To evaluate the incidence of coronary microvascular dysfunction (CMD) and its' prognostic implication in patients who have diagnosed as heart failure with preserved ejection fraction (HFpEF) confirmed by HFA-PEFF scoring system without functionally significant coronary artery disease.

Heart failure with preserved ejection fraction (HFpEF) is a clinical syndrome in patients with current or prior symptoms of HF with a left ventricular ejection fraction (LVEF) ≥ 50 percent and evidence of cardiac dysfunction as a cause of symptoms (abnormal LV filling and elevated filling pressures). Previous studies have reported that HFpEF is related to various clinical risk factors such as hypertension, obesity, diabetes mellitus, chronic kidney disease, atrial fibrillation, myocardial ischemia with or without significant epicardial coronary artery stenosis, or myocardial infiltrative disease. Although its pathophysiology remains incompletely understood, findings from clinical and pre-clinical studies have suggested systemic endothelial dysfunction, oxidative stress, and coronary microvascular dysfunction (CMD) could be important pathophysiologic mechanisms for HFpEF.

In this regard, recent studies evaluated non-invasively measured coronary flow reserve (CFR) from positron emission tomography (PET), cardiac magnetic resonance imaging (MRI), or Doppler echocardiography, and presented the association of depressed global CFR with cardiac diastolic dysfunction and higher risk of clinical events. The presence of CMD can be also evaluated by invasive physiologic assessment using both CFR and index of microcirculatory resistance (IMR). Nevertheless, there has been limited study which evaluated the association between HFpEF and CMD using invasive physiologic indices and their prognostic implications, especially in patients without significant coronary artery stenosis. Therefore, we sought to evaluate the incidence of CMD and its' prognostic implication in patients who have diagnosed as heart failure with preserved ejection fraction (HFpEF) confirmed by HFA-PEFF scoring system without functionally significant coronary artery disease.

Inclusion Criteria:

• Subject must be at least 19 years of age.
• Subject with preserved ejection fraction (ejection fraction > 50%)
• Subject presented with dyspnea on exertion (NYHA Grade 2 or more) and diagnosed as HFpEF using HFA-PEFF scoring system (HFA-PEFF ≥5 or 2-4 with abnormal stress test or invasive hemodynamic test)
• Subject who clinically need coronary angiography
• Subject who is able to voluntarily sign informed consent form

Exclusion Criteria:

• Subject with reduced ejection fraction (<50%)
• Subject with significant coronary artery stenosis on coronary angiography (diameter stenosis ≥90% or 50-90% with fractional flow reserve [FFR] ≤0.80)
• Subject who has other obvious causes of dyspnea (ex, lung disease)
• Subject who have non-cardiac co-morbid conditions with life expectancy <1 year

Patients who have diagnosed as heart failure with preserved ejection fraction (HFpEF) confirmed by HFA-PEFF scoring system without functionally significant coronary artery disease