Abstract 14439: Cardiac 123-Iodine Meta-Iodobenzylguanidine Imaging to Predict Response to Cardiac Resynchronization Therapy
Background: Although reduced myocardial uptake of 123-iodine meta-iodobenzylguanidine (123I-mIBG) is associated with poor outcomes in heart failure (HF) patients, it is unclear if it predicts response to cardiac resynchronization therapy (CRT). This study evaluated the usefulness of baseline myocardial 123I-mIBG parameters to predict CRT response at 6 months.
Methods and Results: A total of 94 consecutive HF patients referred for CRT were included. All patients underwent cardiac 123I-mIBG imaging prior to CRT. Planar imaging was performed to assess heart-to-mediastinum (H/M) ratios and washout rates, while SPECT imaging was performed to obtain summed 123I-mIBG SPECT defect scores. Detailed echocardiographic evaluation was performed at baseline, including the assessment of left ventricular (LV) volumes and LV dyssynchrony. At 6 months, echocardiographic evaluation was repeated and CRT response was defined as a reduction of ≥15% in LV end-systolic volume. Fifty-six (60%) patients showed CRT response, while 38 (40%) patients were non-responders. Responders were less likely to have ischemic etiology (61% vs. 87%, p=0.006) but more extensive LV dyssynchrony (74±43 ms vs. 54±41 ms, p=0.03). On 123I-mIBG imaging, CRT responders had higher early (1.59±0.21 vs. 1.48±0.18, p=0.009) and late H/M ratio (1.48±0.20 vs. 1.33±0.16, p<0.001), lower washout rate (6.6±5.5% vs. 10.0±6.6%, p=0.008) and lower early summed SPECT defect score (20.4±8.9 vs. 25.6±9.9, p=0.01). Multiple logistic regression analysis showed that baseline late H/M ratio was the only independent predictor of CRT response (per 0.1 unit increase, OR=1.49, p=0.013).
Conclusions: Baseline late H/M ratio on 123I-mIBG planar imaging predicts CRT response in HF patients.
- © 2010 by American Heart Association, Inc.