Use of left ventricular pacing in heart failure: Evaluation by gated bloodpool imaging

Background Left ventricular (LV) pacing has been suggested to complement ot her forms of therapy in patients with heart failure. Methods and Results. We investigated 17 patients (15 men, 2 women, aged 68 +/- 6 years, 10 ischemic and 7 primary dilated cardiomyopathy) with heart f ailure (13 were in New York Heart Association class IV and 4 in class III). One month after LV pacer implantation, 12 patients reported clinical impro vement (mean class 3.7 before pacing vs 2.6 with LV pacing; P = .001). We r eport the results of 3 equilibrium-gated blood pool studies performed in ea ch patient, 1 before pacing and 2 after pacer implantation (1 with pacing o n, and 1 after turning off the pacer). LV pacing did not modify LV ejection fraction. Phase analysis demonstrated a significant decrease of the interv entricular phase shift (Delta pi) with LV pacing (no pacing, Delta pi = 8.9 9 degrees +/- 19.05 degrees; Delta pi = -0.97 degrees +/- 27.85 degrees wit h LV pacing). Clinical improvement was observed in patients with an initial positive Delta pi that decreased with pacing and/or an initial LV phase st andard deviation >50 degrees that decreased with pacing. Conclusion. LV pacing induces interventricular and intraventricular synchro nization. A decrease of the interventricular phase shift seems to be the mo st important predictor of functional recovery for paced patients with heart failure.