Sedentary Behavior and Cardiac Events and Mortality After Hospitalization for Acute Coronary Syndrome Symptoms: A Prospective Study

BACKGROUND: Patients hospitalized with symptoms of acute coronary syndrome remain at high risk for adverse events postdischarge, highlighting a need for modifiable therapeutic targets. The role of sedentary behavior in this risk and the potential benefits of replacing sedentary time with other activities remain unclear. This study examined the association between sedentary behavior and 1-year cardiac events/mortality among patients evaluated for acute coronary syndrome and estimated risk reductions from substituting alternative activities for sedentary time. METHODS: Patients presenting to the emergency department of a New York City hospital with acute coronary syndrome symptoms were enrolled from 2016 to 2020. Sedentary behavior, light-intensity physical activity, moderate-to-vigorous physical activity, and sleep were measured via a wrist-mounted accelerometer worn for 30 days postdischarge. Cardiac events and all-cause mortality were ascertained 1 year postdischarge via participant contact, electronic health records, and the Social Security Death Index. Participants were categorized into tertiles of sedentary time, with tertile 1 representing the lowest sedentary time and tertile 3 the highest. Cox proportional hazards regression models were used to evaluate associations. RESULTS: Of 609 participants (mean age, 62 years; 52% male, 58% Hispanic), 8.2% experienced a cardiac event or died within 1 year. Mean sedentary time was 13.6 h/d (SD, 1.8). Sedentary time was associated with increased risk of cardiac events/mortality (tertile 2: hazard ratio [HR], 0.95 [95% CI, 0.37–2.40]; tertile 3: HR, 2.58 [95% CI, 1.11–6.03]; P trend =0.011). In isotemporal substitution analyses, replacing 30 minutes of sedentary time (referent) with sleep (HR, 0.86 [95% CI, 0.78–0.95]), light-intensity physical activity (HR, 0.49 [95% CI, 0.32–0.75]), or moderate-to-vigorous physical activity (HR, 0.39 [95% CI, 0.16–0.96]) was associated with lower cardiac event/mortality risk. CONCLUSIONS: Sedentary behavior was associated with increased risk of 1-year cardiac events/mortality among patients evaluated for acute coronary syndrome. Replacing sedentary behavior with sleep, light-intensity physical activity, or moderate-to-vigorous physical activity was associated with lower risk. These findings highlight reducing sedentary behavior as a potential strategy to improve posthospitalization outcomes.