There are no studies specifically examining the effects of coenzyme Q (CoQ) treatment on echocardiographic indices of diastolic function in elderly patients with heart failure with preserved ejection fraction (HFPEF). In previous studies the only echocardiographic parameters studied were ejection fraction (EF) and chamber size. The objective of the proposed current study is to examine the effect of 16 weeks of ubiquinol therapy on diastolic function assessed by echocardiography in patients over the age of 50 with a clinical diagnosis of HFPEF. Ubiquinol (Kaneka Pharma), the reduced form of CoQ will be utilized for this study as it has been shown to have superior bioavailability when compared to oxidized CoQ.

Inclusion Criteria:

• Typical signs and symptoms of congestive heart failure (CHF) (New York Association Class 2-4).
• Normal ejection fraction on echocardiography (EF ≥50%).
• Evidence of diastolic dysfunction on non-invasive imaging (E:e' > 15 or e:e' > 8 with other measures of diastolic dysfunction such as e/a < 0.5 with elevated deceleration time or left atrial volume index > 40 cc/m2 or presence of elevated left ventricular mass index or elevated pulmonary pressures).
• Stable medical therapy for 4 weeks prior to randomization

Exclusion Criteria:

• Chronic atrial fibrillation.
• Acute coronary syndrome or coronary revascularization within 60 days.
• Clinically significant valvular disease.
• Known infiltrative cardiomyopathy (e.g. amyloidosis), hypertrophic cardiomyopathy or chronic pericardial disease.
• Inability/refusal to provide informed consent