Phasic coronary flow pattern and flow reserve in patients with left bundle branch block and normal coronary arteries

• Published in: Journal of the American College of Cardiology Vol. 33; no. 5; pp. 1338 - 1346
• Main Authors: Skalidis, Emmanuel I, Kochiadakis, George E, Koukouraki, Sophia I, Parthenakis, Fragiskos I, Karkavitsas, Nikolaos S, Vardas, Panos E
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.04.1999; Elsevier Science
• Subjects: Adenosine; Aged; Biological and medical sciences; Blood Flow Velocity - drug effects; Bundle-Branch Block - diagnostic imaging; Bundle-Branch Block - physiopathology; Cardiac dysrhythmias; Cardiology. Vascular system; Coronary Angiography; Coronary Circulation - drug effects; Coronary Vessels - diagnostic imaging; Coronary Vessels - drug effects; Diastole - drug effects; Dipyridamole; Echocardiography, Doppler; Electrocardiography; Exercise Test; Female; Follow-Up Studies; Heart; Humans; Male; Medical sciences; Middle Aged; Tomography, Emission-Computed, Single-Photon; Vascular Resistance - drug effects; Vasodilator Agents; ECG; ANOVA; LBBB; IV; LAD; Radionuclide study; Human; Regional blood flow; Pharmacologic test; Adenosine; Purine nucleoside; Arrhythmia; Pathophysiology; Cardiovascular disease; Exploration; Bundle branch block; Scintigraphy; Conduction disorder; Heart block; Heart disease; Myocardium; Medical imagery; Exercise tolerance test; Anterior intraventricular artery; Hemodynamics
• ISSN: 0735-1097; 1558-3597
• DOI: 10.1016/S0735-1097(98)00698-6

OBJECTIVES 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.