Background--Viral cardiomyopathy resulting from myocardial virus persistence can be associated with inflammatory immune responses that involve the myocardium and coronary blood vessels. The aim of this study was to investigate the differential impact of myocardial virus persistence and inflammation on endothelial function of the coronary microcirculation.

Methods and Results--In 71 patients with nonischemic cardiomyopathy, myocardial biopsies were examined for virus persistence (by polymerase chain reaction) and inflammation (by immunohistology). Endothelial function of the coronary microcirculation was examined during heart catheterization by measuring diameter (by quantitative coronary angiography) and velocity changes (by intracoronary Doppler) of the left anterior descending artery in response to acetylcholine. Coronary blood flow (CBF) was calculated. Endothelium-independent vasoreactivity to adenosine was assessed. Mean age of the patients (37 men, 34 women) was 43±13 years; mean ejection fraction was 64±11%. In 43 patients, adenovirus, enterovirus, parvovirus, or HHV-6 was detected; 28 had no virus. Endothelial function of the coronary microcirculation was significantly impaired in patients with myocardial virus persistence (V) compared with patients without virus (Co) (CBF-V, 22±86%; CBF-Co, 110±113%; P=0.001), which was confirmed in 51 patients with myocardial inflammation (MC) (32 with virus, 19 with no virus) (CBF-MC-V, 12±89%; CBF-MC-Co, 81±109%; P=0.034) and in 20 patients with normal immunohistology of the myocardial biopsies (Co) (11 with virus, 9 with no virus) (CBF-Co-V, 51±72%; CBF-Co-Co, 175±97%; P=0.006). Endothelial function of the coronary microcirculation was also significantly impaired in patients with myocardial inflammation/endothelial activation compared with patients without inflammatory immune response. Endothelium-independent vasodilation was not influenced significantly.

Conclusions--Myocardial virus persistence and myocardial inflammation/endothelial activation are associated with endothelial dysfunction of the coronary microcirculation. Endothelial dysfunction in patients with myocardial virus persistence can occur independently of myocardial inflammation/endothelial activation but is more pronounced in patients with concurrent inflammation.