Early Detection of Pump Thrombosis in Patients With Left Ventricular Assist Device

Abstract

Pump thrombosis (PT) is a serious adverse event in patients receiving left ventricular assist devices (LVAD). The study aims to determine whether pump parameters and clinical data may enable early detection of PT. This retrospective study included 88 patients who received an LVAD between 2012 and 2015 among which those with intra-PT were identified. In a propensity score–matched control group observation, time periods were matched with time before thrombosis. International normalized ratio (INR) time in therapeutic range (TTR) and lactate dehydrogenase (LDH) were analyzed for 60 days preceding PT. Furthermore, pump data (power, flow, and speed) in HeartWare ventricular assist devices (HVAD) patients were analyzed 7 days before PT using a mixed-design analysis of variance to investigate temporal changes in pump data. Pump thrombosis occurred in 15 patients (13 males, age 58 ± 10 years, 7 HeartMate II and 8 HVAD). International normalized ratio therapeutic range (2.0–3.0) and acetylsalicylic acid daily doses (100–200 mg) were similar for both groups, but patients with PT had lower TTR (36% vs. 65%; p = 0.025). No significant difference in LVAD power between groups was seen at baseline (p = 0.31), and power did not change in the control group over time (p > 0.99). Lactate dehydrogenase increased already 1 week prior PT and power from 4.4 ± 0.8 W at baseline to 4.9 ± 0.8 W (p = 0.007) 2 days before readmission and to 6.5 ± 1.8 W (p = 0.015) at readmission. Pump thrombosis is associated with a lower percentage of INR TTR and elevated LDH before the event. A better monitoring of pump parameters would enable PT detection already up to 2 days in advance.

Pump position and thrombosis in ventricular assist devices: Correlation of radiographs and CT data

“…To reduce the selection bias, propensity score matching was applied, which was derived from a non-parsimonous logistic multivariate model. Patients were selected based on one-to-one nearest neighbor matching using a wide range of demographic data, clinical data, and preoperative risk factors 34 to minimize effects of confounding factors. An optimal selection was made among these candidates, resulting in a smaller (15 vs 15 patients) total cohort, but the comparison data sets all have the appearance of a randomized study.…”

The left ventricular assist device as a patient monitoring system

“…On the other hand, the decrease of circadian variations has been associated to thrombotic events, potentially anticipating clinical manifestation by 12±6 days (57). Pump thrombosis can also be observed and managed with the help of log-file analysis of average motor power data (58)(59)(60). A steady decrease of pump flow together with a progressive disappearance of circadian rhythm can be also indicative of GI bleeding and resulting hypovolemia, as shown in Figure 8.…”

Anticoagulant treatment and bleeding complications in patients with left ventricular assist devices

“…Not surprisingly, the risk of thrombotic events is inversely related to INR levels with the highest event rate reported for an INR range <1.5 [53]. In addition, it has been demonstrated that LVAD patients developing pump thrombosis spent significantly less time within therapeutic INR range in the 2 months prior to the event compared to those without pump thrombosis [54]. Bridging LVAD patients with subtherapeutic INR levels with heparin treatment may therefore, be considered.…”