Phasic coronary flow pattern and flow reserve in patients with left bundle branch block and normal coronary arteries.
OBJECTIVE
The purpose of this study was to determine whether scintigraphic myocardial perfusion defects in patients with left bundle branch block (LBBB) and normal coronary arteries are related to abnormalities in coronary flow velocity pattern and/or coronary flow reserve.


BACKGROUND
Septal or anteroseptal defects on exercise myocardial perfusion scintigraphy are common in patients with LBBB and normal coronary arteries.


METHODS
Thirteen patients (7 men, age 61+/-8 years) with LBBB and normal coronary arteries underwent stress thallium-201 scintigraphy and cardiac catheterization. In all patients and in 11 control subjects coronary blood flow parameters were calculated from Doppler measurements of flow velocity in the left anterior descending coronary artery (LAD) before and after adenosine administration.


RESULTS
The time to maximum peak diastolic flow velocity was significantly longer both for the seven patients with (134+/-19 ms) and for the six without (136+/-7 ms) exercise perfusion defects than for controls (105+/-12 ms, p < 0.05), whereas the acceleration was slower (170+/-54, 186+/-42 and 279+/-96 cm/s2, respectively, p < 0.05). Coronary flow reserve in the patients with exercise perfusion defects (2.7+/-0.3) was significantly lower than in those without (3.7+/-0.5, p < 0.05) or in the control group (3.4+/-0.5, p < 0.05).


CONCLUSIONS
Patients with LBBB have an impairment of early diastolic blood flow in the LAD due to an increase in early diastolic compressive resistance resulting from delayed ventricular relaxation. Furthermore, exercise scintigraphic perfusion defects in these patients are associated with a reduced coronary flow reserve, indicating abnormalities of microvascular function in the same vascular territory.
Skalidis
E I
EI
Department of Cardiology, University Hospital of Heraklion, Crete, Greece.
Kochiadakis
G E
GE
Koukouraki
S I
SI
Parthenakis
F I
FI
Karkavitsas
N S
NS
Vardas
P E
PE
D000241:Adenosine; D000368:Aged; D001783:Blood Flow Velocity / Q000187:drug effects; D002037:Bundle-Branch Block / Q000000981:diagnostic imaging / Q000503:physiopathology*; D017023:Coronary Angiography; D003326:Coronary Circulation / Q000187:drug effects; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000187:drug effects; D003971:Diastole / Q000187:drug effects; D004176:Dipyridamole; D015150:Echocardiography, Doppler; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015899:Tomography, Emission-Computed, Single-Photon; D014655:Vascular Resistance / Q000187:drug effects; D014665:Vasodilator Agents
D014665:Vasodilator Agents; D004176:Dipyridamole; D000241:Adenosine