Poster Presentation ESA-SRB-ANZOS 2025 in conjunction with ENSA

Cardiac Autonomic Dysfunction Following Bariatric Surgery: A Case of Presyncope and Postural Intolerance Responsive to Rate-Limiting Therapy (128681)

Tavleen Kaur 1 2 , Christine Madronio 1 3 , Kathryn Williams 1 3
  1. Department of Endocrinology, Nepean Hospital,NBMLHD, Sydney, NSW, Australia
  2. Southwest Clinical School, UNSW Medicine, Sydney, NSW, Australia
  3. Charles Perkins Centre- Nepean, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia

We describe a case of cardiac autonomic dysfunction following sleeve gastrectomy.

A 54-year-old woman presented with recurrent post operative presyncope described as “blacking out” without loss of consciousness. She underwent sleeve gastrectomy in 2020 with a nadir weight of 93.4 kg, followed by modest weight regain managed with liraglutide. Symptoms occurred up to four times weekly and were associated with palpitations. Orthostatic vitals revealed stable blood pressure (sitting 110/60 mmHg; standing 115/70 mmHg) but a fixed heart rate of 60 bpm with no postural acceleration.

ECG was sinus rhythm. Biochemistry demonstrated no electrolyte abnormalities. Haemoglobin was 141 g/L with low serum ferritin 24 mcg/L (30–165). She received intravenous iron.  Preoperative CT coronary angiography and coronary artery calcium score was 0. A loop recorder revealed brief supraventricular tachycardia (186 bpm, 12 beats) correlating with one episode. Multiple device-recorded pauses were confirmed to be artefactual.

The patient was initially treated with metoprolol 25 mg twice daily, which reduced symptom frequency but caused fatigue. She was switched to diltiazem 180 mg extended release, which was well tolerated and led to substantial improvement. Over the next 12 months, she experienced only three to five brief episodes of presyncope, with no further tachycardia or syncope.

Cardiac autonomic dysfunction following bariatric surgery is multifactorial, involving altered baroreflex sensitivity, decreased sympathetic tone, and intravascular volume depletion from weight loss and hormonal changes1,2. The efficacy of beta-blockers and calcium channel blockers may relate to modulation of rate variability and supraventricular ectopy3-5. Loop recorders provide valuable data to exclude high-risk arrhythmia6. Cardiac autonomic dysfunction is a potentially under-recognised complication of rapid weight loss following bariatric surgery. Clinicians should maintain a high index of suspicion for autonomic dysfunction in post-bariatric patients presenting with postural symptoms, especially when standard investigations are unremarkable, and management tailored to symptoms and medication tolerability.

  1. Nguyen N, Varela JE. Bariatric surgery for obesity and metabolic disorders: State of the art. Nat Rev Gastroenterol Hepatol. 2017;14(3):160–169.
  2. Joris PJ, Mensink RP. Role of autonomic nervous system in the metabolic syndrome: A review of the literature. Nutrients. 2020;12(3):701.
  3. Olshansky B, Sami M. The autonomic nervous system and arrhythmias: Current concepts and emerging therapies. Heart Rhythm. 2015;12(9):1860–1869.
  4. Fedorowski A. Postural orthostatic tachycardia syndrome: clinical presentation, aetiology and management. J Intern Med. 2019;285(4):352–366.
  5. Freeman R, Wieling W, Axelrod FB, et al. Consensus statement on the definition of orthostatic hypotension, neurally mediated syncope and postural tachycardia syndrome. Clin Auton Res. 2011;21(2):69–72.
  6. Sheldon R. Loop recorders in syncope: diagnostic yield and clinical utility. CMAJ. 2013;185(17):E755–E762.