The Relationship between Bariatric Surgery-Induced Weight Loss and Heart Rate Variability

Abstract

The study included 30 morbidly obese patients 10 males (33.3%) and 20 females (66.7%) with a baseline BMI ranging from 40 to 53 and mean BMI (45.37 ± 4.14). Their ages range between 20 - 40 years old. The patients had a pre-operative 24 hour-Holter monitoring and another follow up 24 hours Holter monitoring after reaching the target weight loss (20 %) of the baseline BMI. There was a significant decrease in minimal heart rate (from 72.7 ± 10.35 to 56.43 ± 7.34 beat/min), mean heart rate (from 89.4 ± 4.99 to 69.53 ± 5.73 beat/min) and the maximal heart rate (from 150 ± 11.22 to 123.87 ± 9.07 beat/min) in the follow up Holter after reaching the target weight loss (20 % of the baseline BMI) With <.0.001. As regards the heart rate variability parameters, there was a significant increase in all parameters of the heart rate variability (Time domain and frequency domain). As regards time domain, There was a significant increase in the standard deviation of normal to normal R-R intervals (SDNN) from (80.37 ± 10.03) to (141.47 ± 10.55) with P-value <.0.001. Furthermore, There was a significant increase in the square root of the mean of the squared differences between adjacent normal R-R intervals (r MSSD) from (23.85 ± 5.49) to (48.97 ± 5.49) with P-value <.0.001. There was a significant decrease in the ratio of low frequency to high frequency (LF /HF ratio) from (1.41 ± 0.34) to (0.9 ± 0.32) with P-value <.0.001. Therefore, there was a significant increase in the high-frequency (HF) component of the frequency domain representing the vagal activity on the heart. Our study results proved that weight loss after bariatric surgery (Roux-en-Y gastric bypass) improves the heart rate variability and hence cardiac autonomic modulation. This is of importance because decreased the heart rate variability is associated with increased cardiac mortality independent of ejection fraction. Furthermore, Weight loss after bariatric surgery (Roux-en Y gastric bypass) achieved better glycemic control of the diabetic patients.