21 November 2003
Objective: We tested the hypothesis that patients with biopsy-proven inflammatory infiltrates have an impaired vasodilator capacity of the coronary microvasculation. Methods: In 80 patients with clinically suspected inflammatory heart disease, coronary regulation was assessed with the argon method (1) at rest and maximal coronary flow (V<sub>cor</sub>/V<sub>max</sub>) and (2) at rest and minimal coronary resistance (R<sub>cor</sub>/R<sub>min</sub>) both before and after dipyridamole (0.5 mg/kg body weight) treatment. Results: Compared to patients without evidence of myocardial inflammation in endomyocardial biopsy (n = 51) but similar demographic characteristics, patients with biopsy-proven inflammatory infiltrates (n = 29) showed significantly reduced maximal coronary flow (286 ± 122 vs. 189 ± 78 ml/min × 100 g; p = 0.001) and minimal coronary resistance was increased (0.40 ± 0.17 vs. 0.60 ± 0.27 mm Hg × min × 100 g/ml<sup>–1</sup>, p = 0.001). The coronary reserve in patients with inflammatory infiltrates was markedly reduced (3.5 ± 1.1 to 2.4 ± 0.81, p = 0.001). Conclusion: Patients with biopsy-proven inflammatory infiltrates have a diminished coronary reserve due to reduced coronary vasodilator capacity. This may be due to the involvement of the intramural coronary vasculature in inflammatory heart disease.