Patient Selection
The inclusion criteria for this study were the implantation of a
Medtronic Micra LP with pre-procedural and post-procedural
echocardiographic evaluation and a pacing percentage greater than
twenty. Patients with a history of cardiac resynchronization therapy,
those who did not meet pacing threshold, and lack of interval follow up
data were excluded from the study. One patient was excluded due to lack
of data for device implantation location, and one patient was excluded
due to a myocardial infarction and subsequent sudden cardiac arrest
within one week of his procedure which resulted in a decrease in LVEF
that was deemed not to be secondary to PICM. This sudden cardiac arrest
due to coronary thrombosis was determined not to be a procedural
complication. A total of exactly 200 patients in the National Capital
Region Military Health System received a Medtronic Micra LP from 2017 to
2021. Of these patients, 50 were being paced >20% of the
time, which resulted in 48 patients being included in our analysis after
the two exclusions discussed above. 43 of these 48 patients had an
initial ejection fraction of ≥ 50% and were evaluated for PICM with
both criteria while the remaining 5 patients were evaluated for PICM
under the first criteria only.