Daily Physical Activity Measured by Wearable Smartwatch for Patients Undergoing Transcatheter Aortic Valve Replacement: Insights From the SMART TAVR Study

BACKGROUND: This study aims to evaluate limited data about daily physical activity patterns, influential factors, and their association with 1-year mortality or rehospitalization after transcatheter aortic valve replacement (TAVR) through smartwatches. METHODS: Consecutive severe aortic stenosis patients undergoing elective transfemoral TAVR in a Chinese tertiary hospital were enrolled from July 2021 to May 2022 and received a Huawei smartwatch at least 1 day before TAVR. The primary outcome was a composite of all-cause mortality or hospital readmission within 1 year. Linear mixed-effects models were applied to determine influential factors of daily step counts, and Cox proportional hazard regression models were to estimate the association between baseline step counts within 1 month since discharge and composite outcome from months 2 to 12. The dose-response association was assessed using restricted cubic spline curves. RESULTS: A total of 222 participants and 59 469 valid monitoring person-day records were included (mean age, 72.7 years; 61% women). Step counts increased rapidly within the first 2 months ( P <0.001), followed by a slower increase for those without composite outcomes ( P =0.029) and a gradual decrease for those who developed composite outcomes ( P <0.001). In multivariate linear mixed models, a 1-m increase in baseline 6-minute walk test and a 1-month delay after discharge were associated with 4 (95% CI, 1–7) and 170 (95% CI, 145–194) additional step counts, respectively. In restricted cubic spline analysis, the hazard ratio declined progressively until ≈5000 steps per day, after which they leveled. Below 5000 steps, the adjusted hazard ratio of composite outcome associated with each 1000-step count increase was 0.67 (0.50–0.89; P =0.007). However, above 5000 steps, step counts were not significantly associated with the composite outcome ( P =0.645), with a hazard ratio of 1.12 (0.70–1.79). CONCLUSIONS: Daily step counts rapidly increased within the first 2 months post-TAVR. Increased physical activity was associated with a lower risk of 1-year mortality or rehospitalization after TAVR for patients with daily step counts below 5000. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT04454177.