Is There an Incremental Prognostic Value of Evaluating Left Ventricular Dyssynchrony by Gated SPECT in Patients with Systolic Heart Failure and Altered Myocardial Sympathetic Innervation as Evaluated by Cardiac I-123 mIBG Imaging? ()
ABSTRACT
Background: Altered myocardial sympathetic innervation activity (AMSI) is
known to be present in systolic heart failure patients (SHF) and recently SPECT
imaging using I-123 mIBG heart to mediastinum (H/M) ratio <1.6 has been
shown to predict MACE in the ADMIRE-HF trial. Left ventricular mechanical
dyssynchrony (LVMD) is known to be present in a substantial number of SHF patients
and has been studied mainly to guide CRT therapy. Recently gated SPECT has
shown promise to provide an accurate assessment of LVMD. It remains unclear how
the combination of AMSI and LVMD collectively
affect clinical outcomes and other cardiovascular parameters. Objectives: The objectives are to examine the clinical
characteristics and incremental prognostic value for MACE of LVMD
determined by SPECT in SHF patients with or without abnormal cardiac MIBG uptake
(H/M ratio < 1.6). Methods: Out of 30 SHF patients who participated from our
institution in the ADMIRE-HF trial studying MIBG based AMSI, we included 22
patients with abnormal MIBG H/M ratio of <1.6. We performed gated SPECT LVMD
analysis on these patients using the Emory Cardiac Toolbox. The 2 SPECT
variables for LVMD assessed were histogram bandwidth and phase standard deviation both of which assess the extent of dispersion
of LV activation during contraction as a marker of LVMD. Patients were
followed up for a mean period of 6 years. The primary end point was mortality
from any cause and secondary end point was heart failure admission or
myocardial infarction or ICD shock. Results: 2 Groups were defined: Group A: n =
17 with H/M MIBG ratio < 1.6 and +LVMD and Group B, n = 5 H/M MIBG ratio
< 1.6 and −LVMD. Baseline characteristics, cardiac risk factors and
medications were comparable between both groups. LVEF was lower and RBBB was less common in Group A. There was no
statistical difference in achievement of primary or secondary end points
in the two groups including death heart failure readmissions, ICD shocks or MI.
Conclusions: In our pilot study, we did not find definitive value of adding
SPECT based LVMD to abnormal cardiac MIBG
imaging in SHF patients with regards to predicting outcomes. Although
our sample size is too small to make any definitive conclusions, it is possible
that LVMD works independently through different pathways in the progression of
SHF and hence may not necessarily add incremental value to AMSI determination
using MIBG.
Share and Cite:
Mohammed, A. , Jacobsen, G. and Ananthasubramaniam, K. (2016) Is There an Incremental Prognostic Value of Evaluating Left Ventricular Dyssynchrony by Gated SPECT in Patients with Systolic Heart Failure and Altered Myocardial Sympathetic Innervation as Evaluated by Cardiac I-123 mIBG Imaging?.
World Journal of Nuclear Science and Technology,
6, 161-169. doi:
10.4236/wjnst.2016.63018.
Cited by
No relevant information.