Scientific Poster Session I - Original Research

Original Research
  Saturday, October 12, 2024
  11:30 AM–01:00 PM

Abstract

Introduction: Atrial Fibrillation (AF) is the most common sustained arrhythmia whose prevalence and incidence are increasing worldwide. Lamotrigine (L) is widely prescribed for Bipolar I (BPI) disorder. L reduces intracellular sodium through inhibition of voltage-gated sodium channels, which thereby slows cardiac conduction velocity, introducing a potential substrate for AF.

Research Question or Hypothesis: This study aimed to examine the incidence of atrial fibrillation in L patients with and without a history of cardiac arrhythmias or structural heart disease (SHD) vs controls prescribed common medications for Bipolar I disorder.

Study Design: Adult patients with BPI who filled a prescription for lamotrigine were taken from Merative MarketScan^® Commercial Claims and Medicare Supplemental Database. Eligible subjects should be free from AF, arrhythmia, or structural heart disease. Controls (C) were on lithium, quetiapine, valproate, or risperidone for managing BPI. Onset of AF was determined using ICD codes. Calculating the cumulative incidence of AF, patients were censored from follow up at switching between L and C, discontinuation of L or C, or end of follow-up, whichever incurred first.

Methods: The measure of association was hazard ratio (HR) of AF for L versus C calculated from a multi-variable Cox-proportional hazard regression model. As a sensitivity analysis, we analyzed a propensity score matched (PSM) cohort.

Results: The analysis included 150,470 L patients and 204,704 C patients. The 1-year cumulative incidence of AF from L and C was 0.76% and 0.64%, respectively, calculating a HR of 1.257 [95% CI: 1.0878-1.4534], p=0.0118. PSM resulted in a similar HR estimate of 1.177 [1.007 - 1.378]. The number needed to treat for one additional AF was 833.

Conclusion: In adult naïve AF patients, L compared to C taking commonly prescribed BPI medications was associated with a higher risk of AF.

Presenting Author

Landon Welch PharmD
University of Utah College of Pharmacy

Authors

Bertha De Los Santos MS, PharmD
University of Illinois Chicago School of Pharmacy

Kibum Kim PhD
Sodam Kim PharmD
Mark Munger PharmD, FCCP
Przemyslaw Radwański PharmD, PhD, FAHA