Cardiac Magnetic Resonance in the Diagnostic of Arrhythmogenic left ventricular cardiomyopathy

Description of Clinical Presentation: Arrhythmogenic cardiomyopathy (ACM) is a rare genetic disorder marked by progressive fibrofatty myocardial replacement. Recently described, left ventricular (LV) involvement or the biventricular form of ACM has a heterogeneous genetic basis, typically associated with mutations in genes encoding desmosomal proteins. The clinical spectrum of ACM is variable, ranging from ventricular arrhythmias to sudden cardiac death, particularly in young individuals.

Cardiac magnetic resonance (CMR) plays a central role in the non-invasive diagnosis of left ventricular ACM, enabling detailed assessment of ventricular morphology, function, and tissue characterization according to the 2010 Task Force Criteria. Furthermore, late gadolinium enhancement (LGE) sequences demonstrate high concordance with myocardial biopsy in the detection of fibrosis.

Diagnostic Techniques and Their Most Important Findings: A 40-year-old male with no prior medical history was referred for CMR after presenting non-sustained ventricular tachycardia during an exercise treadmill test. He was asymptomatic at rest, with no history of cardiac disease or family history of sudden cardiac death.



Cardiac MRI demonstrated preserved biventricular dimensions, with cine SSFP showing LV ejection fraction at the lower limit of normality and no regional wall motion abnormalities. T1-weighted imaging revealed hyperintensity in the inferoseptal LV wall, consistent with fat infiltration as confirmed by fat-suppression sequences. LGE identified a ring-like distribution involving the subepicardial and mid-myocardial layers of the LV. Collectively, these findings fulfill the major diagnostic criteria for LV arrhythmogenic cardiomyopathy as defined by the 2010 Task Force.

Learning Points from this Case: This case highlights the role of CMR in diagnosing LV ACM, particularly in patients presenting with exercise-induced ventricular arrhythmias. Even in the absence of overt symptoms or abnormalities on conventional imaging, CMR provided a comprehensive evaluation of LV morphology, function, and tissue characteristics, enabling a definitive diagnosis.

LV ACM presents with heterogeneous phenotypic manifestations. CMR plays a crucial role not only in establishing the diagnosis but also in guiding therapeutic decisions. Early detection through CMR, integrated with clinical history and genetic screening, is essential for patient management, risk stratification, and family evaluation and ultimately making it a life-changing tool in cases such as this.

Figure 1. T1-weighted black-blood imaging. Double inversion recovery (right) demonstrates fatty infiltration of the LV inferoseptal wall, corroborated by fat-suppressed sequences (left).
Figure 2. LGE sequences in standard 3-, 4-, and 2-chamber views, highlighting the extent, pattern, and regional distribution of enhancement in the left ventricular myocardium.
Figure 3. Short-axis LGE images demonstrating circumferential/ring-like late gadolinium enhancement in the left ventricular myocardium