Assessment of arrhythmias and cardiac autonomic tone at a relatively young age patients with obesity class III

Bariatric surgery partially reverses subclinical proarrhythmic structural, electrophysiological and autonomic changes in obesity

BACKGROUND

Obesity confers higher risks of cardiac arrhythmias. The extent to which weight loss reverses subclinical proarrhythmic adaptations in arrhythmia-free obese individuals is unknown.

OBJECTIVE

To study structural, electrophysiological and autonomic remodelling in arrhythmia-free obese patients, and their reversibility with bariatric surgery using electrocardiographic imaging (ECGi).

METHODS

Sixteen arrhythmia-free obese patients (43+12years, 13 female, BMI 46.7+5.5kg/m2) had ECGi pre-bariatric surgery (PreSurg), of which twelve had ECGi post-surgery (PostSurg, 36.8+6.5kg/m2). Sixteen age- and sex-matched lean healthy individuals (42+11 years, BMI 22.8+2.6kg/m2) acted as controls and had ECGi once.

RESULTS

Obesity was associated with structural (increased epicardial fat volumes and left ventricular mass), autonomic (blunted heart rate variability) and electrophysiological (slower atrial conduction and steeper ventricular repolarisation gradients) remodelling. Following bariatric surgery, there was partial structural reverse remodelling, with a reduction in epicardial fat volumes (68.7cm3 vs 64.5cm3, p=0.0010) and left ventricular mass (33g/m2.7 vs 25g/m2.7, p<0.0005). There was also partial electrophysiological reverse remodelling with a reduction in mean spatial ventricular repolarisation gradients (26mm/ms vs 19mm/ms, p=0.0009), although atrial activation remained prolonged. Heart rate variability, quantified by standard deviation of successive differences of RR intervals, was also partially improved following bariatric surgery (18.7ms vs 25.9ms, p=0.017). Computational modelling showed PreSurg obese hearts had a greater window of vulnerability to unidirectional block and had earlier spiral-wave break-up with more complex re-entry patterns than PostSurg counterparts.

CONCLUSION

Obesity is associated with adverse electrophysiological, structural and autonomic remodelling that is partially reversed after bariatric surgery. These data have important implications for bariatric surgery weight thresholds and weight loss strategies.

Holter-Derived Autonomic Function, Arrhythmias and Carbohydrate Metabolism in Patients with Class III Obesity Treated with Laparoscopic Sleeve Gastrectomy

The effects of weight loss following bariatric surgery on autonomic balance, arrhythmias and insulin resistance are still of interest. We prospectively investigated 50 patients with BMI > 40 kg/m², aged 36.5 (18–56) years who underwent laparoscopic sleeve gastrectomy. Among other examinations, all subjects had 24-h Holter monitoring with heart rate variability (HRV) and heart rate turbulence (HRT) evaluation. After a median of 15 months, BMI decreased from 43.9 to 29.7 kg/m², the incidence of hypertension decreased from 54 to 32% (p = 0.04) and any carbohydrate disorders decreased from 24 to 6% (p = 0.02). Fasting insulin concentration and insulin resistance index improved significantly (p < 0.001). Improvements in HRV parameters related to the sympathetic autonomic division were also observed (p < 0.001), while HRT evaluation was not conclusive. The enhancement of autonomic tone indices was correlated with reduction of BMI (SDNN-I r = 0.281 p = 0.04; SDNN r = 0.267 p = 0.05), but not with reduction of waist circumference, and it was also associated with decrease of mean heart rate (OR 0.02, 95%CI 0.0–0.1, p < 0.001). The incidence of arrhythmias was low and similar before and after follow-up. In conclusion, improvement of homeostasis of carbohydrate metabolism and autonomic function is observed in relatively young patients after weight loss due to laparoscopic sleeve gastrectomy.