Institute for Experimental and Translational Cardiovascular Imaging
Comparative Analysis: ESC 2025 vs ACC 2024 Myocarditis Guidance
Focus on Imaging Recommendations
Documents Compared: 1. ESC 2025: Schulz-Menger J, Imazio M, et al. 2025 ESC Guidelines for the management of myocarditis and pericarditis. Eur Heart J 2025;46:3952-4041 2. ACC 2024: Drazner MH, et al. 2024 ACC Expert Consensus Decision Pathway on Strategies and Criteria for the Diagnosis and Management of Myocarditis. JACC 2025;85:391-431
1. Document Type and Scope
| ESC 2025 | ACC 2024 | |
|---|---|---|
| Type | Clinical Practice Guideline | Expert Consensus Decision Pathway |
| Evidence grading | Class I/IIa/IIb/III + Level A/B/C | No formal classes; consensus-based |
| Disease scope | Myocarditis AND Pericarditis | Myocarditis only |
| Special populations | Pregnancy, sports, paediatric sections | Athletes, genetic considerations |
Implication: ESC provides stronger evidence-graded recommendations; ACC offers more operational decision pathways.
2. Classification Systems
ESC 2025: Risk-Based
- Low risk: Minimal symptoms, normal/mildly reduced LVEF, no arrhythmias, <2 LGE segments
- Intermediate risk: Moderately reduced LVEF, non-sustained arrhythmias, 2+ LGE segments
- High risk: HF symptoms, severely reduced LVEF, sustained arrhythmias, extensive LGE, haemodynamic instability
ACC 2024: Stage-Based (A-D)
- Stage A: Risk factors, no confirmed disease
- Stage B: Subclinical (abnormal imaging, no symptoms)
- Stage C: Symptomatic myocarditis
- Stage D: Advanced (shock, refractory arrhythmias, MCS)
Key difference: ACC explicitly recognises “Stage B” for patients with incidental CMR findings—a group not specifically addressed in ESC.
3. CMR Diagnostic Criteria
Consensus on Updated Lake Louise Criteria (2018)
Both documents endorse the same diagnostic framework, as established by Ferreira et al.¹:
| Criterion Type | Parameters | Both Agree |
|---|---|---|
| T2-based (oedema) | ↑T2 relaxation time, ↑signal on T2W imaging | ✓ |
| T1-based (injury/fibrosis) | ↑native T1, ↑ECV, non-ischaemic LGE | ✓ |
| Diagnosis | ≥1 T2 + ≥1 T1 criterion | ✓ |
| Supportive | Pericarditis signs, systolic dysfunction | ✓ |
Minor Differences in Emphasis
| Aspect | ESC 2025 | ACC 2024 |
|---|---|---|
| Single criterion | “CMR-uncertain” category | “May support diagnosis with less specificity” |
| Stress perfusion | Not specifically addressed in CMR protocol | “Reasonable to include” to exclude ischaemia |
| Strain imaging | Mentioned for echo, less emphasis for CMR | CMR strain (feature-tracking) explicitly mentioned |
4. CMR Recommendation Classes
ESC 2025 (Formal Grading)
| Indication | Class | Level |
|---|---|---|
| CMR for suspected myocarditis | I | B |
| CMR follow-up within 6 months | I | B |
| CMR for pericarditis when clinical diagnosis unclear | I | B |
ACC 2024 (Consensus Statements)
- CMR is “widely endorsed” with “Class 1 indication” in prior guidelines
- CMR is “gold standard for noninvasive tissue characterisation”
- Follow-up imaging recommended but not formally graded
5. Follow-up Imaging Protocols
This is the most significant practical difference.
ESC 2025: General recommendation - CMR follow-up “within 6 months” (Class I, Level B) - No specific stratification by risk category in follow-up protocol
ACC 2024: Explicit risk-stratified protocol (Table 3)
| Risk Category | 2-4 weeks | 6 months |
|---|---|---|
| Low-risk Stage C | Echo (with strain) | Echo |
| Medium/High-risk Stage C or Stage D | Echo + biomarkers + ECG | CMR |
| Athletes | — | CMR (can do at 3 months) |
Implication: ACC provides more actionable guidance for clinical workflow; ESC provides stronger evidence grading but less operational detail.
6. Prognostic Use of CMR
Areas of Agreement
Both documents recognise: - LGE presence = worse prognosis - Persistent oedema = ongoing inflammation - Serial CMR more sensitive than echo/biomarkers for detecting persistent inflammation
ACC Provides More Specific Prognostic Data
Data primarily from Aquaro et al. (n=202 with follow-up CMR, 7-year follow-up)³:
| CMR Finding | n | Cardiac Events | Event Rate | HR (95% CI) |
|---|---|---|---|---|
| Midwall septal LGE pattern | — | — | — | 2.8 (1.1-7.2) |
| Persistent LGE without oedema | — | — | — | 4.5 (1.3-14.5) |
| LGE + oedema on follow-up | 22 | 19 | 86% | — |
| No LGE, no oedema | — | 0 | 0% | — |
ESC mentions prognostic value but does not detail specific hazard ratios. Both guidelines reference the same underlying evidence base.
7. Alternative Imaging: FDG-PET
| ESC 2025 | ACC 2024 | |
|---|---|---|
| Recommendation | Class IIa when echo/CMR inconclusive | Endorsed for difficult cases |
| Preparation | Carb-free diet specified | 12-24h high-fat/low-carb + 6-12h fasting |
| Hybrid imaging | PET-CT/CMR mentioned | PET/CMR “may offer incremental value” |
| Sarcoidosis | Emphasised for extracardiac involvement | Mentioned |
8. Pericarditis Imaging
ESC 2025 (Dedicated Sections)
- CMR Class I for pericarditis when clinical diagnosis uncertain
- Pericardial thickening, oedema, LGE assessed
- Distinction between “inflammatory” and “non-inflammatory” phenotypes
- CT recommended (Class I) for pericardial calcification assessment
ACC 2024
- Pericarditis mentioned only as supportive criterion for myocarditis diagnosis
- No specific pericarditis recommendations
9. Special Populations
Athletes
| ESC 2025 | ACC 2024 | |
|---|---|---|
| Return to sport | CMR follow-up required (6 months implied) | CMR at 3 months acceptable |
| Restriction criteria | Until normalisation of imaging | Until resolved inflammation, normal biomarkers, no arrhythmias |
Genetic Cardiomyopathies
Both documents note that: - LGE patterns may suggest underlying genetic cause - Ring-like patterns → desmoplakin, ARVC/NDLVC - Genetic testing guided by imaging patterns
10. Practical Synthesis for Clinical Use
When to Use Which Document
| Clinical Question | Preferred Source |
|---|---|
| “What class of recommendation?” | ESC 2025 |
| “When exactly should I repeat imaging?” | ACC 2024 |
| “Pericarditis guidance?” | ESC 2025 |
| “Incidental CMR findings, what stage?” | ACC 2024 |
| “Prognostic data from CMR patterns?” | ACC 2024 |
| “FDG-PET indication class?” | ESC 2025 |
Harmonised Protocol Suggestion
Initial workup: 1. Echo (first-line) → All patients 2. CMR (within 2 weeks if possible) → All suspected myocarditis 3. Apply Lake Louise Criteria → Both documents agree
Follow-up: 1. Low-risk: Echo at 2-4 weeks + 6 months (ACC approach) 2. Medium/high-risk: Echo at 2-4 weeks, CMR at 6 months (ACC approach) 3. Athletes: CMR at 3 months (ACC) or 6 months (ESC) 4. Document as Class I, Level B recommendation (ESC grading)
Pericarditis: Use ESC 2025 guidance exclusively
11. Summary Table: Key Recommendations Compared
| Topic | ESC 2025 | ACC 2024 |
|---|---|---|
| CMR for diagnosis | Class I, Level B | Strongly recommended |
| CMR timing | Best within 2 weeks | Depends on imaging techniques |
| Follow-up CMR | Within 6 months (Class I) | 6 months if medium/high-risk; 3 months athletes |
| Low-risk follow-up | CMR at 6 months | Echo at 6 months |
| Prognostic LGE patterns | Mentioned | Detailed (HRs provided) |
| FDG-PET | Class IIa if CMR inconclusive | Alternative when CMR not feasible |
| Pericarditis | Full coverage | Not covered |
| Stage B (subclinical) | Not addressed | Explicitly defined |
12. Conclusion
Both documents represent significant advances in myocarditis imaging guidance and are largely complementary:
- ESC 2025 is the authoritative reference for evidence-graded recommendations and pericarditis
- ACC 2024 provides practical decision pathways and explicit follow-up protocols
For optimal patient care: Use both documents—ESC for recommendation strength, ACC for operational workflow.
Key CMR References (cited by both documents)
Ferreira VM, Schulz-Menger J, Holmvang G, et al. Cardiovascular magnetic resonance in nonischemic myocardial inflammation: expert recommendations. J Am Coll Cardiol 2018;72:3158-76. [Updated Lake Louise Criteria]
Messroghli DR, Moon JC, Ferreira VM, et al. Clinical recommendations for cardiovascular magnetic resonance mapping of T1, T2, T2* and extracellular volume: a consensus statement by the Society for Cardiovascular Magnetic Resonance. J Cardiovasc Magn Reson 2017;19:75. [T1/T2 mapping standards]
Aquaro GD, Ghebru Habtemicael Y, Camastra G, et al. Prognostic value of repeating cardiac magnetic resonance in patients with acute myocarditis. J Am Coll Cardiol 2019;74:2439-48. [Key prognostic serial CMR study; n=202, 7-year follow-up]
Lurz P, Luecke C, Eitel I, et al. Comprehensive cardiac magnetic resonance imaging in patients with suspected myocarditis: the MyoRacer-Trial. J Am Coll Cardiol 2016;67:1800-11. [Multiparametric CMR diagnostic accuracy]
Document prepared for www.cardiac-imaging.org Last updated: January 2026