What is the diagnostic accuracy of cardiac Computed Tomography (CT) angiogram in diagnosing and characterizing Coronary Artery Disease (CAD)?

From the Guidelines

Cardiac Computed Tomography (CT) angiogram is highly accurate for diagnosing and characterizing Coronary Artery Disease (CAD), with a sensitivity of 95% and specificity of 83% compared to invasive coronary angiography, as reported in the most recent study 1. The diagnostic accuracy of cardiac CT angiography is well-established, with multiple studies demonstrating its high sensitivity and specificity for detecting CAD. The CCTA ACCURACY trial found 95% sensitivity, 83% specificity, 64% PPV, and 99% NPV for detection of CAD, suggesting that CCTA possesses high diagnostic accuracy for detecting coronary stenosis at thresholds of 50% 1. Some of the key benefits of cardiac CT angiography include:

• High negative predictive value, making it particularly valuable for evaluating patients with low to intermediate risk of coronary artery disease
• Detailed visualization of coronary anatomy, plaque composition, degree of stenosis, and vessel remodeling
• Ability to detect non-obstructive plaque, which can aid in risk assessment and guiding treatment
• Non-invasive nature, reducing the risk of complications associated with invasive coronary angiography However, cardiac CT angiography also has some limitations, including:
• Difficulty assessing heavily calcified arteries
• Potential overestimation of stenosis severity in calcified plaques
• Limited functional assessment of stenosis significance Despite these limitations, cardiac CT angiography is a valuable tool for diagnosing and characterizing CAD, and its use is supported by recent guidelines and studies 1, 2, 3. For optimal image quality, patients typically need heart rate control, regular rhythm, and the ability to hold their breath for 5-10 seconds during the scan. Newer techniques like CT fractional flow reserve (CT-FFR) and CT perfusion imaging are also enhancing the ability of cardiac CT angiography to assess the functional significance of stenoses.

From the Research

Diagnostic Accuracy of Cardiac CT Angiogram

The diagnostic accuracy of cardiac Computed Tomography (CT) angiogram in diagnosing and characterizing Coronary Artery Disease (CAD) is supported by several studies.

• A meta-analysis of 29 studies found per-patient accuracy of 96% sensitivity, 74% specificity, 83% positive predictive value, and 94% negative predictive value 4.
• The high negative predictive value of CT angiography is especially helpful in ruling out coronary artery disease in patients who have low to intermediate pretest likelihood of CAD 5.
• CT angiography demonstrated significant higher sensitivity than myocardial perfusion imaging (MPI) (95% vs. 81%, P < .05) and higher specificity than both MPI and coronary artery calcification (CAC) 6.

Comparison with Other Imaging Modalities

Comparative studies have been conducted to evaluate the diagnostic accuracy of CT angiography against other imaging modalities.

• A prospective clinical study involving 208 patients with suspected CAD found that the sensitivity of CT angiography was 90% (95% CI, 82%-95%), whereas the sensitivity of single-photon emission tomography (SPECT) and positron emission tomography (PET) was 57% (95% CI, 46%-67%) and 87% (95% CI, 78%-93%), respectively 7.
• The same study found that the diagnostic accuracy was highest for PET (85%; 95% CI, 80%-90%) compared with that of CT angiography (74%; 95% CI, 67%-79%; P = .003) and SPECT (77%; 95% CI, 71%-83%; P = .02) 7.

Current Practice and Future Directions

Cardiac CT angiography is emerging as a frontline non-invasive diagnostic test for CAD, with evidence supporting its clinical utility in diagnosis and prevention.

• The American Society for Preventive Cardiology (ASPC) has issued a clinical practice statement summarizing the current evidence and clinical applications of cardiac CT in evaluation of CAD 8.
• The statement highlights the advantages of cardiac CT angiography, including its ability to identify and characterize coronary stenosis severity and pathophysiological changes in coronary atherosclerosis and stenosis, aiding in early diagnosis, prognosis, and management of CAD 8.