Murray law-based angiography-derived resistance (μR) correlated with microvascular resistance and had >99% NPV at ≤145 and 88% PPV at ≥500 in INOCA patients.
Does Murray law-based angiography-derived assessment of coronary microcirculatory resistance accurately diagnose microvascular dysfunction compared to invasive thermodilution in patients with suspected INOCA?
Murray law-based angiography-derived assessment of coronary microcirculatory resistance is a feasible, non-wire-based tool that correlates with invasive thermodilution for diagnosing microvascular dysfunction in INOCA patients.
Absolute Event Rate: 0% vs 0%
Abstract Background The current European Society of Cardiology guidelines suggest invasive coronary function testing (CFT) for patients with suspected ischemia and non-obstructive coronary arteries (INOCA). 1 However, the value of novel angiography-derived methods to examine the microvascular function in these patients remains unsettled. Aims We aimed to investigate the diagnostic yield of a novel Murray law-based coronary angiography derived assessment of coronary microcirculatory resistance in patients with INOCA. Methods This is a prospective, investigator-driven, registry including consecutive patients with INOCA undergoing CFT. The index of microvascular resistance (IMR) and coronary flow reserve (CFR) were determined via bolus thermodilution. Absolute flow (Q) and resistance (R) were assessed by continuous thermodilution. Measurements of angiography-derived resistance (μR) were performed in a centralized, independent, corelab, blinded to clinical data and invasive functional tests results. Results Out of 141 patients with suspected INOCA undergoing CFT, 118 patients were included in the final analysis. A positive linear correlation was found between μR and R (R=0.36, p0.001). The discriminatory potential of μR was acceptable, using R ≥500 and IMR ≥25 as reference (AUC 0.675, p=0.001 and AUC 0.639, p=0.010, respectively). Notably, a μR of ≤ 145 had a negative predictive value of 99%. and a μR ≥ 500 a positive predictive value of 88%. Dichotomous concordance between μR and R with the optimal threshold of 333 (as determined by ROC curve analysis) for μR was relatively high, with μR being able to correctly classify 79% of patients. (Figure 1) Conclusions This is the first study specifically devoted to explore the diagnostic yield of a novel Murray law-based angiography-derived assessment of the coronary microvascular resistance (μR) as compared to continuous flow derived microvascular resistance. Our results demonstrate the feasibility and value of this tool in the diagnostic work-up of patients with suspected INOCA. (Central Illustration) The easy implementation of this technique may hold the potential of paving the way for future larger studies and a wider application of guideline recommendations for diagnosing and managing patients with microvascular angina in clinical practice.Central illustration Figure 1, Dichotomic concordance
Marschall et al. (Sat,) reported a other. Murray law-based angiography-derived resistance (μR) correlated with microvascular resistance and had >99% NPV at ≤145 and 88% PPV at ≥500 in INOCA patients.