Management of anticoagulant therapy using a portable point-of-care international normalized ratio device and social networking service in a patient with a left ventricular assist device

Device infection and stroke are still frequently reported as complications of left ventricular assist devices, and strict management of anticoagulation therapy is sometimes difficult at the time of infection status. We report the case of a 55-year-old man with a HeartMate II (Abbott, Inc., Abbott Park, IL, USA) as a bridge to cardiac transplantation. The patient measured his prothrombin time-international normalized ratio (PT-INR) by himself using a point-of-care device at home and reported the result promptly on a social networking service (SNS). Physicians instructed the patient on how to adjust his dose of warfarin based on the result and suggested the next time of measurement on the SNS. Until cardiac transplantation, we adjusted the dose of warfarin 106 times using the SNS because of unexpected PT-INR fluctuations caused by antibiotics. The time in the therapeutic range was maintained at 83.2% without complications, including major bleeding, stroke, or pump replacement; however, there was transient intra-pump thrombosis triggered by severe dehydration due to hyperthyroidism.