Blood haemoglobin, renal insufficiency, fractional flow reserve and plasma NT-proBNP is associated with index of microcirculatory resistance in chronic coronary syndrome

Coronary microvascular dysfunction (CMVD) is associated with adverse cardiovascular outcome. We aimed to determine the prevalence of CMVD and factors related to index of microcirculatory resistance (IMR) in consecutive patients with chronic coronary syndrome (CCS) undergoing elective coronary angiography. Non-interventional physicians enrolled 274 patients with CCS before angiography, to minimize selection bias by PCI-operators. Fractional flow reserve (FFR) and IMR were measured in the LAD. Subjects with extensively diseased LAD, no measures due to technical reasons or violation of protocol were excluded from the analysis (n = 54). The proportion of patients with IMR corrected for collateral flow (IMRcorr) >25 units was 25% (95% confidence interval [CI] 19%–31%) in all 220 patients. In subjects with FFR ≤0.80 in the LAD the proportion of IMRcorr > 25 units was 21% (95% CI 13%–30%) as compared to subjects with FFR >0.80, 29% (95% CI 21%–36%), p = .268. Haemoglobin (p 25 in the LAD. [Display omitted] •IMR is associated with blood haemoglobin, renal dysfunction, NT-proBNP and FFR.•One in four patients undergoing elective coronary angiography have CMVD.•IMR assessment is associated with use of 19 ml contrast and 2.1 min fluoroscopy.