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Isolated defect of adenosine-mediated coronary vasodilation: functional evidence for a new microangiopathic entity
1Medizinische Klinik I, Klinikum Grosshadern, Ludwig-Maximilians-Universität, Munich, Germany. koglin@cvlab.harvard.edu
Objectives:
The present study describes an isolated defect of the coronary vasodilation in response to adenosine in five patients examined for 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 rest and during intracoronary administration of adenosine (80 micrograms/min and 160 micrograms/min over 3 min each), papaverine (10-mg bolus) and acetylcholine (30 micrograms/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-independent and -dependent vasomotion, as assessed with papaverine (mean [+/-SD]-relative coronary flow reserve 2.62 +/- 0.66 vs. 2.97 +/- 0.88, 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-mediated vasodilation compared with control subjects (relative coronary flow reserve in response to 80 micrograms/min of adenosine 1.08 +/- 0.17 vs. 2.45 +/- 0.74 [p < 0.001] and 160 micrograms/min of adenosine 1.03 +/- 0.15 vs. 2.89 +/- 0.65 [p < 0.001]).
Conclusions:
These findings are consistent with functional evidence for a new entity of a coronary microangiopathy affecting a subtype of the endothelium-independent vasomotion.