Cardiovascular magnetic resonance for therapy monitoring in cardiomyopathies.

Cardiomyopathies are increasingly managed with disease-modifying and phenotype-specific therapies, creating a need for imaging biomarkers that can reliably capture treatment response over time. Cardiovascular magnetic resonance (CMR) is uniquely suited to this role because it combines highly reproducible assessment of cardiac structure and function with detailed tissue characterization. Cine imaging enables serial evaluation of ventricular volumes, mass, and ejection fraction; late gadolinium enhancement identifies focal replacement fibrosis and arrhythmogenic substrate; and native T1/T2 mapping with extracellular volume quantification provides quantitative markers of diffuse fibrosis, oedema, inflammation, and infiltrative burden. In this review, we discuss the role of CMR in therapy monitoring across the spectrum of cardiomyopathies. In dilated cardiomyopathy, CMR tracks reverse remodelling and helps identify persistent scar and non-response despite guideline-directed therapy or cardiac resynchronization. In non-dilated and arrhythmogenic cardiomyopathies, serial tissue characterization helps refine dynamic arrhythmic risk. In hypertrophic cardiomyopathy, CMR documents structural and interstitial changes during treatment with myosin inhibitors and after septal reduction. In amyloid and metabolic/storage cardiomyopathies, mapping techniques are particularly useful for demonstrating stabilization or regression of myocardial disease under targeted treatments. Overall, CMR offers a framework for standardized longitudinal follow-up and for the development of biologically meaningful surrogate endpoints in clinical trials. Wider harmonization of acquisition, analysis, and reporting will be essential to fully integrate CMR into individualized therapeutic decision-making.