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

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

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

Single academic medical center in Brazil.

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.

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).

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.