A50-year-old asymptomatic physician referred himself for coronary computed tomography angiography (CTA) because of an elevated low-density lipoprotein (LDL) of 120. His high-density lipoprotein (HDL) was 42. Triglycerides, high-sensitivity C-reactive protein (hsCRP), glucose, and vitamin D levels were normal. He exercised regularly on an elliptical trainer without chest pain or unusual shortness of breath. He had never smoked. His body mass index (BMI) was normal. His father died of an acute myocardial infarction at 50 years of age. CT showed no coronary calcium. Coronary CTA was entirely normal except for the presence of an area of apparent non-calcified plaque in the mid-left anterior descending coronary (see Figure 1). The lesion was seen on images constructed at several different phases of the cardiac cycle. Curved re-formatted images (see Figure 2) confirmed the presence of a lesion primarily in the wall of the vessel, with only moderate impingement on the coronary lumen. Reconstructed ‘virtual intravascular ultrasound (IVUS)’ views (see Figure 3) showed mild to moderate reduction in cross-sectional area in the region of the lesion, again showing most of the abnormality to be confined to the vessel wall, with moderate but definite luminal narrowing. The patient was treated with a statin, niacin, and aspirin. He did not undergo further testing and remains asymptomatic 18 months later. His current LDL is 68, and his HDL is 48.
Commentary
There is no evidence to support the use of CTA to detect non-calcified atherosclerotic plaque in the coronary arteries, while a large body of evidence has accumulated to suggest appropriate use of CT screening for coronary calcification in patients such as this who are at intermediate risk for future coronary events. Nevertheless, we do know that coronary atherosclerosis does exist without coronary calcification, particularly in younger patients. Detection of non-calcified plaque by CTA has not been fully validated, and technical artifacts can be confused with real lesions. Assuming the detection and characterization of the plaque is accurate still leaves us with little scientific guidance for further evaluation and treatment in situations like this. In my opinion, stress testing would be a reasonable option, with or without associated imaging. Invasive angiography would be too aggressive, as interventional therapy is not likely to help. This patient was treated with aggressive secondary preventative measures following serum markers. There are no plans to repeat the CTA.