Premature Ventricular Contractions (PVCs) and nonsustained Ventricular Tachycardia (NSVT) are well-recognized markers of underlying myocardial disease and are associated with an increased risk of sudden cardiac death (SCD). Prognosis is generally favorable in patients with structurally normal hearts but significantly worse among those with reduced left ventricular ejection fraction (LVEF), ischemic heart disease, and nonischemic cardiomyopathy. Identifying high-risk patients through accurate imaging of myocardial pathology is both challenging and clinically essential. While echocardiography provides reliable assessment of global function and gross structural abnormalities, its sensitivity for detecting subclinical myocardial scar or fibrosis is limited by its lack of detailed tissue characterization capability.
Cardiac magnetic resonance (CMR) imaging has become an indispensable diagnostic and prognostic tool in the evaluation and risk stratification of patients with ventricular arrhythmias, including PVCs and NSVT. CMR uniquely enables direct visualization and quantification of myocardial scar and fibrosis through late gadolinium enhancement (LGE) and complementary T1 mapping techniques. It not only helps identify the underlying etiology based on scar distribution patterns but also provides powerful prognostic information on arrhythmic risk and outcomes. LGE-CMR is firmly established as the reference standard for myocardial scar tissue characterization. Clinically, distinguishing patients with potentially malignant ventricular arrhythmias, especially those at risk for SCD, from the majority with benign courses remains a persistent challenge. Structural heart disease and reduced LVEF remain key determinants of elevated risk within this heterogeneous population. Myocardial scar, visualized by LGE-CMR, has emerged as a powerful independent predictor of adverse outcomes in patients with structural heart disease, surpassing LVEF in prognostic value. ,
In this large, real-world retrospective study, Obeidat et al. analyzed 553 patients over an 11-year period and identified LGE on CMR in 38.6% of cases. Age, male sex, heart failure, and polymorphic VT were independent risk factors for LGE. An underlying etiology was identified in approximately one third of patients, including 12.6% who met criteria for highly probable cardiac sarcoidosis. This is the largest single-health system cohort to date characterizing patients undergoing CMR for PVCs or NSVT. The higher prevalence of LGE compared with prior reports likely reflects a real-world selection bias, whereby clinicians appropriately referred patients with higher pretest probabilities of structural heart disease for advanced cardiac imaging. The notable incidence of cardiac sarcoidosis underscores that this was a clinically high-risk population. The constellation of identified risk factors could help refine patient selection by identifying those with a higher likelihood of structural or inflammatory heart disease.
Despite its substantial clinical value, access to CMR remains constrained by scanner capacity, cost, and the specialized expertise required for image acquisition and interpretation. Optimizing patient selection is therefore essential to ensure that those at highest risk receive appropriate imaging in a timely manner. The study by Obeidat et al. makes an important contribution to these ongoing efforts by improving patient selection toward those with higher pretest probabilities of clinically actionable abnormalities, those in whom CMR findings are most likely to refine diagnosis, guide management, alter clinical trajectory, and ultimately improve outcomes.
Another key finding from this study is the performance of CMR in patients with highly probable cardiac sarcoidosis. Among 18 patients without prior biopsy-proven sarcoidosis, 17 demonstrated LGE on CMR, and subsequent myocardial positron emission tomography (PET) revealed active inflammation in 15 of these cases. These results highlight the incremental value of multimodality imaging in the evaluation and management of cardiac sarcoidosis. When performed concurrently or sequentially, CMR and fludeoxyglucose-18 (FDG) PET provide synergistic diagnostic information: LGE-CMR delineates myocardial fibrosis or scar, while FDG-PET identifies regions of active granulomatous inflammation. Together, these modalities offer a comprehensive framework for disease staging, treatment initiation, and longitudinal monitoring of therapeutic response.
The benefits of CMR extend beyond diagnosis and risk stratification into preprocedural planning and intraprocedural guidance for ventricular tachycardia (VT) or PVC ablation. CMR enables direct visualization and quantification of myocardial scar, providing insight into arrhythmogenic substrate characteristics. LGE-CMR depicts both dense replacement scar and adjacent border or “gray” zones, which frequently harbor VT isthmuses, thus serving as a powerful roadmap for identifying VT substrates. Targeted ablation of these scar regions can reduce procedure time, radiation exposure, and arrhythmia recurrence rates. Comprehensive assessment of the location and extent of LGE is therefore invaluable, although accurate interpretation demands specialized expertise, experience, and close collaboration with electrophysiology colleagues. Emerging 3-dimensional LGE sequences provide volumetric datasets that can be coregistered with fluoroscopic or electroanatomic maps, enhancing procedural precision and efficiency.
The presence, distribution, and extent of myocardial LGE have been consistently associated with ventricular arrhythmia recurrence and SCD in both ischemic and nonischemic cardiomyopathies. Conversely, the absence of LGE is a strong predictor of freedom from malignant arrhythmic events and SCD. Multiple meta-analyses have shown that the presence of LGE confers an approximately 2- to 5-fold higher risk of SCD and sustained ventricular arrhythmias compared with the absence of scar. , These findings are corroborated with device-based studies demonstrating higher rates of recorded arrhythmias or aborted SCD events in LGE-positive cohorts with only moderately reduced LVEF, in contrast to remarkably low event rates in LGE-negative patients despite severe LV systolic dysfunction. Beyond the presence or pattern of LGE, its extent or burden also carries significant prognostic value. A dose-dependent association between myocardial scar burden and major adverse cardiovascular events has been demonstrated across ischemic, nonischemic, and inflammatory cardiomyopathies. Although dedicated clinical trials are awaited, it is highly plausible that LGE extent will have similar prognostic implications in this population. However, the lack of standardized quantification methods and the labor-intensive nature of LGE analysis continue to pose major challenges to its broader clinical adoption.
The results of ongoing prospective, multicenter randomized controlled trials, BRITISH and CMR-GUIDE, are eagerly awaited to test the hypothesis that an LGE-CMR-guided management strategy for primary prevention implantable cardioverter-defibrillator (ICD) placement is superior to current standard-of-care approaches in patients with nonischemic cardiomyopathy (NICM). , Should these trials confirm benefit, LGE-CMR would likely become an integral component of the standard diagnostic workup for patients with NICM undergoing evaluation for primary prevention of SCD. In that context, the study by Obeidat et al. would serve as a valuable reference for prioritizing patient selection and promoting efficient, evidence-based utilization of CMR, particularly in the face of limited imaging capacity and resources.
As the role of CMR continues to expand in clinical practice, its integration into the workup and management of ventricular arrhythmias signals a paradigm shift toward precision medicine—linking anatomical, functional and noninvasive tissue characterization insights to individualized care. The work by Obeidat et al. highlights the potential of strategic CMR utilization to refine diagnosis, guide therapy, and ultimately improve patient outcomes. As ongoing clinical trials further clarify its role in device qualification and prognostication, LGE-CMR stands poised to become not merely an adjunct but a central pillar in the contemporary evaluation and management of ventricular arrhythmias.
Declaration of Generative AI and AI-Assisted Technologies in the Writing Process
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