Early therapeutic effects of adaptive servo-ventilation on cardiac sympathetic nervous function in patients with heart failure evaluated using a combination of 11C-HED PET and 123I-MIBG SPECT

123I-MIBG imaging in heart failure: impact of comorbidities on cardiac sympathetic innervation

PURPOSE

Heart failure (HF) is a primary cause of morbidity and mortality worldwide, with significant impact on life quality and extensive healthcare costs. Assessment of myocardial sympathetic innervation function plays a central role in prognosis assessment in HF patients. The aim of this review is to summarize the most recent evidence regarding the clinical applications of iodine-123 metaiodobenzylguanidine (¹²³I-MIBG) imaging in patients with HF and related comorbidities.

METHODS

A comprehensive literature search was conducted on PubMed and Web of Science databases. Articles describing the impact of ¹²³I-MIBG imaging on HF and related comorbidities were considered eligible for the review.

RESULTS

We collected several data reporting that ¹²³I-MIBG imaging is a safe and non-invasive tool to evaluate dysfunction of cardiac sympathetic neuronal function and to assess risk stratification in HF patients. HF is frequently associated with comorbidities that may affect cardiac adrenergic innervation. Furthermore, HF is frequently associated with comorbidities and chronic conditions, such as diabetes, obesity, kidney disease and others, that may affect cardiac adrenergic innervation.

CONCLUSION

Comorbidities and chronic conditions lead to more severe impairment of sympathetic nervous system in patients with HF, with a negative impact on disease progression and outcome. Cardiac imaging with ¹²³I-MIBG can be a useful tool to reduce morbidity and prevent adverse events in HF patients.

The prognostic value of 123I-mIBG SPECT cardiac imaging in heart failure patients: a systematic review

This systematic review aimed to evaluate the prognostic value of Iodine123 Metaiodobenzylguanidine (123I-mIBG) SPECT myocardial imaging in patients with heart failure (HF) and to assess whether semi-quantitative SPECT scores can be useful for accurate risk stratification concerning arrhythmic event (AE) and sudden cardiac death (SCD) in this cohort. A systematic literature search of studies published until November 2020 regarding the application of 123I-mIBG SPECT in HF patients was performed, in Pubmed, Scopus, Medline, Central (Cochrane Library) and Web Of Science databases, including the words "MIBG", "metaiodobenzylguanidine", "heart", "spect", and "tomographic". The included studies had to correlate 123I-mIBG SPECT scores with endpoints such as overall survival and prevention of AE and SCD in HF patients. According to the sixteen studies included, the analysis showed that 123I-mIBG SPECT scores, such as summed defect score (SDS), regional wash-out (rWO), and regional myocardial tracer uptake, could have a reliable prognostic value in patients with HF. An increased SDS or rWO, as well as a reduced 123I-mIBG myocardial uptake, have proven to be effective in predicting AE- and SCD-specific risk in HF patients. Despite achieved results being promising, a more reproducible standardized method for semi-quantitative analysis and further studies with larger cohort are needed for 123I-mIBG SPECT myocardial imaging to be as reliable and, thus, accepted as the conventional 123I-mIBG planar myocardial imaging.

Adaptive Servo-ventilation Therapy Results in the Prevention of Arrhythmias in Patients with Heart Failure Due to Ischemic Heart Disease

Objective Whether or not adaptive servo-ventilation (ASV) is effective in preventing arrhythmias in patients with heart failure (HF) due to ischemic heart disease (IHD) is unclear. This study estimated the effects of ASV therapy on arrhythmias in patients with HF due to IHD. Methods One hundred and forty-one consecutive hospitalized patients with HF due to IHD (mean age: 74.9±11.9 years old) were retrospectively assessed in this study. Of the 141 patients, 75 were treated with ASV (ASV group), and 66 were treated without ASV (Non-ASV group). We estimated the incidence of arrhythmias, including paroxysmal atrial fibrillation (PAF) and ventricular tachycardia (VT), during one-year follow-up in both groups using multivariable logistic regression models. Results Men accounted for 55.3% of the study population. There were no significant differences in the baseline clinical characteristic data between the ASV and Non-ASV groups with respect to age, sex, heart rate, risk factors, oral medication, or laboratory data, including the estimated glomerular filtration rate (eGFR), brain natriuretic peptide, and left ventricular ejection fraction. ASV therapy was associated with a reduced incidence of arrhythmia after adjusting for demographic and cardiovascular disease risk factors (odds ratio, 0.27; 95% confidence interval, 0.11 to 0.63; p<0.01; compared to the Non-ASV group). In addition, at the 1-year follow-up, an improvement (increase) in the eGFR was found in the ASV group but not in the Non-ASV group. Conclusion ASV therapy was able to prevent arrhythmias, including PAF and VT, with short-term improvements in the renal function in patients with HF due to IHD.

Recent advances in radiotracers targeting norepinephrine transporter: structural development and radiolabeling improvements

The norepinephrine transporter (NET) is a major target for the evaluation of the cardiac sympathetic nerve system in patients with heart failure and Parkinson's disease. It is also used in the therapeutic applications against certain types of neuroendocrine tumors, as exemplified by the clinically used ^123/131I-MIBG as theranostic single-photon emission computed tomography (SPECT) agent. With the development of more advanced positron emission tomography (PET) technology, more radiotracers targeting NET have been reported, with superior temporal and spatial resolutions, along with the possibility of functional and kinetic analysis. More recently, fluorine-18-labelled NET tracers have drawn increasing attentions from researchers, due to their longer radiological half-life relative to carbon-11 (110 min vs. 20 min), reduced dependence on on-site cyclotrons, and flexibility in the design of novel tracer structures. In the heart, certain NET tracers provide integral diagnostic information on sympathetic innervation and the nerve status. In the central nervous system, such radiotracers can reveal NET distribution and density in pathological conditions. Most radiotracers targeting cardiac NET-function for the cardiac application consistent of derivatives of either norepinephrine or MIBG with its benzylguanidine core structure, e.g. ¹¹C-HED and ¹⁸F-LMI1195. In contrast, all NET tracers used in central nervous system applications are derived from clinically used antidepressants. Lastly, possible applications of NET as selective tracers over organic cation transporters (OCTs) in the kidneys and other organs controlled by sympathetic nervous system will also be discussed.

How do we establish cardiac sympathetic nervous system imaging with 123I-mIBG in clinical practice? Perspectives and lessons from Japan and the US

Cardiac denervation is associated with progressive left ventricular (LV) dysfunction, ventricular arrhythmias, and sudden cardiac death (SCD) in heart failure (HF). In this regard, it is important to evaluate cardiac-specific sympathetic nervous system (SNS) function. The radiotracer Iodine-123 meta-iodobenzylguanidine (123I-mIBG) can noninvasively evaluate pre-synaptic SNS function. Recent multicenter trials have shown 123I-mIBG to have strong predictive value for fatal arrhythmias and cardiac death in HF. 123I-mIBG was initially developed in the USA in the 1970s. In 1992, the Japanese Ministry of Health and Labour approved 123I-mIBG for the assessment of cardiac function. Following approval, the Japanese nuclear cardiology community developed 123I-mIBG imaging services in various medical centers. Japanese groups have been trying to establish the clinical utility of 123I-mIBG and standardize parameters for data acquisition and image analysis. The US Food and Drug Administration (FDA) has approved clinical use of 123I-mIBG for cardiac and non-cardiac imaging. However, clinical use of 123I-mIBG in the US has been very limited. The number of 123I-mIBG studies in Japan has also been limited. There are similarities and differences between the two countries. To establish the clinical utility of 123I-mIBG in both countries, it is important to characterize the situations of 123I-mIBG in each.