Usefulness of 64-slice coronary computed tomographic angiography in the planning of percutaneous coronary intervention

CASE DESCRIPTION

A 49-year-old African American man (weight 150 lbs, height 510, body mass index 22 kg/m²) with a 2-year history of adult-onset diabetes mellitus presented with dyspnea on exertion and occasional chest discomfort. An electrocardiogram suggested previous inferior wall myocardial infarction of undetermined age. A myocardial perfusion stress test, performed at an outside institution, demonstrated inferior wall myocardial ischemia. The patient was initially unwilling to undergo invasive coronary angiography but was amenable to noninvasive, coronary computed tomographic angiography (CCTA).

A 64-slice gated CCTA demonstrated only mild narrowing of the left system (Figure 1) but a “high-grade” narrowing in the proximal portion of the dominant right coronary artery (RCA) (Figure 2). The length of the RCA narrowing was ~30 mm in an artery that was approximately 3 mm in diameter. It was believed that given the severity and length of the lesion, medical management would be less likely to achieve adequate symptom resolution than percutaneous coronary intervention (PCI) with stent placement.

Figure 1.

Coronary computed tomographic angiography of the left coronary system. (a) Three-dimensional and (b, c) curved reformatted images demonstrate non—flow-limiting plaque in the proximal left anterior descending artery (LAD) (arrowheads). (d) The corresponding invasive angiogram confirmed these findings. OM1 indicates first obtuse marginal.

Figure 2.

Coronary computed tomographic angiography demonstrates a high-grade lesion in the proximal right coronary artery as seen with (a) three-dimensional reconstruction (arrow) and (b) a multiplanar reformatted image (arrow). (c) The severity is suggested by the complex nature of the plaque, with both soft and calcific portions, as well as the compensatory expansion of the artery within the most severe area. (d, e) An invasive coronary angiogram confirmed the high-grade lesion in the right coronary artery (arrow). (f) A stent was selected to cover not only the high-grade area, but also the more moderate plaque proximal and distal to the most severe portions of the lesion.

Cardiac catheterization confirmed minimal disease in the left coronary arteries (Figure 1) and a high-grade narrowing in the proximal RCA (Figure 2). Angiographically, the lesion was estimated at 15 to 20 mm in length. However, based on the CCTA findings, a 3.0 × 32–mm stent (drug eluting) was placed, covering the disease proximal to and distal to the most critical areas of stenosis. The stent was deployed at high pressure, with a final estimated diameter of 3.4 mm (Figure 2).

COMMENTS

CCTA has been shown to be exceptionally accurate in defining patients with minimal or no disease in their coronary arteries. It has an extremely high specificity and negative predictive value when evaluating patients with chest pain (1). In patients with a higher probability of coronary disease, the accuracy of defining stenoses is also extremely high, with sensitivity of detection of coronary disease in the 98% range and lesion-specific accuracy of 99% (2).

When patients are found to have disease by CCTA, that information can be very helpful in planning PCI, as it gives a “preview” of the coronary anatomy before a catheter is placed in the body. Prior to invasive catheterization, the cardiologist can be made aware of the presence of left main or three-vessel disease (3), the presence of coronary anomalies (4), and the location and extent of plaque and can use CCTA for pre-PCI planning of stent placement (5–8).

It is still reasonable for patients with atherosclerotic risk factors and high-risk symptoms to proceed with cardiac catheterization without CCTA. However, it has long been known that invasive angiography can often underestimate total plaque burden and even stenosis severity (9). This can sometimes lead to incorrect placement of stents and even the need for additional stents if a lesion is only partially covered.

If CCTA is used, it can be useful for more than just confirming that an invasive cardiac catheterization is the appropriate next step. As in this case, it can be used to aid in the choice of stent size and placement by giving additional information about true extent of plaque location and severity.