Is the following definition acceptable for identifying lupus myocarditis in a research study: presence of myocarditis symptoms (dyspnea, chest pain, palpitations) and either fulfillment of the 2009 Lake Louise criteria on cardiac magnetic resonance imaging (CMR) or left ventricular T1‑mapping values greater than the mean plus two standard deviations of a normal population?

Is This Definition Acceptable for Identifying Lupus Myocarditis in Research?

Your proposed definition is problematic and should be modified—it relies on outdated 2009 Lake Louise criteria when the 2018 updated criteria are now the standard, and using T1-mapping alone as an alternative criterion is insufficient and not aligned with current expert recommendations.

Critical Issues with Your Proposed Definition

Problem 1: Using Outdated Diagnostic Criteria

The 2009 Lake Louise criteria you reference have been superseded by the 2018 Updated Lake Louise Criteria, which represent the current expert consensus for diagnosing myocarditis 1. The updated criteria require a "2 out of 2" approach rather than the older "2 out of 3" framework, fundamentally changing diagnostic accuracy.

Problem 2: T1-Mapping as a Standalone Alternative

Your definition suggests using elevated T1-mapping values (>mean + 2SD) as an alternative to the Lake Louise criteria. This is methodologically flawed because:

• Native T1 mapping alone cannot differentiate acute inflammation from chronic injury or diffuse fibrosis 1
• T1 is highly sensitive but not specific for active myocarditis—it detects increased free water content from multiple causes including chronic scarring 1
• The 2018 guidelines explicitly state that T1 mapping should be paired with T2-based imaging to augment specificity for active inflammation 1

Problem 3: Special Considerations for Lupus Myocarditis

Recent evidence demonstrates that the Lake Louise criteria have reduced sensitivity (32-65%) in autoimmune rheumatic disease-associated myocarditis compared to viral myocarditis, particularly in patients receiving immunosuppressive therapy 2. This is critical for lupus populations.

Recommended Definition for Research

For a research study identifying lupus myocarditis, you should use:

Primary Diagnostic Approach (2018 Updated Lake Louise Criteria):

Presence of myocarditis symptoms (dyspnea, chest pain, palpitations) AND fulfillment of both of the following CMR criteria 1:

1. One T2-based marker for myocardial edema:

   • Elevated regional or global myocardial T2 relaxation time, OR
   • Increased signal intensity on T2-weighted images

2. One T1-based marker for myocardial injury:

   • Non-ischemic late gadolinium enhancement (LGE), OR
   • Elevated native T1 relaxation time, OR
   • Elevated extracellular volume (ECV)

Important Caveats for Lupus Populations:

Recognize that in lupus patients on immunosuppression, meeting only one criterion may still represent true myocarditis 2. The study by 2 found that requiring both criteria yielded 100% specificity but only 32% sensitivity in autoimmune disease, while accepting either criterion increased sensitivity to 65% with 76% specificity.

Consider a tiered diagnostic approach:

• Definite lupus myocarditis: Both T2-based AND T1-based criteria positive
• Probable lupus myocarditis: One criterion positive in the setting of elevated troponin and appropriate clinical context, particularly if the patient is receiving immunosuppressive therapy

Additional Supportive Criteria to Document:

• Elevated cardiac biomarkers (troponin, NT-proBNP) 3
• ECG abnormalities 3
• Exclusion of acute coronary syndrome 1
• Active SLE disease activity (elevated SLEDAI score, hypocomplementemia) 4
• Presence of specific autoantibodies if relevant 3

Why Not Use Your Original Definition

The combination you proposed (symptoms + 2009 criteria OR elevated T1) creates a heterogeneous diagnostic group that mixes:

• Patients with definite acute myocarditis (meeting updated criteria)
• Patients with chronic myocardial changes (elevated T1 from fibrosis)
• Patients with subclinical disease of uncertain significance

This lack of diagnostic precision will compromise your research validity and make your findings difficult to compare with other studies using standardized criteria.

Practical Implementation

For your research protocol, explicitly state:

• Which T1 and T2 mapping sequences and thresholds you're using (these vary by scanner and technique) 1
• Whether you're using published or local normal values
• How you're defining "regional" abnormalities (≥10 contiguous pixels per guidelines) 1
• Your approach to patients meeting only one criterion given the lupus-specific sensitivity issues 2

The field has moved beyond the 2009 criteria—your research should reflect current diagnostic standards while acknowledging the unique challenges of diagnosing myocarditis in autoimmune disease populations.