Evaluation of baseline contractile reserve vs dyssynchrony as a predictor of functional improvement and long term outcome after resynchronization pacing therapy: a radionuclide stress study

J Nucl Cardiol. 2012 Feb;19(1):53-62. doi: 10.1007/s12350-011-9421-9. Epub 2011 Jul 20.

Abstract

Aim: To assess the predictive value of baseline ventricular dyssynchrony and myocardial contractile reserve (mCR) in identifying responders to cardiac resynchronization therapy (CRT).

Methods: We prospectively studied 57 patients selected for CRT according to current recommendations. Regional dyssynchrony was evaluated by parametric phase imaging of ecg-gated equilibrium radionuclide angiography (ERNA). The mean inter-ventricular phase delay and the standard deviation to mean left ventricular (LV) phase angle were used as a measure of inter- and intra-ventricular dyssynchrony, respectively. Change in LV ejection fraction (LVEF) during low-dose dobutamine (LDD) was measured to assess mCR. ERNA was repeated at 6 months to evaluate changes in LVEF after CRT. Combined end-points of re-hospitalization for heart failure, heart transplantation, and cardiac death were assessed over a period of 76 months (mean 43 ± 31).

Results: Baseline dyssynchrony was present in most patients (85%). After CRT only one half of patients showed a reduction in intra-ventricular dyssynchrony and 33% an increase in LVEF by >5%. Improvement of LVEF was not predicted by baseline LVEF, clinical presentation, dyssynchrony parameters or QRS duration. There was a significant relationship between changes in LVEF during LDD testing and after CRT (r = 0.65; P < .0001). Logistic regression analysis identified mCR as independent predictor of improvement in LVEF (P = .039; OR = 3.84; CI 95% = 1.06-13.9), resynchronization (P = .046; OR = 4.20; CI 95% = 1.03-17.2), and event-free survival (P = .002; OR = 0.10; CI 95% = 0.02-0.43).

Conclusions: In patients with left ventricular dysfunction and baseline dyssynchrony as assessed by ERNA, evaluation of mCR during LDD may help predicting functional improvement and selecting potential responders to CRT.

MeSH terms

  • Cardiac Resynchronization Therapy*
  • Cardiac-Gated Single-Photon Emission Computer-Assisted Tomography*
  • Exercise Test
  • Female
  • Fractional Flow Reserve, Myocardial*
  • Heart Failure / complications
  • Heart Failure / diagnostic imaging*
  • Heart Failure / prevention & control*
  • Humans
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Prognosis
  • Treatment Outcome
  • Ventricular Dysfunction, Left / diagnostic imaging*
  • Ventricular Dysfunction, Left / etiology
  • Ventricular Dysfunction, Left / prevention & control*