title: LV Dyssynchrony Assessed With Phase Analysis on Gated Myocardial Perfusion SPECT Can Predict Response to CRT in Patients With End-Stage Heart Failure.
abstract: BACKGROUND
  Cardiac resynchronization therapy (CRT) is an established treatment in patients with end-stage heart failure and wide QRS complex. However, about 30% of patients do not benefit from CRT (non-responder). Recent studies with tissue Doppler imaging yielded disappointing results in predicting CRT responders. Phase analysis was developed to allow assessment of LV dyssynchrony by gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (GMPS).
  
  
  OBJECTIVE
  The aim of present study was to investigate the role of quantitative GMPS-derived LV dyssynchrony data to predict CRT responder.
  
  
  METHODS
  Thirty eligible patients for CRT implantation underwent GMPS and echocardiography. Response to CRT was evaluated six months after the device implantation. Clinical response to CRT was defined as 50 meters increase in 6-minute walking test (6-MWT) distance. Echocardiographic response to CRT was defined as ≥ 15% decrease in left ventricular end-systolic volume (LVESV). The lead position was considered concordant if it was positioned at the area of latest mechanical activation, and discordant if located outside the area of latest mechanical activation.
  
  
  RESULTS
  Clinical response to CRT was observed in 74% of patients. However, only 57% of patients were responder according to the echo criteria. There were statistically significant differences between CRT responders and non-responders for GMPS-derived variables, including phased histogram bandwidth (PHB), phase SD (PSD), and Entropy. Moreover, a cutoff value of 112° for PHB with a sensitivity of 72% and specificity of 70%, a cutoff value of 21° for PSD with a sensitivity of 90% and specificity of 74%, and a cutoff of 52% for Entropy with a sensitivity of 90% and a specificity of 80% were considered to discriminate responders and non-responders. CRT response was more likely in patients with concordant LV lead position compared to those with discordant LV lead position.
  
  
  CONCLUSIONS
  GMPS-derived LV dyssynchrony variables can predict response to CRT with good sensitivity and specificity.
authors.affiliation: Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Nasrin
authors.initials: N
authors.lastname: Azizian
authors.affiliation: Department of Nuclear Medicine and Molecular Imaging, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Fereydoon
authors.initials: F
authors.lastname: Rastgou
authors.affiliation: Department of Nuclear Medicine and Molecular Imaging, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Tahereh
authors.initials: T
authors.lastname: Ghaedian
authors.affiliation: Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Allahyar
authors.initials: A
authors.lastname: Golabchi
authors.affiliation: Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Behdad
authors.initials: B
authors.lastname: Bahadorian
authors.affiliation: Department of Nuclear Medicine and Molecular Imaging, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Vida
authors.initials: V
authors.lastname: Khanlarzadeh
authors.affiliation: Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Azizian
authors.affiliation: Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Majid
authors.initials: M
authors.lastname: Haghjoo
keywords: Cardiac Resynchronization Therapy; Heart Failure; gated single photon emission computed tomography; left ventricular dyssynchrony