Restoration of Chronotropic Competence in Heart Failure Patients With Normal Ejection Fraction

Inclusion Criteria: * Patients who are in sinus rhythm * Patients who are on stable medical therapy * Patients who exhibit signs and symptoms of heart failure, New York Heart Association (NYHA) Class II or III * Patients who have experienced a hospitalization for decompensated heart failure; treatment for pulmonary congestion or volume overload; chronic treatment with a loop diuretic; or a brain natriuretic peptide (BNP) \> 125 ng/l. * Left ventricular ejection fraction (LVEF) ≥ 50% Exclusion Criteria: * Patients with persistent atrial fibrillation or atrial flutter * Patients who are in complete heart block * Patients who have experienced a recent myocardial infarction (MI) or have unstable angina or require cardiac surgery or other procedures * Patients who have severe heart valve disease or valve replacement * Patients with a contraindication for a pacemaker system * Patients who have a neuromuscular, orthopedic or other non-cardiac condition that prevents patient from exercise testing * Patients who have infiltrative or hypertrophic cardiomyopathy * Patients who have known severe pulmonary disease * Patients with uncontrolled diabetes or blood pressure (systolic blood pressure (SBP) \> 160 mmHg or diastolic blood pressure (DBP) \> 95 mmHg)