Impact of time in therapeutic range after left ventricular assist device placement: a comparison between thrombus and thrombus-free periods

The association between time in therapeutic range (TTR) and clinical outcomes in patients with left ventricular assist devices (LVADs) on chronic warfarin therapy is not well understood. This study assessed TTR using the Rosendaal Method prior to suspected or confirmed pump thrombosis or ischemic stroke. Each patient served as their own control. Characteristics and TTR in 1, 2, and 3 months prior to thrombus (thrombus period) were compared to a thrombus-free period during 6 months to 3 months prior to thrombus (control period). There were 30 thrombus events observed in 25 patients for a rate of 0.06 events per LVAD day. Average TTR (target INR = 2–3) over 3 months for patients combined in both the thrombus and control time period was 53.4%. TTR (target INR = 2–3) was 11.4% lower 1 month prior to thrombus than the comparable month in the control period (p = 0.029). The TTR (target INR = 1.8–2.5) was 11.8% lower in the thrombus time period compared to the control time period 2 months prior to thrombus (p = 0.032). Our study found an increased risk of thrombosis with lower TTR in months leading up to thrombus compared to a thrombus-free period.