Background: Ibrutinib, a relatively new antineoplastic agent, has multiple cardiovascular effects that are still insufficiently known and evaluated, including subclinical myocardial damage.Study Question: The present study aims to assess the role of the myocardial strain, alone and in combination with cardiac biomarkers, in the early detection of ibrutinib-induced cardiotoxicity.Study Design: We included 31 outpatients with normal left ventricular ejection fraction (LVEF) on ibrutinib, in a tertiary University Hospital between 2019 and 2020, and evaluated them at inclusion and after 3 months.Measures and Outcomes: Data on myocardial strain, cardiac biomarkers [high-sensitive troponin T (hs TnT) and N-terminal probrain natriuretic peptide (NT-proBNP)], and ambulatory electrocardiographic monitoring were collected.Results: Myocardial deformation decreased significantly (P , 0.001) at later evaluation and hs TnT and NT-proBNP increased significantly (P 5 0.019 and P 5 0.03, respectively). The increase in hs TnT correlated with the increase in the left ventricle global longitudinal strain (LVGLS); in other words, it correlated with the decrease in myocardial deformation. No association was found between LVGLS increase and the increase in NT-proBNP. LVGLS modification was not significantly influenced by age, anemia, or arrhythmia burden quantified by 24-hour Holter monitoring (P 5 0.747, P 5 0.072, respectively; P 5 0.812). LVEF did not change significantly during follow-up.Conclusions: In patients on ibrutinib, evaluation of myocardial strain is useful in identifying early cardiac drug toxicity, surpassing the sensitivity and specificity limits of LVEF. In these patients, concomitant assessment of hs TnT increases the predictive power for subclinical myocardial involvement.