title: Sympathetic autonomic dysfunction and impaired cardiovascular performance in higher risk surgical patients: implications for perioperative sympatholysis.
abstract: Recent perioperative trials have highlighted the urgent need for a better understanding of why sympatholytic drugs intended to reduce myocardial injury are paradoxically associated with harm (stroke, myocardial infarction). We hypothesised that following a standardised autonomic challenge, a subset of patients may demonstrate excessive sympathetic activation which is associated with exercise-induced ischaemia and impaired cardiac output.
  
  
  
  Heart rate rise during unloaded pedalling (zero workload) prior to the onset of cardiopulmonary exercise testing (CPET) was measured in 2 observation cohorts of elective surgical patients. The primary outcome was exercise-evoked, ECG-defined ischaemia (>1 mm depression; lead II) associated with an exaggerated increase in heart rate (EHRR ≥12 bpm based on prognostic data for all-cause cardiac death in preceding epidemiological studies). Secondary outcomes included cardiopulmonary performance (oxygen pulse (surrogate for left ventricular stroke volume), peak oxygen consumption (VO2peak), anaerobic threshold (AT)) and perioperative heart rate.
  
  
  
  EHRR was present in 40.4-42.7% in both centres (n=232, n=586 patients). Patients with EHRR had higher heart rates perioperatively (p<0.05). Significant ST segment depression during CPET was more common in EHRR patients (relative risk 1.7 (95% CI 1.3 to 2.1); p<0.001). EHRR was associated with 11% (95%CI 7% to 15%) lower predicted oxygen pulse (p<0.0001), consistent with impaired left ventricular function.
  
  
  
  EHRR is common and associated with ECG-defined ischaemia and impaired cardiac performance. Perioperative sympatholysis may further detrimentally affect cardiac output in patients with this phenotype.
authors.affiliation: Division of Medicine, Department of Clinical Physiology , University College London , London , UK.
authors.forename: John
authors.initials: J
authors.lastname: Whittle
authors.affiliation: UCL Medical School, University College London , London , UK.
authors.forename: Alexander
authors.initials: A
authors.lastname: Nelson
authors.affiliation: Division of Surgery and Interventional Science , University College London, Royal Free Hospital , London , UK.
authors.forename: James M
authors.initials: JM
authors.lastname: Otto
authors.affiliation: Department of Anaesthesia , University College London Hospitals NHS Trust , London , UK.
authors.forename: Robert C M
authors.initials: RC
authors.lastname: Stephens
authors.affiliation: Division of Surgery and Interventional Science , University College London, Royal Free Hospital , London , UK.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Martin
authors.affiliation: Plymouth University, Peninsula Schools of Medicine and Dentistry, Plymouth , London , UK.
authors.forename: J Robert
authors.initials: JR
authors.lastname: Sneyd
authors.affiliation: Plymouth University, Peninsula Schools of Medicine and Dentistry, Plymouth , London , UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Struthers
authors.affiliation: Plymouth University, Peninsula Schools of Medicine and Dentistry, Plymouth , London , UK.
authors.forename: Gary
authors.initials: G
authors.lastname: Minto
authors.affiliation: Division of Medicine, Department of Clinical Physiology , University College London , London , UK ; Department of Neuroscience, Physiology and Pharmacology , Centre for Cardiovascular and Metabolic Neuroscience, University College London , London , UK ; William Harvey Research Institute, Queen Mary University of London, London, UK.
authors.forename: Gareth L
authors.initials: GL
authors.lastname: Ackland
keywords: MYOCARDIAL ISCHAEMIA AND INFARCTION (IHD)