Immune Checkpoint Inhibitor-Related Myocarditis With or Without Concomitant Myopathy: Clinical Findings and Cardiovascular Outcomes.

BACKGROUND

Data on cardiovascular outcomes in patients with both immune checkpoint inhibitor-induced immune-related myocarditis (irMyocarditis) and immune-related myopathy (irMyopathy) are limited.

OBJECTIVES

The aim of this study was to describe clinical characteristics and cardiovascular outcomes in patients with isolated irMyocarditis vs those with concomitant irMyocarditis and irMyopathy.

METHODS

A retrospective cohort study was conducted among patients diagnosed with irMyocarditis at Massachusetts General Brigham between 2015 and 2023. Clinical, laboratory, and imaging characteristics were evaluated, and cardiovascular outcomes were compared between patients with and those without concomitant irMyopathy. The outcomes assessed included acute heart failure requiring diuresis, significant arrhythmias (ventricular arrhythmias and high-degree atrioventricular block), and cardiovascular and all-cause mortality during the index hospitalization.

RESULTS

Among 101 patients with irMyocarditis, 32 (31.7%) had concomitant irMyopathy. Patients with irMyocarditis and irMyopathy had higher high-sensitivity troponin T (median 716 ng/L vs 75 ng/L; P < 0.001) and creatine kinase levels (median 3441 U/L vs 232 U/L; P < 0.001) and were more likely to present with significant arrhythmias (HR: 2.12; 95% CI: 1.13-3.97; P = 0.019). Conversely, patients with isolated irMyocarditis had higher N-terminal prohormone of brain natriuretic peptide levels (median 2043 pg/mL vs 606 pg/mL; P = 0.007), lower left ventricular ejection fractions (median 56% vs 65%; P = 0.008), and a higher likelihood of acute decompensated heart failure (HR: 5.88; 95% CI: 1.45-25; P = 0.013). Cardiovascular and all-cause death during admission were numerically higher in patients with concomitant irMyopathy but were not significantly different between the 2 groups.

CONCLUSIONS

Patients with irMyocarditis and irMyopathy and those with isolated irMyocarditis have distinct biomarker profiles and cardiovascular complications. These differences should be confirmed in larger prospective cohorts to guide tailored management strategies.