Long-term changes in cardiac geometry and mechanics after bariatric surgery- insights from the FatWest study

Abstract Background Patients with severe obesity have a high prevalence of subclinical cardiac organ damage including impaired longitudinal and radial cardiac mechanics. Previous studies on the impact of bariatric surgery on cardiac remodeling, most of them with short patient follow-up, have yielded inconsistent results. Purpose To assess progressive changes in cardiac geometry and mechanics up to five years following bariatric surgery. Methods In the prospective Bariatric Surgery on the West Coast of Norway (FatWest) study, cardiac remodeling was assessed by 2D echocardiography preoperatively and at six months, one year and five years after Roux-en-Y gastric bypass in a cohort of 97 patients (44±10 years, 72% women, body mass index [BMI] 41.8±4.8 kg/m²). Excess weight loss (EWL) was calculated as: absolute weight loss/(initial weight-ideal weight)x100. Left ventricular (LV) size was assessed by the LV mass/ height^2.7, LV longitudinal mechanics by the peak global longitudinal strain (GLS) and radial mechanics by the midwall shortening (MWS). LV myocardial oxygen demand was estimated from the LV mass-wall stress-heart rate product. Right ventricular diameter was measured in the basal one-third of the ventricular cavity. Left atrial (LA) reservoir function was assessed by the LA emptying fraction. Results After a mean follow-up of 63±13 months, the average postoperative EWL was 66%. Overall, both right ventricular diameter, LV mass index, LV GLS, myocardial oxygen demand and LAEF (68% vs. 64%) improved significantly at the 5-year follow-up (all p<0.05), while MWS remained unchanged (Figure). Prevalence of normal LV geometry increased gradually from 56% to 80%, while that of LV hypertrophy fell from 36% to 16% (p<0.001). Analyses of temporal trends showed that improvement in BMI, LV mass and LV GLS occurred during the first postoperative year (Figure). In Cox regression analysis, a low 5-year GLS was associated with preoperative hypertension after adjustment for age, sex, preoperative diabetes mellitus, and postoperative changes in BMI, mean blood pressure and myocardial oxygen demand (p<0.01). In a similar linear model, after adjustment for the same covariates, LV mass index at the 5-year follow-up was independently related to the magnitude of the postoperative BMI reduction (R² = 0.58, p<0.001). Conclusion Ventricular size and longitudinal mechanics are significantly improved 5 years after bariatric surgery, with the reverse remodeling occurring during the first postoperative year. Residual abnormal 5-year LV geometry and mechanics are related to preoperative hypertension and suboptimal BMI reduction.Figure