Limitations
This study has several limitations. The observational design did not
allow for control of several important variables, in particular the
heparin dose received, which was at physician discretion. In the
protocol guided arm, there was operator adherence to the proposed bolus
in those on pre-procedure DOAC. However, in the protocol guided arm the
average bolus dose administered in those who received pre-procedure
warfarin and no anticoagulant were greater than the protocol recommended
bolus dose. There was an absolute increase of 17% in the proportion of
heparin given prior to transseptal puncture in the protocol guided
cohort, and an absolute decrease of 17% in the proportion of heparin
bolus which were split before and after transseptal puncture. The change
in bolus modality and timing may have been an additional effect of the
protocol on physician practice, and certainly affected the reduction in
time from transseptal to therapeutic ACT. However, a reduction in time
to therapeutic ACT persisted when measured from time of heparin
administration Anticoagulant therapy and dosing was prescribed at the
operator’s discretion, and not prospectively assigned, possibly
introducing selection bias. Additionally, there is assumption that
patients were adherent to preoperative instructions for managing their
anticoagulant therapy. Finally, the ACT machine did not provide an
absolute value for values over 400, rather a truncated value.