Association between cardiac axis changes and excess weight loss following bariatric surgery.

Background: Excess weight has been linked to leftward QRS axis deviation, but the impact of significant weight loss on cardiac axis remains unclear.

Objectives: To evaluate the association between excess weight loss following bariatric surgery and changes in the electrocardiographic cardiac axis.

Setting: Single academic medical center in Brazil.

Methods: Retrospective cohort including patients who underwent bariatric surgery at a multidisciplinary obesity treatment center in Southern Brazil. Pre- and postoperative electrocardiographies (ECGs) were analyzed, with exact cardiac axis determined using the Novosel equation. The main outcome was the association between the percentage of excess weight loss (EWL%) and the change in cardiac axis (Δθ_a), defined as the difference between the pre- and postoperative cardiac axis values. Multivariable linear regression models were applied, adjusting for time since bariatric surgery.

Results: A total of 60 participants (mean age of 42.15 years, 68.3% female) were included. The mean preoperative body mass index was 42.9 ± 6.2 kg/m², decreasing to 28.9 ± 5.2 kg/m² postoperatively, with an average EWL% of 66.7 ± 16%. The mean cardiac axis shifted from 27.99 ± 30.77 degrees preoperatively to 42.37 ± 34.06 degrees postoperatively (Δθ_a = 14.38 ± 26.61 degrees). A 1% increase in EWL% was associated with a .44-degree increase in the cardiac axis (B = .44; 95% confidence interval [CI]: .15-.80; P = .009).

Conclusions: Weight loss following bariatric surgery is associated with changes in the electrocardiographic cardiac axis, with a trend toward rightward shifts. The clinical significance of these findings remains uncertain, and further studies are needed to confirm and clarify the prognostic value of these electrocardiographic adaptations.