Marco J. W. Götte

Ventricular tachycardia (VT) and ventricular fibrillation remain major contributors to sudden cardiac death, with current therapies limited by our incomplete understanding of the arrhythmogenic substrate. This narrative review explores recent developments in computer-aided techniques for characterizing the arrhythmogenic substrate, focusing on post-myocardial infarction VT. High-resolution cardiac imaging now enables detailed visualization of structural abnormalities, including heterogeneous scar architecture and fatty infiltration. Sophisticated invasive mapping techniques provide insights into local electrophysiological properties, while novel non-invasive mapping approaches offer complementary views of global electrical patterns. Integration of these modalities through computational simulations allows for mechanistic insights into arrhythmia initiation and maintenance, particularly in post-myocardial infarction VT, where structural and functional substrates interact in complex ways. Emerging artificial intelligence applications enhance substrate analysis through automated feature extraction and pattern recognition, enabling more sophisticated risk stratification. These computer-aided approaches are advancing from research tools to clinical applications, with early evidence suggesting improved ablation outcomes and better risk prediction. However, significant challenges remain in validation, standardization, and clinical implementation of these innovations. This narrative review highlights recent methodological advances and clinical applications of computer-aided substrate characterization, and conceptualizes future directions towards personalized arrhythmia management, also beyond post-infarction VTs.

Importance: Catheter ablation is a cornerstone therapy for symptomatic ventricular arrhythmias, yet current techniques rely on fluoroscopy and electroanatomic mapping, which provide limited soft-tissue detail and expose patients and staff to ionizing radiation. Real-time magnetic resonance (MR)–guided ablation may overcome these limitations by enabling direct visualization of cardiac anatomy, substrate, and lesion formation, all within a radiation-free environment. Objective: To demonstrate the technical feasibility and safety of the first-in-human real-time MR-guided radiofrequency ventricular ablation procedure. Design, Setting, and Participant: This was a prospective, worldwide-first roll-in case from the ongoing VISABL-VT nonrandomized clinical trial assessing MR-guided radiofrequency ablation of ventricular tachycardia. The procedure and analysis were performed in April 2025 at an academic tertiary care center equipped with a standard 1.5-T MR imaging (MRI) suite and dedicated MR-compatible electrophysiology platform, MR-compatible 12-lead electrocardiographic monitoring and recording system, MR-conditional defibrillator, and real-time catheter tracking integrated with the MRI scanner for synchronized imaging and ablation. The patient was a 73-year-old man with symptomatic, drug-refractory outflow tract premature ventricular complexes (PVCs). Intervention: The ablation was performed under general anesthesia inside the MRI scanner. Intraprocedurally acquired noncontrast 3-dimensional MR angiographic imaging was used to create an anatomical roadmap for the procedure. Real-time catheter tracking and activation mapping were performed using actively tracked diagnostic and ablation catheters. Mapping identified earliest activation first in the posterior septal right ventricular outflow tract, where ablation transiently suppressed PVCs. Ectopy recurred but was ultimately resolved by ablation performed via a retrograde aortic approach in the left coronary cusp. Lesion formation was confirmed via postprocedural MRI. Main Outcomes and Measures: Suppression of PVCs and presence or absence of procedural complications. Results: The procedure was performed under real-time MRI guidance without complications. PVCs were completely suppressed, with no recurrence during 30-minute observation or at 2-month follow-up. Conclusions: This first-in-human case demonstrates that ventricular ablation can be safely and effectively performed entirely under real-time MR guidance. Further evidence from the VISABL-VT trial will clarify clinical utility and long-term outcomes.

Interventional cardiac magnetic resonance imaging (iCMR) offers distinct advantages for guiding complex cardiac procedures, including 3D visualization, soft tissue characterization, and avoidance of ionizing radiation. Transseptal puncture (TSP), essential for left heart access, poses specific challenges under MR-guidance. The development of MR-compatible TSP sets comprising non-ferromagnetic sheaths, dilators, and needles, represents a major step toward safe execution of TSP in the MRI environment. This report provides practical, step-by-step guidance for MR-guided TSP, focusing on imaging strategies and integration of advanced 2D and 3D navigation tools. Real-time cine imaging in dedicated planes enables precise localization of the fossa ovalis, confirmation of septal tenting, and avoidance of adjacent structures. Complementary use of a vendor-neutral MR-compatible 3D navigation system allows dynamic catheter tracking within a segmented static 3D anatomical shell, enhancing spatial orientation and procedural accuracy. Feasibility was demonstrated in a porcine model, where an MR-compatible sheath and trackable dilator were successfully navigated to the interatrial septum and TSP was achieved, enabling left atrial (LA) access. Subsequent mapping confirmed catheter positioning within the LA. Remaining challenges include limited guidewire visibility, low image temporal resolution compared with fluoroscopy, and the investigational status of current MR-compatible TSP sets. These factors must be addressed before clinical translation. In conclusion, MR-guided TSP using dedicated imaging planes and MR-compatible devices is technically feasible and may facilitate future radiation-free left heart interventions. Continued device refinement, including improved passive instrument visibility and active tracking technologies, faster real-time cine imaging, and regulatory approval are critical for safe and widespread clinical adoption.

Participating in lifelong endurance sports is associated with an increased risk of atrial fibrillation (AF), potentially mediated through the process of left atrial (LA) remodeling which includes the progression of atrial fibrosis. This cross-sectional cohort study aimed to investigate LA remodeling including the presence and localization of LA fibrosis in lifelong endurance athletes. 42 master endurance athletes (76% male, age 54 ± 9 years), participating in Ironman races, (ultra) marathons and the Cape Epic Mountain Bike races, underwent clinical assessment with questionnaires, physical examination, and cardiac MRI (CMR). LA function, volumes, and left ventricular volumes were assessed. The extent of LA fibrosis, both global and regional, was derived from post-processed 3D late gadolinium-enhanced images using ADAS 3D. The median LA fibrotic burden as assessed by LGE-CMR was 2.5% (interquartile range, 1.1 to 7.6%). Fibrosis was heterogeneously distributed across the LA wall, with the highest burden observed along the left aspect of the posterior wall. There were no significant associations between LA fibrotic burden and atrial volume or functional parameters. Similarly, no associations were observed between fibrotic burden and sports level or training duration. LA fibrotic burden was significantly higher in participants who competed in long-distance mountain bike races versus participants who did not (7.3% [4.1–9.5] vs. 2.0% [0.5–5.6], p = 0.03). This study demonstrates the limited amount of LA fibrosis in lifelong master endurance athletes, with uneven distribution along the LA wall, most notably around the posterior side of the left inferior pulmonary vein. Participants engaged in long-distance mountain bike races exhibited significantly higher LA fibrotic burden, underscoring the potential impact of specific sports disciplines on LA remodeling, which may play a role in AF development.