title: Confounders of Cardioprotection by Remote Ischemic Preconditioning in Patients Undergoing Coronary Artery Bypass Grafting.
abstract: OBJECTIVE
  Remote ischemic conditioning (RIC) by repetitive blood pressure cuff inflation/deflation around a limb provides cardioprotection in patients undergoing coronary artery bypass grafting (CABG). Cardioprotection is confounded by risk factors, comorbidities and comedications. We aimed to identify confounders that possibly attenuate the protection provided by RIC.
  
  
  METHODS
  In a retrospective analysis of our single-center, randomized, double-blind trial of patients undergoing elective CABG with/without RIC prior to ischemic cardioplegic arrest, we analyzed demographics, medications and intraoperative variables. The primary end point was myocardial injury, as reflected by the area under the curve for serum troponin I (TnI) from baseline to 72 h after surgery.
  
  
  RESULTS
  In models with 2 independent variables and in the multivariate analysis, age and aortic cross-clamp time impacted on TnI release. Subgroup analyses confirmed RIC-induced protection in all age tertiles. There was no protection with an aortic cross-clamp time ≤56 min (RIC/control = 1.026 not significant), but there was protection with 57-75 min (RIC/control = 0.757; p = 0.0348) and ≥76 min (RIC/control = 0.735; p = 0.0277). Gender, β-blockers, statins, angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) and intraoperative nitroglycerine did not impact on TnI release.
  
  
  CONCLUSIONS
  Age, gender, β-blockers, statins, ACE inhibitors, ARBs and intraoperative nitroglycerine have no significant impact on RIC-induced cardioprotection during CABG. However, greater myocardial ischemia/reperfusion injury at longer cross-clamp time facilitates the detection of protection by RIC.
authors.affiliation: Institute for Pathophysiology, West German Heart and Vascular Center Essen, University Hospital Essen, Essen, Germany.
authors.forename: Petra
authors.initials: P
authors.lastname: Kleinbongard
authors.forename: Markus
authors.initials: M
authors.lastname: Neuhäuser
authors.forename: Matthias
authors.initials: M
authors.lastname: Thielmann
authors.forename: Eva
authors.initials: E
authors.lastname: Kottenberg
authors.forename: Jürgen
authors.initials: J
authors.lastname: Peters
authors.forename: Heinz
authors.initials: H
authors.lastname: Jakob
authors.forename: Gerd
authors.initials: G
authors.lastname: Heusch
mesh_terms: D000328:Adult; D000368:Aged; D015986:Confounding Factors, Epidemiologic; D001026:Coronary Artery Bypass; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D005996:Nitroglycerin / Q000008:administration & dosage; D012189:Retrospective Studies; D019210:Troponin I / Q000097:blood*; D014665:Vasodilator Agents / Q000008:administration & dosage
chemical_list: D019210:Troponin I; D014665:Vasodilator Agents; D005996:Nitroglycerin