title: Determination of the longest intrapatient left ventricular electrical delay may predict acute hemodynamic improvement in patients after cardiac resynchronization therapy.
abstract: BACKGROUND
  One of the reasons for patient nonresponse to cardiac resynchronization therapy is a suboptimal left ventricular (LV) pacing site. LV electric delay (Q-LV interval) has been indicated as a prognostic parameter of cardiac resynchronization therapy response. This study evaluates the LV delay for the optimization of the LV pacing site.
  
  
  RESULTS
  Thirty-two consecutive patients (23 men; mean age, 71±11 years; LV ejection fraction, 30±6%; 18 with ischemic cardiomyopathy; QRS, 181±25 ms; all mean±SD) underwent cardiac resynchronization therapy device implantation. All available tributary veins of the coronary sinus were tested, and the Q-LV interval was measured at each pacing site. The hemodynamic effects of pacing at different sites were evaluated by invasive measurement of LV dP/dtmax at baseline and during pacing. Overall, 2.9±0.8 different veins and 6.4±2.3 pacing sites were tested. In 31 of 32 (96.8%) patients, the highest LV dP/dtmax coincided with the maximum Q-LV interval. Q-LV interval correlated with the increase in LV dP/dtmax in all patients at each site (AR1 ρ=0.98; P<0.001). A Q-LV value >95 ms corresponded to a >10% in LV dP/dtmax. An inverse correlation between paced QRS duration and improvement in LV dP/dtmax was seen in 24 patients (75%).
  
  
  CONCLUSIONS
  Pacing the LV at the latest activated site is highly predictive of the maximum increase in contractility, expressed as LV dP/dtmax. A positive correlation between Q-LV interval and hemodynamic improvement was found in all patients at every pacing site, a value of 95 ms corresponding to an increase in LV dP/dtmax of ≥10%.
authors.affiliation: From the Arrhythmia and Electrophysiology Unit (F.Z., E.B., G.P.), Division of Cardiology (C.F., L.R., S.A.), and Department of Internal Medicine (A.M.), Santa Maria Della Misericordia Hospital, Rovigo, Italy; Department of Molecular Medicine, of Padua, Padua, Italy (F.N.); and Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands (F.P.). franc.zanon@iol.it.
authors.forename: Francesco
authors.initials: F
authors.lastname: Zanon
authors.affiliation: From the Arrhythmia and Electrophysiology Unit (F.Z., E.B., G.P.), Division of Cardiology (C.F., L.R., S.A.), and Department of Internal Medicine (A.M.), Santa Maria Della Misericordia Hospital, Rovigo, Italy; Department of Molecular Medicine, of Padua, Padua, Italy (F.N.); and Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands (F.P.).
authors.forename: Enrico
authors.initials: E
authors.lastname: Baracca
authors.affiliation: From the Arrhythmia and Electrophysiology Unit (F.Z., E.B., G.P.), Division of Cardiology (C.F., L.R., S.A.), and Department of Internal Medicine (A.M.), Santa Maria Della Misericordia Hospital, Rovigo, Italy; Department of Molecular Medicine, of Padua, Padua, Italy (F.N.); and Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands (F.P.).
authors.forename: Gianni
authors.initials: G
authors.lastname: Pastore
authors.affiliation: From the Arrhythmia and Electrophysiology Unit (F.Z., E.B., G.P.), Division of Cardiology (C.F., L.R., S.A.), and Department of Internal Medicine (A.M.), Santa Maria Della Misericordia Hospital, Rovigo, Italy; Department of Molecular Medicine, of Padua, Padua, Italy (F.N.); and Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands (F.P.).
authors.forename: Chiara
authors.initials: C
authors.lastname: Fraccaro
authors.affiliation: From the Arrhythmia and Electrophysiology Unit (F.Z., E.B., G.P.), Division of Cardiology (C.F., L.R., S.A.), and Department of Internal Medicine (A.M.), Santa Maria Della Misericordia Hospital, Rovigo, Italy; Department of Molecular Medicine, of Padua, Padua, Italy (F.N.); and Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands (F.P.).
authors.forename: Loris
authors.initials: L
authors.lastname: Roncon
authors.affiliation: From the Arrhythmia and Electrophysiology Unit (F.Z., E.B., G.P.), Division of Cardiology (C.F., L.R., S.A.), and Department of Internal Medicine (A.M.), Santa Maria Della Misericordia Hospital, Rovigo, Italy; Department of Molecular Medicine, of Padua, Padua, Italy (F.N.); and Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands (F.P.).
authors.forename: Silvio
authors.initials: S
authors.lastname: Aggio
authors.affiliation: From the Arrhythmia and Electrophysiology Unit (F.Z., E.B., G.P.), Division of Cardiology (C.F., L.R., S.A.), and Department of Internal Medicine (A.M.), Santa Maria Della Misericordia Hospital, Rovigo, Italy; Department of Molecular Medicine, of Padua, Padua, Italy (F.N.); and Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands (F.P.).
authors.forename: Franco
authors.initials: F
authors.lastname: Noventa
authors.affiliation: From the Arrhythmia and Electrophysiology Unit (F.Z., E.B., G.P.), Division of Cardiology (C.F., L.R., S.A.), and Department of Internal Medicine (A.M.), Santa Maria Della Misericordia Hospital, Rovigo, Italy; Department of Molecular Medicine, of Padua, Padua, Italy (F.N.); and Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands (F.P.).
authors.forename: Alberto
authors.initials: A
authors.lastname: Mazza
authors.affiliation: From the Arrhythmia and Electrophysiology Unit (F.Z., E.B., G.P.), Division of Cardiology (C.F., L.R., S.A.), and Department of Internal Medicine (A.M.), Santa Maria Della Misericordia Hospital, Rovigo, Italy; Department of Molecular Medicine, of Padua, Padua, Italy (F.N.); and Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands (F.P.).
authors.forename: Frits
authors.initials: F
authors.lastname: Prinzen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D058406:Cardiac Resynchronization Therapy / Q000379:methods / Q000401:mortality; D015331:Cohort Studies; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000503:physiopathology*; D006333:Heart Failure / Q000175:diagnosis / Q000401:mortality / Q000628:therapy*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007297:Inpatients; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology; D017202:Myocardial Ischemia / Q000175:diagnosis / Q000401:mortality / Q000628:therapy; D011237:Predictive Value of Tests; D020127:Recovery of Function; D013318:Stroke Volume / Q000502:physiology; D015996:Survival Rate; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000502:physiology*
keywords: cardiac resynchronization therapy; cardiomyopathies; heart failure; hemodynamics