The role of peak VO2 in prognosis in patients undergoing a Cardiac Rehabilitation program

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Peak oxygen uptake (peak VO2) is a strong predictor of mortality and is commonly used in the evaluation of patients for cardiac transplantation. Although guidelines suggest a peak VO2<14mL/(kg.min) as a cut-off for transplant and a peak VO2<12mL/(kg.min) in patients under beta-blockade (BB), recent data emerged, questioning the suitability of such cut-offs. Purpose To correlate CPET and echo data with outcomes after CR programs and to determine the best cut off for peak VO2 in a population with a high percentage of BB therapeutics. Methods Single center prospective study which included consecutive pts who were participating in a centre-based CR program lasting 8-12 weeks from 2019 to 2021. The CR program included initial evaluation by cardiologist and rehabilitation specialist with collection of clinical characteristics, three times weekly supervised exercise sessions, appointment with rehabilitation nurse, nutritionist and psychologist and educational sessions. Lab tests, echocardiogram and CPET were done before and after completion of the program. Multivariate analysis with Cox regression was used to correlate with events and survival was analyzed with Kaplan Meier curves. Results We analyzed 349 patients who underwent CR (82% male, mean age 60 ±11,4 years). The majority was referred for ischemic heart disease (83%) followed by valvular heart disease (7%). Mean follow-up was 36,7± 19,2 months. During FUP, 7,2% pts had CV related admissions (n=25), 4 of which were myocardial infarction. Sixteen pts died (4,6%) of which 2,3% were from cardiovascular causes. On multivariate analysis peak VO2 (HR 0.827 CI 95% 0.72-0.949, p=0.07), ejection fraction (HR 0.962 CI 95% 0.933-0.991, p=0.01) and test duration (HR 0.756 CI 95% 0.712-0.778, p=0.01) correlated with hospital admissions. Regarding mortality only peak VO2 showed statistical significance (HR 0.8 CI 95% 0.69-0.93, p=0.04). On this matter we further analyzed the best cut-off in predicting events: a peak VO2 > 14 mL/(kg.min) was a better predictor of event free-survival in these patients when comparing with a peak VO2 of 12 mL/(kg.min). Conclusions Cardiac rehabilitation has an established impact in prognosis. Echo and CPET data obtained at the beginning of the CR program can be used to identify patients who might benefit from a more closed surveillance in order to reduce risks of hospitalization. Moreover, in our population, a peak VO2 cut-off of 14mL/(kg.min) seemed to better correlate with event-free survival.