ISOLATED DEFECT OF ADENOSINE-MEDIATED CORONARY VASODILATION - FUNCTIONAL EVIDENCE FOR A NEW MICROANGIOPATHIC ENTITY

Objectives. The present study describes an isolated defect of the coro nary vasodilation in response to adenosine in five patients examined f ar clinically suspected coronary microangiopathy. Background. Coronary microangiopathies can be defined functionally as dysregulation of the microcirculatory vasomotion. Methods. The five patients were compared with 24 control subjects. Coronary flow velocity was measured with an intracoronary Doppler guide wire (0.018 in. [0.046 cm], 12 MHz) at re st and during intracoronary administration of adenosine (80 mu g/min a nd 160 mu g/min over 3 min each), papaverine (10-mg bolus) and acetylc holine (30 mu g/min over 5 min). Diameters of the epicardial coronary arteries were measured by quantitative coronary angiography. Results. All subjects (patients and control) exhibited angiographically normal epicardial coronary arteries and normal and comparable endothelium-ind ependent and -dependent vasomotion, as assessed with papaverine (mean [+/- SD] relative coronary flow reserve 2.62 +/- 0.66 vs. 2.97 +/- 0.8 8, p = 0.32) and acetylcholine (volumetric coronary flow reserve 2.61 +/- 0.27 vs. 2.91 +/- 0.67, p = 0.58), respectively. Affected patients were identified by an isolated complete defect of the adenosine-media ted vasodilation compared with control subjects (relative coronary how reserve in response to 80 mu g/min of adenosine 1.08 +/- 0.17 vs. 2.4 5 +/- 0.74 [p < 0.001] and 160 mu g/min of adenosine 1.03 +/- 0.15 vs. 2.89 +/- 0.65 [p < 0.001]). Conclusions. These findings are consisten t with functional evidence far a new entity of a coronary microangiopa thy affecting a subtype of the endothelium-independent vasomotion. (C) 1997 by the American College of Cardiology.