Transthyretin cardiac amyloidosis (ATTR-CA) leads to myocardial infiltration, affecting prognosis and survival. Diagnosing early-stage ATTR-CA remains challenging due to its subtle manifestations. This study investigates subclinical myocardial alterations in asymptomatic ATTR mutation carriers (ATTR-MC) using advanced cardiac magnetic resonance (CMR) techniques, including T1 mapping and myocardial strain analysis. A retrospective cohort of 60 subjects was analyzed, comprising 20 ATTR-CA patients, 20 asymptomatic ATTR-MC, and 20 controls. Standard CMR parameters were compared alongside myocardial strain analysis. Results indicated that despite preserved ejection fraction and myocardial morphology, ATTR-MC exhibited significantly impaired left ventricular global longitudinal strain (LV GLS), left atrial reservoir, conduit, and booster pump strain (LA RS, CS, and BPS) compared to controls. However, native T1 and extracellular volume (ECV) values remained within normal ranges, distinguishing early dysfunction from overt amyloid deposition seen in ATTR-CA. These findings suggest that myocardial strain analysis could serve as an early biomarker for subclinical ATTR-CA, offering a potential target for selecting patients who may benefit from early intervention. Implementing CMR-derived strain parameters in clinical practice may improve risk stratification and timely therapeutic decisions in ATTR-MC.