Diagnosis of relative contributions of large artery blockages and microvascular blockages is very much needed in the treatment of coronary artery disease. In order to achieve this, two novel parameters, pressure drop coefficient (CDP), which combines flow and pressure readings and Lesion flow coefficient (LFC), which combines anatomical details of the lesion with pressure and flow readings, are being investigated.

Diagnosis of relative contributions of large artery blockages and microvascular blockages is very much needed in the treatment of coronary artery disease. In order to achieve this, two novel parameters, pressure drop coefficient (CDP), which combines flow and pressure readings and Lesion flow coefficient (LFC), which combines anatomical details of the lesion with pressure and flow readings, are being investigated. The diagnostic parameters will be correlated with Coronary Flow Reserve (CFR)values obtained using Positron Emission Tomography (PET) imaging. They will also be correlated with Fractional Flow Reserve (FFR).

Inclusion Criteria:

• 18 years of age or above
• Patients referred to a stress test by a Cardiologist
• Acute Chest pain, as per patient input.
• Risk Assessment with prior test results and/or previous history of known chronic stable CAD.
• Borderline or discordant stress testing where obstructive CAD remains a concern.
• New or worsening symptoms- Abnormal coronary angiography or abnormal prior stress imaging study.
• Coronary stenosis or anatomic abnormality of uncertain significance.
• In absence of reliable diagnostic information from another imaging modality.

Exclusion Criteria:

• Left ventricular ejection fraction less the 25% determined by gated SPECT imaging
• Non-dialysis dependent chronic kidney disease with baseline serum creatinine greater than 2.5 gm/dL.
• History of type II heparin-induced thrombocytopenia.
• Significant co-morbid condition that is medically unstable and would make coronary angiography prohibitive or contraindicated.
• Pregnant women.
• Incapacitated for Consent

Patients with chest pain and suspected ischemia that needs to be assessed by a stress test