Statistical Analysis

Continuous variables are presented as mean (SD) and compared with the use of the 1-way analysis of variance; pairwise comparisons are reported if the overall test was significant. Categorical variables were compared with the use of the χ² test or Fisher exact tests.

Survival curves for time-to-event variables were constructed on the basis of all available follow-up data with the use of Kaplan-Meier estimates and were compared with the use of the log-rank test. Multivariable analysis was performed with the Cox proportional hazards model. The PVR was entered into the models in binary (≥moderate vs <moderate PVR). Other variables entered into the multivariable models for adjustment were the Society of Thoracic Surgeons score and the variables that showed a statistically significant difference between the PVR groups. A paired comparison of the rate of PVR at 1 year vs at 30 days was performed using the McNemar test. Statistical significance was defined at 2-sided P value of less than .05. All statistical analyses were performed with the use of SAS software, version 9.4 (SAS Institute Inc).

The database for the study is maintained at the Cardiovascular Research Foundation, where independent analyses can be requested by investigators with statistical assistance provided. All of the analyses were performed with data from the as-implanted population. Data are based on an extract date of September 2, 2016, and December 10, 2015, for the inoperable/high-risk and intermediate-risk cohorts, respectively.