Standard provocative manoeuvres in patients with and without left bundle branch block studied with myocardial SPECT

Abstract

Myocardial SPECT with technetium compounds, using standard provocation manoeuvres, can be used in patients with LBBB with only a mild decrease in diagnostic accuracy as compared to patients without LBBB.

Comparison of myocardial contrast echocardiography with SPECT in the evaluation of coronary artery disease in asymptomatic patients with LBBB

“…Employment of noninvasive imaging has also several limitations because of the possible myocardial scintigraphic anteroseptal perfusion artifacts and echocardiographic abnormal septal motion, occurring also in patients free of left anterior descending artery stenosis [4][5][6][7][8][9]. As a result, coronary arteriography remains the Fgold standard_ procedure for CAD detection in patients with permanent LBBB.…”

“…Various mechanisms have been proposed to explain these false-positive myocardial perfusion defects. Among these are the following: a reduction of myocardial blood flow within the interventricular septum as a result of the delayed septal contraction, camera-field nonuniformity, partial-volume effects, patients' motion during imaging of septal fibrosis, myocardial cell dysfunction including reduced glucose uptake that is not necessarily related to septal ischemia, and small-vessel disease associated with fibrodegenerative changes which may cause both the conduction abnormality and the exercise perfusion defects [1,7]. Further, in LBBB, the septum contracts late in systole at a time when the ejection is already in progress.…”

“…Although some authors reported improved specificity by applying different interpretation criteria or quantitative methodology, other authors prefer pharmacological coronary vasodilatation with intravenous adenosine or dipyridamole as the first option in these patients [7]. Adenosine thallium imaging is safe and has been proved superior to exercise thallium imaging in the detection of CAD in patients with LBBB, obviating septal artifacts (thereby markedly improving the specificity in the left anterior descending artery territory) [5].…”

Diagnostic and prognostic value of gated myocardial perfusion single-photon emission computed tomography in low-risk patients with left bundle-branch block

“…Various mechanisms have been proposed to explain false-positive myocardial perfusion defects in LBBB patients. Among these are the following: (a) reduction of myocardial blood flow within the interventricular septum as a result of the delayed septal contraction, (b) septal fibrosis and smallvessel disease associated with fibrodegenerative changes, which may cause both the conduction abnormality and the exercise perfusion defect, (c) camera-field non-uniformity, (d) patients' movement during imaging, and (e) partialvolume effects [9,18].…”

“…Alternative approaches, including the use of coronary vasodilators (i.e. dipyridamole and adenosine) as stress agents and the application of different interpretation criteria, have reduced but not eliminated the incidence of falsepositive results [9]. The introduction of gated singlephoton emission computed tomography (SPECT) has allowed the evaluation of myocardial perfusion and function in one study, thus increasing diagnostic accuracy and prognostic value over perfusion data alone.…”