Incremental Utility of First-Pass Perfusion CMR for Prognostic Risk Stratification of Cancer-Associated Cardiac Masses.

Background: Cardiac magnetic resonance (CMR) differentiates cardiac metastasis (C) and cardiac thrombus (C) based on tissue characteristics stemming from vascularity on late gadolinium enhancement (LGE). Perfusion CMR can assess magnitude of vascularity; utility for cardiac masses (C) is unknown.

Objectives: This study sought to determine if perfusion CMR provides diagnostic and prognostic utility for C beyond binary differentiation of C and C.

Methods: The population comprised adult cancer patients with C on CMR; C and C were defined using LGE-CMR: C+ patients were matched to C- control subjects for cancer type/stage. First-pass perfusion CMR was interpreted visually and semiquantitatively for C vascularity, including contrast enhancement ratio (CER) (plateau vs baseline) and contrast uptake rate (CUR) (slope). Follow-up was performed for all-cause mortality.

Results: A total of 462 cancer patients were studied, including patients with (C = 173, C = 69) and without C on LGE-CMR. On perfusion CMR, CER and CUR were higher within C vs C (P < 0.001); CUR yielded better performance (AUC: 0.89-0.93) than CER (AUC: 0.66-0.72) (both P < 0.001) to differentiate LGE-CMR-evidenced C and C, although both CUR (P = 0.10) and CER (P = 0.01) typically misclassified C with minimal enhancement. During follow-up, mortality among C patients was high but variable; 47% of patients were alive 1 year post-CMR. Patients with semiquantitative perfusion CMR-evidenced C had higher mortality than control subjects (HR: 1.42 [95% CI: 1.06-1.90]; P = 0.02), paralleling visual perfusion CMR (HR: 1.47 [95% CI: 1.12-1.94]; P = 0.006) and LGE-CMR (HR: 1.52 [95% CI: 1.16-2.00]; P = 0.003). Among patients with C on LGE-CMR, mortality was highest among patients (P = 0.002) with lesions in the bottom perfusion (CER) tertile, corresponding to low vascularity. Among C and cancer-matched control subjects, mortality was equivalent (P = NS) among patients with lesions in the upper CER tertile (corresponding to higher lesion vascularity). Conversely, patients with C in the middle (P = 0.03) and lowest (lowest vascularity) (P = 0.001) CER tertiles had increased mortality.

Conclusions: Perfusion CMR yields prognostic utility that complements LGE-CMR: Among cancer patients with LGE-CMR defined C, mortality increases in proportion to magnitude of lesion hypoperfusion.