Cardiac computed tomography (CT) is often performed in patients who are at high risk for lung cancer in whom screening is currently recommended. This pilot randomized study will test the feasibility, safety and diagnostic ability of a novel ultra-low-dose CT protocol that allows concomitant coronary artery evaluation and lung screening. Current or former heavy smoker subjects with suspected or known coronary artery disease will be randomized to undergo CT assessment of either thoracic area only or both coronary arteries and thoracic area. Primary end-points will be the effective contrast and radiation doses.

Cardiac computed tomography (CT) scan is an ideal diagnostic tool for identifying coronary artery disease in patients with low or intermediate risk. In recent years, cardiac CT is being often performed in patients who are at high risk either for coronary artery disease or lung cancer. The update edition of the National Institute for Health and Care Excellence (NICE) guidelines recommends cardiac CT as the first-line diagnostic tool for patients with new-onset chest pain due to suspected coronary artery disease. Also, symptomatic patients with known coronary artery disease and previous percutaneous coronary intervention who have an unclear stress test but whose presentation suggests a high likelihood of having an in-stent restenosis or a 'de novo' stenosis might benefit from cardiac CT. In 2014, the U.S. Preventive Services Task Force recommended annual lung cancer screening with ultra-low dose computed tomography for current and former heavy smokers aged 55 to 80 years. Indeed, lung cancer screening in patients with suspected or known coronary artery disease undergoing cardiac CT may provide the opportunity to implement recommendation for lung cancer screening in clinical practice.This pilot randomized study will test the feasibility, safety and diagnostic ability of a novel ultra-low-dose CT protocol that allows concomitant coronary artery evaluation and lung screening. Current or former heavy smoker subjects with suspected or known coronary artery disease will be randomized to undergo CT assessment of either thoracic area only or both coronary arteries and thoracic area. Primary end-points will be the effective contrast and radiation doses.

Inclusion Criteria:

• Symptomatic subjects with effort-induced or typical chest pain
• High probability of coronary artery disease
• Known coronary artery disease
• Willing to participate to the study
• Informed consent to undergo CT scan

Exclusion Criteria:

• Contraindications to iodinated contrast such as allergies and chronic kidney failure
• Any suspicion of pregnancy