Anemia does not preclude increments in cardiac performance during a short period of intensive, exercise-based cardiac rehabilitation

Background and aims: Anemia seems to be rather common in cardiac rehabilitation patients but it is not known whether it could influence cardiovascular performance indexes and prognosis immediately after an acute cardiac event. The purposes of this study were to define its prevalence and to investigate the safety and efficacy of an intensive exercise-based cardiac rehabilitation in patients with and without anemia. Methods: 436 participants (77% males; mean age 64 +/- 13 years) were submitted to a two-week cardiac rehabilitation program consisting of low to medium intensity, individualized training with respiratory, aerobic and callisthenic exercises (three sessions daily, six times per week). A six-minute walking test was performed at enrolment and repeated at discharge together with a cardiopulmonary test. Results: Anemia, as defined according to World Health Organization criteria, was detected in 328 patients (75.2% of the entire population). The distance walked increased from 381 +/- 117m at baseline to 457 +/- 110m (p < 0.001) after a mean period of 12.4 +/- 4 days. A direct correlation was found between hemoglobin concentrations and both the absolute distance walked (r = 0.48; p < 0.001) and peak VO2 (r = 0.39; p < 0.001). Anemic patients walked a significantly shorter distance at baseline and at discharge (p < 0.001); however, both groups showed the same increment in the distance walked: 76.0 +/- 61m vs 76.0 +/- 60m (p = 0.99). Conclusions: Our data indicate: 1) a high prevalence of anemia in the study population and 2) that, in spite of a clear reduction in exercise capacity, a moderate anemia does not preclude increments in cardiac performance during a short period of intensive, exercise-based cardiac rehabilitation.