Perfusion and functional abnormalities outside the septal region in patients with left bundle branch block assessed with gated SPECT.

BACKGROUND: The presence of a left bundle branch block (LBBB) pattern on the electrocardiogram may frequently lead to perfusion defects in the septum not necessarily due to ischemic heart disease, but probably due to abnormal septal wall motion. The introduction of gated single photon emission computed tomography (SPECT) allows the evaluation of myocardial perfusion and function in one study. Accordingly, we analysed perfusion and function and the relation between perfusion and regional function in the septal region in patients with a LBBB without evidence of a previously sustained myocardial infarction. METHODS: We selected 37 patients with a LBBB without a history of a previous myocardial infarction, which was confirmed by echocardiography and/or coronary angiography. All patients underwent technetium-99m tetrofosmin gated SPECT myocardial imaging. Twelve control patients with a low likelihood of coronary artery disease and a normal technetium-99m tetrofosmin gated SPECT myocardial perfusion scintigram were selected as a reference population. The left ventricle (LV) was divided into 18 segments, which were scored for perfusion and function (wall motion and wall thickening) on a 4-point scale. RESULTS: The average LV end-diastolic volume was higher and the average LV ejection fraction was lower in patients with LBBB as compared to controls (142+/-90 vs. 81+/-18 ml, and 48+/-19 vs 62+/-7%, p=0.03 and p=0.02, respectively). Not only in the septum, but also in the other segments, reduced myocardial perfusion and abnormal wall motion/wall thickening was observed in the patients with LBBB (p<0.0001 vs controls). Patients with LBBB showed no correlation between perfusion and function in the septum, and between perfusion in septum and global LV function (r=0.21, p=0.2; r=0.10, p=0.6, respectively). Conversely, a good correlation was found between perfusion and function, either regional or global, in the remote segments (both r=0.79, p<0.0001). CONCLUSIONS: We conclude that patients with LBBB without a previous myocardial infarction show cardiomyopathic changes with perfusion and wall motion abnormalities, involving the entire left ventricle. The severity of diminished septal perfusion is not directly associated with the severity of septal wall motion abnormalities or global LV function. However, in the myocardial segments remote from the septum, reduced perfusion is closely associated with functional abnormalities.

Assessment of regional myocardial wall motion and thickening by gated 99Tcm-tetrofosmin SPECT: a comparison with magnetic resonance imaging.

Gated single photon emission computed tomography (SPECT) imaging allows the simultaneous assessment of both perfusion and function by using one single study. The assessment of regional wall motion and thickening pattern with gated SPECT allows viability studies to be performed. Magnetic resonance imaging (MRI) is well validated for the assessment of myocardial wall motion and thickening in patients with normal and impaired ventricular function. The aim of the study was to analyse the concordance between wall motion and thickening scores derived by gated SPECT and MRI imaging. Furthermore, the agreement for myocardial wall motion and thickening according to myocardial perfusion was analysed with both techniques. We studied a group of 21 patients, including 13 with a previous myocardial infarction (all more than 4 months before the study), using both gated SPECT 99Tcm-tetrofosmin myocardial perfusion imaging and MRI. A 13-segment model was used for both gated SPECT and MRI and each segment was visually scored using a scale of 1-3 for wall motion and thickening. There was a high agreement between gated SPECT and MRI for both wall motion (229/273, 84%; k = 0.72, P<0.001) and wall thickening (236/273, 86%; k = 0.77, P<0.001). The agreement for wall motion and thickening was 80% (k = 0.66) and 83% (k = 0.70), respectively, for patients with myocardial infarction; and 90% (k = 0.81) and 92% (k = 0.86), respectively (P = NS), for patients without myocardial infarction. Agreement in segmental wall motion and thickening scores between gated SPECT and MRI was 90% (k = 0.80) and 91% (k = 0.84), respectively, for segments with normal or mild to moderate hypoperfusion; and 71% (k = 0.45) and 77% (k = 0.57), respectively, for segments with severe hypoperfusion or no perfusion. Of the 70 (41%) segments that had severely diminished or no perfusion in post-myocardial infarction patients, 22 (31%) showed preserved wall motion and 17 (24%) showed preserved wall thickening both by gated SPECT and MRI, suggesting residual myocardial viability in malperfused segments. Our results suggest that gated SPECT imaging is a reliable tool for the assessment of regional wall motion and thickening in patients with known or suspected coronary artery disease. In patients with a previous myocardial infarction gated SPECT imaging has the potential to detect preserved wall motion and thickening in regions with fixed perfusion defects indicating the potential presence of residual myocardial viability.

Detection of residual wall motion after myocardial infarction by gated technetium-99m tetrofosmin SPET: a comparison with contrast ventriculography.

The differentiation of residual viability from necrotic myocardium in patients with a prior myocardial infarction is important when deciding whether revascularization is indicated. Myocardial viability can be assessed by studying perfusion and regional wall motion. Gated single-photon emission tomography (SPET) imaging allows the simultaneous assessment of perfusion and function through a single study. The aim of this study was to analyse the concordance between wall motion score derived by gated SPET and by contrast ventriculography. Furthermore, the agreement between myocardial perfusion and regional myocardial wall motion was analysed for both techniques. We studied a homogeneous group of 26 consecutive patients with a prior myocardial infarction, using both gated technetium-99m tetrofosmin SPET and contrast ventriculography. A seven-segment model of the left ventricle was employed to score regional myocardial wall motion on images obtained with gated SPET and contrast ventriculography using a four-point scale. Contrast ventriculography was performed within 2 weeks of the gated SPET study. Prevalence of abnormal wall motion (akinetic or dyskinetic) was 24/182 (13%) for gated SPET and 25/182 (14%) for contrast ventriculography (P = NS). There was a high agreement (80%) in wall motion score between gated SPET and contrast ventriculography (kappa = 0.67, P < 0.001). The agreement was better in segments with normal or mild to moderate hypoperfusion (82%, kappa = 0.69) than in those with severe hypoperfusion (67%, kappa = 0.56). The agreement between myocardial perfusion and myocardial wall motion was 89% (162/182), kappa = 0.57, for gated SPET and 80% (145/182), kappa = 0.21, for contrast ventriculography. The relation between the summed wall motion scores per patient on gated SPET and contrast ventriculography was excellent (y = 0.81x + 2.9, r = 0.82, P < 0.01). Thirteen (43%) out of 30 segments with severely diminished or no myocardial perfusion showed normal or hypokinetic wall motion on gated SPET, suggesting residual myocardial viability in malperfused regions. Our results suggest that gated SPET imaging is a reliable tool for the assessment of regional wall motion in post-myocardial infarction patients. Furthermore, in patients with a previous myocardial infarction, gated SPET imaging has the potential to detect preserved wall motion in regions with fixed perfusion defects, which might be indicative of residual myocardial viability.

Detection of residual wall motion after sustained myocardial infarction by gated 99Tcm-tetrofosmin SPECT: a comparison with echocardiography.

The differentiation of residual viability from necrotic myocardium in patients with a previously sustained myocardial infarction is important in deciding indications for revascularization. Myocardial viability can be assessed by studying perfusion and regional wall motion. With gated single photon emission computed tomography (SPECT), it is possible to augment SPECT perfusion data with ventricular functional data both at a global and regional level. The aim of the study was to analyse the concordance between wall motion score derived by gated SPECT and echocardiography. Furthermore, the agreement between myocardial perfusion and left ventricular wall motion was analysed with both techniques. We studied a homogenous group of 25 consecutive patients with a previous myocardial infarction (MI) using both gated SPECT 99Tcm-tetrofosmin myocardial perfusion imaging and two-dimensional echocardiography. Echocardiography was performed within 2 weeks of the gated SPECT study. Both for gated SPECT and for echocardiography the left ventricle was divided into seven regions per patient. For comparison, the gated SPECT regions were matched to the echocardiographic regions, resulting in a total of 175 regions. Prevalence of abnormal wall motion (akinetic or dyskinetic) was 23% (39/171) for echocardiography and 21% (36/175) for gated SPECT (P = NS). There was a high agreement in wall motion score between echocardiography and gated SPECT of 80% (136/171). The agreement between myocardial perfusion and myocardial wall motion was 82% (143/175) for gated SPECT and 76% (130/171) for echocardiography (P = NS). Nineteen (34%) of the 56 regions with severely diminished or absent myocardial perfusion showed normal or hypokinetic wall motion both by gated SPECT and echocardiography suggesting residual myocardial viability in malperfused regions. Our results suggest that, gated SPECT imaging is a reliable tool for the assessment of regional wall motion in post myocardial infarction patients. Furthermore, in patients with a previous myocardial infarction gated SPECT imaging has the potential to detect preserved wall motion in regions with fixed perfusion defects, which might be indicative of residual myocardial viability.