Invasive evaluation of patients with angina in the absence of obstructive coronary artery disease

Abstract

Background: More than 20% of patients presenting to the cardiac catheterization laboratory with angina have no angiographic evidence of coronary artery disease. Despite a "normal" angiogram, these patients often have persistent symptoms, recurrent hospitalizations, a poor functional status, and adverse cardiovascular outcomes, without a clear diagnosis.

Methods and results: In 139 patients with angina in the absence of obstructive coronary artery disease (no diameter stenosis >50%), endothelial function was assessed; the index of microcirculatory resistance, coronary flow reserve, and fractional flow reserve were measured; and intravascular ultrasound was performed. There were no complications. The average age was 54.0±11.4 years, and 107 (77%) were women. All patients had at least some evidence of atherosclerosis based on an intravascular ultrasound examination of the left anterior descending artery. Endothelial dysfunction (a decrease in luminal diameter of >20% after intracoronary acetylcholine) was present in 61 patients (44%). Microvascular impairment (an index of microcirculatory resistance ≥25) was present in 29 patients (21%). Seven patients (5%) had a fractional flow reserve ≤0.80. A myocardial bridge was present in 70 patients (58%). Overall, only 32 patients (23%) had no coronary explanation for their angina, with normal endothelial function, normal coronary physiological assessment, and no myocardial bridging.

Conclusions: The majority of patients with angina in the absence of obstructive coronary artery disease have occult coronary abnormalities. A comprehensive invasive assessment of these patients at the time of coronary angiography can be performed safely and provides important diagnostic information that may affect treatment and outcomes.

Keywords: chest pain; endothelium; fractional flow reserve, myocardial; myocardial bridging.

Figure 1

Demonstrative cases of (A) epicardial endothelial dysfunction, (B) low FFR with occult diffuse epicardial disease, (C) microvascular dysfunction, and (D) myocardial bridging A. Paradoxical vasoconstriction after intracoronary acetylcholine injection. B. This angiographically non-obstructive LAD showed diffuse atherosclerosis on IVUS and low FFR. C. There was no significant angiographic stenosis in the LAD, but the IMR was high. D. An IVUS image of myocardial bridging during diastole and systole. An echolucent area surrounding the coronary artery is seen during the entire cardiac cycle.

Figure 2

A. Results of Invasive Assessment for Coronary Circulation. B=myocardial bridging; E=endothelial dysfunction; F=low fractional flow reserve (<0.80); R= high index of microcirculatory resistance (≥25). B. Prevalence of occult coronary abnormalities on invasive assessment in patients with angina and angiographically non-obstructive coronary arteries. Endothelial dysfunction = a decrease in luminal diameter of ≥ 20% with intracoronary acetylcholine; Microvascular dysfunction = index of microcirculatory resistance ≥25; Low FFR = fractional flow reserve ≤0.80; Myocardial bridging = an echolucent half‐moon sign and/or ≥10% systolic compression on intravascular ultrasound.

Figure 2

A. Results of Invasive Assessment for Coronary Circulation. B=myocardial bridging; E=endothelial dysfunction; F=low fractional flow reserve (<0.80); R= high index of microcirculatory resistance (≥25). B. Prevalence of occult coronary abnormalities on invasive assessment in patients with angina and angiographically non-obstructive coronary arteries. Endothelial dysfunction = a decrease in luminal diameter of ≥ 20% with intracoronary acetylcholine; Microvascular dysfunction = index of microcirculatory resistance ≥25; Low FFR = fractional flow reserve ≤0.80; Myocardial bridging = an echolucent half‐moon sign and/or ≥10% systolic compression on intravascular ultrasound.