I rank Metoprolol 25 out of the 33 drugs I carry.
Our indication for Metoprolol is for rapid atrial fibrillation and PSVTs in patients already on oral beta blockers. We do not use Metoprolol for Acute Coronary Syndrome care. A few years back Metoprolol was considered life-saving in ACS care, but then more research came out and while it is life-saving for some patients, it is detrimental to others and the experts felt it would be too difficult for us (and I agree0 to distinguish the best candidates lacking our ability to know the patient’s ejection fractions and other considerations.
Despite not being used for ACS, I was very excited to get Metoprolol and anxious for the first time I could use it.
The patient, an elderly gentleman on Atenolol (another beta blocker), was in a rapid afib in the 160-170 range. I drew up the 5 mg of Metoprolol, pushed it slowly and waited. Nothing happened. I waited and waited. Nothing. Our next step is to call medical control, but since we were already arriving at the hospital, I just brought him on in. I gave my report, got him in the room, went and wrote my run form, came back, looked up at the monitor and saw he had slowed considerably and was in a controlled afib in the 70’s.
“So, the Metoprolol finally worked,” I said to the nurse.
“No,” she said, “We gave him Cardizem.”
After that episode I would be tempted to put Metoprolol at the bottom of my list. Here was a drug that prevented me from giving a drug that would have done the trick. But, subsequently I have talked to medics who have given the 5 mg and had it work. I have also learned that the 5 mg is often followed with another 5 mg after five minutes or so and then another 5 mg to a total of 15 mg. That usually does the trick, and if it doesn’t, well then you can go to Cardizem if the blood pressure is still decent.
And I have to ask myself, if I am on beta blockers, and I go into a rapid afib, would I rather have more beta blocker or Cardizem, which can really drop my pressure? A little more beta blocker seems the most reasonable. I just need to be prepared to call medical control and ask for additional doses if needed and indicated.
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Metoprolol (Lopressor)
Class: Beta Blocker
Action: Partial blockade of Beta Receptors
Indication: Atrial fibrillation, Atrial flutter, narrow complex tachycardia
Contraindication: Hypotension (SBP < 110mmHg)
Bradycardia (HR < 70bpm)
Hypersensivity to drug
1st, 2nd or 3rd Degree Heart Block
Asthma
Acute Pulmonary Edema
Recent Cocaine Use
Side effect: Pulmonary Edema
Hypotension
Weakness
Dose: 5mg SIVP
Route: IV push (bolus) given over 5 minutes
Pedi dose: None
Important points: Utilize Metoprolol for patients experiencing narrow complex tachycardias that
are taking oral Beta Blockers.
