Distinguishing NSTEMI from Infarct-like Myocarditis via Cardiac MRI Visual Patterns

Overview

This study evaluated the ability of various cardiac MRI techniques to visually differentiate acute non-ST elevation myocardial infarction (NSTEMI) from infarct-like myocarditis. Visual pattern analysis of conventional and parametric CMR sequences demonstrated distinct myocardial injury patterns, aiding non-invasive diagnosis without reliance on invasive coronary angiography.

Background

Acute myocarditis and NSTEMI often present with similar clinical symptoms, complicating early differential diagnosis. Cardiac magnetic resonance (CMR) imaging is the reference standard for non-invasive myocardial tissue characterization, traditionally using late gadolinium enhancement (LGE) and T2-weighted imaging. Recent advances include parametric T1 and T2 mapping, which quantify myocardial relaxation times and have been integrated into updated diagnostic criteria, potentially improving detection of myocardial injury patterns.

Data Highlights

Key Findings

• Visual pattern analysis of conventional CMR sequences (cine, T2w, LGE) reliably differentiated ischemic from non-ischemic myocardial injury.
• Parametric T1 and T2 mapping sequences provided complementary tissue characterization but visual analysis alone may miss focal myocardial alterations.
• The study population included 20 patients each with NSTEMI and infarct-like myocarditis, matched by sex but differing in median age and timing of CMR.
• Omission of conventional T2w imaging in favor of parametric mapping risks missing focal myocardial damage patterns critical for diagnosis.
• Combining cine, T2w, and LGE imaging remains the most effective visual approach for distinguishing NSTEMI from myocarditis without invasive angiography.

Clinical Implications

Early differentiation between NSTEMI and infarct-like myocarditis using non-invasive CMR visual pattern analysis can reduce unnecessary invasive coronary angiography, especially in younger patients with low coronary risk. Maintaining conventional T2w and LGE sequences alongside parametric mapping is advisable to ensure accurate detection of focal myocardial injury patterns. Streamlining CMR protocols should balance efficiency with diagnostic accuracy to avoid missed diagnoses.

Conclusion

Visual pattern analysis of combined conventional CMR techniques effectively distinguishes acute NSTEMI from infarct-like myocarditis. Parametric mapping adds valuable tissue characterization but should complement rather than replace conventional imaging for comprehensive assessment.

References

1. Friedrich et al. 2018 -- Updated Lake Louise Criteria for Myocarditis Diagnosis
2. Thavendiranathan et al. 2012 -- T1 and T2 Mapping in Myocardial Tissue Characterization
3. Luetkens et al. 2016 -- Differentiation of Myocarditis and Myocardial Infarction by CMR