This article is more than 5 years old. Information may no longer be current.
Quantitative flow ratio effective, but less so in coronary microvascular dysfunction
Click Here to Manage Email Alerts
The diagnostic performance of quantitative flow ratio is lessened in patients with coronary microvascular dysfunction, but using quantitative flow ratio remained superior in determining stenosis severity compared with angiography alone, researchers reported.
The researchers measured 300 vessels in 248 patients from an international registry. Vessels were stratified by whether they qualified as coronary microvascular dysfunction, defined as index of microcirculatory resistance of at least 23 U.
The researchers then assessed the effect of coronary microvascular dysfunction on the performance of quantitative flow ratio, as well as on the value of quantitative flow ratio plus angiography over angiography alone, using fractional flow reserve as a reference.
Percent diameter stenosis was similar in vessels with and without coronary microvascular dysfunction (53% vs. 51%, respectively; P = .16), as was FFR (0.81 vs. 0.8, respectively; P = .23), Hernán Mejía-Rentería, MD, from the department of cardiology, Hospital Clínico San Carlos IDISSC and Universidad Complutense de Madrid, Spain, and colleagues wrote.
Classification agreement between quantitative flow reserve and FFR was high (88%), as was diagnostic efficiency of quantitative flow reserve (area under the curve = 0.93; 95% CI, 0.9-0.96), according to the researchers.
However, those metrics were lower in vessels with coronary microvascular dysfunction than in those without it (classification agreement, 76% vs. 92%; P < .001; AUC, 0.88 vs. 0.96; P < .05).
Compared with angiographic assessment alone, quantitative flow ratio increased the AUC of percent diameter stenosis by 0.2 in vessels without coronary microvascular dysfunction and by 0.16 in vessels with coronary microvascular dysfunction (P < .001 for both), according to the researchers.
Mejía-Rentería and colleagues determined that independent predictors of misclassification between quantitative flow ratio and FFR were coronary microvascular dysfunction and ACS.
In a related editorial, James P. Howard, MA, MB BChir, from National Heart and Lung Institute, Imperial College London, and Venkatesh L. Murthy, MD, PhD, from the division of cardiovascular medicine, department of internal medicine and the Frankel Cardiovascular Center at the University of Michigan, wrote that quantitative flow ratio appears to give false positives in patients without hemodynamically significant lesions but with high microvascular resistance, but these may not actually be false, and “one could argue that [quantitative flow ratio’s] utility could lie in identifying patients at low risk who do not need to proceed to direct FFR measurement with a pressure wire. If so, this study’s results are encouraging, with the negative predictive value remaining as high as 87% even in patients with coronary microcirculatory dysfunction.” – by Erik Swain
Disclosures: Mejía-Rentería and Howard report no relevant financial disclosures. Murthy reports he owns stock in GE, Johnson & Johnson and Medtronic and receives grant support from Siemens Medical Imaging. Please see the study for the other authors’ relevant financial disclosures.
Click Here to Manage Email Alerts