The goal of this clinical trial is to screen all types of electrocardiographic changes and rhythm disorders in adult patients with a hematologic malignancy requiring a treatment by Bruton's tyrosine kinase (BTK) inhibitor (ibrutinib, acalabrutinib, zanubrutinib) using an insertable subcutaneous cardiac monitor (ISCM) and occurring from inclusion and within 12 months.

This study consists of the implantation of an ISCM at inclusion and before BTK inhibitor initiation. Then patients will have medical visits every 3 months (+/- 7 days) during 12 months and a continuous cardiac telemonitoring using the ISCM.

Inclusion Criteria:

• Adult patients,
• Definite diagnosis of hematologic malignancy requiring a BTK inhibition with ibrutinib, acalabrutinib or zanubrutinib,
• Expected BTK inhibitor duration estimated to be at least 12 months,
• Sinus rhythm at enrolment,
• Willing to sign patient consent form and to comply with scheduled visits, as outlined in the protocol

Exclusion Criteria:

• Age < 18 years old,
• Adults with protective measures (curatorship or tutorship) and vulnerable patients,
• Pregnant or nursing women,
• Permanent atrial fibrillation or long-standing persistent atrial fibrillation as defined by the European Society of Cardiology guidelines,
• Atrial fibrillation on the electrocardiogram at the inclusion visit,
• Previous left atrial ablation or previous maze or maze-like surgery,
• Indication for or patients with a pacemaker or implantable cardioverter-defibrillator at baseline,
• Untreated hyperthyroidism,
• Uncorrected kaliaemia disorders at the inclusion visit,
• Hemoglobin < 8 g/L at the inclusion visit,
• Thrombopenia < 50,000/mm3 at the inclusion visit,
• Active bleeding,
• Myocardial infarction < 1 month,
• Surgery < 1 month,
• Mechanical heart valve,
• Valvular heart disease requiring surgery,
• Inability to follow the required procedures of the clinical investigation plan,
• No signature of patient consent form.