A retrospective review included patients prescribed LTG for any indication and at least one EKG at the William S Middleton Memorial Veterans Hospital between 10-01-2017 and 07-06-2021. Patients were classified based on a cardiac related ICD-10-CM code, previous diagnosis of cardiac disease, or cardiology visits during their care. Data collected include: dates of LTG use, highest LTG dose, any concomitant medications prescribed with known potential to cause cardiac abnormalities, and EKG findings. Study was approved by the UW-Madison IRB.

Initial review identified 233 (189 male/43 female) patients. Mean age was 63.5 years and mean LTG dose concurrent with EKG was 229 mg. Forty-one percent (N=96) of patients had an abnormal EKG while prescribed LTG. Of these 96 patients, 47.9% (N=46) had concomitant Na channel blocking drug. Of these 96 patients, 12.5% (N=12) had no prior cardiac diagnosis, with 8.3% (N=1) deemed potentially associated with LTG. Of the 87.5% (N=84) with a prior cardiac diagnosis, 27.4% (N=23) had a change in EKG findings (1^st degree AV block) and in 7.1% (N=6) an association with LTG was deemed possible.

No unambiguous association between LTG and EKG abnormalities were found in this population. Several potential associations (N=8) were identified, though due to the retrospective nature of the study could not be confirmed or definitively excluded. The incidence of potential associations did not differ based on a prior cardiac history. Further studies are warranted to evaluate any causal link between EKG changes and the use of LTG, particularly when given with concomitant medications.