Incidence and Outcomes of Non-Dilated LV Cardiomyopathy in Cardiac MRI Patients

Overview

This retrospective cohort study evaluated the prevalence and prognosis of non-dilated left ventricular cardiomyopathy (NDLVC) compared to dilated cardiomyopathy (DCM) and controls in patients undergoing cardiac magnetic resonance imaging (CMR). The study also assessed differences in LV global longitudinal strain (LV-GLS), left atrial strain (LAS), and extracellular volume fraction (ECV) among these groups, providing novel insights into this emerging cardiomyopathy phenotype.

Background

Cardiomyopathies are classified into genetic, mixed, and acquired types, with evolving criteria and nomenclature. The European Society of Cardiology (ESC) recommends contrast-enhanced CMR as the primary diagnostic tool for suspected cardiomyopathies, including the recently defined non-dilated left ventricular cardiomyopathy (NDLVC). NDLVC is characterized by LV hypokinesia without dilatation or non-ischemic late gadolinium enhancement (LGE) without LV dilatation, distinguishing it from dilated cardiomyopathy (DCM). Despite recognition as a distinct entity, evidence on its prognosis and clinical implications remains limited.

Data Highlights

The study included patients referred for CMR between July 2017 and July 2020, excluding those with ischemic heart disease, hypertrophic or arrhythmogenic right ventricular cardiomyopathy, or isolated LV dilatation without reduced ejection fraction. Patients were categorized into DCM (LV dilatation with low LVEF), NDLVC (low LVEF without LV dilatation or non-ischemic LGE without LV dilatation), and controls (normal LVEF, no LV dilatation, no LGE). CMR protocols included cine imaging, stress perfusion, LGE, and T1 mapping for tissue characterization. Feature-tracking techniques assessed LV-GLS and LAS, while T1 mapping quantified ECV.

Key Findings

• NDLVC was identified as a distinct cardiomyopathy phenotype characterized by LV hypokinesia or non-ischemic LGE without LV dilatation.
• Patients with NDLVC demonstrated differences in LV-GLS, LAS, and ECV compared to both DCM patients and controls, indicating altered myocardial mechanics and tissue characteristics.
• The prevalence of NDLVC among patients undergoing CMR for myocardial perfusion or viability assessment was significant, highlighting its clinical relevance.
• NDLVC showed a prognosis distinct from DCM, though further studies are needed to clarify long-term outcomes.
• CMR with contrast enhancement and advanced tissue characterization techniques is essential for accurate phenotyping and risk stratification in cardiomyopathy patients.

Clinical Implications

Clinicians should consider NDLVC as a separate entity when evaluating patients with suspected cardiomyopathy using CMR. Incorporating LV-GLS, LAS, and ECV measurements can enhance diagnostic accuracy and aid in prognostication. Early identification of NDLVC may influence management strategies and follow-up planning distinct from those for DCM.

Conclusion

This study underscores the importance of recognizing NDLVC as a distinct cardiomyopathy phenotype with unique imaging features and prognostic implications. Contrast-enhanced CMR with advanced functional and tissue characterization is pivotal for accurate diagnosis and guiding clinical management.

References

1. American Heart Association 2006 -- Classification of Cardiomyopathies
2. MOGES Classification 2014 -- Morphofunctional Phenotypes in Cardiomyopathy
3. ESC Guidelines 2022 -- Role of CMR in Cardiomyopathy Assessment
4. Feature-Tracking CMR Studies 2019-2021 -- Prognostic Value of LV-GLS and LAS
5. ESC 2022 Guidelines -- Definition and Classification of NDLVC