Presence of Mid-Myocardial Fibrosis in Ventricular Endocardial Electrograms is Related to Power of Patient-Specific Frequency Bands.

ORAL PRESENTATION

Introduction Recent evidence has shown that intramyocardial lipomatous metaplasia (LM) can be directly identified with cardiac computer tomography (CT) and plays a significant role in ventricular arrhythmogenesis and facilitation in structural heart disease. Purpose We sought to explore the diagnostic performance of three different CT features (LM, CT channels, wall thinning) identified at ADAS3D post-processing as electroanatomical substrate predictors and their potential role in planning and aiding ventricular tachycardia (VT) scar dechanneling procedures. Methods All patients undergoing VT ablation at our institution were enrolled. CT images were post-processed with ADAS3D software to assess LM and left ventricle wall thickness. Images were then retrospectively imported into CARTO3 software and concordance between CT and electroanatomical features (conducting channels, channel entrances, bipolar scar, voltage channels, ablation VISITAGs) was assessed at a cardiac segment level. Results From July 2016 to December 2022 131 patients underwent VT ablation at our institution. 88 patients did not undergo preprocedural CT examination, 15 patients had a low-quality CT scan and, at ADAS3D analysis 9 patients did not have significant LM. 19 patients (14 ischemic and 5 non-ischemic, 323 cardiac segments) were then included for analysis. 90 segments (27,86%) showed LM, 93 segments (28,79%) showed thickness < 5 mm and 12 segments (3,72%) held CT channels. In terms of conducting channel prediction, in ischemic patients, LM showed 70% sensitivity, 89% specificity, 73% PPV and 88% NPV when compared to CT channels (10% sensitivity, 98% specificity, 70% PPV, 72% NPV) or wall thinning (61% sensitivity, 82% specificity, 58% PPV and 84% NPV). In non-ischemic patients LM showed with 69% sensitivity, 81% specificity, 39% PPV and 94% NPV when compared to CT channels (15% sensitivity, 100% specificity, 100% PPV, 87% NPV) or wall thinning (46% sensitivity, 82% specificity, 32% PPV and 89% NPV). Overall, at multivariate analysis only LM (OR 12,46 95% C.I. 6,59-23,58) and wall thinning (OR 4,73 95% C.I. 2,45-9,14) were independent predictors for conducting channel. Conclusion Lipomatous metaplasia is the best CT predictor for conducting channel presence both in ischemic and non-ischemic patients with scar related ventricular tachycardia and a potentially useful tool for procedure planning and guidance.CT predictors for EAM substrate findingsMultivariate forest plots

Ventricular arrhythmias and sudden cardiac death

to evaluate the diagnostic accuracy of late iodine enhancement (LIE) in cardiac computed tomography (CCT) compared to late gadolinium enhancement (LGE) in cardiac magnetic resonance (CMR) for myocardial tissue characterization. EMBASE, PubMed/MEDLINE, and CENTRAL were searched for studies reporting the accuracy of LIE with LGE as the gold standard of reference. QUADAS-2 tool was used to assess the risk of bias. A bivariate random-effects model was used to analyze, pool, and plot the diagnostic performance measurements across studies. Pooled sensitivity, specificity, positive (+LR) and negative (-LR) likelihood ratio, diagnostic odds ratio (DOR), and hierarchical summary ROC curve (HSROC) were computed. Prospero registration number: CRD42023484045. Fourteen studies involving 526 patients and 5758 myocardial segments were included. At the patient level, LIE in CCT showed a pooled sensitivity of 0.96 (95% CI: 0.88-0.99), specificity of 0.95 (95% CI: 0.88-0.98) and the HSROC AUC of 0.98 (95% CI: 0.97-0.99). The +LR was 20.97 (95% CI: 7.54-58.38) and the -LR was 0.04 (95% CI: 0.01-0.13), resulting in a DOR of 535 (95% CI: 94-3024). At the segment level, sensitivity was 0.86 (95% CI: 0.79-0.91), specificity was 0.98 (95% CI: 0.96-0.99), and the HSROC AUC was 0.97 (95% CI:0.95-0.98). The +LR was 55.08 (95% CI: 19.94-152.16) and the -LR was 0.14 (95% CI: 0.09-0.22) with a DOR of 388 (95% CI: 113-1333). Dual-energy CCT improved segment-level sensitivity to 0.93 (95% CI: 0.88-0.96). LIE in CCT shows excellent diagnostic accuracy when compared to LGE in CMR for myocardial tissue characterization, suggesting its potential as a promising alternative to CMR. Question How does myocardial tissue characterization by late iodine enhancement (LIE) on cardiac CT (CCT) compare to late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR)? Findings LIE in CCT demonstrates excellent diagnostic accuracy, with high sensitivity and specificity at both patient and segment levels, using LGE in CMR as the reference. Clinical relevance LIE in CCT provides a reliable alternative to LGE in CMR, especially for patients for whom CMR is not available or feasible or is contraindicated, thus improving access to myocardial tissue characterization.

Introduction Cardiac computed tomography (CT) has emerged as a promising alternative to cardiac magnetic resonance (CMR) for myocardial characterization. However, the quantification of late iodine enhancement (LIE) and its threshold values have not been previously reported. The Full Width Half Maximum (FWHM) technique established a cut-off value of 50% of the maximum intensity signal to quantify late gadolinium enhancement (LGE) in CMR. Nevertheless, the distinction between healthy and fibrotic myocardium in CT is less pronounced, prompting the need for specific threshold values for accurate quantification of LIE with this technique. Purpose Our primary aim was to validate and determine the optimal cut-off values for quantifying LIE using cardiac CT. Methods We included consecutive patients who underwent both LIE and LGE within a period of less than 2 months. Late enhancement quantification was performed using a commercially available software (figure 1). The FWHM technique was applied for LGE quantification. Various signal density cut-off values (70%, 75%, 80%, 85%, and 90%) were explored for LIE quantification. The total myocardial mass, total scar mass and scar proportion were calculated. The Intraclass Correlation Coefficient (ICC) was computed for each of the specified cut-off values. Results From November 2022 to February 2024, 58 patients underwent cardiac CT with LIE. Among them, 17 patients (48 (33;59) years; 13 (68,4%) male) had concomitant LGE and were included in the final analysis. The most common indication for CT was myocardial infarction with non-obstructive coronary arteries (52,9%). The total myocardial mass by CT was 108.83 ± 21.69 g, while the total myocardial mass by CMR was 100.33 ± 25.19 g. The ICC between both techniques was good (0.78, p=0.001). A cut-off value of 75% for the CT showed the strongest correlation with the CMR, both for total scar mass and scar proportion. Total scar mass was 9.43 ± 8.29 g for CT and 10.7 ± 8.46 g for CMR, with an ICC of 0.68 (p=0.01). Scar proportion was 9.97 ± 8.26% for CT and 11.09 ± 9% for CMR, showing a good correlation (ICC 0.73, p=0.006). Conclusion Late iodine enhancement quantification by cardiac computed tomography is feasible. A signal density threshold of 75% showed the strongest correlation with the cardiac magnetic resonance.Example of late iodine enhancement

Sustained ventricular tachycardia (VT) is an important cause of morbidity and sudden death in patients with heart disease.1 Implantable cardioverter-defibrillators (ICDs) terminate VT episodes, reducing the risk of sudden death. Recurrent VT develops in 40% to 60% of patients who receive an ICD after an episode of spontaneous sustained VT. A first episode of VT occurs in ≈20% of patients within 3 to 5 years after ICD implantation for primary prevention of sudden death in high-risk groups.2–4 ICD shocks reduce quality of life and are associated with an increased risk of death.2–4 Antiarrhythmic drug therapy with amiodarone or sotalol reduces VT episodes but with disappointing incidence of side effects and efficacy.2 Catheter ablation is useful for reducing VT episodes and can be life-saving when VT is incessant.1,5,6 Idiopathic VTs occur in patients without structural heart disease and rarely cause sudden death. Electrophysiological study with catheter ablation is often warranted to confirm the diagnosis, to provide further evidence for the absence of ventricular scar or other disease, and often to cure the arrhythmia. Ablation is also an option for symptomatic nonsustained VT and frequent ventricular ectopy in these patients.1 The appearance of the VT on ECG often suggests its likely cause and associated heart disease (Figure 1). Monomorphic VT has the same QRS complex from beat to beat, indicating repetitive ventricular activation from a structural substrate or focus that can be targeted for ablation. Most are due to reentry through regions of ventricular scar.7 Figure 1. ECG types of VT and most common causes are shown with characteristic ECG features of selected VTs. LBBB indicates left bundle-branch block; LVOT, LV outflow tract; RBBB, right bundle-branch block; L, left; and R, right. Polymorphic VTs have a changing ventricular activation sequence that can be due to …

Scar tissue characterization to predict arrhythmia recurrence in patients undergoing ventricular tachycardia ablation: cardiac computed tomography compared with cardiac magnetic resonance

Radio frequency ablation for VT – A cost-effective tool to combat SCD in developing countries

Background Cardiac magnetic resonance (CMR)-aided ventricular tachycardia (VT) substrate ablation has shown to improve VT recurrence-free survival, through a better identification of the arrhythmogenic substrate. However, the access to CMR may be limited in certain centers or sometimes Its use can be contraindicated in patients with cardiac implantable electronic device. Cardiac computed tomography (CT) has shown to improve the results of substrate ablation, correlating with low-voltage areas and local abnormal ventricular activity, and identifying ridges of myocardial tissue (CT-channels) that may be appropriate target sites for ablation. Purpose To evaluate the correlation between CT and CMR imaging in identifying anatomical heterogeneous tissue channels (CMR-channels) or CT-channels in ischemic patients undergoing VT substrate ablation. Methods The study included 30 post-myocardial infarction (MI) patients (mean age 69±10; 94% male, left ventricular ejection fraction 35±10%), who underwent both CMR and cardiac CT before VT substrate ablation. Using a dedicated post-processing software, the myocardium was segmented in 10 layers from endocardium to epicardium both for the CMR and CT, characterizing the presence of CMR-channels and CT-channels, respectively, by two blinded operators, assigned either to CMR or CT analysis. CMR-channels were classified as endocardial (CMR-channels in layer <50%), epicardial (CMR-channels in layers ≥50%) or transmural (in both endo and epicardial layers). Presence and location of CT and CMR-channels were compared. Results In 26/30 patients (86.7%) 91 CT-channels (mean 3.0±1.9 per patient) were identified while 30/30 (100%) showed CMR-channels (n=76; mean 2.4±1.2 per patient). We found 190 CT-channel entrances (mean 6.3±4.1 per patient), and 275 CMR-channel entrances (mean 8.9±4.9 per patient) on cardiac CT and CMR, respectively. There were 47/91 (51.6%) true positive CT-channels. On the contrary, 44/91 (48.4%) CT-channels were considered false positives [19/91 (20.9%) identified out of CMR scar], and 29/76 (38.2%) CMR-channels could not be identified on CT. Thirty-six out of 76 (47.4%) CMR-channels were considered as non-endocardial (epi- or transmural). Twenty-nine out of 36 (80.5%) non-endocardial CMR-channels were coincident with CT-channels. CT and CMR Channels Conclusion CT shows a modest sensitivity in identifying CMR-channels and fails in ascertain their complexity, underestimating the number of entrances; however, channels location at CT fit well with CMR for those classified as transmural or epicardial.

Concordance of cardiac computed tomography in the identification of deceleration zones and the value of lipomatous metaplasia

The implantable cardioverter-defibrillator (ICD) was devised to satisfy the unmet need for an effective, instantaneous therapy to prevent sudden cardiac death (SCD) due to ventricular fibrillation (VF) in at-risk, ambulatory patients. That therapy was a high-voltage electric shock delivered directly into the heart muscle. More than 3 decades later, shocks are still the defining operating characteristic of ICDs, and no other instantaneously effective therapy for VF exists. This elite status was clinched by large randomized clinical trials1,2 which demonstrated that ICDs improved mortality in patients with reduced left ventricular ejection fraction, regardless of pathogenesis or accompanying symptoms of heart failure (HF), by primary prevention of SCD due to ventricular tachyarrhythmia (VTA). Like bradycardia pacemakers for asystole, the ICD resides as a therapy genre of one, with no peer, and no competitor on the horizon. These sibling therapies for lethal heart rhythm disturbances will stand prominently among the greatest medical achievements of the 20th century. The ICD is a mature technology, and neither the technique nor the tools have changed much for several decades. Despite a certain evolutionary elegance of the operating system, the ICD is still a blunt instrument. Although it is true that some innovation has occurred, it is still a matter of a shock delivered by insulated metal conductors residing somewhere in direct proximity to the heart. No innovation beyond the fundamental of a timed shock for VF has proven to enhance mortality benefit. The basic design persists simply because no one can think of a suitable alternative and the self-satisfying aphorism that “shocks save lives.” Yet there is a growing intellectual dissatisfaction with the unintended consequences of this powerful, irreplaceable therapy. The stimulus for this self-inspection is an awareness of the very high morbidity risk overhead borne by the primary prevention patient, in particular, …

PO-04-137 SCAR TRANSMURALITY IN VENTRICULAR ENDOCARDIAL UNIPOLAR ELECTROGRAMS IS RELATED TO POWER OF PATIENT-SPECIFIC FREQUENCY BANDS

B-PO02-126 LATE-IODINE ENHANCEMENT COMPUTED TOMOGRAPHY AS A MARKER FOR SCAR LOCALIZATION FOR VENTRICULAR TACHYCARDIA ABLATION IN CARDIAC SARCOIDOSIS

PO-05-100 DETECTION OF THE CRITICAL SUBSTRATE FOR VENTRICULAR TACHYCARDIA ABLATION WITH THE COMBINED IMAGE OF TC-99M SCINTIGRAM AND LATE IODINE ENHANCEMENT CT

Ventricular tachycardia ablation in a patient with Ehlers-Danlos syndrome