Clinical Scorecard: Distinguishing Acute Non-ST Elevation Myocardial Infarction from Infarct-like Myocarditis through Visual Pattern Analysis: A Comparative Study of Various Cardiac MRI Techniques

At a Glance

Key Highlights

• Clinical differentiation between NSTEMI and infarct-like myocarditis is challenging due to overlapping symptoms and initial findings.
• CMR is the reference standard for non-invasive myocardial tissue characterization, using conventional and parametric imaging techniques.
• Parametric T1 and T2 mapping techniques enhance detection of diffuse myocardial injury and have been integrated into updated Lake Louise criteria.

Guideline-Based Recommendations

Diagnosis

• Use CMR imaging to differentiate ischemic from non-ischemic myocardial injury patterns based on visual pattern analysis.
• Apply updated Lake Louise criteria incorporating parametric T1 and T2 mapping for myocarditis diagnosis.
• Consider early CMR in young patients with low coronary risk to avoid unnecessary invasive coronary angiography.

Management

• Reperfused NSTEMI patients should be managed according to established clinical criteria including troponin elevation and ECG changes.
• Exclude patients with concomitant coronary artery disease or other cardiomyopathies when diagnosing infarct-like myocarditis.

Monitoring & Follow-up

• Perform CMR imaging within days of symptom onset (median 8 days for NSTEMI, 15 days for myocarditis) to assess myocardial injury.
• Use serial troponin and natriuretic peptide measurements to support clinical diagnosis.

Risks

• Potential for missing focal myocardial tissue alterations if T2w imaging is omitted in favor of parametric mapping alone.
• Avoid unnecessary invasive coronary angiography in low-risk patients by utilizing non-invasive CMR techniques.

Patient & Prescribing Data

Patients presenting with acute chest pain suspected of NSTEMI or infarct-like myocarditis

Early CMR imaging can guide diagnosis and management, potentially reducing invasive procedures and optimizing treatment pathways.

Clinical Best Practices

• Combine conventional CMR sequences (cine, T2w, LGE) with parametric T1 and T2 mapping for comprehensive myocardial tissue characterization.
• Perform blinded visual pattern analysis of CMR images to differentiate ischemic from non-ischemic injury without relying solely on quantitative values.
• Exclude patients with phenotypes of cardiomyopathy-like myocarditis or other confounding cardiac conditions to improve diagnostic accuracy.

References

• Clinical presentation of acute myocarditis
• CMR as reference technique for myocardial tissue characterization
• Updated Lake Louise criteria including parametric mapping
• Diagnostic criteria for NSTEMI
• Study protocol and ethics approval