title: Clinical and prognostic role of pressure-volume relationship in the identification of responders to cardiac resynchronization therapy.
abstract: BACKGROUND
  The identification of responders remains challenging in cardiac resynchronization therapy (CRT). Pressure-volume relationship (PVR) is a method to evaluate left ventricular myocardial contractility during stress. The aim of the study was to assess the role of PVR to identify responders to CRT.
  
  
  METHODS
  Seventy-two patients (57% with ischemic etiology) referred to CRT: ejection fraction ≤ 35%, New York Heart Association ≥ III and QRS duration ≥ 120 milliseconds, underwent dobutamine stress echocardiography (up to 40 μg/kg per minute). PVR was defined as systolic cuff pressure/end-systolic volume index difference between rest-peak dobutamine stress echocardiography. Responders were identified by clinical and/or echocardiographic (end-systolic volume decrease ≥ 15%) follow-up criteria. We divided retrospectively the patient population into 2 groups, accordingly to the presence of myocardial contractile reserve that was set at the value of PVR (0.72 mm Hg/mL per square meter) obtained by a receiver operating characteristic analysis.
  
  
  RESULTS
  During a median follow-up of 12 months, 8 patients (11%) died. Patients with lower PVR, showed higher brain natriuretic peptide levels (853 ± 1211 vs 342 ± 239, P = .044) larger left ventricular end-diastolic (196 ± 82 mL vs 152 ± 39 mL, P = .005) and end-systolic (147 ± 66 vs 112 ± 30 mL, P = .006) volumes. Intraventricular dyssynchrony was similar in the 2 groups (88 ± 45 vs 70 ± 32 milliseconds, P = .175). Patients with higher PVR presented a larger incidence of clinical (86% vs 46% P < .001), and echocardiographic responders to CRT (79% vs 40%, P = .002). Event-free survival was significantly better in patients with higher PVR (log rank = 5.78, P = .01).
  
  
  CONCLUSIONS
  Patients with preserved contractility, assessed by PVR during stress echocardiography show a favor clinical outcome and left ventricular reverse remodeling after CRT. In particular, PVR may have a significant clinical role in patients undergoing CRT, providing critical information for risk stratification.
authors.affiliation: Division of Cardiology, Fatebenefratelli Hospital, Benevento, Italy. qciampi@iol.it
authors.forename: Quirino
authors.initials: Q
authors.lastname: Ciampi
authors.forename: Lorenza
authors.initials: L
authors.lastname: Pratali
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Citro
authors.forename: Bruno
authors.initials: B
authors.lastname: Villari
authors.forename: Eugenio
authors.initials: E
authors.lastname: Picano
authors.forename: Rosa
authors.initials: R
authors.lastname: Sicari
mesh_terms: D000368:Aged; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D002306:Cardiac Volume / Q000502:physiology*; D025401:Echocardiography, Stress; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D009200:Myocardial Contraction; D011379:Prognosis; D011446:Prospective Studies; D012372:ROC Curve; D016896:Treatment Outcome; D017725:Ventricular Pressure / Q000502:physiology*; D020257:Ventricular Remodeling / Q000502:physiology*