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.