Fluxes in heart specific nitrite production before and after coronary intervention in patients with recent acute coronary syndromes: A comparison with indices of myocardial microvascular function

Abstract

In an ongoing study 15 patients were recruited following presentation with non-ST elevation myocardial infarction. Patients underwent coronary angiography and continued in the study if they required a coronary stent in the “culprit” lesion. Baseline bloods from aortic root, coronary sinus and systemic venous were taken together with the measurement of the index of microvascular resistance, coronary flow reserve, coronary wedge pressure using a pressure/flow wire and thermodilution measurement. This was repeated immediately following successful stent implantation and treatment of the epicardial stenosis. Three distinct groups are seen and these can be defined according to the baseline systemic nitrite concentrations: ⩽100, >100 to 200 and >200 to ⩽500 nM. At baseline the heart specific A–V gradient is progressively more positive according to starting systemic venous nitrite concentration (−30.7, −4.1 and +113.5 nM, respectively). Following coronary intervention this heart specific A–V gradient is progressively more negative following coronary intervention (+0.8, −4.2 and −72.3 nm, respectively). As the baseline A–V heart gradient of nitrite progressively increases (−30.7, −4.1 and +113.5 nM) this is associated with baseline myocardial microvascular resistance (IMR) becoming progressively lower (36.15, 22.63 and 23.07 U). Following intervention, A–V gradient shows the opposite trend with a progressive reduction in nitrite concentrations in the three groups. This is associated with a progressive increase in microvascular resistance in the three groups (−23.3, −0.2 and +13.5 U). This suggests that at baseline, a heart specific increase in NO production is associated with improved microvascular function. This trend is reversed with respect to both post procedure heart specific A–V gradients and IMR.