Role of Cardiac MRI in Arrhythmogenic Right Ventricular Dysplasia (ARVD)
Cardiac MRI is essential in ARVD diagnosis, providing both diagnostic confirmation and risk stratification with a Class I recommendation (Level B-NR) for patients with suspected ARVD who have ventricular arrhythmias or electrocardiographic abnormalities. 1
Diagnostic Value of Cardiac MRI in ARVD
Cardiac MRI offers several unique advantages in ARVD evaluation:
Key Diagnostic Features on MRI
- Wall Motion Abnormalities: Detection of RV aneurysms, akinesis, dyskinesis, or asynchronous contraction 1
- Ventricular Function Assessment:
- Major criteria: RV wall motion abnormality with either low RVEF (<40%) or dilated RV (end-diastolic volume index >100 mL/m² in men; >90 mL/m² in women)
- Minor criteria: RVEF 40-45% or mildly dilated RV 1
- Tissue Characterization: Visualization of fibro-fatty replacement of myocardium, appearing as bright signal in the RV wall 2
- Left Ventricular Involvement: Detection of LV abnormalities, present in up to 76% of ARVD cases 1
Diagnostic Accuracy
MRI provides superior visualization of the right ventricle compared to other imaging modalities, with high sensitivity and specificity:
- Fat infiltration: 84% sensitivity, 79% specificity
- RV enlargement: 68% sensitivity, 96% specificity
- Regional RV dysfunction: 78% sensitivity, 94% specificity 1
Role in Clinical Management
Risk Stratification
MRI findings help identify patients at increased risk for sudden cardiac death, particularly:
- Significant ventricular dysfunction (RVEF or LVEF ≤35%)
- Extensive RV involvement
- LV involvement (associated with higher risk of ventricular arrhythmias) 1
Treatment Decision Support
MRI findings guide critical management decisions:
- ICD Implantation: Recommended for patients with ARVD and additional risk markers including significant ventricular dysfunction (RVEF or LVEF ≤35%) 1
- Medical Therapy: Beta blockers are recommended for all patients with clinical ARVD diagnosis, regardless of arrhythmia presence 1
- Activity Restrictions: Avoiding intensive exercise is recommended for all patients with ARVD diagnosis 1
Follow-up Imaging
- For patients with definite or possible diagnosis without ICD: Close monitoring as worsening of imaging findings should prompt consideration of ICD implantation 1
- For family members:
- Complete imaging at first visit
- Repeat CMR every 1-2 years in mutation carriers with borderline diagnosis
- Repeat CMR every 3-5 years in patients without clinical, ECG, or morphological findings 1
Comprehensive Diagnostic Approach
ARVD diagnosis requires a multi-modality approach, with cardiac MRI as a cornerstone:
Initial Evaluation:
- Clinical history (family history, arrhythmia symptoms)
- 12-lead ECG and signal-averaged ECG
- 24-hour Holter monitoring
- Exercise stress testing 1
Imaging Workup:
- Cardiac MRI (primary imaging modality)
- Echocardiography (complementary assessment)
- CT heart function and morphology (alternative when MRI contraindicated) 1
Additional Testing (when diagnosis remains uncertain):
- Genetic testing and counseling (Class IIa recommendation)
- Electrophysiological study for risk stratification (Class IIb)
- Endomyocardial biopsy (in select cases) 1
Pitfalls and Caveats
Differential Diagnosis: Important to distinguish ARVD from conditions with similar presentations:
Technical Considerations:
- Fatty infiltration alone is nonspecific and insufficient for diagnosis
- Requires both functional and morphological criteria
- Optimal imaging requires ECG-gated sequences in multiple planes 1
Diagnostic Limitations:
- Current Task Force Criteria primarily address classical RV variant
- Limited specific diagnostic guidelines for LV-dominant forms
- Need for experienced cardiac MRI readers to avoid misdiagnosis 1
In summary, cardiac MRI provides comprehensive assessment of both structure and function in ARVD, allowing for accurate diagnosis, risk stratification, and management guidance, making it the optimal imaging modality for this condition.