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Evaluation of von Willebrand factor with a fully magnetically levitated centrifugal continuous-flow left ventricular assist device in advanced heart failure

https://doi.org/10.1016/j.healun.2016.05.019Get rights and content

Background

Contemporary continuous-flow left ventricular assist devices (CF-LVADs) are associated with degradation of von Willebrand factor (vWF) high-molecular-weight multimers (HMWMs), a critical factor supporting platelet function. We hypothesized that the HeartMate 3 fully magnetically levitated LVAD, designed to reduce circulatory shear stress, favorably influences these hemostatic parameters.

Methods

Fifteen consecutive HeartMate 3 LVAD patients were compared with 11 consecutive HeartMate II controls. Serial plasma samples were collected pre-implant and on Days 2, 7, 30 and 45 post-operatively. Changes in vWF HMWMs were evaluated by 2 independent, study-blind hematologists and confirmed using densitometry-based computerized software. Ristocetin cofactor (RiCO) and vWF antigen (vWF Ag) were measured using standard protocols with enzyme-linked immunosorbent assay.

Results

HeartMate 3 patients and HeartMate II controls had a mean age of 67.3 ± 1.4 and 52.8 ± 2.5 years, respectively (INTERMACS Profiles 2 to 4 in 93.3% and 91%, respectively). HeartMate 3 group demonstrated a significantly greater preservation of HMWMs compared with the HeartMate II group, with the most prominent decrease occurring by Day 2 post-operatively and sustained through 45 days (71.94% vs 31.16%, p = 0.001). Laboratory values (normalized to baseline) for RiCO activity, vWF Ag and RiCO:vWF Ag ratio remained in the functional range with no statistically significant differences observed between groups.

Conclusion

The HeartMate 3 LVAD is associated with enhanced hemocompatibility compared with the HeartMate II LVAD, as demonstrated by the improved preservation of vWF HMWMs, In contrast, effects on HMWM degradation appeared to be dissociated from functional attributes. Further confirmation of these findings in randomized clinical trials is warranted.

Section snippets

Patients

The study was approved by the institutional ethics committee and informed consent was obtained from all patients before LVAD implantation.

Patients were enrolled at a single center within the HeartMate 3 CE Mark Trial and sequentially within the HeartMate 3 LIS (less invasive study) along with a consecutive control cohort of HeartMate II patients (Figure 1). The procedure was performed either via median sternotomy or as a less invasive implant via left lateral mini-thoracotomy combined with

Patients

The cohorts comprised 15 HeartMate 3 patients and 11 HeartMate II controls, with mean ages of 67.3 ± 1.4 years and 52.8 ± 2.5 years, respectively. Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) profiles were typical of severe advanced heart failure patients receiving LVAD therapy, with 93.3% and 91% of patients, respectively, in Profiles 2 to 4. Detailed baseline characteristics, including indication, mean INTERMACS profile, blood type, cardiovascular history and

Discussion

In this comparative analysis we have demonstrated significant differences in the degree of vWF HMWM degradation between the HeartMate 3 and HeartMate II CF-LVADs. Notably, the effects of the HeartMate 3 on preserving vWF HMWMs provide further corroboration that this device reduces blood element disruption in plasma, similar to observations of reduced red blood cell-related hemolysis. Alterations in HMWMs occur as early as 48 hours and these changes are sustained through 6 weeks. Serial studies

Limitations

There are obvious limitations to this single-center, prospective, observational study with relatively small numbers of patients. We urge caution in interpreting these findings as the patients were not randomized, which resulted in unmatched subsets of patients who were significantly older, with more destination therapy indications and instances of ischemic cardiomyopathy seen in the HeartMate 3 cohort. In addition, the anti-platelet strategy was markedly different between the groups. It is

Disclosure statement

I.N. is a consultant and advisory board member at St. Jude Medical, Inc. J.M. is a consultant for St. Jude Medical, Inc. J.M.C. is a consultant for St. Jude Medical, Inc. M.R.M. is a consultant for St. Jude Medical, Boston Scientific, Teva, Johnson and Johnson and Medtronic. P.S. and K.S.S. are employees of St. Jude Medical, Inc. The other authors have no conflicts of interest to disclosure.

This study was supported by a research grant from the Czech Ministry of Health (RVO VFN 64 165).

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