Left ventricular pacing in patients with heart failure: evaluation study with Fourier analysis of radionuclide ventriculography

BACKGROUND: In order to correct the activation, contraction, and relaxation asynchronism, multisite biventricular stimulation has been proposed as a non-pharmacological alternative for the treatment of patients with congestive heart failure (CHF) NYHA class II-III-IV, resistant to maximal drug therapy and with a QRS duration > 120 ms. Fourier analysis appears a feasible technique for the quantitative and non-invasive evaluation of the inter- and intraventricular conduction delays. The aim of our study was to evaluate the usefulness of Fourier analysis when estimating the electromechanical resynchronization in CHF biventricular paced patients and to follow up these patients. METHODS: Forty-five male patients (mean age 64 +/- 5 years) with severe drug-refractory CHF, were submitted to radionuclide ventriculography 14 +/- 7 days, 24 and 36 months after the implantation of a biventricular pacemaker, in order to assess left ventricular ejection fraction using Fourier analysis of the right and left ventricular phase images. Each patient was examined during spontaneous sinus rhythm, P-synchronous right ventricle and P-synchronous biventricular pacing. RESULTS: Fourteen days after biventricular pacemaker implantation, QRS duration decreased from 170 +/- 25 to 147 +/- 25 ms (p < 0.01), left ventricular ejection fraction increased from 24 +/- 6 to 31 +/- 9% (p < 0.005), while standard deviation of the left ventricular phase decreased from 53 +/- 6 to 35 +/- 9 degrees (p < 0.0005). Similar results were obtained at 24 and 36 months. CONCLUSIONS: Biventricular pacing appears to be associated with shortening of QRS duration and an improvement in NYHA class and left ventricular ejection fraction in CHF patients with inter- and intraventricular conduction delays as assessed at Fourier analysis radionuclide ventriculography