Insufficient recruitment of eligible patients

Patients with HFpEF suffer from exercise intolerance, increased risk for hospitalization and mortality, and poor QOL. Unlike patients with HFrEF, no drug or device therapies appear to be consistently beneficial in treating these problems. However, increasing evidence suggests that exercise training is effective for both partially reversing exercise intolerance and improving quality of life in these patients. Most such trials to date have been conducted in controlled research setting, versus integrating these patients in to a standard CR program. Also, since functional capacity is related to outcomes in these patients, exercise strategies aimed at further improving fitness are warranted. One such strategy is using higher intensity interval training (HIIT) in the CR setting, a strategy shown to be effective in patients with other types of CVD. This project is designed to test the feasibility of incorporating these patients into the CR setting, and training them using a methodology (i.e., HIIT) already shown to yield (in other patients with CVD) greater gains in fitness when compared to what was achieved using standard MCT alone.

Inclusion Criteria:

1. NYHA class II or III symptoms
2. Referred by physician to CR with echocardiographic evidence of HFpEF defined as an ejection fraction ≥ 50 % and moderate to severe (grade II-III) diastolic dysfunction.
3. ≥ 50 years of age
4. Free of orthopedic or other medical problems that would limit participation in CR
5. Peak VO2 on baseline cardiopulmonary exercise test (CPX) < 24 mL/kg/min in men and <21 mL/kg/min in women

Exclusion Criteria:

1. Systolic dysfunction, per ejection fraction < 50%; those with mild (grade I) diastolic dysfunction
2. Initial clinical responses observed during first 3 visits in CR or baseline exercise test that would preclude participation in study over-all (e.g., new onset/troublesome arrhythmia that warrants further investigation) or undergoing HIIT (e.g., claudication, balance issue)
3. Patients with exercise induced angina during CR or CPX testing or ST segment depression representative of myocardial ischemia during CPX testing
4. Pregnant or planning to become pregnant
5. Any patient recently hospitalized for heart failure will have to wait at least 2 weeks before starting CR, or until clinically stable per physician(whichever time period is greater)
6. Atrial fibrillation