ECG gives a ‘low voltage’ finding
Dear Dr. Roach: I will be undergoing a thyroidectomy to reduce the chances of thyroid cancer, given my family history, a CHEK2 mutation and ongoing thyroid nodule growth. My concern is that I had an ECG for preop purposes and received results that stated I had low voltage on the extremity leads. Otherwise, I have normal results. I have a BMI of 30, very low blood pressure and high to average cholesterol. In addition, I have been taking anastrozole for ER-positive breast cancer since 2017.
How concerning is the ECG result given the other pieces at play? I have read that anastrozole can impact the heart. I have been cancer-free for five years, but my oncologist wants me to continue the medication for 10 years because of the CHEK2 mutation.
G.C.
Answer: Abnormalities on electrocardiograms are very common, and although they can be anxiety-provoking, they often do not represent anything seriously wrong with the heart.
Low voltage on the extremity leads on an ECG can sometimes occur when there is a large amount of fluid in the sac surrounding the heart, called a pericardial effusion. It may also indicate infiltration of the heart muscle by abnormal protein, called cardiac amyloidosis.
Neither of them is likely, and the vast majority of people who get this abnormality on a routine ECG have nothing identifiably wrong, even after an exhaustive search. I have seen this finding in my own patients numerous times and never had a person with any serious problem. (But, if a person is sick enough to be in the hospital and has this, that would be much more concerning.)
Anastrozole can cause heart problems, but these are usually related to the blood vessels of the heart, not the heart muscle or the pericardium. It is unlikely that the anastrozole has anything to do with the low voltage. People who are very overweight (not you, with your BMI of 30) and people with a severely low thyroid level can have low voltage, but I suspect that you are one of the many people who has nothing particularly wrong and has this as an incidental finding.