57Impact of cardiac rehabilitation programs among myocardial infarction survivors not undergoing revascularization

Abstract

Introduction: Cardiac rehabilitation programs (CRP) are pivotal in the management of myocardial infarction (MI). Patients not undergoing revascularization, however, are substantially less referred to these programs. In addition, this group's functional characterization remains lacking. The aim of this work was to assess the impact of a contemporary CRP in MI survivors not undergoing revascularization during hospitalization. Methods: Retrospective cohort study of patients admitted to the Cardiology Department of a tertiary hospital for a MI, between 09/2013 and 03/2017. Only those who completed a phase II CRP [and performed a symptom-limited cardiopulmonary exercise test (CPET) at the beginning and end of this program] were included. We analyzed demographic, clinical, analytical and functional data. CPET parameters under study were peak oxygen consumption (pVO2), percentage of pVO2 (pVO2%) and respiratory exchange ratio (RER). Results: A total of 349 patients were included (age 59.0±10.5 years, 81.2% male sex, 65.9% ST elevation MI). Of these, 44 (12.6%) were not revascularized during hospitalization (NR group). The NR group had significant differences in terms of sex (65.9 vs 82.6% male sex, <0.01), age (62.1±12.1 vs 58.5±10.2 years, p<0.05), prior history of coronary artery disease (36.4 vs 16.0%, p<0.001), prevalence of arterial hypertension (68.2 vs 52.1%, p=0.046) and smoking status (50 vs 67.5%, p=0.026) when compared to the revascularized group. No significant differences were present concerning the presence of diabetes (38.6 vs 24.9%, p=0.054), dyslipidemia (61.4 vs 60.6%, p=0.928) or body mass index (27.2±4.1 vs 26.6±3.4, p=0.263). Baseline pVO2 was significant lower in the NR group (19.9±6.0 vs 23.2±5.9 mL/kg/min, p<0.001). After the CRP (21.1±6.7 sessions) the NR group still had a lower pVO2 (20.8±5.9 vs 24.6±6.1 mL/kg/min, p<0.001). There were no differences in the RER. Both groups, however, had a significant improvement in pVO2 after the CRP [20.8±5.9 vs 19.9±6.0 mL/kg/min (p<0.05) in the NR group; 24.6±6.1 vs 23.2±5.9 mL/kg/min (p<0.001) in the remainder]. There were no differences between the NR group and the revascularized group in terms of CRP benefits, as assessed by VO2 [delta pVO2 0.9±2.8 vs 1.4±3.0 mL/kg/min (p=0.306), delta pVO2% 4.5±10.8 vs 4.7±10.2% (p=0.908)], even after adjusting for age and sex. Conclusion: Although non-revascularized MI survivors present significantly lower pVO2 than those who undergo revascularization during hospitalization, this group also had a significant benefit with a contemporary CRP, as assessed by CPET. Given the association between pVO2 and cardiovascular events, these results support the referral of these patients for CRP.