- Stands for computed tomography coronary angiography
- CTCA is an excellent 'rule out' test, eith negative predictive value approaching 100%.
- Radiation exposure is no longer a concern for CTCA, with doses routinely <5 mSv, and as low as <1mSv in selected patients.
- CTCA is useful for excluding coronary artery disease, investigating the anatomy of coronary anomalies or fistulae, and for the patency of coronary bypass grafts
Indications for CTCA (endorsed by the Cardiac Society of Australia and New Zealand)
- Chest pain and low to intermediate pre-test probability of coronary artery disease (CAD)
- Chest pain with uninterpretable or equivocal stress test or imaging results
-Normal stress test results but continued or worsening symptoms
- Suspected coronary or great vessel anomalies
- Evaluation of coronary artery bypass grafts (with symptoms)
- Exclude coronary artery disease in new onet left bundle branch block or heart failure
In Australia Medicare reimbursement is available via specialist referral for three indications:
1. Chest symptoms consistent with coronary ischaemia in low to intermediate risk patients
2. Evaluation of suspected coronary anomaly or fistula
3. Exclusion of CAD before heart transplant or valve surgery (non-coronary cardiac surgery).
Medicare-reimbursed indications do not cover asympotomatic patients with a strong family history of coronary artery disease (in which a coronary calcium score may suffice).
An important factor in CTCA is heart rate control, which remains essential for good quality CTCA imaging. Ideal heart rates are in the 50-60 beats per minute range for optimal imaging, requiring pre-medication with beta blockers and/or ivabradine.
Recent data from the PROMISE trial in 10,000 patients showed equivalence of a CTCA versus functional testing strategy in symptomatic patients, but with a reduced rate of 'normal' invasive angiograms and decreased downstream testing in the CTCA group. Further, the SCOT-HEART trial recently demonstrated that adding CTCA to standard heart care reduced the need for additional stress testing, and was associated with a 38% reduction in fatal and non-fatal myocardial infarction.
Hamilton-Craig, C., & Chan, J. (2016). The clinical utility of new cardiac imaging modalities in Australasian clinical practice. The Medical Journal of Australia,205(3), 134-139. doi:10.5694/mja16.00438