Outcomes
This analysis focuses on chronic complications, device reinterventions,
heart failure-related hospitalizations and all-cause mortality at 3
years as acute complications have been reported
previously.2 Chronic complications have been reported
previously and include those prospectively defined using the relevant
ICD-10 and CPT codes as complications most likely attributable to the
implant procedure or device itself that may continue to occur or persist
outside the time period of the implant procedure. These included
embolism, thrombosis, device-related complications, including device
breakdown, dislodgment, infection, and pocket complications,
pericarditis, and hemothorax (Appendix Table 2 ). Device
reinterventions were identified using the relevant procedure codes and
were defined as system revision, lead revision or replacement, system
replacement (e.g. replacing a leadless VVI with another leadless VVI),
system removal, switch to the alternative type of system (i.e. switch
from leadless VVI to transvenous VVI or transvenous VVI to leadless
VVI), upgrade to a dual chamber system, or upgrade to a cardiac
resynchronization therapy (CRT) device. A post-hoc composite endpoint of
any reinterventions requiring a wholly new device (composite of
replacement, system switch, removal, upgrade to dual chamber system,
upgrade to CRT) was also defined. The rationale for defining this
post-hoc endpoint was that these types of reinterventions are
particularly burdensome and costly to patients, providers, and payers.
Date of death was determined from the Medicare Beneficiary Summary File.
A heart failure-related hospitalization was defined as an inpatient
hospitalization with an ICD-10 diagnosis code for heart failure in the
primary position on an inpatient claim following discharge from the
implant procedure hospitalization or encounter. A composite endpoint of
heart failure hospitalization or death was also defined, as this is a
common measure in the heart failure literature.8 These
heart failure hospitalization endpoints were newly-defined for the
present analysis and were not previously reported on in the Micra CED
Study.2,3 Similar to reporting on upgrades to CRT,
heart failure hospitalizations can provide evidence of and serve as a
proxy measure for pacing-induced cardiomyopathy or potentially worsening
heart failure among pacemaker patients and may be useful for evaluating
long-term device performance. This novel endpoint is designed to be
hypothesis generating and is the first health care utilization-related
endpoint reported from the Micra CED Study. Medicare claims were
available through December 31, 2020; patients alive and without an event
were censored on that date.