Outcomes and Pre-procedure Anticoagulation Regimen
When outcomes were assessed based upon pre-procedure oral anticoagulant
regimen, patients on DOAC demonstrated significant outcome differences
between cohorts. For those on DOAC, the initial weight-based bolus of
heparin increased from 99±25 units/Kg to 118±23 units/Kg
(p<0.001). Therapeutic values on first draw increased from
58% to 77% with protocol guidance (p=0.010). However,
supra-therapeutic values on first ACT draw did significantly increase
from 6% with usual care, to 18% in the protocol guided cohort
(p=0.026). Therapeutic proportions increased from 78% with usual care
to 86% in the protocol guided cohort (OR 1.89, 95% CI 1.36 – 2.64,
p=<0.001). Supra-therapeutic proportions did not significantly
increase from 18% with usual care versus 23% in the protocol guided
cohort (OR 1.44, 95% CI 0.98 – 2.13, p=0.067). Time to therapeutic
ACT, when measured after heparin administration, deceased from 38±20
minutes to 30±17 minutes (p=0.032), and time to therapeutic ACT after
transseptal access decreased from 32±23 with usual care to 19±17 minutes
with protocol guidance (p=0.001).
For those patients receiving pre-procedure warfarin, the dose of heparin
administered in the protocol guided cohort was higher (71±39 units/Kg),
than the recommended protocol dose (50 units/Kg) and compared similarly
to the usual cohort 70±36 units/Kg. As a result, the proportion of
therapeutic ACT values on first draw (100%), and the proportion of
supra-therapeutic (45.5%) values were higher than any of the other
pre-procedure oral anticoagulant strategies. However lower patient
numbers in this subgroup limited meaningful analysis.
For the patients that received no oral anticoagulant before the
procedure, the average bolus dose in the protocol guided cohort was
higher (116±28 units/Kg) than that recommended by the protocol (75 U/Kg)
and compared similarly to the usual cohort 112±10 units/Kg. Despite this
observation, the proportions of therapeutic ACT values on first draw
remained lower (58 %) than the overall protocol guided cohort findings
(77%), and there was no significant change between the usual care and
protocol guided cohorts. This suggests that patients not anticoagulated
pre-procedure may be under dosed by the protocol design. To gain insight
into the proper bolus dosing for this subgroup, we plotted the
weight-based heparin bolus dose versus the first ACT value after
administration, and performed linear regression analysis (Figure 4). As
a result, a weight-based bolus of at least 120 U/Kg may be a more
appropriate for those on no pre-procedure oral anticoagulant, however a
prospective validation of such a weight-based dose is required.