Abstract 4139355: Improvement in Cardiorespiratory Fitness During Cardiac Rehabilitation: Effect of Smoking Status

Background: Patients who smoke have high-risk cardiovascular profiles. However, it is less well-known whether smoking interferes with gains made during cardiac rehabilitation (CR), such as improvements in cardiorespiratory fitness (VO 2peak ). Hypothesis: Current smoking impedes improvement in VO 2peak during CR. Aims: To determine if smoking status was independently associated with improvement in directly measured VO 2peak . Methods: Data were obtained from a prospectively collected clinical database at the University of Vermont Medical Center. Individuals were included if data was available on entry and exit VO 2peak (measured during a symptom-limited treadmill test) and self-reported smoking status (current, former, or never). Data were extracted on sex, age, body mass index, comorbidity score (severity of exercise-limiting comorbidities) and number of CR sessions completed. Analyses of variance and linear regressions were used to test for associations between the aforementioned variables and change in VO 2peak . Variables with significant associations were entered into multivariable general linear models predicting change in VO 2peak . Results: 2390 patients (111 current, 1114 former and 1165 never smokers) were included. Current smokers differed significantly from former/never smokers, being younger (58.3±10.8 vs. 65.4±10.2 and 64.2±11.2), having higher comorbidity scores (0.8±1.4 vs. 0.6±1.2 and 0.5±1.0), and attending fewer CR sessions (25.3±11.1 vs. 29.5±9.2 and 29.1±9.6). All variables examined were significantly associated with change in VO 2peak except for number of CR sessions attended and remained significantly associated with change in VO 2peak in the multivariable models. Estimated mean improvement (controlling for other variables) in VO 2peak was [mean(SE)]: 1.6(0.3), 2.8(0.1), and 3.2(0.1) mLO 2 *kg-1*min-1 in current, former, and never smokers, respectively. Percent improvement in VO 2peak also varied across groups [11.6(2.1), 16.8(0.7), and 18.2(0.7)%]. In both models, improvement in the current smoking group was significantly less than the other two groups (ps<.05 for all comparisons). Conclusion: Smoking status at CR entry was significantly, independently associated with improvement in VO 2peak during CR.