Walking as a Window to Risk and Resiliency

Feasibility of a Smartwatch Platform to Assess Ecological Mobility: Real-Time Online Assessment and Mobility Monitor

BACKGROUND

Early detection of mobility decline is critical to prevent subsequent reductions in quality of life, disability, and mortality. However, traditional approaches to mobility assessment are limited in their ability to capture daily fluctuations that align with sporadic health events. We aim to describe findings from a pilot study of our Real-time Online Assessment and Mobility Monitor (ROAMM) smartwatch application, which uniquely captures multiple streams of data in real time in ecological settings.

METHODS

Data come from a sample of 31 participants (Mage = 74.7, 51.6% female) who used ROAMM for approximately 2 weeks. We describe the usability and feasibility of ROAMM, summarize prompt data using descriptive metrics, and compare prompt data with traditional survey-based questionnaires or other established measures.

RESULTS

Participants were satisfied with ROAMM's function (87.1%) and ranked the usability as "above average." Most were highly engaged (average adjusted compliance = 70.7%) and the majority reported being "likely" to enroll in a 2-year study (77.4%). Some smartwatch features were correlated with their respective traditional measurements (eg, certain GPS-derived life-space mobility features (r = 0.50-0.51, p < .05) and ecologically measured pain (r = 0.72, p = .01), but others were not (eg, ecologically measured fatigue).

CONCLUSIONS

ROAMM was usable, acceptable, and effective at measuring mobility and risk factors for mobility decline in our pilot sample. Additional work with a larger and more diverse sample is necessary to confirm associations between smartwatch-measured features and traditional measures. By monitoring multiple data streams simultaneously in ecological settings, this technology could uniquely contribute to the evolution of mobility measurement and risk factors for mobility loss.

Functional Status After Transcatheter and Surgical Aortic Valve Replacement: 2-Year Analysis From the SURTAVI Trial

OBJECTIVES

This study sought to evaluate patient-centered metrics in intermediate-surgical-risk aortic stenosis patients enrolled in the SURTAVI (Surgical Replacement and Transcatheter Aortic Valve Implantation) trial treated with self-expanding transcatheter aortic valve replacement (TAVR) or surgery.

BACKGROUND

Studies have shown TAVR to be an alternative to surgery in patients with severe symptomatic aortic stenosis but have focused on "hard endpoints," including all-cause mortality and stroke, rather than on comparative patient-centered metrics, such as functional status and symptom burden.

METHODS

The study analyzed functional status (6-minute walk test [6MWT]) and symptom burden (Kansas City Cardiomyopathy Questionnaire) in 1,492 patients from the SURTAVI trial at baseline, 30 days, 1 year, and 2 years. Patients were categorized by baseline functional status into tertiles of slow, medium, and fast walkers.

RESULTS

Patients with lowest capacity baseline functional status were commonly women, had higher Society of Thoracic Surgeons scores, and had more New York Heart Association functional class III or IV symptoms; reduced baseline functional status was associated with higher aortic valve- and heart failure-related hospitalization at 2 years. There was greater improvement in 6MWT distance in TAVR compared with surgery patients at 30 days (P < 0.001) and 1 year (P = 0.012), but at 2 years, both groups had similar improvement (P = 0.091). The percentage of patients with large improvement in 6MWT was greatest in patients categorized as slow walkers and lowest in fast walkers. Symptom burden improved after TAVR at 30 days and after both procedures at 1 and 2 years.

CONCLUSIONS

In this substudy of patients from the SURTAVI trial, patients receiving TAVR demonstrated a more rapid improvement in functional status and symptom burden compared with patients undergoing surgery; however, both groups had similar improvements in long-term follow-up. (Safety and Efficacy Study of the Medtronic CoreValve® System in the Treatment of Severe, Symptomatic Aortic Stenosis in Intermediate Risk Subjects Who Need Aortic Valve Replacement [SURTAVI]; NCT01586910).

The Physiological Burden of the 6-Minute Walk Test Compared With Cardiopulmonary Exercise Stress Test in Patients With Severe Aortic Atenosis

BACKGROUND

Management of aortic stenosis (AS) relies on symptoms. Exercise testing is recommended for asymptomatic patients with significant AS but is often experienced as forbidding and/or technically unrealistic for patients who are often frail, deconditioned, and intimidated by the exercise test. We compared the physiological burden assessed with gas exchange assessments to gauge and respiratory exchange ratio (RER) of a 6-minute walk test (6MWT) to a cardiopulmonary exercise stress test (CPET) in patients with severe AS. peak oxygen utilization.

METHODS

Adults with equivocal symptoms and severe AS (1-aortic valve area [AVA] ≤ 1.0 cm2 or AVA index ≤ 0.6 cm2/m2, 2-peak aortic jet velocity ≥ 4.0 m/sec, 3-mean transvalvular pressure gradient ≥ 40 mm Hg by rest or dobutamine stress echocardiography, or 4-aortic valve calcification ≥ 1200 in women or ≥ 2000 AU in men) were studied. All participants completed both a 6MWT and symptom-limited progressive bicycle exercise testing. Breath-by-breath gas analysis and 12-lead electrocardiography were completed during 6MWT and CPET. Results: Eleven patients were studied. Patients walked on average 330 ± 75 m during the 6MWT and achieved a maximal workload of 48 ± 14 watts during the CPET. During the 6MWT, peak maximal oxygen uptake (V ˙ O2peak) was 12.8 ± 2.5 vs 10.8 ± 4.2 mL/kg/min during the CPET. Respiratory exchange ratio exceeded 1.1 in both the 6MWT and CPET indicating similarly high exertion. Compared with the CPET, a larger proportion of the 6MWT was performed at a high intensity level (78% ± 28% vs 33% ± 24% at > 85% V̇O2peak; P = 0.004).

CONCLUSIONS

The 6MWT with breath-by-breath gas analysis was well tolerated and able to achieve a physiological intense RER andV ˙ O2peak that are similar to symptom-limited CPET in patients with severe AS.

Gait Speed and 1-Year Mortality Following Cardiac Surgery: A Landmark Analysis From the Society of Thoracic Surgeons Adult Cardiac Surgery Database

Background

In older adults undergoing cardiac surgery, prediction of downstream risk is critical. Our objective was to determine the association of 5‐m gait speed with 1‐year mortality and repeat hospitalization following cardiac surgery.

Methods and Results

In this prospective cohort of patients undergoing cardiac surgery at centers participating in the Society of Thoracic Surgeons Database with gait speed recorded, we examined all‐cause mortality using a landmark analysis at 0 to 30, 30 to 365, and >365 days, as well as repeat hospitalization. The cohort consisted of 8287 patients (median age, 74 years; 32% females). At 1 year, survival was 90% in the slow (<0.83 m/s), 95% in the middle (0.83–1.00 m/s), and 97% in the fast (>1.00 m/s) gait speed tertiles, and risk of hospitalization was 45%, 33%, and 27%, respectively (both P<0.0001). After adjustment, gait speed remained predictive of mortality (hazard ratio, 2.16 per 0.1‐m/s decrease in gait speed; 95% confidence interval, 1.59–2.93) and rehospitalization (hazard ratio, 1.71 per 0.1‐m/s decrease in gait speed; 95% confidence interval, 1.45–2.0). In a landmark analysis, the effect of slow gait speed on mortality was most marked from 30 to 365 days after surgery, where each decline in 0.1 m/s of gait speed conferred a 2‐fold increased risk of mortality.

Conclusions

Gait speed is a simple tool to screen for frailty and identify older adults at risk for adverse events in the early and midterm postoperative periods.