Fractional flow reserve with dobutamine challenge and coronary microvascular endothelial dysfunction in symptomatic myocardial bridging.
BACKGROUND
Myocardial bridging (MB) results in compression of the coronary artery lumen in systole, extending into diastole with resultant hemodynamic alternation as reflected by fractional flow reserve (FFR). MB has also been associated with coronary endothelial dysfunction. The objective of this study was to investigate relationship between FFR with dobutamine challenge and coronary microvascular endothelial dysfunction in symptomatic MB.


RESULTS
Seventeen consecutive patients who had cardiac catheterization assessment of MB were enrolled. The patients were divided into 2 groups according to normal (% increase in coronary blood flow [%CBF] ≥50%, n=7) or impaired (%CBF <50%, n=10) coronary microvascular endothelial function assessed on vasoreactivity in the coronary artery with intracoronary infusion of acetylcholine (Ach). Myocardial ischemia was then assessed using FFR at rest and during i.v. dobutamine infusion challenge across the MB with intracoronary pressure wires. FFR was significantly decreased at peak dobutamine infusion compared to at rest in the impaired group (0.85±0.06 vs. 0.91±0.05, P=0.001), but not in the normal group (0.93±0.05 vs. 0.91±0.07, P=0.618). Both FFR at rest and at peak dobutamine infusion had a positive correlation with %CBF by Ach in the impaired group (r(2)=0.46, P=0.030; r(2)=0.52, P=0.018, respectively).


CONCLUSIONS
Microvascular endothelial dysfunction was associated with decreased FFR at peak dobutamine stress in patients with symptomatic MB.
Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic and College of Medicine.
Satoshi
S
Yoshino
Andrew
A
Cassar
Yoshiki
Y
Matsuo
Joerg
J
Herrmann
Rajiv
R
Gulati
Abhiram
A
Prasad
Ryan J
RJ
Lennon
Lilach O
LO
Lerman
Amir
A
Lerman
D000109:Acetylcholine / Q000008:administration & dosage; D058665:Adrenergic beta-1 Receptor Agonists / Q000008:administration & dosage*; D000328:Adult; D001783:Blood Flow Velocity; D018679:Cholinergic Agonists / Q000008:administration & dosage; D003326:Coronary Circulation / Q000187:drug effects*; D004280:Dobutamine / Q000008:administration & dosage*; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000473:pathology / Q000503:physiopathology*; D055815:Young Adult
D058665:Adrenergic beta-1 Receptor Agonists; D018679:Cholinergic Agonists; D004280:Dobutamine; D000109:Acetylcholine