Clinical Characteristics of Veterans Participating in Cardiac Rehabilitation

Heart failure with preserved ejection fraction (HFpEF) is a common phenotype of heart failure caused by prolonged left ventricular afterload. The consequences of HFpEF are severe, with 5-year morbidity, mortality, and rehospitalization rates exceeding 70%. Furthermore, many patients with HFpEF also have coronary heart disease (CHD), a leading cause of death and disability in the United States. Few viable treatment options exist for HFpEF patients. Exercise training such as moderate continuous training (MCT) offered in cardiac rehabilitation programs improves symptoms and cardiorespiratory fitness (CRF), the foremost indicator of long-term health and survival, in HFpEF patients. However, approximately half of patients completing MCT do significantly improve CRF.

Given the limited success of MCT in improving CRF, more aggressive exercise programs such as High Intensity Interval Training (HIIT) may prove to be superior options for CHD and HFpEF patients. Numerous clinical studies have demonstrated that High Intensity Interval Training (HIIT) improves CRF in CHD patients. Despite the established trend in CHD patients, we currently have insufficient information to recommend HIIT as a viable treatment option for patients with HFpEF.

As a precursor for later studies comparing CRF following exercise training in patients with HFpEF, our initial goals are to establish protocols for measuring CRF in response to exercise and to characterize the cardiac rehabilitation population, particularly regarding the presence of concurrent HFpEF and CHD. As part of this effort, we have established the testing protocol for symptom and CRF assessment and compiled an extensive source document with relevant objective metrics.