Evaluation of Rate Adaptive Pacing on Chronotropic Response in Preserved Ejection Fraction HF

Inclusion Criteria: * Age ≥ 18 years or legal age to provide informed consent * Willing and be able to provide informed consent * Previous clinical diagnosis of HF and exhibits HF signs and symptoms consistent with NYHA II or III (or class B or C) * Chronic Rx for heart failure with loop diuretic or a mineralocorticoid receptor antagonist (MRA) * LVEF ≥ 45% within previous 12 months. Acceptable methods include echo, ventriculogram (angiography or nuclear), nuclear stress test. If patient has a prior history of significant left ventricular systolic dysfunction defined as EF \< 0.40, patient must have a HF event within previous 12 months defined as: * Hospitalization for decompensated HF * Unscheduled treatment for HF with intravenous loop diuretic or hemofiltration * On stable HF medical therapy for previous 30 days. Dose changes of ACEI / ARB and beta blockers of less than 50% increase or decrease are acceptable for stability * Treadmill exercise time using modified Naughton protocol of greater than 3 min and less than 15 min for men and 14 for women * Medtronic dual chamber pacemaker implanted for ≥ 30 days * Sinus rhythm at rest Exclusion Criteria: * Women who are pregnant or plan to become pregnant * Life expectancy less than 1 year * Enrollment in any concurrent study that could potentially be confounding * Orthopedic, neuromuscular or any other condition limiting exercise testing * Unstable angina or MI or have undergone CABG/PTCA within previous 60 days * A candidate for CABG/PTCA at the time of informed consent * Use of inotrope therapy on a regular basis (e.g. daily, weekly etc.) * Severe and/or poorly controlled major active comorbidity, including (but not limited to): * Diabetes: Hb1AC \> 9.5 * Severe COPD: e.g. end stage emphysema managed using 2 or more inhalers and/or using home oxygen * Severe pulmonary disease limiting functional capacity * Hypertension: SBP \> 160 mmHg at time of screening * Cancer: Ongoing therapy or therapy within previous 3 months * Severe valvular disease * Renal impairment with serum creatinine \> 3 mg/dL * Anemia with hemoglobin \< 8 g/dL or major bleeding event within the past 60 days * Primary diagnosis of pulmonary arterial hypertension with ongoing severe pulmonary hypertension and treatment * Known familial hypertrophic cardiomyopathy or hypertrophic obstructive cardiomyopathy * Known restrictive cardiomyopathy or systemic illness known to be associated with infiltrative myocardial disease (e.g. amyloidosis, sarcoidosis, hemochromatosis) * Pericardial restriction or hemodynamically significant pericardial effusion * Patients expected to undergo device or lead replacement within study follow-up duration * Allergies to hydrogel in SEEQ/AVIVO patch * Patients who are expected to be ventricular paced over 40% of the time * Long standing persistent AF Or Ongoing episode of persistent AF