This is a single-center study of subjects undergoing clinically indicated heart scans for evaluation of known or suspected heart disease. We will also include 10 healthy subjects without known heart disease. We would like to study stress testing of the heart using exercise and a medication called regadenoson. Imaging of the heart will be performed.

Regadenoson is stress agent approved by the FDA for use with myocardial perfusion imaging with technetium-99m single photon emission computed tomography (SPECT) in patients that are unable to exercise adequately. We would like to study Regadenoson in conjunction with Exercise Rubidium-82 positron emission tomography myocardial perfusion imaging (PET MPI). Regadenoson is not approved by FDA for use with Rubidium-82 PET MPI. Also, we would like to study a novel stress protocol of Regadenoson combined with symptom limited exercise stress (not FDA approved).

The objectives of this study are to assess the tolerability and safety of combined symptom limited exercise stress test with Lexiscan (Lexercise PET) compared to Lexiscan alone (Lexiscan PET), to assess image quality of Lexercise compared to Lexiscan PET and to compare relative and absolute myocardial perfusion imaging with Lexercise compared to Lexiscan PET to identify CAD.

Inclusion Criteria:

• Age > 18 years
• Clinically indicated N-13 ammonia PET study or ten healthy volunteers
• Known coronary artery disease (prior percutaneous coronary intervention, prior coronary artery bypass surgery or Q wave MI on ECG) or intermediate to high pretest likelihood of CAD
• Able to exercise on a treadmill
• Able and willing to provide informed consent to participate in the study

Exclusion Criteria:

• Contraindications to exercise stress testing such as, unstable angina, known severe left main coronary artery stenosis, severe heart failure, uncontrolled arrhythmias, symptomatic hypotension or severe hypertension (systolic blood pressure < 90 or > 200 mmHg, respectively), or > 1st degree atrioventricular block in the absence of a functioning pacemaker.
• Subject requires emergent cardiac medical intervention or catheterization after the clinical study.
• Documented myocardial infarction (MI) ≤ 30 days prior to enrollment.
• History of percutaneous coronary intervention (PCI) ≤ 4weeks prior to enrollment.
• History of coronary artery bypass graft (CABG) ≤ 8 weeks prior to enrollment.
• History of heart transplantation.
• Allergy or intolerance to aminophylline or regadenoson
• Known severe or oxygen dependent bronchoconstrictive or bronchospastic lung disease [e.g., asthma, wheezing, chronic obstructive pulmonary disease (COPD), etc.].
• Severe LV dysfunction, with ejection fraction of < 30%
• Serious non-cardiac medical illness (e.g., disseminated malignancy, severe neurological dysfunction at time of baseline PET study) or a social situation which will preclude research study participation
• History of Seizures.

Adverse events were collected on the day of the research study which was in week 2 for most patients.