The Differences of Quantitative Flow Ratio in Coronary Artery Stenosis with or without Atrial Fibrillation

Quantitative flow ratio (QFR) is a new method for the assessment of the extent of coronary artery stenosis. But it may be obscured by the cardiac remodeling and abnormal blood flow of the coronary artery when encountering atrial fibrillation (AF). The present study aimed to examine the impact of these changed structures and blood flow of coronary arteries on QFR results in AF patients. Methods and Results. We evaluated QFR in 223 patients (112 patients with AF; 111 non-AF patients served as controls) who had undergone percutaneous coronary intervention (PCI) due to severe stenoses in coronary arteries. QFR of the target coronary was determined according to the flow rate of the contrast agent. Results showed that AF patients had significantly higher QFR values than control (0.792 ± 0.118 vs. 0.685 ± 0.167, <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" id="M1"> <a:mi>p</a:mi> <a:mo><</a:mo> <a:mn>0.001</a:mn> </a:math> ). We further analyzed local QFR around the stenoses (0.858 ± 0.304 vs. 0.756 ± 0.146, <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" id="M2"> <c:mi>p</c:mi> <c:mo>=</c:mo> <c:mn>0.002</c:mn> </c:math> ), residual QFR (0.958 ± 0.055 vs. 0.929 ± 0.093, <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" id="M3"> <e:mi>p</e:mi> <e:mo>=</e:mo> <e:mn>0.005</e:mn> </e:math> ), and index QFR (0.807 ± 0.108 vs. 0.713 ± 0.152, <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" id="M4"> <g:mi>p</g:mi> <g:mo><</g:mo> <g:mn>0.001</g:mn> </g:math> ) in these two groups of patients with and without AF. Further analysis revealed that QFR in AF patients was negatively correlated with coronary flow velocity (R = −0.22, <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" id="M5"> <i:mi>p</i:mi> <i:mo>=</i:mo> <i:mn>0.02</i:mn> </i:math> ) and area of stenosis (R = −0.70, <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" id="M6"> <k:mi>p</k:mi> <k:mo><</k:mo> <k:mn>0.001</k:mn> </k:math> ) but positively correlated with the minimum lumen area (MLA) (R = 0.47, <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" id="M7"> <m:mi>p</m:mi> <m:mo><</m:mo> <m:mn>0.001</m:mn> </m:math> ). Conclusion. AF patients with coronary artery stenosis have higher QFR values, which are associated with decreased blood flow velocity, smaller stenosis, and larger MLA in AF patients upon cardiac remodeling.