Post-implantation CMR imaging to study biventricular pacing effects on the right ventricle in left bundle branch block patients.

Cardiac resynchronization therapy (CRT) is an established treatment for heart failure patients with left ventricular dysfunction and a left bundle branch block. However, its impact on right ventricular (RV) function remains uncertain. This cardiac magnetic resonance imaging study found that CRT did not improve RV volumes and function, and CRT-off during follow-up had an immediate detrimental effect on the RV, which may suggest potential unfavorable RV remodeling with RV pacing during CRT.

Arrhythmogenic vulnerability of re-entrant pathways in post-infarct ventricular tachycardia assessed by advanced computational modelling.

AIMS: Substrate assessment of scar-mediated ventricular tachycardia (VT) is frequently performed using late gadolinium enhancement (LGE) images. Although this provides structural information about critical pathways through the scar, assessing the vulnerability of these pathways for sustaining VT is not possible with imaging alone.This study evaluated the performance of a novel automated re-entrant pathway finding algorithm to non-invasively predict VT circuit and inducibility. METHODS: Twenty post-infarct VT-ablation patients were included for retrospective analysis. Commercially available software (ADAS3D left ventricular) was used to generate scar maps from 2D-LGE images using the default 40-60 pixel-signal-intensity (PSI) threshold. In addition, algorithm sensitivity for altered thresholds was explored using PSI 45-55, 35-65, and 30-70. Simulations were performed on the Virtual Induction and Treatment of Arrhythmias (VITA) framework to identify potential sites of block and assess their vulnerability depending on the automatically computed round-trip-time (RTT). Metrics, indicative of substrate complexity, were correlated with VT-recurrence during follow-up. RESULTS: Total VTs (85 ± 43 vs. 42 ± 27) and unique VTs (9 ± 4 vs. 5 ± 4) were significantly higher in patients with- compared to patients without recurrence, and were predictive of recurrence with area under the curve of 0.820 and 0.770, respectively. VITA was robust to scar threshold variations with no significant impact on total and unique VTs, and mean RTT between the four models. Simulation metrics derived from PSI 45-55 model had the highest number of parameters predictive for post-ablation VT-recurrence. CONCLUSION: Advanced computational metrics can non-invasively and robustly assess VT substrate complexity, which may aid personalized clinical planning and decision-making in the treatment of post-infarction VT.

Loss of capture of conduction system pacemaker caused by fibrosis surrounding the lead: a case report.

BACKGROUND: Conduction system pacing (CSP) is a novel technique that involves pacing the His-Purkinje system instead of the traditional right ventricular (RV) apex. This technique aims to avoid the adverse effects of RV apical pacing, which can lead to ventricular dyssynchrony and heart failure over time. CSP is gaining popularity but its long-term efficacy and challenges remain uncertain. This report discusses a case where CSP was initially successful but faced complications due to an increasing pacing threshold. CASE PRESENTATION: A 65-year-old female with total atrioventricular block was referred for brady-pacing. Due to the potential for chronic RV pacing, CSP was chosen. The CSP implantation involved subcutaneous device placement, with a CSP lead in the left bundle branch area (LBBA) and an RV backup lead. A year after successful implantation, the LBBA pacing threshold progressively increased. Subsequent efforts to correct it led to anodal capture and battery depletion. Cardiac magnetic resonance imaging (CMR) revealed mid-septal fibrosis at the area of LBBA lead placement and suggested cardiac sarcoidosis as a possible cause. CONCLUSION: CSP is a promising technique for treating bradyarrhythmias, but this case underscores the need for vigilance in monitoring pacing thresholds. Increasing thresholds can render CSP ineffective, necessitating alternative pacing methods. The CMR findings of mid-septal fibrosis and the potential diagnosis of cardiac sarcoidosis emphasize the importance of pre-implantation assessment, as CSP may be compromised by underlying structural abnormalities. This report highlights the complexities of pacing strategy selection and the significance of comprehensive evaluation before adopting CSP.

Impaired left atrial reservoir and conduit strain in patients with atrial fibrillation and extensive left atrial fibrosis.

BACKGROUND: Atrial fibrillation (AF) is associated with profound structural and functional changes in the atria. In the present study, we investigated the association between left atrial (LA) phasic function and the extent of LA fibrosis using advanced cardiovascular magnetic resonance (CMR) imaging techniques, including 3-dimensional (3D) late gadolinium enhancement (LGE) and feature tracking. METHODS: Patients with paroxysmal and persistent AF (n = 105) underwent CMR in sinus rhythm. LA global reservoir strain, conduit strain and contractile strain were derived from cine CMR images using CMR feature tracking. The extent of LA fibrosis was assessed from 3D LGE images. Healthy subjects underwent CMR and served as controls (n = 19). RESULTS: Significantly lower LA reservoir strain, conduit strain and contractile strain were found in AF patients, as compared to healthy controls (- 15.9 ± 3.8% vs. - 21.1 ± 3.6% P < 0.001, - 8.7 ± 2.7% vs. - 12.6 ± 2.5% P < 0.001 and - 7.2 ± 2.3% vs. - 8.6 ± 2.2% P = 0.02, respectively). Patients with a high degree of LA fibrosis (dichotomized by the median value) had lower reservoir strain and conduit strain compared to patients with a low degree of LA fibrosis (- 15.0 ± 3.9% vs. - 16.9 ± 3.3%, P = 0.02 and - 7.9 ± 2.7% vs. - 9.5 ± 2.6%, P = 0.01, respectively). In contrast, no difference was found for LA contractile strain (- 7.1 ± 2.4% vs. - 7.4 ± 2.3%, P = 0.55). CONCLUSIONS: Impaired LA reservoir and conduit strain are present in AF patients with extensive atrial fibrosis. Future studies are needed to examine the biologic nature of this association and possible therapeutic implications.

Differences between gap-related persistent conduction and carina-related persistent conduction during radiofrequency pulmonary vein isolation.

BACKGROUND: During pulmonary vein isolation (PVI), nonisolation after initial encircling of the pulmonary veins (PVs) may be due to gaps in the initial ablation line, or alternatively, earliest PV activation may occur on the intervenous carina and ablation within the wide-area circumferential ablation (WACA) circle is needed to eliminate residual conduction. This study investigated prognostic implications and predictors of gap-related persistent conduction (gap-RPC) and carina-related persistent conduction (carina-RPC) during PVI. METHODS AND RESULTS: Two hundred fourteen atrial fibrillation (AF) patients (57% paroxysmal, 61% male, mean age 62 ± 9 years) undergoing first contact force-guided radiofrequency PVI were studied. Preprocedural cardiac computed tomography imaging was used to assess left atrial and PV anatomy. PVI was assessed directly after initial WACA circle creation, after a minimum waiting period of 30 minutes, and after adenosine infusion. Persistent conduction was targeted for additional ablation and classified as gap-RPC or carina-RPC, depending on the earliest activation site. The 1-year AF recurrence rate was higher in patients with gap-RPC (47%) compared to patients without gap-RPC (28%; P = .003). No significant difference in 1-year recurrence rate was found between patients with carina-RPC (37%) and patients without carina-RPC (31%; P = .379). Multivariate analyses identified paroxysmal AF and WACA circumference as independent predictors of gap-RPC, whereas carina width and WACA circumference correlated with carina-RPC. CONCLUSIONS: Gap-RPC is associated with increased AF recurrence risk after PVI, whereas carina-RPC does not predict AF recurrence. Moreover, gap-RPC and carina-RPC have different correlates and may thus have different underlying mechanisms.

Comparison between quantitative cardiac magnetic resonance perfusion imaging and [15O]H2O positron emission tomography.

PURPOSE: To compare cardiac magnetic resonance imaging (CMR) with [15O]H2O positron emission tomography (PET) for quantification of absolute myocardial blood flow (MBF) and myocardial flow reserve (MFR) in patients with coronary artery disease (CAD). METHODS: Fifty-nine patients with stable CAD underwent CMR and [15O]H2O PET. The CMR imaging protocol included late gadolinium enhancement to rule out presence of scar tissue and perfusion imaging using a dual sequence, single bolus technique. Absolute MBF was determined for the three main vascular territories at rest and during vasodilator stress. RESULTS: CMR measurements of regional stress MBF and MFR showed only moderate correlation to those obtained using PET (r = 0.39; P < 0.001 for stress MBF and r = 0.36; P < 0.001 for MFR). Bland-Altman analysis revealed a significant bias of 0.2 ± 1.0 mL/min/g for stress MBF and - 0.5 ± 1.2 for MFR. CMR-derived stress MBF and MFR demonstrated area under the curves of respectively 0.72 (95% CI: 0.65 to 0.79) and 0.76 (95% CI: 0.69 to 0.83) and had optimal cutoff values of 2.35 mL/min/g and 2.25 for detecting abnormal myocardial perfusion, defined as [15O]H2O PET-derived stress MBF ≤ 2.3 mL/min/g and MFR ≤ 2.5. Using these cutoff values, CMR and PET were concordant in 137 (77%) vascular territories for stress MBF and 135 (80%) vascular territories for MFR. CONCLUSION: CMR measurements of stress MBF and MFR showed modest agreement to those obtained with [15O]H2O PET. Nevertheless, stress MBF and MFR were concordant between CMR and [15O]H2O PET in 77% and 80% of vascular territories, respectively.

Continuous thermodilution to assess absolute flow and microvascular resistance: validation in humans using [15O]H2O positron emission tomography.

AIMS: Continuous thermodilution is a novel technique to quantify absolute coronary flow and microvascular resistance (MVR). Notably, intracoronary infusion of saline elicits maximal hyperaemia, obviating the need for adenosine. The primary aim of this study was to validate continuous thermodilution in humans by comparing invasive measurements to [15O]H2O positron emission tomography (PET). As a secondary goal, absolute flow and MVR were compared between invasive measurements obtained with and without adenosine. METHODS AND RESULTS: Twenty-five patients underwent coronary computed tomography angiography (CCTA), [15O]H2O PET, and invasive assessment. Absolute coronary flow and MVR were measured in the left anterior descending and left circumflex artery using a dedicated infusion catheter and a temperature/pressure sensor-tipped guidewire. Invasive measurements were performed with and without adenosine. In order to compare invasive flow measurements with PET perfusion, subtending myocardial mass of the investigated vessels was derived from CCTA using the Voronoi algorithm. Invasive and non-invasive measurements of adenosine-induced hyperaemic flow and MVR showed strong correlation (r = 0.91; P < 0.001 for flow and r = 0.85; P < 0.001 for MVR) and good agreement [intraclass correlation coefficient (ICC) = 0.90; P < 0.001 for flow and ICC = 0.79; P < 0.001 for MVR]. Absolute flow and MVR also correlated well between measurements with and without adenosine (r = 0.97; P < 0.001 for flow and r = 0.98; P < 0.001 for MVR) and showed good agreement (ICC = 0.96; P < 0.001 for flow and ICC = 0.98; P < 0.001 for MVR). CONCLUSIONS: Continuous thermodilution is an accurate method to measure absolute coronary flow and MVR, which is evidenced by strong agreement with [15O]H2O PET derived flow and resistance. Absolute flow and MVR correlate highly between invasive measurements obtained with and without adenosine, which confirms that intracoronary infusion of room temperature saline elicits steady-state maximal hyperaemia.

Strain analysis is superior to wall thickening in discriminating between infarcted myocardium with and without microvascular obstruction.

OBJECTIVES: The aim of the present study was to evaluate the diagnostic performances of strain and wall thickening analysis in discriminating among three types of myocardium after acute myocardial infarction: non-infarcted myocardium, infarcted myocardium without microvascular obstruction (MVO) and infarcted myocardium with MVO. METHODS: Seventy-one patients with a successfully treated ST-segment elevation myocardial infarction underwent cardiovascular magnetic resonance imaging at 2-6 days after reperfusion. The imaging protocol included conventional cine imaging, myocardial tissue tagging and late gadolinium enhancement. Regional circumferential and radial strain and associated strain rates were analyzed in a 16-segment model as were the absolute and relative wall thickening. RESULTS: Hyperenhancement was detected in 418 (38%) of 1096 segments and was accompanied by MVO in 145 (35%) of hyperenhanced segments. Wall thickening, circumferential and radial strain were all significantly diminished in segments with hyperenhancement and decreased even further if MVO was also present (all p < 0.001). Peak circumferential strain (CS) surpassed all other strain and wall thickening parameters in its ability to discriminate between hyperenhanced and non-enhanced myocardium (all p < 0.05). Furthermore, CS was superior to both absolute and relative wall thickening in differentiating infarcted segments with MVO from infarcted segments without MVO (p = 0.02 and p = 0.001, respectively). CONCLUSIONS: Strain analysis is superior to wall thickening in differentiating between non-infarcted myocardium, infarcted myocardium without MVO and infarcted myocardium with MVO. Peak circumferential strain is the most accurate marker of regional function. KEY POINTS: • CMR can quantify regional myocardial function by analysis of wall thickening on cine images and strain analysis of tissue tagged images. • Strain analysis is superior to wall thickening in differentiating between different degrees of myocardial injury after acute myocardial infarction. • Peak circumferential strain is the most accurate marker of regional function.

MR feature tracking in patients with MRI-conditional pacing systems: The impact of pacing.

PURPOSE: To develop feature tracking (FT) software to perform strain analysis on conventional (nontagged) cardiac magnetic resonance imaging (MRI) function images. With the advent of MRI-conditional pacemaker systems, effects of cardiac pacing on myocardial strain can be studied using MR. In this study the impact of pacing on left ventricular (LV) strain was investigated using MR-FT in patients with an MRI-conditional cardiac implantable electronic device (CIED). MATERIALS AND METHODS: FT was performed on 32 1.5T MR studies (16 patients with an MRI-conditional CIED and 16 control patients with normal scans). Short- and long-axis steady state free precession (SSFP) cines were used for the FT analysis. Strain was assessed using CVI(42) software (Circle Cardiovascular Imaging, Alberta, Canada). In addition, the intra- and interobserver variability was determined using the intraclass correlation coefficient. RESULTS: Of the 16 patients with an MRI-conditional CIED, five patients were paced during the MRI exam. Despite the occasional presence of susceptibility artifacts induced by the CIED, radial, circumferential, and longitudinal strain parameters could be derived for all patients. Peak radial strain and peak circumferential strain were reduced during pacing when compared to the control group; for radial strain: 20.1 ± 4.7% vs. 33.1 ± 6.9%, P < 0.001, and for circumferential strain -7.5 ± 3.5% vs. -14.9 ± 3.2%, P < 0.05. Peak strain parameters were reproducible on an intra- and interobserver level. CONCLUSION: MR-FT is feasible in patients with an MRI-conditional CIED and can be used to quantify regional wall motion. J. MAGN. RESON. IMAGING 2016;44:964-971.

Computing volume potentials for noninvasive imaging of cardiac excitation.

BACKGROUND: In noninvasive imaging of cardiac excitation, the use of body surface potentials (BSP) rather than body volume potentials (BVP) has been favored due to enhanced computational efficiency and reduced modeling effort. Nowadays, increased computational power and the availability of open source software enable the calculation of BVP for clinical purposes. In order to illustrate the possible advantages of this approach, the explanatory power of BVP is investigated using a rectangular tank filled with an electrolytic conductor and a patient specific three dimensional model. METHODS: MRI images of the tank and of a patient were obtained in three orthogonal directions using a turbo spin echo MRI sequence. MRI images were segmented in three dimensional using custom written software. Gmsh software was used for mesh generation. BVP were computed using a transfer matrix and FEniCS software. RESULTS: The solution for 240,000 nodes, corresponding to a resolution of 5 mm throughout the thorax volume, was computed in 3 minutes. The tank experiment revealed that an increased electrode surface renders the position of the 4 V equipotential plane insensitive to mesh cell size and reduces simulated deviations. In the patient-specific model, the impact of assigning a different conductivity to lung tissue on the distribution of volume potentials could be visualized. CONCLUSION: Generation of high quality volume meshes and computation of BVP with a resolution of 5 mm is feasible using generally available software and hardware. Estimation of BVP may lead to an improved understanding of the genesis of BSP and sources of local inaccuracies.

Noninvasive imaging of cardiac excitation: current status and future perspective.

Noninvasive imaging of cardiac excitation using body surface potential mapping (BSPM) data and inverse procedures is an emerging technique that enables estimation of myocardial depolarization and repolarization. Despite numerous reports on the possible advantages of this imaging technique, it has not yet advanced into daily clinical practice. This is mainly due to the time consuming nature of data acquisition and the complexity of the mathematics underlying the used inverse procedures. However, the popularity of this field of research has increased and noninvasive imaging of cardiac electrophysiology is considered a promising tool to complement conventional invasive electrophysiological studies. Furthermore, the use of appropriately designed electrode vests and more advanced computers has greatly reduced the procedural time. This review provides descriptive overview of the research performed thus far and the possible future directions. The general challenges in routine application of BSPM and inverse procedures are discussed. In addition, individual properties of the biophysical models underlying the inverse procedures are illustrated.

Virtual Reality for Pain and Anxiety Management in Cardiac Surgery and Interventional Cardiology.

Pain and anxiety are common in patients undergoing cardiac surgery and percutaneous cardiac interventions. Virtual reality (VR) is an emerging non-pharmacological tool for pain and anxiety management. However, its application around cardiac procedures remains relatively unexplored. In this review, we perform a targeted non-systematic literature review to assess the current state-of-the-art of VR for pain and anxiety management in patients undergoing cardiac procedures. Contexts of interest were preprocedural, periprocedural, and postprocedural applications. Existing trials show inconsistent results. The majority of studies in the preprocedural (7 studies, n = 302), periprocedural (1 study, n = 99), and postprocedural stage (4 studies, n = 214) demonstrate significant reduction of pain and anxiety through VR distraction therapy or VR patient education. However, larger-scale trials (2 preprocedural studies [n = 233], 1 periprocedural study [n = 32], 2 postprocedural studies [n = 300]) report no effect. Current literature on effectiveness of VR for pain and anxiety management in cardiac surgery and interventional cardiology remains inconclusive.

The role of myocardial blood volume in the pathophysiology of angina with non-obstructed coronary arteries: The MICORDIS study.

BACKGROUND: Angina with Non-Obstructed Coronary Arteries (ANOCA) involves abnormal vasomotor responses. While reduced coronary flow is an established contributor to myocardial hypoxia, myocardial blood volume (MBV) independently regulates myocardial oxygen uptake but its role in ANOCA remains unclear. OBJECTIVES: We hypothesized that reduced MBV contributes to ANOCA, and associates with insulin resistance in ANOCA. METHODS: MBV in ANOCA patients was compared to age- and sex-matched healthy controls. ANOCA patients underwent coronary angiography with invasive coronary function testing (CFT) to identify vasospasm and coronary microvascular dysfunction. In all subjects MBV was quantified at baseline, during hyperinsulinemia and during dobutamine-induced stress using myocardial contrast echocardiography (MCE). The hyperinsulinemic-euglycemic clamp was used to assess insulin resistance. RESULTS: Twenty-eight ANOCA patients (21% men, 56.8 ± 8.6 years) and 28 healthy controls (21% men, 56.5 ± 7.0 years) were included. During CFT 11% of patients showed epicardial vasospasm, 39% microvascular vasospasm, 25% coronary microvascular dysfunction, and 11% of patients had a negative CFT. ANOCA patients had significant lower insulin-sensitivity (p < 0.01). During MCE, ANOCA patients showed a significantly lower MBV at baseline (0.388 vs 0.438 mL/mL, p = 0.04), during hyperinsulinemia (0.395 vs 0.447 mL/mL, p = 0.02), and during dobutamine-induced stress (0.401 vs 0.476 mL/mL, p = 0.030). CONCLUSIONS: In ANOCA patients MBV is diminished at baseline, during hyperinsulinemia and dobutamine-induced stress in the absence of differences in microvascular recruitment. These findings support the presence of capillary rarefaction in ANOCA patients. ANOCA patients showed metabolic insulin resistance, but insulin did not acutely alter myocardial perfusion.

Clinical implications of different methods to assess left atrial remodeling: A comparative study between echocardiography and cardiac magnetic resonance imaging for left atrial volume index quantification.

BACKGROUND: Left atrial volume index (LAVI) serves as a crucial marker for assessing left atrial (LA) remodeling, particularly in patients with mitral valve regurgitation (MR). Recent guidelines recommend a LAVI exceeding 60 mL/m2 as Class IIa recommendation for mitral valve repair surgery in asymptomatic MR patients with preserved left ventricular function. Traditionally, echocardiography is the standard for assessing LAVI in MR patients. However, cardiac magnetic resonance imaging (CMR) is increasingly recognized for its more precise measurements of cardiac dimensions and volumes. But still, literature remains scarce on comparing the efficacy of both modalities in assessing LAVI measurements. METHODS: This retrospective study included 168 MR patients undergoing both echocardiography and CMR assessments within a six-month period. LAVI measurements were compared using Pearson correlation and Bland-Altman plots. Patients were stratified based on MR grades, and clinical implications were assessed. RESULTS: Mean LAVI differed significantly between echocardiography and CMR (47.1 ± 20.8 mL/m2 versus 70 ± 20.3 mL/m2, p < 0.001, respectively). CMR consistently yielded higher LAVI measurements compared to echocardiography, with a mean difference of approximately 20 mL/m2. CMR measurements resulted in an increased incidence of patients meeting the class IIa LAVI criterion (LAVI >60 mL/m2) by 37%. Variations in LAVI did not differ across MR grades. CONCLUSION: Echocardiography systematically underestimates LAVI compared to CMR in MR patients. While current guidelines rely on echocardiography, CMR's precision suggests the need for CMR-specific LAVI cutoff values to guide clinical management effectively. Establishing such values could refine patient stratification and timing of surgery, potentially improving clinical outcomes for MR patients.

Performance of Image-navigated and Diaphragm-navigated 3D Late Gadolinium-enhanced Cardiac MRI for the Assessment of Atrial Fibrosis.

Purpose To perform a qualitative and quantitative evaluation of the novel image-navigated (iNAV) 3D late gadolinium enhancement (LGE) cardiac MRI imaging strategy in comparison with the conventional diaphragm-navigated (dNAV) 3D LGE cardiac MRI strategy for the assessment of left atrial fibrosis in atrial fibrillation (AF). Materials and Methods In this prospective study conducted between April and September 2022, 26 consecutive participants with AF (mean age, 61 ± 11 years; 19 male) underwent both iNAV and dNAV 3D LGE cardiac MRI, with equivalent spatial resolution and timing in the cardiac cycle. Participants were randomized in the acquisition order of iNAV and dNAV. Both, iNAV-LGE and dNAV-LGE images were analyzed qualitatively using a 5-point Likert scale and quantitatively (percentage of atrial fibrosis using image intensity ratio threshold 1.2), including testing for overlap in atrial fibrosis areas by calculating Dice score. Results Acquisition time of iNAV was significantly lower compared with dNAV (4.9 ± 1.1 minutes versus 12 ± 4 minutes, P < .001, respectively). There was no evidence of a difference in image quality for all prespecified criteria between iNAV and dNAV, although dNAV was the preferred image strategy in two-thirds of cases (17/26, 65%). Quantitative assessment demonstrated that mean fibrosis scores were lower for iNAV compared with dNAV (12 ± 8% versus 20 ± 12%, P < .001). Spatial correspondence between the atrial fibrosis maps was modest (Dice similarity coefficient, 0.43 ± 0.15). Conclusion iNAV-LGE acquisition in individuals with AF was more than twice as fast as dNAV acquisition but resulted in a lower atrial fibrosis score. The differences between these two strategies might impact clinical interpretation. ©RSNA, 2024.

Optimizing ventricular tachycardia ablation through imaging-based assessment of arrhythmic substrate: A comprehensive review and roadmap for the future.

Ventricular tachycardia (VT) is a life-threatening heart rhythm and has long posed a complex challenge in the field of cardiology. Recent developments in advanced imaging modalities have aimed to improve comprehension of underlying arrhythmic substrate for VT. To this extent, high-resolution cardiac magnetic resonance (CMR) and cardiac computed tomography (CCT) have emerged as tools for accurately visualizing and characterizing scar tissue, fibrosis, and other critical structural abnormalities within the heart, providing novel insights into VT triggers and substrate. However, clinical implementation of knowledge derived from these advanced imaging techniques in improving VT treatment and guiding invasive therapeutic strategies continues to pose significant challenges. A pivotal concern lies in the absence of standardized imaging protocols and analysis methodologies, resulting in a large variance in data quality and consistency. Furthermore, the clinical significance and outcomes associated with VT substrate characterization through CMR and CCT remain dynamic and subject to ongoing evolution. This highlights the need for refinement of these techniques before their reliable integration into routine patient care can be realized. The primary objectives of this study are twofold: firstly, to provide a comprehensive overview of the studies conducted over the last 15 years, summarizing the current available literature on imaging-based assessment of VT substrate. Secondly, to critically analyze and evaluate the selected studies, with the aim of providing valuable insights that can inform current clinical practice and future research.

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.