Is your institution a milrinone shop or a dobutamine shop? Or do you have a mixed shop?
It seems that most institutions are accustomed to use mostly one or the other in cardiogenic shock.
Some argue that milrinone is better.
Some argue that dobutamine is better.
But do we know the answer?
This was answered late in 2021 in the New England Journal of Medicine.
Hat tip to the authors. Download the article for yourself as this is not medical advice.
They randomized 192 patients in cardiogenic shock to either milrinone or dobutamine.
Baseline characteristics were similar between the two groups.
They had a cardiac index of less than 1.8.
Most patients did not have a PA catheter.
The primary outcome is a composite outcome with included numerous parameters.
There was no difference between the two groups.
They tried to tease out benefits in the subgroup analysis of the primary outcome.
There appears to be a trend where milrinone is better, but trends don’t mean anything.
The secondary outcomes were also numerous.
Due to the faster metabolism of dobutamine with a half life of 2 minutes versus >2 hours in milrinone, I would have figured that there would be a difference in length of stay or total time receiving inotropes but this was not the case.
There was no difference in any of these either.
All in all, there was no difference between milrinone and dobutamine in cardiogenic shock.
Keep doing whatever you were doing before.
If you want to learn more about mechanical circulatory support in cardiogenic shock, CLICK HERE.

Citation for Dobutamine vs Milrinone

Mathew R, Di Santo P, Jung RG, Marbach JA, Hutson J, Simard T, Ramirez FD, Harnett DT, Merdad A, Almufleh A, Weng W, Abdel-Razek O, Fernando SM, Kyeremanteng K, Bernick J, Wells GA, Chan V, Froeschl M, Labinaz M, Le May MR, Russo JJ, Hibbert B. Milrinone as Compared with Dobutamine in the Treatment of Cardiogenic Shock. N Engl J Med. 2021 Aug 5;385(6):516-525. doi: 10.1056/NEJMoa2026845. PMID: 34347952.
Link to Article
Link to FULL FREE PDF

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Podcast Script

Welcome to the Saving Lives Podcast. For historical context, today is the 25th of August of 2022.
The article that I am using as a reference to this post is over a year now. It was published on August 5th, 2021.
Is your institution a milrinone shop or a dobutamine shop? Or do you have a mixed shop?
It seems that most institutions are accustomed to use mostly one or the other in cardiogenic shock.
Some argue that milrinone is better.
Some argue that dobutamine is better.
But do we know the answer?
This was answered late in 2021 in the New England Journal of Medicine. Or was it?
Hat tip to the authors. Download the article for yourself as it is completely free. This is not medical advice. As I always say, do not trust me.
They randomized 192 patients in cardiogenic shock to either milrinone or dobutamine as their primary inotrope.
The mechanism of action of milrinone is that it is a phosphodiesterase 3 inhibitor. This means that it increases cardiac inotropy, lusitropy, and peripheral vasodilation. In case this is the first time that you hear this word, lusitropy is the rate of myocardial relaxation.
Given that milrinone increases inotropy and causes peripheral vasodilation, in clinical practice we see that the patient’s cardiac index increases and the systemic vascular resistance decreases. Sometimes, this decrease in systemic vascular resistance means that milrinone needs to bring along a friend named norepinephrine.
On the other hand, dobutamine is a catecholamine. It works as a beta1 and beta2 agonist. Intern, this improves the patient’s cardiac output.
Some clinicians may prefer milrinone because it is said to be better than dobutamine in improving right ventricular function. Also, it is said that dobutamine increases the heart rate and increases myocardial oxygen consumption.
This trial set out to sort out all these theories.
Baseline characteristics were similar between the two groups. Nothing really caught my eye here with regards to the baseline characteristics. The median ejection fraction in both groups was 25%. The majority of causes of ventricular dysfunction was due to ischemia. I found it interesting that they stratified the degree of cardiogenic shock based on the definition provided by the society for cardiovascular angiography and interventions. I have covered this definition in the past on both my Instagram accounts as well as my website. It only takes about a minute to learn.
They had a cardiac index of less than 1.8.
Most patients did not have a PA catheter. I am personally a fan of the PA Catheter.
The primary outcome is a composite outcome with included numerous parameters.
This primary outcome included a composite of in hospital death, cardiac arrest, need for mechanical circulatory support, and other factors.
There was no difference between the two groups.
They tried to tease out benefits in the subgroup analysis of the primary outcome.
There appears to be a trend where milrinone is better, but trends don’t mean anything.
Even for primarily right sided cardiogenic shock, with a sample size of only eight patients in each group, one cannot make the determination of whether milrinone or dobutamine is better.
The secondary outcomes were also numerous.
This is where you could find the length of stay which had no difference, time receiving inotropes which also had no difference. Heck, there was no difference in any of the secondary outcomes. If you can imagine it, there’s no difference in it.
Due to the faster metabolism of dobutamine with a half life of 2 minutes versus >2 hours in milrinone, I would have figured that there would be a difference in length of stay or total time receiving inotropes but this was not the case.
There was no difference in any of these either.
When I initially posted this study onto Instagram, people asked me about arrhythmias. There tends to be a thought process that dobutamine leads to more arrhythmias. The data, however, shows that there is no difference between milrinone and dobutamine with regards to arrhythmias.
All in all, there was no difference between milrinone and dobutamine in cardiogenic shock.
I did learn something from Dr. Benjamin Miller who is a NeuroIntensivist. He taught me that milrinone is used in patients with subarachnoid hemorrhages due to it’s vasodilator properties.
Joy Stewart who is a pharmacist asked a valid question regarding practice patterns in patients with ESRD. Manny Alfonso brought up a good point about cost. I looked up the price on UpToDate and found that milrinone costs between 18 to 40 cents per mL. Dobutamine is less expensive at between 6 to 19 cents per mL. The question then is how many CC will it take to reach therapeutic effect? That’s something I am definitely not digging into on this podcast. Nor am I going to touch the whole dosing scheme of milrinone with a 10 foot pole. You know, the 0.125, 0.25, 0.375. 0.5, etc. dosing scheme that we all follow in clinical practice.
Keep doing whatever you were doing before.