Data and Cohort Identification
For this analysis, Medicare claims (inpatient, outpatient, and carrier)
and enrollment data were used to identify Medicare fee-for-service (FFS)
beneficiaries implanted with a leadless VVI or transvenous VVI pacemaker
from March 9, 2017 (the first date of Medicare coverage for leadless VVI
pacemakers) through December 31, 2018. Pacemaker implants were
identified using the International Classification of Diseases,
10th Revision, Procedure Coding System (ICD-10) and
the Current Procedural Terminology (CPT) codes for inpatient and
outpatient implants respectively (Appendix Table 1 ). The index
date for outcomes ascertainment was defined as the date of each
patient’s first observed pacemaker implant procedure during the study
period. Patients with evidence of a prior cardiovascular implantable
electronic device (CIED) were excluded to facilitate comparison ofde novo pacemaker implants and to reduce the risk of
misattribution of outcomes related to a prior device. Patients with less
than 12 months of continuous enrollment in FFS Medicare were excluded to
ensure that patient baseline clinical and demographic characteristics
could be adequately captured. Among the patients implanted with a
transvenous VVI pacemaker, the cohort was limited to patients implanted
in facilities with evidence of leadless implants over the same time
period, to increase the likelihood that patients in the study cohort
would have had access to and a chance to receive either system. SeeAppendix Figure 1 for the study cohort diagram.