Optical Coherence Tomography during Angiography to Inform Decision Making for Treating Coronary Artery Disease

Proprietary names: C7 Dragonfly™ Intravascular Imaging Catheter; C7 XR™ Imaging System; Extreme Resolution™; Ilumien™ System; Terumo-OFDI system

Generic names: Frequency-domain optical coherence tomography (OCT); Fourier-domain optical coherence tomography (FD-OCT); functional measurement; intracoronary imaging; intravascular diagnostic; intravascular physiologic testing; optical frequency domain imaging (OFDI); time-domain optical coherence tomography (TD-OCT)

Coronary artery disease (CAD) is characterized by systemic changes in endothelial vasomotor responses and by localized thickening of the artery walls due to fatty deposits within the coronary arteries.1,2 Caps of smooth-muscle cells and collagen form over the fatty deposits, creating atherosclerotic plaques. Most atherosclerotic plaques do not cause symptoms. Even large plaques may not impede blood flow because of compensatory enlargement of the artery.3,4 The plaques that cause symptoms do so through two distinct mechanisms.2,3 First, stable plaques may become large enough to cause narrowing (i.e., stenosis) and impede blood flow at their site of origin. Second, unstable or vulnerable plaques consisting of calcium, macrophages, a lipid pool, and/or a thin fibrous cap may rupture and trigger formation of a "thrombus" that can block blood flow. Most acute cardiovascular events, including myocardial infarction and stroke, are caused by ruptured unstable plaques2,3,5 rather than the presence of severely stenotic lesions.6

Noninvasive tests that aid diagnosis of CAD and its severity include:

Invasive coronary angiography is considered the gold standard for evaluating patients with suspected myocardial ischemia. Intravascular ultrasound (IVUS) is commonly performed during cardiac catheterization procedures to determine lumen dimensions (i.e., percent diameter stenosis, percent area stenosis, stent apposition, stent expansion, reference vessel sizes, length, dissection).7 Clinicians may use IVUS to identify and characterize arterial atheromatous plaque and complex vessel lesions that angiography alone cannot detect.8

According to the American Heart Association, approximately 16.3 million people 20 years of age or older in the United States have CAD, and about 1.3 million cases of new or recurrent CAD are diagnosed annually.9 An estimated 406,000 Americans die of CAD each year, of whom more than 80% are 65 years of age or older.9 The lifetime risk of developing CAD after 40 years of age is about 49% for men and 32% for women.9

Worldwide, CAD is the leading cause of death.10 In 2008, an estimated 7.3 million deaths were due to CAD.11 Most of the global burden of...