The patients the trials left out
The drugs at the core of modern heart failure treatment were mostly tested on stable patients. The paper makes this point directly: those trial patients do not reflect the full range of haemodynamic profiles or the true severity of the disease.
Patients in the cold profiles, with low flow and often low blood pressure, are frequently excluded from trials. They also frequently fail to tolerate target doses of standard drugs, with a higher risk of side effects and intolerance due to excessive vasodilation and poor perfusion.
So there is a group of heart failure patients for whom the textbook plan was never really tested. This last part is about them, and about what the paper suggests.
Why a helpful drug can backfire
In a healthy person, relaxing the blood vessels (vasodilation) lowers resistance and increases blood flow. Good.
In someone with very low cardiac output, the same effect can drop blood pressure too far. The paper explains why: in these patients, organs lose their ability to regulate their own blood flow (autoregulation). Tissue perfusion becomes directly dependent on blood pressure. If pressure falls, organs like the kidneys get less blood.
And then something counterproductive happens. When pressure drops, the body tries to restore it by switching on the neurohormonal systems: the sympathetic nervous system, the renin-angiotensin-aldosterone system, and arginine vasopressin. Those are the very systems heart failure treatment is trying to calm down.
So in low output patients, a drug meant to reduce neurohormonal activation can, by lowering pressure too much, end up triggering more of it.
The same logic applies to drugs that slow the heart rate. Cardiac output is stroke volume multiplied by heart rate. If the stroke volume is already low and fixed, slowing the rate can reduce output further.
Two realms
The paper offers a clean mental model.
Patients who are haemodynamically stable live in what the authors call a neuroendocrine realm. Their main problem is chronic neurohormonal activation driving slow damage. For them, the four pillar drugs up-titrated to target doses are the priority.
Patients who are unstable, with wet and cold profiles, live in a haemodynamically driven realm. Their immediate problem is pressure and flow. For them, restoring stable haemodynamics comes first, while keeping neurohormonal blockade going wherever possible.
The authors write that in an unstable setting, the value of reversing haemodynamic problems appears to outweigh the importance of counteracting neurohormonal disorders.
What the paper suggests for each profile
The paper's table sets out a proposed approach. I will summarise it plainly, because it shows how different the four profiles can look.
Warm and dry. Up-titrate the standard drugs: ACE inhibitor or ARB or sacubitril/valsartan, mineralocorticoid antagonist, SGLT2 inhibitor, beta-blocker. Limit diuretics. This is the group expected to benefit most from guideline treatment.
Warm and wet. Clear the fluid first, with loop diuretics, acetazolamide, and natriuretic doses of mineralocorticoid antagonists. Then up-titrate standard drugs as for warm and dry.
Cold and dry. Reduce or avoid beta-blockers, ivabradine and vasodilating drugs. Reduce or avoid diuretics. SGLT2 inhibitors and mineralocorticoid antagonists can be considered because they have very little effect on blood pressure. Consider digoxin and a myosin activator. Consider non-drug options. Consider palliative care.
Cold and wet. Clear the fluid, with loop diuretics, acetazolamide and metolazone. Reduce or avoid beta-blockers, ivabradine and vasodilators. Consider SGLT2 inhibitors and mineralocorticoid antagonists. Consider digoxin and a myosin activator, non-drug options and palliative care.
For the sickest patients, the paper points toward non-drug treatments like cardiac resynchronisation therapy and mitral valve procedures as possible routes to improvement.
The quiet good news inside the table
One line in that table caught my attention. SGLT2 inhibitors and mineralocorticoid antagonists appear as options in every profile, including the cold ones, because they have a very modest impact on blood pressure.
That matters. It means even patients who cannot tolerate full doses of the pressure-lowering drugs may still be able to benefit from two of the four pillars. Being cold does not have to mean going without.
How to use this in the room
Part 7 set out the caution: this framework is a reasoned proposal, not a tested one. So nothing here is a reason to change your own medication. But it gives you a much sharper set of questions.
If you keep failing to tolerate your heart failure drugs because of dizziness, low blood pressure or worsening kidney numbers: "Could my cardiac output be low? Have we measured it on echo?"
If your doses have been reduced: "Which of my drugs matter most for me right now, and can we keep the ones that do not drop my pressure much, like an SGLT2 inhibitor or MRA?"
If you are stable and feeling well: "Am I on target doses? If not, why not?" Part 6 showed that patients who reached target doses had better remodelling.
If you have been told nothing more can be done: "Have we considered device or valve options?" The paper lists them as a real route for patients where drugs are limited.
Where the series lands
Heart failure has long been managed around one number, ejection fraction, and one plan, the four pillars for everyone. This paper argues for a finer picture: how much blood is getting through, whether fluid is backing up, and what your own dry peptide level looks like.
The idea is not fully proven. It is grounded in solid physiology, a half century old classification that still predicts survival, and tools you probably already have access to.
The people who get the most out of heart failure care are the ones who understand that a single diagnosis can hide four very different situations, and who ask which one they are in. After eight parts, you know how to ask.
This series discusses a peer-reviewed clinical review. Nothing here is medical advice. Heart failure treatment should always be guided by your own cardiology team.
