This study aims to reduce patient risk and costs to the healthcare system by improving the diagnostic yield of invasive coronary angiography through existing triage processes to improve risk stratification using Coronary Computed Tomographic Angiography (CCTA) as a first step in low risk patients. All low-risk patients referred for invasive coronary angiography will be potentially eligible for CCTA instead of invasive angiography as a first-line diagnostic test. All CCTAs will be read by both a level 3-trained cardiologist and a radiologist. The results of the CCTA, coupled with evidence-based management recommendations will be sent to the referring physician and an invasive angiogram will be arranged by the HIU triage, only when clearly indicated

Inclusion Criteria:

1. Non urgent outpatient referral
2. Canadian Cardiovascular Society class I or II
3. Indication for invasive angiogram includes: Rule out Coronary Artery Disease (CAD) and Cardiomyopathy

Exclusion Criteria:

1. Age <18 years old, Men >65 years old or women >75 years old

2. Patient refusal to provide verbal consent for CCTA at time of triage contact or unable to provide informed consent

3. Referring physician refusal for their eligible patients to be approached for the CarDIA study

4. Any prior CCTA

5. Atrial Fibrillation

6. Creatinine > 150 mmol/L

7. Diabetes mellitus

8. High risk Exercise Stress Test or Functional Imaging

9. Known severe valvular disease being considered for valve surgery

10. Any known CAD

    • Prior Acute Coronary Syndrome (ACS)
    • Prior Percutaneous Coronary Intervention (PCI) or Coronary Artery Bypass Graft (CABG)

All eligible low-risk patients referred for invasive angiography will be recruited from the two interventional sites (approximately 240) via centralized triage process. Patients treated before the intervention implementation will be the control group (approximately 480).