title: Mechanism of decreased sensitivity of dobutamine associated left ventricular wall motion analyses for appreciating inducible ischemia in older adults.
abstract: BACKGROUND
  Dobutamine associated left ventricular (LV) wall motion analyses exhibit reduced sensitivity for detecting inducible ischemia in individuals with increased LV wall thickness. This study was performed to better understand the mechanism of this reduced sensitivity in the elderly who often manifest increased LV wall thickness and risk factors for coronary artery disease.
  
  
  METHODS
  During dobutamine cardiovascular magnetic resonance (DCMR) stress testing, we assessed rate pressure product (RPP), aortic pulse wave velocity (PWV), LV myocardial oxygen demand (pressure volume area, PVA, mass, volumes, concentricity, and the presence of wall motion abnormalities (WMA) and first pass gadolinium enhanced perfusion defects (PDs) indicative of ischemia in 278 consecutively recruited individuals aged 69 ± 8 years with pre-existing or known risk factors for coronary artery disease. Each variable was assessed independently by personnel blinded to participant identifiers and analyses of other DCMR or hemodynamic variables.
  
  
  RESULTS
  Participants were 80% white, 90% hypertensive, 43% diabetic and 55% men. With dobutamine, 60% of the participants who exhibited PDs had no inducible WMA. Among these participants, myocardial oxygen demand was lower than that observed in those who had both wall motion and perfusion abnormalities suggestive of ischemia (p = 0.03). Relative to those with PDs and inducible WMAs, myocardial oxygen demand remained different in these individuals with PDs without an inducible WMA after accounting for LV afterload and contractility (p = 0.02 and 0.03 respectively), but not after accounting for either LV stress related end diastolic volume index (LV preload) or resting concentricity (p = 0.31-0.71).
  
  
  CONCLUSIONS
  During dobutamine stress testing, elderly patients experience increased LV concentricity and declines in LV preload and myocardial oxygen demand, all of which are associated with an absence of inducible LV WMAs indicative of myocardial ischemia. These findings provide insight as to why dobutamine associated wall motion analyses exhibit reduced sensitivity for identifying inducible ischemia in elderly.
  
  
  BACKGROUND
  This study was registered with Clinicaltrials.gov (NCT00542503).
authors.affiliation: Department of Internal medicine, Section on Cardiology, Wake Forest School of Medicine, Winston Salem, North Carolina, 27157, USA. svasu@wakehealth.edu.
authors.forename: Sujethra
authors.initials: S
authors.lastname: Vasu
authors.affiliation: Department of Internal Medicine, University of Mississippi, Jackson, Mississippi, 39216, USA. wlittle@wakehealth.edu.
authors.forename: William C
authors.initials: WC
authors.lastname: Little
authors.affiliation: Department of Biostatistical sciences, Wake Forest School of Medicine, Winston Salem North Carolina, 27157, USA. tomorgan@wakehealth.edu.
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Morgan
authors.affiliation: Department of Internal medicine, Section on Cardiology, Wake Forest School of Medicine, Winston Salem, North Carolina, 27157, USA. bstacey@wakehealth.edu.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Stacey
authors.affiliation: Mid Carolina Cardiology, Charlotte North Carolina, 28204, USA. wntim@novanthealth.org.
authors.forename: William O
authors.initials: WO
authors.lastname: Ntim
authors.affiliation: Department of Biomedical Engineering, Wake Forest School of Medicine, Winston Salem, North Carolina, 27157, USA. crhamilt@wakehealth.edu.
authors.forename: Craig
authors.initials: C
authors.lastname: Hamilton
authors.affiliation: Aurora Cardiovascular Services, Milwaukee, Wisconsin, 53215, USA. vinay.thohan@aurora.org.
authors.forename: Vinay
authors.initials: V
authors.lastname: Thohan
authors.affiliation: Department of Radiology, Wake Forest School of Medicine, Winston Salem, North Carolina, 27157, USA. cchiles@wakehealth.edu.
authors.forename: Caroline
authors.initials: C
authors.lastname: Chiles
authors.affiliation: Department of Internal medicine, Section on Cardiology, Wake Forest School of Medicine, Winston Salem, North Carolina, 27157, USA. ghundley@wakehealth.edu.|Department of Radiology, Wake Forest School of Medicine, Winston Salem, North Carolina, 27157, USA. ghundley@wakehealth.edu.
authors.forename: William Gregory
authors.initials: WG
authors.lastname: Hundley
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002316:Cardiotonic Agents / Q000008:administration & dosage*; D003287:Contrast Media / Q000008:administration & dosage; D003326:Coronary Circulation; D004280:Dobutamine / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D017202:Myocardial Ischemia / Q000175:diagnosis* / Q000503:physiopathology; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D009657:North Carolina; D010101:Oxygen Consumption; D011237:Predictive Value of Tests; D063177:Pulse Wave Analysis; D015203:Reproducibility of Results; D012307:Risk Factors; D016277:Ventricular Function, Left; D020257:Ventricular Remodeling
chemical_list: D002316:Cardiotonic Agents; D003287:Contrast Media; D004280:Dobutamine