Simultaneous assessment of myocardial perfusion and adrenergic innervation in patients with heart failure by low-dose dual-isotope CZT SPECT imaging

BACKGROUND

In patients with heart failure (HF) sequential imaging studies have demonstrated a relationship between myocardial perfusion and adrenergic innervation. We evaluated the feasibility of a simultaneous low-dose dual-isotope 123I/99mTc-acquisition protocol using a cadmium-zinc-telluride (CZT) single-photon emission computed tomography (SPECT) camera.

METHODS AND RESULTS

Thirty-six patients with HF underwent simultaneous low-dose 123I-metaiodobenzylguanidine (MIBG)/99mTc-sestamibi gated CZT-SPECT cardiac imaging. Perfusion and innervation total defect sizes and perfusion/innervation mismatch size (defined by 123I-MIBG defect size minus 99mTc-sestamibi defect size) were expressed as percentages of the total left ventricular (LV) surface area. LV ejection fraction (EF) significantly correlated with perfusion defect size (P < .005), innervation defect size (P < .005), and early (P < .05) and late (P < .01) 123I-MIBG heart-to-mediastinum (H/M) ratio. In addition, late H/M ratio was independently associated with reduced LVEF (P < .05). Although there was a significant relationship (P < .001) between perfusion and innervation defect size, innervation defect size was larger than perfusion defect size (P < .001). At multivariable linear regression analysis, 123I-MIBG washout rate (WR) correlated with perfusion/innervation mismatch (P < .05).

CONCLUSIONS

In patients with HF, a simultaneous low-dose dual-isotope 123I/99mTc-acquisition protocol is feasible and could have important clinical implications.

Prediction of appropriate ICD therapy in patients with ischemic heart failure

BACKGROUND

Previous studies show inconsistent results on the role of innervation imaging (with I-123-mIBG) and perfusion imaging in predicting appropriate ICD therapy (aICDth). These studies included patients with both dilated and ischemic cardiomyopathy. This study compared the ability of 123I-mIBG imaging along with perfusion imaging (using thallium-199) to predict aICDth in patients with ischemic heart failure (IHF) in relation to indication for ICD implantation (primary vs. secondary prevention of sudden cardiac death (SCD)).

METHODS

mIBG/thallium SPECT imaging were performed before ICD implantation in 80 patients with IHF: 49 candidates for primary and 31 for secondary SCD prevention.

RESULTS

During a mean follow-up of 18 months, the imaging results could not predict patients with appropriate ICD therapy among patients with ICD implants for primary SCD prevention. While in the secondary SCD prevention group, those who received a ICDth had significantly larger summed scores of regional perfusion and innervation impairment, but not higher heart-to-mediastinal mIBG ratio. The best results to predict aICDth were using mIBG summed score (cut-off point > 34%, sensitivity 72%, specificity 100%, AUC 0.909, P < 0.0001).

CONCLUSION

The prognostic value of innervation and perfusion imaging in patients with IHF differ based on indication for ICD implantation (primary vs. secondary prevention of SCD).