Tc-99m Sestamibi Gated SPECT in Patients with Left Bundle Branch Block

Abstract

These preliminary data indicate that end-diastolic images can significantly reduce artifactual defects in patients with LBBB. The resolution of an LBBB pattern on end-diastolic data would significantly improve the diagnostic role of myocardial perfusion studies in these patients.

Non-invasive assessment of coronary artery disease in patients with left bundle branch block

“…In the general population with suspected obstructive SPECT has a sensitivity of 87% and specificity of 73% [13]. It is recognized that in LBBB however SPECT does suffer some limitations, predominantly explained by the impact of LBBB on the myocardium described earlier in this review; because of these several early studies found a high rate of positive test results in the LAD territory with inducible perfusion defects being seen in patients without CAD on angiography [14,15].…”

QRS complex duration and dipyridamole gated SPECT findings in the left bundle branch block

“…Regional wall motion abnormalities, decreased systolic wall thickening, left ventricular dilation, and thinned myocardial walls can cause regional perfusion abnormality, of which the latter was related to the partial volume effects of SPECT systems [5,6,[14][15][16]. Recent evidence with N-13 ammonia and O-15 water positron emission tomography demonstrated normal blood fl ow in LBBB patients, which is inconsistent with the concept of down-regulated septal perfusion in these patients [17,18].…”

“…In patients with LBBB, septal systolic wall thickening and wall motion abnormalities seem to be responsible for the creation of LBBB artifacts on SPECT, because of abnormalities in segmental contraction rather than heterogeneity in perfusion. Today, we know that SPECT perfusion artifacts owing to LBBB can resolve on the frozen images of the end-diastolic phase of the cardiac cycle [5,6]. Disappearance of perfusion abnormalities on the end-diastolic images, in which the myocardial walls were thinner, and the aggravation of defects at end-systole suggest a more pronounced effect of the systolic parameters (i.e., regional wall thickening or wall motion) in the creation of LBBB artifacts given that the myocardial counts actually measure considerably depend on systolic thickening [17].…”

“…In patients with left bundle branch block (LBBB), myocardial perfusion defects and left ventricular functional abnormalities can occur especially in the territory of the left anterior descending coronary artery despite the absence of stenosed vessel(s) [1][2][3][4][5][6]. To decrease falsepositive scintigraphic reports in this particular patient population, methodological modifi cations [the use of 1 3 vasodilator stress, technetium-99m (Tc-99m) sestamibi, and electrocardiography (ECG)-gated single-photon emission computed tomography (SPECT)] and different interpretation criteria (reversible perfusion defects especially on the end-diastolic images and a concomitant reversible apical defect) have been found as useful maneuvers [2][3][4][5][6][7].…”

“…To decrease falsepositive scintigraphic reports in this particular patient population, methodological modifi cations [the use of 1 3 vasodilator stress, technetium-99m (Tc-99m) sestamibi, and electrocardiography (ECG)-gated single-photon emission computed tomography (SPECT)] and different interpretation criteria (reversible perfusion defects especially on the end-diastolic images and a concomitant reversible apical defect) have been found as useful maneuvers [2][3][4][5][6][7]. ECG-gated SPECT permits the evaluation of both perfusion and functions of the left ventricular myocardium, and can considerably help to distinguish true and artifactual abnormalities owing to the LBBB [5,6]. The width of the QRS complex is an electrocardiographic refl ection of ventricular conduction abnormality as well as intra-and inter-ventricular dyssynchrony [8,9].…”