Statistical Analysis
The statistical adjustments used in the analysis were prespecified and have been used for all comparative analyses of the Micra CED Study cohort. Propensity score overlap weights9,10 were used to account for differences in baseline and encounter characteristics between the leadless-VVI and transvenous-VVI cohorts. Unadjusted and overlap-weight adjusted 3-year complication, reintervention, and heart failure hospitalization rates were estimated using the cumulative incidence function. Fine-Gray competing risk models were used to compare the unadjusted and adjusted risk for 3-year chronic complications, device reinterventions, and heart failure hospitalizations between study groups, and Cox proportional hazards models were used to compare all-cause mortality and the composite of heart failure hospitalization and all-cause mortality through 3 years. A sub-analysis of the heart failure hospitalization endpoints was also conducted among patients in the study cohort without a history of heart failure at baseline. Because heart failure hospitalizations are not a primary or pre-specified secondary endpoint of the Micra CED Study, the inclusion of this endpoint is designed to be hypothesis-generating. Thus, no statistical correction for the additional endpoint was made and all endpoints were evaluated at a significance level of P<.05 and all P values were 2-tailed. Events occurring in between one and 10 patients were suppressed to protect beneficiary privacy as required by CMS.11 All statistical analyses were conducted in SAS version 9.4 (SAS Institute).