Myocardial T1 and T2 Mapping by Magnetic Resonance in Patients With Immune Checkpoint Inhibitor-Associated...

Area of Science:

• Cardiology
• Immunology
• Radiology

Background:

• Myocarditis is a serious complication of immune checkpoint inhibitor (ICI) therapy.
• Limited data exist on the effectiveness of cardiovascular magnetic resonance (CMR) T1 and T2 mapping for diagnosing ICI myocarditis.

Purpose of the Study:

• To evaluate the diagnostic and prognostic utility of CMR T1 and T2 mapping in patients with ICI myocarditis.

Main Methods:

• Retrospective analysis of clinical and CMR data, including T1 and T2 mapping, from an international registry of ICI myocarditis patients.
• Abnormal T1/T2 values defined as 2 SD above site-specific reference values; z-scores calculated.
• Major adverse cardiovascular events (MACE) defined as a composite of cardiovascular death, cardiogenic shock, cardiac arrest, and complete heart block.

Main Results:

• Among 136 patients, 86 had T1 maps and 79 had T2 maps. Elevated mean T1 and T2 z-scores (2.9 and 2.2, respectively) were observed (p < 0.001).
• Abnormal T1 and T2 values were present in 78% and 43% of patients, respectively. 95% met modified Lake Louise Criteria for nonischemic myocardial injury.
• Native T1 values demonstrated excellent discriminatory value for MACE (AUC 0.91) and were independently associated with MACE (HR 1.44 per unit increase in z-score, p=0.004).

Conclusions:

• T1 mapping and the modified Lake Louise Criteria offer significant diagnostic value in ICI myocarditis.
• T1 mapping provides prognostic information regarding MACE in patients with ICI myocarditis.