Complex stenosis morphology and vasomotor responses to inhibition of nitric oxide synthesis

Objective-To assess the relation between coronary vasomotor effects of NG-m onomethyl-L arginine (LNMMA) administration and coronary stenosis morpholog y, length, and severity in patients with stable angina. Design-In 28 patients (24 male, four female) with coronary artery disease a nd chronic stable angina, intracoronary normal saline and 4 mu mol/min LNMM A were infused for four minutes each, followed by an intracoronary bolus of 250 mug glyceryl trinitrate. Coronary stenoses were classified as concentr ic (smooth), eccentric (smooth), or complicated (irregular). The diameters of these stenoses and their adjacent reference proximal segments were measu red by quantitative angiography. Results-During LNMMA infusion a significantly larger proportion of complica ted stenoses than concentric and eccentric stenoses constricted by greater than or equal to 5% (p < 0.01) and the magnitude of vasoconstriction was gr eater in complicated than in concentric and eccentric stenoses (p < 0.05). For complicated stenoses the magnitude of constriction (in mm) with referen ce to normal saline was greater than that of the concentric and eccentric s tenoses (p < 0.05), whereas concentric and eccentric stenoses constricted s imilarly. Irrespective of the type of morphology, there was a correlation ( p < 0.05) between both the severity and the length of stenoses and the magn itude of vasoconstriction to LNMMA. A similar proportion of concentric, ecc entric, and complicated stenoses showed greater than or equal to 5% increas e in diameter with glyceryl trinitrate, and the magnitude of the response w as similar in the three groups. Conclusions-In patients with coronary artery disease, the response to LNMMA is greater when stenosis morphology is complex, indicating greater nitric oxide activity. This provides further evidence that plaques with complex mo rphology are in an active state.