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