Page 117 - Read Online

Page 10 of 14 Obeid et al. Vessel Plus 2022;6:43 https://dx.doi.org/10.20517/2574-1209.2021.136

Hemocompatibility related adverse events and management of anticoagulation in LVAD patients
Hemocompatibility or the interaction of mechanical surface and blood products lead to the
[57]
activation/destruction of circulating blood elements , including bleeding and TE events. Imamura et al.
studied hemocompatibility related adverse events in 190 LVAD patients with a goal INR 2 to 2.5 regardless
of AF status, and found comparable hemocompatibility adverse events in an AF vs. no AF Japanese LVAD
population within 1 year (17% vs. 24%; P = 0.5) using propensity score matching; their propensity score-
adjusted for age, aspirin use, INR and angiotensin-converting enzyme inhibitors . Worse outcomes were
[33]
documented for patients of advanced age and patients not placed on aspirin therapy.

In LVAD patients with pre-op AF, the predisposition to TE events is conflicting in the literature. Certain
studies have indicated no differences in postoperative TE between patients with pre-op AF and no pre-op
AF [43,58,59] . Enriquez et al. found similar rates of TE events in LVAD patients with and without AF (17%
incidence), although AF patients had higher INR levels (INR 2.3 vs. 1.5 in the four weeks leading to the TE
[14]
events) . Another study noted pre-op AF to be significantly associated with increased TE event rates (38%
vs. 21% TE events at 1 year, P < 0.001) . Interestingly, Noll et al. found TE to be decreased in patients with
[15]
preoperative AF, which appears likely to be attributed to differences in anticoagulation treatment
regimens . All current pooled analyses of population-based studies have indicated that preoperative AF
[31]
does not increase the risk of TE events post-LVAD implantation [49-51] . On the other hand, as previously
discussed, TE events are more common in postoperative AF patients.

The current anticoagulation management recommendations for HeartMate II LVAD patients include
anticoagulation with warfarin to a target INR between 2.0-3.2 with a goal of 2.6, as well as treatment with
aspirin [44,60] . Some authors have used higher INR goals for AF patients [14,51] . Further optimization of the
[61]
surface coating of LVAD devices may reduce TE events . In fact, a lower INR goal of 1.5-1.9 is
recommended in HeartMate III devices .
[62]
Resolution of AF post LVAD implantation
Heart failure may improve after LVAD implantation due to cardiac remodeling. In fact, 1.4% to 5% of
LVAD patients have sufficient cardiac recovery for successful device explantation [14,63-66] . Purportedly, left
ventricular diameter decreases and wall thickness increases due to decreased stretching of the left ventricle
[67]
from LVAD unloading . Biopsies from pre-LVAD and post-LVAD explants showed a decrease in collagen
deposition and decreased myocardial TNF-alfa content . Electrical remodeling was also found after LVAD
[68]
[69]
implantation with decreased QRS . Ventricular unloading and decreased pre-load after LVAD
implantation result in decreased atrial stretching. Left atrial size and volume index were found to be
[17]
significantly decreased post-LVAD implantation as seen on echocardiogram . Patients with AF present
pre-LVAD may recover from AF after implantation due to cardiac remodeling. Rates of AF recovery post-
LVAD implantation range from 18% to 26% [16,33] and 43% from paroxysmal AF .
[17]
[13]
CONCLUSION
Although AF may be associated with worse outcomes in the majority of cardiac surgery patients, AF is a
marker for a more severely ill mechanical circulatory support patient population which may predispose to
increased TE events and bleeding-related events. For mechanical circulatory support patients, at least so far,
there has been no clear association documented between either preoperative or postoperative AF with post-
procedural mortality. This lack of an AF-related impact may be due to the more complex treatment course
and inherently shorter longevity of this unique cardiac surgical patient population. Given that AF and HF
are so intimately associated, moreover, it is difficult to assess the effect of either preoperative or
postoperative AF separately upon patient outcomes.