Anticoagulation Control in Patients With Ventricular Assist Devices

Abstract

Anticoagulation control has been associated with risk of thromboembolism and hemorrhage. Herein, we explore the relationship between anticoagulation control achieved in Left Ventricular Assist Device Patients (LVADs) and evaluate the association with risk of thromboembolism and hemorrhage. Patients (aged 19 or older) with a continuous flow LVAD placed from 2006–2012. Proportion of time spent in target range (PTTR) for INR was estimated with target range of 2.0–3.0. PTTR was categorized into PTTR>60%, PTTR≥50<60% and PTTR<50%. The relationship between PTTR and thromboembolism and hemorrhage was assessed. The 115 participants contributed 624.5 months of follow-up time. Only 20% of patients achieved anticoagulation control (PTTR >60% for INR range of 2–3). After adjusting for chronic kidney disease, history of diabetes, history of atrial fibrillation and age at implant, compared to patients with PTTR<50%, the relative risk of thromboembolism in patients with PTTR≥60% (HR 0.37, 95%CI 0.14–0.96, p=0.042) was significantly lower, but not for patients with a PTTR of ≥50<60% (HR 0.21, 95%CI 0.02–1.82, p=0.16). The relative risk for hemorrhage was also significantly lower among patients with a PTTR≥60 % (HR 0.45, 95%CI 0.21–0.98, p=0.045), but not among those with PTTR of ≥50<60% (HR 0.47, 95%CI 0.14–1.56, p=0.22). This current study demonstrates that LVAD patients remain in the INR target range an average of 42.9% of the time. To our knowledge, this is the first report with regard to anticoagulation control as assessed by PTTR and its association with thromboembolism, hemorrhage or death among patients with VADs.

Predictors of Warfarin Time in Therapeutic Range after Continuous‐Flow Left Ventricular Assist Device

“…The average TTR for all patients in this study was 52.6%, which is consistent with other recently published data in patients with CF‐LVADs . Maintenance of TTR is difficult in this patient population because of individual variation in the pharmacodynamics of warfarin therapy, and it is further compounded by the complexities of LVAD management of issues such as driveline infections and heart failure exacerbations from right ventricular dysfunction.…”

“…The average TTR for all patients in this study was 52.6%, which is consistent with other recently published data in patients with CF-LVADs. 2,3 Maintenance of TTR is difficult in this patient population because of individual variation in the pharmacodynamics of warfarin therapy, and it is further compounded by the complexities of LVAD management of issues such as driveline infections and heart failure exacerbations from right ventricular dysfunction. These LVAD-specific factors influence anticoagulation control and can contribute to the higher INR variability seen in this population despite the strict INR monitoring protocols many institutions have established.…”

“…Previous studies demonstrated that patients taking warfarin with a low time in therapeutic range (TTR) have increased thromboembolic and bleeding events. [2][3][4] Additionally, prior publications showed that patients with CF-LVADs spend less time in therapeutic range (31-51%) than patients receiving warfarin for other indications (64-81%). 5 Considering these circumstances, it is important to understand the risk factors that may prevent patients from maintaining a therapeutic INR.…”

Meta‐Analysis of Time in Therapeutic Range in Continuous‐Flow Left Ventricular Assist Device Patients Receiving Warfarin

“…Five studies published between 2011 and 2017 as full‐text articles were included in this meta‐analysis (Table ; 3,4,6–8). All studies were single‐center, retrospective investigations that calculated TTR using the Rosendaal linear interpolation method.…”

“…Halder et al examined TTR in 51 CF‐LVAD recipients and showed that patients who experienced a bleeding event spent a higher proportion of time above therapeutic range than those that experienced a thrombotic event (41% vs. 17%; P = 0.007). Boehme et al demonstrated an increased risk of thromboembolism and hemorrhage in 155 CF‐LVAD patients with TTR less than 50% versus those with TTR greater than 60% (HR: 0.37; 95% CI: 0.14–0.96; and HR: 0.45; 95% CI: 0.21–0.98, respectively). Poor anticoagulation control (TTR less than 50%) was also identified as an independent predictor of thromboembolic events (HR: 2.91, 95% CI: 1.18–7.14; P = 0.02) in this cohort .…”