Tirabrutinib (ONO/GS-4059), a similarly selective BTK inhibitor, achieved objective responses in 96% of patients with R/R CLL in a Phase I clinical trial, with no atrial fibrillation observed after a median follow up of three years, although one Grade III haematoma has been reported and low grade arthralgias and bruising are common[153,154]. This evidence concerns the gene BTK and atrial fibrillation.