Low Heart Rate with Atenolol

I have been put on 50mg of Atenolol and I have been on it for a month for Supra Ventialar Tachycardia, I take it at 9:00PM and within the 1st 3-4hrs of taking the medicine my heart rate goes down to the Mid-50's Is this Normal? or Should I be concerned and I have no symptoms. I already asked my Heart Doctor and he said that could be a normal reaction to the medicine. I am very nervous and concerned about this. I would like to get another opinion about this.
Thank You

[NTB]

I think that degree of heart-rate reduction is normal for beta blockers, of which atenolol is one.

Should you be concerned? Well, as you say you have no symptoms.

But there is another angle at work here which is not that well known yet. It probably is more than you wanted to know, but I'll post it anyway because maybe some of the regulars might find it interesting.

It has to do with the concept of central blood pressure. When a beta blocker reduces heart rate, there is a tendency for the body to compensate with an increase in "central pressure" (that which is in the heart and brain), in an effort to maintain  the rate|pressure constant. There was a recent review in Journal of the American College of Cardiology, which showed that when you slow the heart rate with a beta blocker in patients with hypertension, you actually get more heart attacks, heart failure and strokes. (It's important to note that using BBs in people who have heart failure or previous heart attack is a different case.) Your heart and brain arteries don't know what the pressure is in the arm, so to speak. The lower the rate, the higher the CV events.

So, it's possible that all non-vasodilating beta blockers are dangerous. Or perhaps it's something peculiar to atenolol (since atenolol was the BB used IIRC in ~80% of the subjects).

Invasive in vivo experiments on sheep aorta demonstrated the effect on central pressure. Also, work is being done to use a tonometer on humans, and to accurately calculate central pressure from the arm pressure waveform.

Anyway, the offshoot is that you might be better off switching to nebivolol, which is a vasodilating beta blocker. A researcher named Cockroft is doing a lot of work in that area.

[Magicalrose333]

I was wondering if you could tell me where you found this study on the American college of cardiology I would like to read more about it and show it to my doctor.

[NTB]

wonderful attitude! :)  I've gotten used to people not even acknowledging if they've read an answer, much less asking for more information. I salute you. Info is on the way. Best wishes to you.

Also:

I believe that the minimum dose of atenolol is 25 mg. So maybe if you were on that lower dose, your heart rate wouldn't have been so reduced. Just a curiosity: drinking orange juice with atenolol reduces blood concentrations. Drinking coffee might increase heart rate.

You might also like to know that atenolol, as well as other standard beta blockers, have been deemed not suitable in England for first line therapy in hypertension any longer. The main reason is that they tend to increase Blood Glucose, and might provoke diabetes. Nebivolol does not increase BG, btw. But carvedilol does. Nebivolol though is quite expensive, and might not be on a formulary. Atenolol is inexpensive.

There is also a new drug called ivabradine that gives pure control of heart rate without being a beta blocker.

You also might think about changing the timing of your medication. The time to peak plasma concentration is probably in those 3-4 hours that you mention. If the drug does not make you tired, you might think about taking it during the day - while being wary of orthostatic hypotension.

--

NT

[Magicalrose333]

Yes I read everything I can about this so I can talk to my doctor and be 100% informed about my health. I am taking Lisinopril for my Hypertension and Also the Atenolol.

[NTB]

Hi, Rose. Some suggestions: you might in the meantime want to shift the timing of your BB. IOW, determine at which hour of the day your HR is highest. Then find out the time to peak plasma (Tmax) for atenolol - which is likely around 3-4 hrs. Then you'd want to take the atenolol those 3-4 hours before your typical peak HR hour.

Or conversely, take the atenolol to coincide with your sleep time, if taking it in the day makes you too tired.

Or, take your BP every two hours and make sure to not get theTmax of the meds to coincide with the time when your BP is lowest in its natural cycle.

A doc would generally advise shifting the time of the dose by two hours per day until you arrive at the target time.