Abstract 16319: Large Weight Loss Improves Left Ventricular Geometry but Not Myocardial Function 6 Months After Bariatric Surgery (the Fatwest Study)

Abstract

Background: Bariatric surgery causes rapid and large weight loss and improves cardiovascular risk profile, yet the effect on left ventricular (LV) systolic function has been less explored. Methods: In the prospective FatWest (Bariatric Surgery on the West Coast of Norway) study 98 severely obese patients (44±10 years, 72% women, preoperative body mass index [BMI] 41.8±4.8 kg/m 2 , 36% with hypertension) underwent echocardiography before and 5.9 months after gastric bypass surgery. We assessed changes in LV geometry and systolic function by biplane ejection fraction (EF), midwall shortening (MWS) and mitral annular systolic velocity (s′). LV hypertrophy was defined based on LV mass/height 2.7 . Myocardial O 2 demand was derived from the LV mass-wall stress-heart rate product. Results: Patients experienced on average a 10 kg/m 2 reduction in BMI, and a significant drop in heart rate and blood pressure (all p<0.001). LV mass (-12 g) and myocardial O 2 demand improved significantly (all p<0.01). However, LV EF (60 vs. 61%), s’ (8.5 vs. 8.3cm/s) and MWS (16.1 vs. 15.7%) remained unchanged, and 45% of patients had low MWS 6 months after surgery (Figure). In multivariable regression analyses, LV mass reduction was predicted by weight loss and female sex, independent of changes in blood pressure and heart rate (R 2 0.24, p <0.001) while lower myocardial O2 demand was explained by improvement in its three components, particularly lower LV end-systolic wall stress (R 2 0.9, p<0.001). Conclusion: In severely obese patients with normal EF, bariatric surgery induces a significant reduction in BMI, LV mass and myocardial O 2 demand, but no improvement in LV myocardial systolic function 6 months after surgery.