Quantitative assessment of cardiac mechanical dyssynchrony and prediction of response to cardiac resynchronization therapy in patients with non-ischaemic dilated cardiomyopathy using equilibrium radionuclide angiography.

<bold>Aims: </bold>The aim of this study was to evaluate equilibrium radionuclide angiography (ERNA) in prediction of response to cardiac resynchronization therapy (CRT) in non-ischaemic dilated cardiomyopathy (DCM) patients.<bold>Methods and Results: </bold>Thirty-two patients (23 males, 57.5 ± 12.1 years) were prospectively included. Equilibrium radionuclide angiography and clinical evaluation were performed before and 3 months after CRT implantation. Standard deviation of left ventricle mean phase angle (SD LVmPA) and difference between LV and right ventricle mPA (LV-RVmPA) expressed in degrees (°) were used to quantify left intraventricular synchrony and interventricular synchrony, respectively. Left ventricular ejection fraction (LVEF) was also evaluated. At the baseline, mean NYHA class was 3.3 ± 0.5, LVEF 22.5 ± 5.6%, mean QRS duration 150.3 ± 18.2 ms, SD LVmPA 43.5 ± 18°, and LV-RVmPA 30.4 ± 15.6°. At 3-month follow-up, 22 patients responded to CRT with improvement in NYHA class ≥1 and EF >5%. Responders had significantly larger SD LVmPA (51.2 ± 13.9 vs. 26.5 ± 14°) and LV-RVmPA (35.8 ± 13.7 vs. 18.4 ± 13°) than non-responders. Receiver-operating characteristic curve analysis demonstrated 95% sensitivity and 80% specificity at a cut-off value of 30° for SD LVmPA, and 81% sensitivity and 80% specificity at a cut-off value of 23° for LV-RVmPA in prediction of response to CRT.<bold>Conclusion: </bold>Baseline SD LVmPA and LV-RVmPA derived from ERNA are useful for prediction of response to CRT in non-ischaemic DCM patients. [ABSTRACT FROM AUTHOR]