Discussion
Infection prevention strategies during the COVID-19 pandemic have
impacted the workflow significantly at high volume centers performing
catheter ablation of AF. Omission of routine pre-ablation TEE use in
appropriately selected patients is associated with improved workflow
efficiency in the EP laboratory and promotes cost-effective utilization
of health care resources. Additionally, it may reduce the risk of viral
transmission to health care providers. We investigated the safety of a
pre-ablation CT-only imaging protocol for the evaluation of LAA thrombus
at our center to minimize the use of pre-procedural TEE. The following
are the main findings of our study: 1) Implementation of pre ablation
CT-only imaging strategy with selective use of TEE for LAA thrombus
evaluation does not lead to significantly increased CVE risk; 2)
Incidence of peri-procedural CVE is low; 3) Patients with CT imaging
suggestive of LAA thrombus may have TEE imaging that is negative for
thrombus.
Previous studies have investigated the sensitivity and specificity of
pre-ablation CT by comparing it with TEE and reported conflicting
findings3-6,8,11-13.
Our study design precluded head-to-head comparison of pre-ablation CT
with TEE for LAA thrombus evaluation. Nevertheless, our study provides
data for the utility of pre-ablation CT-only approach to LAA thrombus
assessment during the COVID-19 pandemic and supports the findings of
previous reports7-9published during the non-COVID era. Bilchick et
al7, demonstrated the
safety of the pre-ablation CT-only approach to assessment of LAA
thrombus in low-risk patients undergoing AF
ablation7. However,
unlike the current study, they restricted the use of pre-ablation
CT-only protocol for LAA thrombus evaluation to patients with PAF,
without a history of prior CVE/LAA thrombus and
CHA2DS2-VASc score <4. In
contrast to previous
studies7-9, which
included patients with low to intermediate stroke risk based on a
younger age of the study cohort, lower
CHA2DS2-VASc score and lower burden of
comorbidities, our study included patients at a high stroke risk given a
higher burden of comorbidities, older age, and a higher
CHA2DS2-VASc score. Moreover, in our
study, the pre-ablation CT-only protocol for LAA thrombus evaluation was
offered to all the patients regardless of the previous history of
stroke/TIA, type of AF, and CHA2DS2-VASc
score. Additionally, we followed the current practice of minimally
interrupted peri-procedural anticoagulation protocol with DOAC.
Similar to the previously published reports, our results suggest that
the incidence of peri-procedural stroke following atrial fibrillation
ablation remains
low8,14.
However, an interesting finding of our study is the development of
peri-procedural stroke in a patient with unremarkable pre-ablation CT.
Previous
investigations4,5,7-9,11suggest that pre-ablation CT has a high sensitivity for LAA thrombus
detection. Nevertheless, it is possible that our patient had a
false-negative CT result, or that he had an embolic event from a
different source (air embolism from a transseptal sheath; char at the
catheter tip; non-LAA cardiac
thrombus)15,16.
Previously published reports suggest an increased propensity for LAA
thrombus formation in patients with PsAF, and high
CHA2DS2-VASc
scores3,13,17.
Whether patients with PsAF and high
CHA2DS2-VASc scores would benefit from
the routine use of pre-ablation TEE regardless of pre-ablation CT
findings is a topic worthy of further investigation.
The findings of our study should be interpreted with attention to the
associated limitations, including: 1) Those limitations inherent to a
single-center, retrospective, and observational study; 2)We could not
perform the adjusted predictor analysis for CVE given the low event
rates; 3) The anticoagulation protocol at our center may be different
from other centers, limiting the generalization of our findings; 4)
There may be an underestimation of subclinical CVE or silent cerebral
infarcts given the fact that not all the patients underwent
post-procedural cardiac magnetic resonance imaging evaluation.5) We
cannot exclude the possibility of a significant difference in a larger
patient cohort.
In conclusion, based on our experience, implementation of pre ablation
CT-only imaging strategy with selective use of TEE for LAA thrombus
evaluation does not lead to significantly increased CVE risk during the
COVID- 19 pandemic, has greater physician acceptance, and improved
workflow efficiency. Further prospective randomized studies are required
to identify the patients deriving the maximum benefit from pre-ablation
TEE.