title: Relationship between left ventricular stimulation characteristics at implantation and echocardiographic response after 6 months of cardiac resynchronization therapy.
abstract: OBJECTIVE
  Although the electrical stimulation of an ischaemic tissue adversely affects the left ventricular (LV) systolic function, the optimal stimulation site in patients with non-ischaemic cardiomyopathy has not been systematically studied. We hypothesized that the local stimulation characteristics at the time of device implantation predict the response to cardiac resynchronization therapy (CRT).
  
  
  RESULTS
  We measured the impedance, sensing, and capture threshold of a bipolar LV lead in 138 patients with non-ischaemic cardiomyopathy undergoing first implantation of CRT device for drug refractory heart failure. All patients underwent echocardiography at baseline and at 6 months post-implantation. An absence of favourable response to CRT was defined as <15% decrease in echocardiographic LV end-systolic volume (LVESV) at 6 months. Echocardiographic response to CRT was observed in 70% of patients. The LV lead measurements predicted neither the optimal stimulation site nor the response to CRT. Left ventricular capture threshold (1.50 ± 1.1 vs. 1.32 ± 0.8 V) and impedance (725 ± 287 vs. 720 ± 261 Ω) were similar between the responders and the non-responders. Independent of baseline LV ejection fraction or ESV, the LV R-wave amplitude at implantation was significantly higher (P = 0.0038) in responders (12.7 ± 5.2 mV) than in non-responders (9.7 ± 6.3 mV), with an area under the receiver operating characteristic curve of 0.7.
  
  
  CONCLUSIONS
  Response to CRT, as determined by decrease in LVESV at 6 months, was associated with significantly higher LV R-wave amplitude at the time of device implantation.
authors.affiliation: Hopital Cardiologique HautLeveque, University Bordeaux 2, CHU of Bordeaux, Bordeaux-Pessac, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Deplagne
authors.forename: Sylvain
authors.initials: S
authors.lastname: Ploux
authors.forename: Philippe
authors.initials: P
authors.lastname: Ritter
authors.forename: Stephane
authors.initials: S
authors.lastname: Lafitte
authors.forename: Patricia
authors.initials: P
authors.lastname: Reant
authors.forename: Pierre
authors.initials: P
authors.lastname: Jais
authors.forename: Michel
authors.initials: M
authors.lastname: Haissaguerre
authors.forename: Jacques
authors.initials: J
authors.lastname: Clementy
authors.forename: Pierre
authors.initials: P
authors.lastname: Bordachar
mesh_terms: D000368:Aged; D058406:Cardiac Resynchronization Therapy; D058409:Cardiac Resynchronization Therapy Devices; D009202:Cardiomyopathies / Q000503:physiopathology / Q000628:therapy*; D004452:Echocardiography; D005260:Female; D005500:Follow-Up Studies; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve; D012044:Regression Analysis; D012189:Retrospective Studies; D013318:Stroke Volume / Q000502:physiology*; D013997:Time Factors; D016896:Treatment Outcome