Differential Diagnosis of Coronary Angiographic Filling Defect

J INVASIVE CARDIOL 2021;33(8):E678. 

Key words: cardiac imaging, intravascular ultrasound

An 80-year-old woman with a history of inferior myocardial infarction and type 2 diabetes mellitus presented to our clinic complaining of chest and left shoulder pain. Coronary angiography revealed a 75% stenosis of proximal to mid right coronary artery (RCA) and a filling defect at the mid RCA (Figure 1A). We proceeded with percutaneous coronary intervention. After successful guidewire crossing, intravascular ultrasound (IVUS) confirmed the filling defect as a trapped air bubble in an ectatic mid RCA (Figure 1B). After predilation with a non-compliant balloon, a drug-eluting stent was successfully implanted in the proximal to mid RCA. Final angiogram no longer showed a filling defect (Figure 1C). During contrast injection, a calcified lesion, thrombus, or trapped air bubble appear as hazy areas with inhomogeneous contrast staining and differentiation is difficult using angiography alone. In general, accidentally injected air bubbles in the coronary artery move to the distal artery or they are cleared after the next injection. In this case, an air bubble was trapped in the mid RCA and it was difficult to differentiate with calcification or thrombus. A correct diagnosis of “filling defect” is necessary because device selection is different for each case. IVUS is useful for differential diagnosis of calcification, thrombus, or air bubble.