUT if it is too low, we will give you the higher dose anyway!!" Still messed me around - but now I am on my original dose of 200 mcg T4 and 20 mcg of T3! and still battle my weight caused because of the initial mismanagement.
The medical professional baffles me.
Take care
It is an ongoing battle.
I'm trying the aip protocol to try to find out if any other food group is hindering my wellness. I'm coeliac too and, urghh horrible word, obese. The 30 day reset and then gradual reintroduction of foods one by one might help. However I had silent coeliac disease, so it could tell me nothing.
I'm a bit bored of sweet potatoes but other than that I will press on.
Ongoing battle that I'm betting most endos won't appreciate. If I get told, you're fat, lose weight, I'll be tempted to sit on them 🤣 Lost 5lbs it's a good start and side effect of eating dust. I mean vegetables, meat, fish and some fruit....
Ha ha, I have threatened to sit on someone before now because of their insensitivity. I was checked for coeliac disease and gluten intolerance but I am only sensitive evidently. I have to be careful with white bread and or pizza dough, so perhaps it is a yeast intolerance there. Just keep away from it if I can. Have you ever tried the Keto plans, The diet dr.com is a good one but quite restrictive.
However, just been for some breathing tests today and I have dropped 12 kilo's in nine weeks! I have been doing the Slimming World eating plan since end of January and trying my best - so I am liking the hospital scales at the moment! I know I can lose weight now as I am on the right dose of T4 for me and that makes a big difference, my main downfall is mobility partly because of the problems caused before this. I also have sciatica and the pain is beyond words, so needless to say, I get quite breathless as well.
I'm really glad for you that SW plan is working. That's an achievement and you should be suitably chuffed with yourself.
Sorry to hear about your mobility issues and the inconvenience and pain caused by sciatica. I can only imagine how that must be. Pain is no fun.
I've probably got most diet advice plans. A ridiculous amount and my husband says for goodness sake not another one. I've got a keto book with recipes.
I am going to stick to Chris Kesslers plan at the moment, as I've started, and try to introduce foods after 30 days to see if I'm sensitive. Dairy might be a problem as there's potential for casein sensitivity. Apparently no test, just have to eliminate and reintroduce. Same with nightshades and legumes.
I'm on a voyage of discovery. That is my mantra and keeps me focused. I've not cheated either which in itself is a result. But.... I'm only on day 8.
Maybe the key to success in weight loss with hypothyroidism is having your thyroid medication balanced properly. As it's the metabolic controller I suppose it makes sense. Otherwise are you a hiding to nothing? I don't know the answer,
Best wishes to you x
All the best on your plan as well. I truly believe that having the right balance on your meds is the key to controlling our weight. All I know is that when my meds were dramatically reduced, my weight dramatically increased sadly - I was eating exactly the same before the only difference was due to fatigue and pain, my mobility was not the same.
Best wishes to you as well and always here for a chat.
Surely it has to be cheaper than the consequences of treating serious heart disease
Or even do some heart monitoring rather than simply reduce the dose. Its easier (for people) to not do some thing than to do something.
I think that's what I'll suggest tomorrow when I ask for an increase in levo 
if you are asking for an increase, please read my little script above. Good luck
My Ecg was fine also........echocardiogram not.
That surprises me...I thought both tests would give same overall result. How did echocardiogram result differ, if you don't mind me asking?
(I thought echo would be done only if ECG showed issues.)
Well my ecg showed no problem.
But my ejection fraction was 38%
Wow, there is a difference then. Did you or do you suffer the effects of such a reading?
Yeah breathlessness and fatigue
Oh, not good. Are you on medication as a result?
I’ve only had the two ECG’s. First years ago because I mentioned a ‘niggle’ in my left chest region, between shoulder and breast. Second as part of the new Endo’s bones and heart scare spiel at first meeting in January last year.
On t4 when I had heart failure, they put me on perindopril an ace inhibitor.......now I'm on t3, I don't need it.
Presuming you’re now on T3 all is well. Are you one of the lucky ones that will get your T3 supply through the NHS? I’ve read so many horror stories on here.
I’ve been fine on an optimal dose of Levo (apart from the messing about by Diabetes doctors) and feel lucky too that I am well otherwise. At least I think I am! 🤪🙃
Yes I'm on t3 and a lot better........but still have ups and downs.
Yes I get my t3 on the NHS.
I am the same as you ZippyAppletush!
Been on T4 since I was five weeks old - I am now 57! Never had a problem with thyroid condition until GP/Endo started messing with my meds. I even went into diabetic land once or twice, because of my meds but fortunately in normal range now.
Due to above, I am on combination of T4 and T3 now. The T4 level is back to where it was when my troubles started. I have no heart problems or cholesterol problems either. But I do have respiratory problems. (going for breathing tests tonight)
Take care
Hi, JollyDolly! Having problems putting your name in capitals/bold at the mo so will leave it for now.
Wow, a kindred spirit, lol! Thank you so much for writing. My troubles started in 2009/10 when my hospital doctor retired and our local Trust created a ‘Register’! I never got to see the man who blighted my life but even when I suffered a bad fall in 2014 he wasn’t interested. Same as you, prior to that no heart/cholesterol/diabetes issues. Still none, despite the scaremongering currrent Endo. I really thought he was going to be different but sadly not, and now that he can’t scare me any more he’s decided I’m depressed!!! Happy to throw anti-depressants at me, but not Levo. Ah well, now I have a cunning plan, lol!
I hope your tests go well and you get the treatment/relief to help you.
Take care too! 😁👋🏻
Hiya,
Yes we seem to be kindred spirits don't we?
I have had anti depressants thrown at me too but not for me. I don't know if you agree, but sometimes, I feel am banging my head against a brick wall in frustration as no one is listening let alone helping? I think these so called professionals, put us all in the same basket, one pill fits all and it is simply not the case. We are all individual and this certainly applies to our needs.
My problems started around 1994 - The GP that caused the problems in the first place, reduced my then medication from 200 to 75 mcg (yes i thought it was typo error at first, but not the case ) Never ever before in my then 32 years did I have a problem with weight, fertility anything, but since, a completely different story and by all accounts my fault!
So now after many many moons and a lot of heartache, I am where I am, back on the same original dose, plus T3, was unable to have anymore children, gained a lot of weight and oedema, so body shamed as well to add insult to injury and finally permanent respiratory problems with sleep apnoea, which they believe I have always had but went undetected.
Just so unfair. I always joke but really it isn't a laughing matter - but if I got a penny for every time someone raised their eyebrow at my thyroid condition and what problems come from it, I would be a very rich lady.
You take care too and keep in touch
Hi JOLLYDOLLY ! Yay, it worked! I’m out and about at the mo but will reply asap.
Take care! 👋🏻
No problems, I have been at a hospital myself. Catch up when you can.
Take care
Does anyone know what 'incident treatment' means?
I just checked on Google...found this -
Most patients with chronic pain, including palliative care and hospice patients, are given medication to use as needed to treat breakthrough pain. Medication for BTP is typically fast acting with a relatively short duration of action (usually providing relief for two to four hours).
Hope that helps explain.
The study says:
"Increased risk of MI (IRR 1.32 [95% CI: 1.23-1.41]) was
observed for on-going treatment, reduced risk (IRR 0.87 [95% CI: 0.81-0.93]) was observed for incident treatment."
I don't understand what it means here, as 'incident' treatment as opposed to ongoing treatment seems to imply that someone may have an incidence of hypothyrodism 🤔 I'm saying incidence of hypothyroidism as the study was about treatment or not with LT4.
Sorry, I took it literally and therefore out of context; in that case I’m not able to comment.
I should've put the quote in initially.
My thoughts, for what they're worth:
"Several studies have indicated cardiovascular benefit of T4
substitution treatment with L-T4, including a decrease of total plasma cholesterol in patients
with hypercholesterolemia."
It's well noted on this forum that people who are hypo have or mostly have? (I don't know if it's always the case) high cholesterol - I'm not sure above whether they are saying LT4 decreases total plasma cholesterol or that treating people with LT4 and lowering their cholesterol is of benefit.
"14,697 patients were censored due to a prescription of amiodarone during the study period."
I didn't see any mention of any other meds being taken into account - the possibility that medication for HF may affect absorption of, or interact adversely with LT4.
"Another interpretation of our results is that the elevated risk of death and adverse cardiovascular death is due to thyroid dysfunction rather than levothyroxine treatment."
It's good to note they're not merely saying treatment with LT4 causes HF.
"Our findings could be influenced by confounding by indication since we do not have
any knowledge as to what caused physicians to prescribe L-T4 treatment to some patients and not to others. One could speculate that physicians might, be more likely to prescribe L-T4 to
patients with severe HF, which could potentially explain the increased risk observed in patients treated with L-T4."
One could also speculate that physicians might be likely not to prescribe the correct dose of LT4 when patients' TSH is low as they believe it could cause HF!
This is what some commentators made of the paper in Thyroid Physiology: My take on it is that if odds ratios of less than 2 are mentioned, the chance of this being other than as it says, chance is very great.
Both hypothyroidism and hyperthyroidism are associated with the development of heart failure (1), and subclinical hypothyroidism (and presumably overt hypothyroidism) is associated with excess mortality in patients with heart failure (2). The report by Einfeldt et al. deals with the question of thyroid hormone substitution in heart failure patients (and, more broadly, in elderly people with chronic comorbidities) (3). Using data from a group of validated Danish nationwide registries, the authors conclude that treatment with levothyroxine (prescribed either before or after a heart-failure diagnosis) increases the risk of all-cause mortality, cardiovascular death, and MACE.
In the United States, levothyroxine use has become increasing common; it was the most prescribed drug in 2016 (4). The use of thyroid hormone therapy in Denmark has also increased linearly in the past decade (5). In northeast England, 15.1% of individuals >90 years are prescribed levothyroxine (6). A study from the United States found that among persons >65 years, older age, obesity, and, oddly, existing coronary artery disease were all factors associated with levothyroxine initiation (7). Patients >65 years are at particular risk of iatrogenic exogenous subclinical hyperthyroidism, which may result in adverse outcomes (8), including increased mortality.
In the study by Einfeldt et al. (3), no information is provided about the severity of heart disease or about the reason for levothyroxine administration. Therefore, this cohort may include patients with overt hypothyroidism (of note, patients that underwent radioiodine therapy or thyroid surgery were not identified), subclinical hypothyroidism, or even nonthyroidal illness. Perhaps most importantly, the appropriateness of the substitution therapy was not assessed in this study, in terms of both the indication for treatment and whether serum TSH levels were within an acceptable range (no serum TSH or thyroid hormone levels were collected at any time point). It is well known that overreplacement and underreplacement with levothyroxine are common, especially in an elderly cohort (9). Of note, another register-based Danish study (10) reported an increased risk of mortality for untreated hypothyroid patients, but also for those who had low TSH levels (HR, 1.18; 95% CI, 1.15–1.21; P<0.0001 for every 6 months a patient exhibited decreased TSH). Although a recent double-blind, randomized, placebo-controlled trial of levothyroxine use in patients >65 years with subclinical hypothyroidism failed to detect any serious adverse events, the study was underpowered to detect an effect of levothyroxine on incident cardiovascular events or mortality (11).
From a clinical point of view, this study does not answer any of the important questions about the potential effects of levothyroxine on left ventricular function or on the long-term outcome in specific groups of patients (e.g., in those with “low-T3 syndrome,” subclinical hypothyroidism, or with different New York Heart Association functional classes), and it does not suggest an appropriate TSH target. However, these data strongly encourage physicians to “think twice” before prescribing levothyroxine to heart failure patients, who are likely to be elderly, to be sure that serum TSH levels are within the target range for older persons (12), and, above all, to consider levothyroxine withdrawal if the benefits are uncertain.
Thyroid hormone homeostasis in levothyroxine-treated patients: Findings from ELSA-BrasilSerum Thyrotropin and Triiodothyronine Levels in Levothyroxine-Treated Patients 
Hypothyroidism Overtreatment Linked to Risk of Atrial FibrillationPermanent atrial fibrillation in heart failure patients as another condition with increased reverse triiodothyronine concentrationAdding carbimazole to levothyroxine increases triiodothyronine and improves outcome in patients with primary hypothyroidism
