Abstract 4365771: Exercise Dose During Home-Based Cardiac Rehabilitation and Mortality

Background: Cardiac rehabilitation (CR) improves cardiovascular outcomes. While a dose-response relationship is well established in center-based CR (CBCR), the optimal exercise “dose” in home-based CR (HBCR) remains undefined. Objective: To examine the association between weekly exercise minutes during HBCR and all-cause mortality in a diverse population with cardiovascular disease. Methods: We conducted a retrospective cohort study of 855 adults with qualifying cardiac events who participated in ≥1 HBCR session in Kaiser Permanente Southern California between April 2018 and April 2019. Exercise minutes were tracked via smartwatch over an 8-week program. The primary exposure was average weekly exercise, categorized as <150 vs ≥150 minutes/week[MM1] , per guideline recommendations. Separately, lower weekly exercise thresholds (≥60, ≥90, ≥120 minutes/week) and total cumulative exercise minutes during the HBCR program were examined. Logistic regression estimated adjusted odds ratios (aORs) for all-cause mortality through April 2023, adjusting for age, sex, race/ethnicity, diabetes, heart failure, chronic kidney disease, prior myocardial infarction, depression, BMI category, Charlson Comorbidity Index, and prior-year hospitalization. Results: Of the 855 participants (mean age 63.7 years, 73.2% male, 50.9% non-White), 462 (54.0%) exercised ≥150 minutes/week. Over 4.2 years of follow-up, 78 patients (9.1%) died. Mortality was significantly lower in the ≥150 minutes/week group vs <150 minutes/week (6.5% vs 12.2%, aOR 0.45; 95% CI, 0.27–0.76; p=0.003). Lower mortality was also observed at lower exercise thresholds: aORs for ≥60, ≥90, and ≥120 minutes/week were 0.43 (95% CI, 0.25–0.75), 0.45 (0.27–0.75), and 0.43 (0.26–0.71), respectively, compared to those below each threshold. In cumulative analyses, patients with 1200–1800 minutes (aOR 0.34; 95% CI, 0.15–0.75) and 1800–2400 minutes (aOR 0.34; 95% CI, 0.14–0.86) had lower mortality than those with <600 minutes. Conclusions: Achieving at least 150 minutes of exercise per week during HBCR was associated with a 55% lower odds of all-cause mortality Importantly, even lower amounts of exercise — as little as 60 to 120 minutes per week — were still linked to meaningful survival benefits. These findings underscore the importance of aiming for the widely recommended target of 150 minutes per week, while also suggesting that any amount of regular exercise is better than none.