To Örebro University

Background and aims: To study the effects of obesity treatment with gastric bypass surgery on hospitalization for heart failure (HF) and atrial fibrillation (AF) in patients with type 2 diabetes (T2D) and obesity. We also studied the effects of gastric bypass surgery on mortality in a subgroup of individuals with preexisting heart failure.

Materials and methods: In this register-based nationwide cohort study we compared individuals with T2D and obesity that underwent Roux-en-Y gastric bypass surgery (RYGB) with matched individuals with T2D and obesity that did not undergo surgery. Data was gathered by linking the Swedish National Diabetes Register and Scandinavian Obesity Surgery Registry. Matching of individuals for age, gender, BMI and calendar time was done using a time updated propensity score. The main outcome measures were hospitalization for HF and/or AF, and mortality in patients with preexisting HF. The risk for heart failure, AF and death were assessed using a Cox-proportional hazards regression model that addressed measured confounding.

Results: We identified 5321 individuals with T2D and obesity that had undergone RYGB between January 2007 and December 2013 and 5321 matched controls. The individuals includedwere between 18 and 65 years old and had a BMI > 27.5 kg/m2. The follow-up time for hospitalization was until the end of 2015 (mean 4.5 years) and the end of 2016 for death. Our results show a 73% lower risk for HF (HR 0.27 (0.19, 0.38) p<0.001), 41% for AF (HF 0.59 (0.44, 0.78) p < 0.001), and 77% for concomitant AF and HF (HR0.23 (0.12, 0.46) p < 0.001) in the surgically treated group. In patients with preexisting HF we observed significantly lower mortality in the group that underwent surgery (HR0.23 (0.12, 0.43) p < 0.001).

Conclusion: Bariatric surgery may reduce risk for HF and AF in patients with T2D and obesity, speculatively via positive cardiovascular and renal effects. Obesity treatment with surgery may also be a valuable alternative in selected patients with T2D and HF.