Prediction of appropriate ICD therapy in patients with ischemic heart failure

Predicting postinfarct ventricular tachycardia by integrating cardiac MRI and advanced computational reentrant pathway analysis

BACKGROUND

Implantable cardiac defibrillator (ICD) implantation can protect against sudden cardiac death after myocardial infarction. However, improved risk stratification for device requirement is still needed.

OBJECTIVE

The purpose of this study was to improve assessment of postinfarct ventricular electropathology and prediction of appropriate ICD therapy by combining late gadolinium enhancement (LGE) and advanced computational modeling.

METHODS

ADAS 3D LV (ADAS LV Medical, Barcelona, Spain) and custom-made software were used to generate 3-dimensional patient-specific ventricular models in a prospective cohort of patients with a myocardial infarction (N = 40) having undergone LGE imaging before ICD implantation. Corridor metrics and 3-dimensional surface features were computed from LGE images. The Virtual Induction and Treatment of Arrhythmias (VITA) framework was applied to patient-specific models to comprehensively probe the vulnerability of the scar substrate to sustaining reentrant circuits. Imaging and VITA metrics, related to the numbers of induced ventricular tachycardias and their corresponding round trip times (RTTs), were compared with ICD therapy during follow-up.

RESULTS

Patients with an event (n = 17) had a larger interface between healthy myocardium and scar and higher VITA metrics. Cox regression analysis demonstrated a significant independent association with an event: interface (hazard ratio [HR] 2.79; 95% confidence interval [CI] 1.44-5.44; P < .01), unique ventricular tachycardias (HR 1.67; 95% CI 1.04-2.68; P = .03), mean RTT (HR 2.14; 95% CI 1.11-4.12; P = .02), and maximum RTT (HR 2.13; 95% CI 1.19-3.81; P = .01).

CONCLUSION

A detailed quantitative analysis of LGE-based scar maps, combined with advanced computational modeling, can accurately predict ICD therapy and could facilitate the early identification of high-risk patients in addition to left ventricular ejection fraction.

Ischemic cardiomyopathy: epidemiology, pathophysiology, outcomes, and therapeutic options

Ischemic cardiomyopathy (ICM) is the most prevalent cause of heart failure (HF) in developed countries, with significant morbidity and mortality, despite constant improvements in the management of coronary artery disease. Current literature on this topic remains fragmented. Therefore, this review aimed to summarize the most recent data on ICM, focusing on its definition, epidemiology, outcomes, and therapeutic options. The most widely accepted definition is represented by a left ventricular dysfunction in the presence of significant coronary artery disease. The prevalence of ICM is largely influenced by age and sex, with older individuals and males being more affected. Its pathophysiology is characterized by plaque buildup, thrombus formation, hypoperfusion, ischemic cell death, and left ventricular remodeling. Despite improvements in therapy, ICM still represents a public health burden, with a 1-year mortality rate of 16% and a 5-year mortality rate of approximately 40% in the USA and Europe. Therefore, optimization of cardiovascular function, prevention of progressive remodeling, reduction of HF symptoms, and improved survival are the main goals of treatment. Therapeutic options for ICM include lifestyle changes, optimal medical therapy, revascularization, device therapy, mechanical circulatory support, and cardiac transplantation. Personalized management strategies and tailored patient care are needed to improve the outcomes of patients with ICM.

Thallium exposure interfered with heart development in embryonic zebrafish (Danio rerio): From phenotype to genotype

Thallium (Tl) is a rare trace metal element but increasingly detected in wastewater produced by coal-burning, smelting, and more recently, high-tech manufacturing industries. However, the adverse effects of Tl, especially cardiotoxicity, on aquatic biota remain unclear. In this study, zebrafish model was used to elucidate the effects and mechanisms of Tl(I) cardiotoxicity in developing embryos. Exposure of embryonic zebrafish to low-dose Tl(I) (25-100 μg/L) decreased heart rate and blood flow activity, and subsequently impaired swim bladder inflation and locomotive behavior of larvae. Following high-level Tl(I) administration (200-800 μg/L), embryonic zebrafish exhibited pericardial edema, incorrect heart looping, and thinner myocardial layer. Based on RNA-sequencing, Tl(I) altered pathways responsible for protein folding and transmembrane transport, as well as negative regulation of heart rate and cardiac jelly development. The gene expression of nppa, nppb, ucp1, and ucp3, biomarkers of cardiac damage, were significantly upregulated by Tl(I). Our findings demonstrate that Tl(I) at environmentally relevant concentrations interfered with cardiac development with respect to anatomy, function, and transcriptomic alterations. The cardiotoxic mechanisms of Tl(I) provide valuable information in the assessment of Tl-related ecological risk in freshwater environment.

Review of cardiovascular imaging in the Journal of Nuclear Cardiology 2022: single photon emission computed tomography

In this review, we will summarize a selection of articles on single-photon emission computed tomography published in the Journal of Nuclear Cardiology in 2022. The aim of this review is to concisely recap major advancements in the field to provide the reader a glimpse of the research published in the journal over the last year. This review will place emphasis on myocardial perfusion imaging using single-photon emission computed tomography summarizing advances in the field including in prognosis, non-perfusion variables, attenuation compensation, machine learning and camera design. It will also review nuclear imaging advances in amyloidosis, left ventricular mechanical dyssynchrony, cardiac innervation, and lung perfusion. We encourage interested readers to go back to the original articles, and editorials, for a comprehensive read as necessary but hope that this yearly review will be helpful in reminding readers of articles they have seen and attracting their attentions to ones they have missed.

Optimal Protocol and Clinical Usefulness of 123I-MIBG Cardiac Scintigraphy for Differentiation of Parkinson’s Disease and Dementia with Lewy Body from Non-Parkinson’s Diseases

Purpose

¹²³I-metaiodobenzylguanidine (MIBG) cardiac scintigraphy was a useful imaging modality for the diagnosis of Parkinson's disease, but its diagnostic performances were variably reported. This retrospective study compared the diagnostic performances and investigated the optimal imaging protocol of ¹²³I-MIBG cardiac scintigraphy at various imaging time points in patients suspected of Parkinson's disease in clinical practice.

Methods

In patients suspected of Parkinson's disease, clinical records, autonomic function tests, and ¹²³I-MIBG cardiac scintigraphy were retrospectively reviewed. Semi-quantitative parameters such as heart-to-mediastinum ratio (HMR) and washout rate (WR) were calculated and compared at 15 min, 1 h, 2 h, 3 h, and 4 h post-injection (p.i.). of ¹²³I-MIBG cardiac scintigraphy. Group A consisted of Parkinson's disease (PD), Parkinson's disease dementia (PDD), and dementia with Lewy body (DLB), and group B consisted of non-Parkinson's diseases such as multiple system atrophy (MSA), progressive supranuclear palsy (PSP), drug-induced parkinsonism (DIP), essential tremor (ET), Parkinson-plus syndrome (PPS), and unspecified secondary parkinsonism (NA). The diagnostic performances of HMR and WR were compared for differentiation of group A from group B, and their clinical usefulness and optimal imaging time points were explored.

Results

Seventy-eight patients were included in group A (67 PD, 7 PDD, 4 DLB), and 18 patients were included in group B (5 MSA, 3 PSP, 2 DIP, 2 ET, 1 PPS, and 1 NA). Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value of HMR and WR were maximized at 4 h p.i., (82.1%, 85.7%, 82.6%, 97.0%, and 46.2%; cutoff threshold < 1.717; area under curve 0.8086) and at the time interval between 1 and 4 h p.i. (65.4%, 85.7%, 68.5%, 96.2%, and 30.8%; cutoff threshold > 24.1%; area under curve 0.8246), respectively, and PPVs of both HMR and WR persistently showed greater than 92.7% at earlier time points and shorter time intervals.

Conclusion

This study reassured that 4-h-delayed imaging is recommended for the best diagnostic performances in ¹²³I-MIBG cardiac scintigraphy. Although it showed suboptimal diagnostic performances to differentiate PD, PDD, and DLB from non-Parkinson's diseases, it can be useful as an auxiliary measure for the differential diagnosis in usual clinical practice.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13139-023-00790-w.

The value of cardiac sympathetic activity and mechanical dyssynchrony as cardiac resynchronization therapy response predictors: comparison between patients with ischemic and non-ischemic heart failure

BACKGROUND

Impaired cardiac sympathetic activity and mechanical dyssynchrony (MD) are associated with poor prognosis in patients with heart failure (HF) after cardiac resynchronization therapy (CRT). The study aims to assess the significance of scintigraphic evaluation of cardiac sympathetic innervation and contractility in predicting response to CRT in patients with ischemic and non-ischemic chronic HF.

METHODS AND RESULTS

The study includes 58 HF patients, who were referred for CRT. Prior to CRT all patients underwent 123I-metaiodobenzylguanidine (123I-MIBG) imaging and gated myocardial perfusion imaging (MPI) using a cadmium-zinc-telluride (CZT) SPECT/CT device. At a one-year follow-up post-CRT, the delayed heart-to-mediastinum 123I-MIBG uptake ratio was an independent predictor of CRT response in non-ischemic HF patients (OR 1.469; 95% CI 1.076-2.007, p = .003). In ischemic HF patients the MD index histogram bandwidth (HBW) obtained by CZT-gated MPI had a predictive value (OR 1.06, 95% CI 1.001-1.112, p = .005) to CRT response.

CONCLUSION

CRT response can be predicted by cardiac 123I-MIBG scintigraphy, specifically by the heart-to-mediastinum ratio in non-ischemic HF and by the MD index HBW in ischemic HF. These results suggest the value of a potentially useful algorithm to improve outcomes in HF patients who are candidates for CRT.

Cardiac 123I-mIBG scintigraphy for prediction of catheter ablation outcome in patients with atrial fibrillation

BACKGROUND

Previous studies show inconsistent results on the role of innervation imaging (with 123I-mIBG) in predicting late atrial fibrillation (AF) recurrence after catheter ablation (CA). These studies included patients with paroxysmal AF and studied prognostic value of post-CA I-123-mIBG parameters. Current study investigated the ability of pre CA 123-I-mIBG imaging to predict late AF recurrence in patients with persistent AF.

METHODS

123I-mIBG cardiac imaging was performed before CA in 82 patients with persistent AF. Patient was followed for 12 months.

RESULTS

Multivariable analysis demonstrated that late heart-to-mediastinum ratio (H/Mlate) and washout rate (WR) were independent predictors of AF recurrence. ROC-curve analysis data showed that H/Mlate <1.6 (sensitivity 73.53%, specificity 81.3%, AUC 0.792, P < .001) and WR > 25.11 (sensitivity 70.6%, specificity 70.8.3%, AUC 0.712, P < .001) indicate high probability of AF relapses during 12 months after CA.

CONCLUSION

Pre-CA parameters of global cardiac sympathetic activity estimated by 123I-mIBG scintigraphy are associated with late AF relapses in persistent AF patients with normal LVEF and absence of significant CAD.

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.

Cardiac 123I-mIBG Imaging in Heart Failure

Cardiac sympathetic upregulation is one of the neurohormonal compensation mechanisms that play an important role in the pathogenesis of chronic heart failure (CHF). In the past decades, cardiac ¹²³I-mIBG scintigraphy has been established as a feasible technique to evaluate the global and regional cardiac sympathetic innervation. Although cardiac ¹²³I-mIBG imaging has been studied in many cardiac and neurological diseases, it has extensively been studied in ischemic and non-ischemic CHF. Therefore, this review will focus on the role of ¹²³I-mIBG imaging in CHF. This non-invasive, widely available technique has been established to evaluate the prognosis in CHF. Standardization, especially among various combinations of gamma camera and collimator, is important for identifying appropriate thresholds for adequate risk stratification. Interestingly, in contrast to the linear relationship between ¹²³I-mIBG-derived parameters and overall prognosis, there seems to be a “bell-shape” curve for ¹²³I-mIBG-derived parameters in relation to ventricular arrhythmia or appropriate implantable cardioverter defibrillator (ICD) therapy in patients with ischemic CHF. In addition, there is a potential clinical role for cardiac ¹²³I-mIBG imaging in optimizing patient selection for implantation of expensive devices such as ICD and cardiac resynchronization therapy (CRT). Based on cardiac ¹²³I-mIBG data risk models and machine learning, models have been developed for appropriate risk assessment in CHF.