Nonobstructive coronary artery disease on CT coronary angiography and abnormal coronary flow reserve: Two sides of the same coin

Excerpt

Early publications pertaining to the use of CT coronary angiography (CTCA) for evaluation of patients with chest pain, emphasized the excellent negative predictive value for excluding significant CAD as well as the somewhat limited positive predictive value for detection of ≥50% stenoses because of the tendency of the test to overestimate severity of coronary artery lesions. With respect to the latter, inducible ischemic perfusion defects were reported to be associated with only 40% of the coronary artery stenoses deemed significant by CCTA. Thus, the test was considered mainly of value in low-intermediate risk patients when no CAD was detected. More recently, studies have shown that the presence and the extent of nonobstructive CAD (≤50% stenoses) are associated with an intermediate risk of cardiac events between those patients with obstructive CAD and those with completely normal, plaque-free CAD.1 The greater the number of coronary vessels with nonobstructive plaque, the greater the mortality during follow-up. The inclusion of nonobstructive plaque as a variable has enhanced the prognostic value of CTCA because patients with nonobstructive CAD would presumably have normal exercise or pharmacologic SPECT myocardial perfusion imaging studies. Focal reversible defects are most often seen in the presence of flow-limiting coronary stenoses. …