Efficacy of equilibrium radionuclide angiography to predict acute response to cardiac resynchronization therapy in patients with heart failure

Equilibrium radionuclide angiography compared with tissue doppler imaging for detection of right ventricular dyssynchrony and prediction of acute response to cardiac resynchronization therapy

OBJECTIVE

The aim of this study was to compare tissue doppler imaging (TDI) and equilibrium radionuclide angiography (ERNA) for detection of right ventricular (RV) dyssynchrony and prediction of the acute response to cardiac resynchronization therapy (CRT).

METHODS

This study was approved by the local ethics committee of Huai'an First People's Hospital. Patient consent was not provided due to the use of completely anonymous images from which the individual could not be identified in this study. Thirty-three patients with nonischemic dilated cardiomyopathy underwent both TDI and ERNA before and within 48 hour after CRT implantation. RV dyssynchrony was measured with TDI using the difference in time to peak systolic velocity between the RV free wall and ventricular septum (RV-T). With ERNA, the standard of RV mean phase angle and RV phase standard deviation (RVmPA% and RVPSD%) were assessed.

RESULTS

Moderate positive correlations were observed among baseline RVmPA%, RVPSD% and RV-T (r = 0.689 and 0.716, P < .001). Twenty patients (61%) with a reduction of at least 15% in LV end-systolic volume were categorized as acute responders after CRT. Responders showed significant reduction in RVmPA% and RVPSD% after CRT (53.60 ± 4.15% to 43.95 ± 6.88% and 14.00 ± 2.41% to 10.40 ± 1.67%, P < .05), whereas RV-T remained unchanged (50.10 ± 10.28 ms to 49.25 ± 13.64ms, NS). Receiver operating characteristic curve showed that the cut-off value of RV-T was 48.5ms, yielding 65% sensitivity and 77% specificity to predict acute respond to CRT. The cut-off value of RVmPA% was 49.5%, yielding 85% sensitivity and 85% specificity and the cut-off value of RVPSD% was 11.5%, yielding 85% sensitivity and 92% specificity.

CONCLUSION

ERNA might be an appropriate alternative to TDI for assessment of RV dyssynchrony. Either RVmPA% or RVPSD% was highly predictive for acute response to CRT.

Automated Classification of Severity in Cardiac Dyssynchrony Merging Clinical Data and Mechanical Descriptors

Cardiac resynchronization therapy (CRT) improves functional classification among patients with left ventricle malfunction and ventricular electric conduction disorders. However, a high percentage of subjects under CRT (20%–30%) do not show any improvement. Nonetheless the presence of mechanical contraction dyssynchrony in ventricles has been proposed as an indicator of CRT response. This work proposes an automated classification model of severity in ventricular contraction dyssynchrony. The model includes clinical data such as left ventricular ejection fraction (LVEF), QRS and P-R intervals, and the 3 most significant factors extracted from the factor analysis of dynamic structures applied to a set of equilibrium radionuclide angiography images representing the mechanical behavior of cardiac contraction. A control group of 33 normal volunteers (28 ± 5 years, LVEF of 59.7% ± 5.8%) and a HF group of 42 subjects (53.12 ± 15.05 years, LVEF < 35%) were studied. The proposed classifiers had hit rates of 90%, 50%, and 80% to distinguish between absent, mild, and moderate-severe interventricular dyssynchrony, respectively. For intraventricular dyssynchrony, hit rates of 100%, 50%, and 90% were observed distinguishing between absent, mild, and moderate-severe, respectively. These results seem promising in using this automated method for clinical follow-up of patients undergoing CRT.