GDMT
GDMT (Guideline Directed Medical Therapy) is a cluster of medications from four different medication categories that work together to improve heart function and patient outcomes (less hospital, less death) when the ejection fraction (EF) is low. The goal is to reach the highest tolerable dose of each medication.
The general idea with GDMT is to get the patient on a medication from each of four different categories, increasing the dose of each to get to the highest dose/combination the patient can tolerate. A limited echo to reassess the EF is usually done after they have been brought up to max dose for at least three months, with the expectation or hope to see it has improved.
Limitations that we run into with this are often with blood pressure being pushed too low, too much strain on the kidneys, or side effects like fatigue, so we monitor blood pressure and labs after making changes to make sure they are being tolerated.
Key medication categories:
Beta blockers (like metoprolol or carvedilol): Reduce heart workload and lower blood pressure/heart rate
Anti-RAAS medications (two types/categories):
ARNi/ACEi/ARBs: Entresto is preferred, with ACEi/ARBs as alternatives
MRAs: Spironolactone or eplerenone, which reduce mortality in heart failure patients
SGLT-2 inhibitors (like Jardiance): Originally diabetes medications that reduce heart workload and mortality
These are the four main categories, or families, of drugs that make up the foundation of GDMT:
Beta blockers to step in and tell the heart to ease up on it’s workload. Metoprolol is a common beta blocker, though carvedilol seems to be preferred in this setting. These can lower both blood pressure and heart rate.
Anti RAAS (Renin-Angiotensin-Aldosterone System) medications interrupt and slow down a process that tightens up blood vessels and puts more strain on the heart. These take up two slots here, one family works on one part of this process, the other family on another part.
ARNi(angiotensin receptor/neprilysin inhibitor), ACEi(Angiotensin-converting enzyme inhibitors), ARB’s(Angiotensin receptor blockers) make up one group. Entresto is the best medication in this category, it is superior to ACEi’s and ARB’s like lisinopril or losartan, though it seems like half the time insurance doesn’t cover it very well and we end up setting a patient up with a Canadian pharmacy to get this. If that does not work out, ACEi and ARB’s are effective alternate options.
MRA’s (mineralocorticoid receptor antagonists) make up the other group. They work on a different part of the RAAS. Spironolactone is the most common MRA, eplerenone is the next in line. These have been shown to reduce death in patients with CM. In some part by reducing how hard the heart has to work, but there is a clear reduction in mortality w/ patients taking these. These medications also have a monitoring protocol to keep track of renal functions.
SGLT-2i’s (Sodium-glucose cotransporter 2 inhibitors) were initially a medication for diabetes management, they were found to also reduce how hard the heart has to work, and also have been shown to offer a clear reduction in mortality. Jardiance is the most common medication in this family. It can cause a little renal strain a few weeks after starting that tends to resolve over a few more weeks. This one also suffers from similar insurance coverage problems as Entresto and will sometimes end up coming through a Canadian pharmacy.
Treatment approach:
Monitor blood pressure regularly
Adjust medications gradually while watching for side effects like low blood pressure, fatigue, or kidney strain
After reaching optimal doses, wait three months before reassessing EF
The goal with GDMT is to get medication optimized; this may include seeing if we can titrate them to higher doses, or advance treatment and add in one or two other medications, so this does tend to take a little time and monitoring.
We do recommend patients check their blood pressure at home, at least several times a week, so we know where they tend to run, as that is one of the factors we look at when deciding if we can try to increase medications. For patients with severe cardiomyopathy, we aim for a goal MAP of about 65.
It is common that after finding a low EF a patient will get started on some form of GDMT then titrate/advance (sometimes on an accelerated schedule; managing CM with aggressive GDMT seems to be one area in medicine where there is benefit to aggressive initial onboarding with a goal to then get to maximally tolerated doses.
Once we get to the point where GDMT has been optimized to what the patient can tolerate, it is usually recommended to let their heart bask in the glorious relief it has been given by this medication regime for at least three (3) months, then remeasure their EF to make sure it has improved. A Limited echo is usually used here, as we’re just looking for the EF as far as GDMT evaluation.
If they need valve or structure follow up or update, a regular echo can be done to cover all of it, but otherwise a limited echo is all that is needed for this recheck.
Special consideration: If EF remains around 30%, additional intervention may be needed due to increased risk of dangerous heart rhythms.
The point of concern seems to be a sustained EF around 35% or under Seems like this is where the heart gets considerably more irritable and the chance of going into a lethal heart rhythm steps over a line where it makes a substantial jump in how likely it is to happen, enough that someone who remains below this threshold is often sent to get an implantable cardioverter defibrillator (ICD) for when their heart acts up.
The idea is to be prepared ahead of time for an event and is referred to, or seen in charts as, “primary prevention”. Patients’ are likely to be referred to EP for this (Electrophysiology; specialized cardiologist who just deals with electrical issues of the heart. Not heart attacks, heart failure, or heart hole flappers. Mainly rhythm issues and devices.).
