Diffusely impaired myocardial perfusion in patients with suspected coronary artery disease: Clinical utility of relative perfusion

BACKGROUND: In patients with suspected coronary artery disease (CAD), diffusely impaired hyperaemic myocardial blood flow (MBF) may indicate a multivessel epicardial CAD but also impaired coronary microcirculation. We assessed whether relative hyperaemic MBF-that is, the ratio of the lowest to the highest regional hyperaemic MBF-predicts obstructive CAD in patients with diffusely impaired hyperaemic MBF. METHODS: O myocardial perfusion imaging with positron emission tomography at Kuopio University Hospital, Finland, in 2017-2023. The final analyses included 64 patients who had diffusely impaired hyperaemic MBF and were subsequently referred to invasive coronary angiography (ICA). RESULTS: In ICA, 34/64 (53%) patients had obstructive CAD. Compared to patients with non-obstructive CAD, those with obstructive CAD had lower relative hyperaemic MBF: 66% (95% CI 62-69%) versus 52% (95% CI 47-57%), respectively (p < 0.001). When relative hyperaemic MBF was used to predict the presence of obstructive CAD in ICA, the receiver operating characteristic analysis showed an area under the curve of 0.778 (95% CI 0.666-0.891). In binary logistic regression analysis, relative hyperaemic MBF independently predicted obstructive CAD (OR = 0.92 [95% CI 0.86-0.97], p = 0.004). CONCLUSION: Obstructive CAD is more likely in patients with lower relative hyperaemic MBF. Consequently, relative hyperaemic MBF may have clinical utility in patients with suspected CAD and diffusely impaired hyperaemic MBF.