Evaluation of Ventricular Synchrony with Equilibrium Radionuclide Angiography: Assessment of Variability and Accuracy

Background and Aims

Equilibrium radionuclide angiography (ERNA) has become an established method for assessing cardiac function. However, limited data are available to evaluate ventricular synchrony with ERNA. The aim of this study was to assess the variability and accuracy of ERNA to evaluate ventricular synchrony by means of phase images in healthy individuals and to compare them with a group of subjects with left bundle-branch block (interventricular dyssynchrony, LBBB) and with a group of patients with nonischemic, dilated cardiomyopathy (DCM) (inter- and intraventricular dyssynchrony).

Methods

The population was divided into groups as follows: group 1 included 22 healthy subjects, group 2 included 11 patients with LBBB and normal left ventricular ejection fraction (LVEF), and group 3 included 14 DCM patients with LVEF <35% and LBBB. Interventricular synchrony was measured as the difference between LV mean phase angle (mPA) and RV mPA (LV−RV mPA). Intraventricular synchrony for each ventricle was measured as the standard deviation (SD) of the RV mPA and LA mPA blood pools.

Results

Intra- and interobserver correlation coefficients were high for both inter- and intraventricular synchrony parameters. Area under the curve (AUC) was 0.98 for LV−RV mPA (p <0.001; 95% CI: 0.947–1.0). A cutoff value of 10° yielded 96% sensitivity and 99% specificity to identify interventricular dyssynchrony. AUC was high for SD RV mPA and SD LV mPA (AUC = 1.0, p <0.001; 95% CI: 1.0–1.0 and AUC = 0.99, p <0.001; 95% CI: 0.979–1.0). A cutoff value of 22° for SD LV mPA yielded 100% sensitivity and 100% specificity to identify LV intraventricular dyssynchrony. A cutoff value of 20° for SD RV mPA yielded 100% sensitivity and 99% specificity to identify RV intraventricular dyssynchrony.

Conclusions

ERNA is an accurate and highly reproducible technique for evaluation of ventricular function and synchrony.

Key Words: Equilibrium radionuclide angiography, Phase image analysis, Interventricular dyssynchrony, Intraventricular dyssynchrony, Cardiac resynchronization therapy