Can A Change in Thyroid Medication Prevent Tachycardia?

[ILynnSB]

I have been taking Toprol XL 50mg for tachycardia for two and one-half months. My thyroid medication was increased from 50 mcg to 75 mcg about four months ago because my TSH was 6. I have had tachycardia with rates of 100-140 for a while before I was treated. I was treated for stage III breast cancer beginning almost two years ago. The tachycardia started with the anemia that was worsened by chemotherapy. I also received radiation that caused pneumonitis and scarring of portions of the right lung. I have had several surgeries, and resulting pleural effusion that has since cleared. My potassium has been low for about four months even though I am on KCL 8meq daily. I would very much like not to continue the Toprol. My question is would a Thyroid replacement of both T3 and T4 be advantageous and cause less tachycardia? Also, would another class of medications be as affective as a beta blocker to treat tachycardia? I don't know if my decreased lung capacity is contributing to the tacycardia or exactly what the cause is. I am seeing a cardiologist. My echocardiogram looked good except my pulmonary valve could not be seen because of breast reconstruction. I am also concerned that even though my lipid profile was excellant before I started the Toprol will the levels rise since Toprol inhibits lypolosis? My HR is still about 100. I exersise at a gym 5-6 times a week but I must limit the intensity because of shortness of breath. I also continue to gain fat even though I am still relatively thin. I exercise and watch my diet. I am 48 years old and thought I was pretty healthy until all this happened. Thanks for time.

[Kevin Pho, MD]

To answer your questions:
1) Tachycardia is normally associated with an elevated thyroid level - thus adding more thyroid hormones would not likely improve the tachycardia you are currently experiencing.

2) Other than beta blockers, the other major class of medications used to treat tachycardia are calcium channel blockers (i.e. diltizem or verapamil).

3) I am not aware of Toprol adversely affecting the lipid profile.  

Followup with your personal physician is essential.

This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.

Thanks,
Kevin, M.D.