Left bundle branch block and coronary artery disease: Accuracy of dipyridamole thallium-201 single-photon emission computed tomography in patients with exercise anteroseptal perfusion defects

Background  Reduced septal or anteroseptal uptake of thallium-201 during exercise is frequently observed in patients with left bundle branch block (LBBB) even in the absence of left anterior descending (LAD) coronary artery disease. The purpose of this study was to evaluate prospectively the accuracy of dipyridamole²⁰¹TI single-photon emission computed tomography (SPECT) in detecting LAD coronary artery disease in patients with LBBB and septal or anteroseptal perfusion defects on exercise²⁰¹TI SPECT. Methods and Results  Twelve consecutive patients (10 men and two women) with complete LBBB and septal or anteroseptal perfusion defects on exercise²⁰¹TI SPECT underwent dipyridamole²⁰¹TI SPECT. The delay between dipyridamole and exercise was 2 to 30 days. Coronary angiography was performed during this period in all patients. Six (50%) of 12 patients with exercise perfusion defects showed normal perfusion after dipyridamole; all had normal coronary angiograms. The remaining six patients also had positive results of dipyridamole studies, two with moderate and four with severe septal or anteroseptal perfusion defects. Coronary angiography showed significant (>50%) LAD coronary artery stenosis in three patients; three patients with severe septal or anteroseptal perfusion defects after dipyridamole had normal coronary angiograms. Neither the evaluation of apical involvement nor the presence of dilated ventricles, decreased left ventricular ejection fraction, or wall motion abnormalities could help to identify (or explain) false-positive results. Conclusion  This study confirms that dipyridamole is more accurate than exercise in excluding LAD coronary artery disease. However, there are still false-positive results and the severity of the septal or anteroseptal perfusion defect does not add additional information to identify LAD coronary artery disease. Coronary angiography is thus necessary for positive dipyridamole study results to identify coronary artery disease as a major prognostic factor in patients with LBBB.     

Segmental myocardial velocities in dilated cardiomyopathy with and without left bundle branch block

Purpose:

To quantify three‐directional left ventricular (LV) myocardial velocities and intraventricular synchrony in dilated cardiomyopathy (DCM) with and without left bundle branch block (LBBB) using MR tissue phase mapping (TPM).

Materials and Methods:

Regional velocities were assessed by TPM (spatial/temporal resolution = 1.3 × 1.3 mm² × 8 mm/14 ms) in DCM patients with (n = 12) and without LBBB (n = 7) compared with age‐matched volunteers (n = 20). For the evaluation the AHA 16‐segment and an extended LV visualization model was used.

Results:

Radial velocities in DCM patients were reduced in 75% (systole) and in 94% (diastole) (P = 0.0001 – P = 0.0360), long‐axis velocities in 31% (systole) and in 75% (diastole) of the 16 segments compared with controls (P = 0.0001 – P = 0.0310). LBBB resulted in inferolaterally delayed diastolic long‐axis velocities (P = 0.0012 – P = 0.0464) and shortened TTP for septal systolic radial velocities (P = 0.0002). Intra‐ventricular radial systolic TTP differed up to 150 ms between segments in patients with LBBB (89 ms without LBBB, 34 ms in volunteers) reflecting an increased dyssynchrony. LV twist was altered in all patients with reduced and delayed systolic and diastolic peak velocities.

Conclusion:

TPM identified previously not described alterations of the spatial distribution and timing of all myocardial velocities in patients with DCM and LBBB. This may help to optimize therapy management in future. J. Magn. Reson. Imaging 2013;37:119–126. © 2012 Wiley Periodicals, Inc.     

Left ventricular mechanical synchrony from stress and rest <Superscript>82</Superscript>Rb PET myocardial perfusion ECG-gated studies: Differentiating normal from LBBB patients

Background  

We have previously reported normal values for LV mechanical synchrony from post-stress exercise ^99mTc SPECT studies; the goal of this study was to develop normal values for mechanical synchrony from pharmacologic stress and rest ⁸²Rb PET studies and compare these values to a population of LBBB patients.     

Myocardial scintigraphy with thallium-201 and technetium-99m-hexakis-methoxyisobutylisonitrile in left bundle branch block: a study in patients with and without coronary artery disease

In left bundle branch block (LBBB) thallium-201 myocardial scintigraphy frequently reveals septal abnormalities in the absence of coronary artery disease (CAD) and gives rise to false-positive results in patients with suspected CAD. It has not yet been clarified which pathophysiological mechanism is responsible for these perfusion abnormalities. A total of 66 patients with constant LBBB were investigated with ²⁰¹T1 or technetium-99m-hexakis-methoxyisobutylisonitrile (MIBI), 62 underwent coronary angiography. Of 12 patients without left anterior descending artery (LAD) or right coronary artery (RCA) stenoses, 11 had a reversible septal activity deficit after ²⁰¹T1 stress injection, whereas 20 of 22 patients without relevant CAD showed a constant stress/rest septal deficit using MIBI. Regarding patients with significant LAD and/or RCA stenoses, both radiopharmaceuticals almost always showed a reversible septal deficit: with ²⁰¹T1 in 15 of 16 individuals and with MIBI in 14 of 15. In 12 patients ²⁰¹T1 was reinjected at rest. In those who had LAD or RCA stenoses (n = 5), early septal activity uptake after stress injection was poorer than that after rest injection; in the absence of CAD (n = 7), septal stress uptake corresponded with that of rest injection. It is concluded that septal perfusion abnormalities in LBBB and the absence of CAD are characterized by an exercise-independent reduction of septal blood flow per mass of viable myocardium and that stress/rest injection protocols of myocardial perfusion tracers are able to differentiate between LBBB with and without CAD.Dedicated to Prof. Dr. Dr. h.c. H. Hundeshagen on the occasion of his 65th birthday Correspondence to: W.H. Knapp     

Myocardial perfusion SPECT identifies patients with left bundle branch block patterns at high risk for future coronary events

Background  

The value of myocardial perfusion SPECT (MPS) for patients with left bundle branch block (LBBB) or right ventricular apical (RVA) pacing seems reduced. The prognosis of patients with only abnormal activation related perfusion defects (AARD) due to LBBB or RVA-pacing is similar to those with a normal MPS. We assessed the prognostic value of MPS in patients with LBBB or RVA pacing.     

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

BACKGROUND: The objective of this study was to determine the prevalence of anterior and septal defects in patients with left bundle branch block (LBBB), and to assess the diagnostic accuracy of myocardial single photon emission computed tomography (SPECT) with technetium compounds in patients with and without LBBB using standard provocative manoeuvres. METHODS: Five hundred and nine consecutive patients (456 without LBBB and 53 with LBBB) without previous infarction who had a coronary angiography performed within <3 months of the scintigraphic study were retrospectively evaluated. The same stress procedures were followed in all patients. (1) Only exercise when it was sufficient; and (2) exercise + simultaneous administration of dypiridamole if exercise was insufficient. Only reversible defects were considered positive and > or =50% of coronary stenosis was considered significant. RESULTS: Prevalence of reversible anterior and septal defects was low (33% and 12%, respectively) in patients with LBBB. Although lower values of global sensitivity (81%) and specificity (73%) were obtained in these patients, there were no significant differences with respect to the patients without LBBB (89% and 86%, respectively). Specificity values for the diagnosis of stenosis of left anterior descending (78%), left circumflex (96%) and right coronary artery (74%) in patients with LBBB were lower, but without significant statistical differences with respect patients without LBBB (90%, 96% and 82%, respectively). CONCLUSIONS: 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.     

Early and delayed Tc-99m-tetrofosmin myocardial SPECT in patients with left bundle branch block

To determine the utility of the myocardial tracer Tc-99m-tetrofosmin in the examination of patients with left bundle branch block (LBBB) and to investigate Tc-99m-tetrofosmin uptake and retention in the myocardium, early and delayed Tc-99m-tetrofosmin SPECT was performed in 10 patients having LBBB without coronary stenosis.Methods: After 740 MBq of Tc-99m-tetrofosmin injection in the resting state, the early and delayed SPECT imaging was done at 30 min and 180 min, respectively.Results: Decreased Tc-99m-tetrofosmin uptake in the septal segments was observed in 4 patients (40%) at 30 min and in 9 (90%) at 180 min. Reverse redistribution was seen in 9 of 10 patients. In patients with LBBB, the septal-to-lateral uptake ratio was lower in the delayed images than in the early images (0.80 ± 0.09 vs. 0.89 ± 0.09, p < 0.001). In patients with LBBB, the washout rate of Tc-99m-tetrofosmin was higher in the septal segments than in the lateral segments (28.3 ±4.3% vs. 22.8 ± 3.3%, p < 0.001).Conclusion: The SPECT data indicate that in LBBB without coronary stenosis, the uptake of Tc-99m-tetrofosmin is decreased in the septal wall, and that reverse redistribution occurs frequently. Our results contribute to the elucidation of both the cellular biokinetics of Tc-99m-tetrofosmin in the myocardium and the hemodynamics of the septum in LBBB, and indicate the possible clinical utility of Tc-99m-tetrofosmin.     

Is septal glucose metabolism altered in patients with left bundle branch block and ischemic cardiomyopathy?

Left bundle branch block (LBBB) is common in patients with heart failure (HF) and contributes to left ventricular (LV) dysfunction. The abnormal septal motion may alter septal metabolic demand but this has not been well characterized in patients with ischemic cardiomyopathy (ICM) and LV dysfunction. The aim of this study was to determine the effect of LBBB on septal metabolism in patients with ICM, LV dysfunction, and LBBB. METHODS: Fifty-three patients with LV dysfunction and ICM were identified: 34 with LBBB, 19 with normal QRS (30% of this patient population. Absence of this finding was often associated with lateral wall perfusion defects, suggesting an alteration in the metabolic demand on the septum. This may have implications for HF therapies such as resynchronization and requires further study.     

Decreased septal wall thickening in patients with left bundle branch block

OBJECTIVES: Septal wall motion abnormalities are frequently observed in patients with left bundle branch block (LBBB). However, septal wall thickening in LBBB patients has not been thoroughly evaluated. METHODS AND RESULTS: To investigate the relationship between septal wall motion and wall thickening, we studied 31 normal control subjects, 24 LBBB patients with normal wall motion (LBBB-NWM), and 24 LBBB patients with septal dyssynchrony (LBBB-SDS), all with a low likelihood (<15%) of coronary artery disease. The septal and lateral quadrants of the left ventricle were analyzed in stress 8-frame gated technetium 99m sestamibi tomograms. The percent wall thickening was calculated by use of a 25-segment polar map with the p-FAST software program by two independent methods: the regional count density increase from end diastole to end systole (CD method) and the geometric increase in the distance between the 50% thresholded endocardial and epicardial borders from end diastole to end systole (GD method). In addition, the ratio of septal/lateral percent wall thickening was calculated. The relative septal wall thickening in the entire LBBB population was decreased as compared with the normal control subjects (0.35 +/- 0.37 vs 0.81 +/- 0.17, P <.001). Decreased wall thickening was observed in not only LBBB-SDS patients but also to a lesser degree in LBBB-NWM patients (0.12 +/- 0.35, P <.001; 0.57 +/- 0.24, P =.005, respectively). This abnormality was most apparent when the CD method was used. CONCLUSIONS: Septal wall thickening is decreased in patients with LBBB even with normal wall motion. LBBB per se may compromise septal wall thickening, and dyssynchronous wall motion results in further deterioration of wall thickening.     

Effects of left bundle branch block on myocardial FDG PET in patients without significant coronary artery stenoses.

Cardiac PET studies in patients with left bundle branch block (LBBB) are few, and the results are conflicting. In particular, even if a reduced uptake of FDG is reported, confirmation in a large group of patients and exact understanding of the underlying cause are lacking. METHODS: We selected 29 consecutive patients who had complete LBBB and no significant stenosis on coronary angiography scheduled for FDG and 13N-NH3 PET for myocardial viability evaluation at our center. Wall motion was evaluated using 2-dimensional echocardiography. Ten volunteers without coronary stenosis or LBBB served as a control group. RESULTS: All LBBB patients had a reverse mismatch in the septum, defined as reduced uptake of FDG in comparison with 13N-NH3. The mismatch extended to the anterior and inferior walls in 17 patients. The mean (+/-SD) septal-to-lateral ratio was 0.57 +/- 0.11 for FDG (range, 0.28-0.76) and 0.99 +/- 0.12 for 13N-NH3 (range, 0.75-1.18), with P < 0.0001. In contrast, no significant differences in uptake were seen in the control group, which had a septal-to-lateral ratio of 0.95 +/- 0.13 for FDG (range, 0.78-1.15; P < 0.01 with respect to LBBB patients) and 0.94 +/- 0.11 (range, 0.85-1.20) for 13N-NH3. CONCLUSION: Our study suggests that in LBBB patients without significant coronary stenosis, FDG uptake in the septum changes without a correlating change in perfusion. To avoid possible overestimation of necrosis, especially in the LAD territory, this phenomenon must be considered in evaluations of myocardial viability using FDG images.     

Risk stratification and prognostic assessment by myocardial perfusion-gated SPECT in patients with left bundle-branch block and low-intermediate cardiac risk

Objective

In high-risk patients with left bundle-branch block (LBBB), functional but not perfusion parameters yield incremental prognostic information. The aim of our study was to evaluate the prognostic value of gated single photon emission computed tomography (SPECT) in low-intermediate risk LBBB patients.

Methods

One hundred seventy-six subjects underwent stress-rest dual-day protocol 99mTc sestamibi-gated SPECT and were dichotomized in two groups: without LBBB (Group 1, n = 86) and with LBBB (Group 2, n = 90). Patients were followed for 32 ± 18 months. Cox regression multivariate analysis was used to determine which variable was the best predictor of cardiac event. Event-free survival curves were computed by Kaplan–Meier method.

Results

Myocardial perfusion scintigraphy was abnormal in 32 and 60 patients for Groups 1 and 2, respectively (37 vs. 67 %, p < 0.001). In Groups 1 and 2, the mean summed stress score (SSS) was 3.7 ± 5.6 versus 6.7 ± 6.4, while the mean summed difference score (SDS) was 1.6 ± 2.5 versus 2.7 ± 3.3 (both p < 0.005); therefore 34 % of patients in Group 1 and 53 % of those in Group 2 presented myocardial ischemia. All functional parameters were significantly different between the two subsets (all p < 0.005). Follow-up was completed in 161 patients (92 %); 10 events occurred in Group 1 and 20 in Group 2 (14 vs. 25 %). The event-free survival was significantly higher in patients with normal than in those with abnormal scan (85 vs. 63 %, p < 0.005); moreover, the prognosis of patients with LBBB was significantly worse. At multivariate analysis, SDS was found to be the only independent predictor of cardiac events both in all patients and in LBBB population (HR 3.08, and HR 4.99, p < 0.05).

Conclusions

This is the first study to assess the prognostic value of gated SPECT in patients with LBBB and low-intermediate cardiac risk. Both perfusion and functional data obtained by gated SPECT are different between patients with and without LBBB. However, SDS is the only predictor of events. Thus, the amount of reversible ischemia at gated SPECT has a discriminative power in stratifying the cardiac risk of LBBB population.

     

射频导管消融犬左束支电位对心脏电机械活动的影响

目的 探讨射频导管消融犬左束支电位(LBP)对心脏传导及心功能的影响,以及犬左束支传导阻滞(LBBB)模型的制备方法.方法 应用射频消融导管在10只实验犬左心室内膜标测到LBP处进行消融,观察能否成功制备犬LBBB模型以及其对心脏传导的影响.对成功复制LBBB的模型犬应用超声心动图比较LBBB前后心脏收缩功能及舒张功能的变化.结果 10只犬接受LBP处消融后,8只(80％)成功制备LBBB模型.消融靶点处心房与心室电压比值＜1:10,局部记录的LBP至心室电位间期为17.1±3.2(12～22)ms,消融后QRS波宽度由52.8±4.8ms增至100.5±11.1ms(P＜0.001),而PR间期、AH间期、HV间期无明显变化.另外2只犬在LBP至心室电位间期分别为30ms、32ms处消融,导致完全性房室传导阻滞.8只犬发生LBBB后超声心动图检查示:收缩功能指标左室射血分数和主动脉血流速度积分降低(P＜0.05);舒张功能指标E/A下降为＜1,伴有等容舒张时间和二尖瓣减速时间延长(P＜0.05);出现显著室间与室内不同步,表现为间隔后壁运动延迟及左右心室射血前期时间差明显延长(P＜0.001).结论 射频导管消融左束支电位可导致LBBB,是制备犬LBBB模型成功率较高的方法,但有发生完全性房室传导阻滞的危险.LBBB即刻可导致左室激动延迟,左右室间及左室内收缩不同步,左心室收缩及舒张功能降低.     

Cardiac efficiency and oxygen consumption measured with 11C-acetate PET after long-term cardiac resynchronization therapy.

Cardiac resynchronization therapy (CRT) is a treatment option in patients with severe heart failure and left bundle-branch block (LBBB). This study evaluated the effects of 4 and 13 mo of CRT on myocardial oxygen consumption (MVO2) and cardiac efficiency as compared with mild heart failure patients without LBBB. METHODS: Sixteen patients with severe heart failure and LBBB due to idiopathic cardiomyopathy were studied at baseline and after 4 and after 13 mo of therapy. Thirteen patients with mild heart failure without LBBB served as a comparison group. The clearance rate (k2) of 11C-acetate was measured with PET to assess MVO2. Stroke volume was derived from the dynamic PET data according to the Stewart-Hamilton principle and, furthermore, cardiac efficiency using the work metabolic index. RESULTS: After 4 mo of CRT, stroke volume index (SVI) increased by 50% (P = 0.012) and cardiac efficiency increased by 41% (P < 0.001). Global k2 remained unchanged but regional k2 demonstrated a more homogeneous distribution pattern. The parameters showed no significant changes during therapy. Under CRT, cardiac efficiency, SVI, and the distribution pattern of regional k2 did not differ from mild heart failure patients without LBBB. CONCLUSION: CRT improves cardiac efficiency for at least 13 mo, as demonstrated by a higher SVI, whereas MVO2 remains unchanged. Cardiac efficiency, SVI, and the MVO2 distribution pattern reach the level of patients with mild heart failure without LBBB. The unfavorable hemodynamic performance in heart failure with LBBB is effectively restored by long-term CRT to the level of an earlier disease state.     

Comparison of regional myocardial blood flow and perfusion in dilated cardiomyopathy and left bundle branch block: role of wall thickening.

Heterogeneous perfusion in left bundle branch block (LBBB) has been demonstrated by (99m)Tc-methoxyisobutylisonitrile (MIBI) SPECT. Locally different contraction is also associated with LBBB. Quantitative analysis of myocardial SPECT is influenced by partial-volume effects depending on systolic wall thickening. Therefore, partial-volume effects may mimic perfusion heterogeneity in LBBB. METHODS: Fifteen patients with nonischemic dilated cardiomyopathy and LBBB underwent resting (15)O-water PET, (99m)Tc-MIBI SPECT, and gated (18)F-FDG PET for analysis of wall thickening. Myocardial blood flow corrected for rate-pressure product (corrMBF), (99m)Tc-MIBI uptake, and wall thickening were determined in 4 left ventricular wall areas. In 14 patients, M-mode echocardiographic recordings were available for comparison. RESULTS: Homogeneous distribution was found for corrMBF (1.09 +/- 0.41 to 1.19 +/- 0.31 mL x g(-1) x min(-1)). (99m)Tc-MIBI uptake and wall thickening were heterogeneous (P < 0.0001), with the lowest values septal ((99m)Tc-MIBI, 65% +/- 10%; wall thickening, 16% +/- 14%) and the highest lateral ((99m)Tc-MIBI, 84% +/- 5%; wall thickening, 55% +/- 17%). Similar relationships in systolic wall thickening were observed by M-mode echocardiography (anteroseptal, 20% +/- 11%; posterolateral, 37% +/- 18%; P < 0.001). CONCLUSION: Heterogeneity of (99m)Tc-MIBI uptake in LBBB corresponds to differences in wall thickening and does not reflect distribution of corrMBF. Supplementary analysis of wall thickening is recommended when assessing (99m)Tc-MIBI SPECT in LBBB.     

Relationship of decreased accumulation of 99mTc-tetrofosmin on myocardial single-photon emission computed tomography images between QRS duration in dilated cardiomyopathy patient with left bundle branch block

Purpose

This study aimed to clarify the relationship between severity of conduction delay in the left ventricle and myocardial uptake of ^99mTc-tetrofosmin (TF) in dilated cardiomyopathy (DCM) patients with left bundle branch block (LBBB).

Methods and Results

Thirty-two DCM patients with LBBB underwent electrocardiography and ^99mTc-TF myocardial single-photon emission computed tomography (SPECT). SPECT images were acquired at 30 min (early images) and 3 h (late images) after injection. We calculated the total defect score (TDS) using a 20-segment model with a 5-point scoring system. The TDS in early and late images was defined as the summed early score (SES) and summed late score (SLS), respectively. On early images, 29 of 32 patients (91%) had decreased tracer uptake in the septum. All patients showed a decreased tracer uptake in the septum on late images. A significant correlation was observed between TDS (both SES and SLS) and QRS duration, with SLS showing an excellent correlation (SES: r = 0.554, P < 0.001; SLS: r = 0.779, P < 0.0001).

Conclusions

These findings suggest that in DCM patients with LBBB, hypoperfusion and myocardial damage in the septum might occur in accordance with an increase in the QRS duration.     

Accuracy of non-invasive techniques for diagnosis of coronary artery disease and prediction of cardiac events in patients with left bundle branch block: a meta-analysis

Purpose Non-invasive evaluation of coronary artery disease (CAD) in patients with left bundle branch block (LBBB) has limitations inherent to different tests, and the relative merits of these tests are unclear. This meta-analysis assessed the accuracy of the frequently used non-invasive techniques, including exercise electrocardiography (ECG), myocardial perfusion imaging (MPI) and stress echocardiography (SE), for detection of CAD and prediction of cardiac events in patients with LBBB. Methods A review was conducted of all reports on detection of CAD and prediction of cardiac events in patients with LBBB (published between January 1970 and December 2004), and revealed 55 diagnostic and nine prognostic reports with sufficient details to calculate test accuracy. Weighted (by sample size) sensitivity and specificity were calculated. Summary relative risk ratios (95% confidence intervals) were calculated. Results Overall sensitivity was higher for exercise ECG and (quantitatively analysed) MPI than for SE (83.4% and 88.5% versus 74.6% respectively, p<0.0001). SE had a higher specificity (88.7%) than MPI (41.2%) and exercise ECG (60.1%) (p<0.0001). Based on analysis of eight reports, the relative risk of cardiac death or myocardial infarction in patients with an abnormal SE and MPI was elevated more than sevenfold, but it did not differ by imaging modality (p=0.9). Conclusion Meta-analysis of non-invasive CAD assessment in LBBB patients revealed that exercise ECG and MPI had the highest sensitivity, while SE had the highest specificity. The prognostic accuracy of MPI and SE appeared similar.     

Short membranous septum length in bicuspid aortic valve stenosis increases the risk of conduction disturbances

BackgroundDistinct anatomical features predispose bicuspid AS patients to conduction disturbances after TAVR. This study sought to evaluate whether the incidence of permanent pacemaker implantation (PPMI) and left bundle branch block (LBBB) in patients with bicuspid aortic stenosis (AS) following transcatheter aortic valve replacement (TAVR) is related to an anatomical association between bicuspid AS and short membranous septal (MS) length.MethodsSixty-seven consecutive patients with bicuspid AS from a Bicuspid AS TAVR multicenter registry and 67 propensity-matched patients with tricuspid ASunderwent computed tomography before TAVR.ResultsMS length was significantly shorter in bicuspid AS compared with tricuspid AS (6.2 ± 2.5 mm vs. 8.4 ± 2.7 mm, respectively; p < 0.001). In patients with bicuspid AS, MS length and aortic valve calcification were the most powerful pre-procedural independent predictors of PPMI or LBBB (odds ratio [OR]: 1.38, 95% confidence interval [CI]: 1.15 to 1.55, p = 0.003 and OR: 1.92, 95% CI: 1.1 to 3.34, p = 0.022, respectively). When taking into account pre- and post-procedural parameters, aortic valve calcification and the difference between MS length and implantation depth were the most powerful independent predictors of PPMI or LBBB in patients with bicuspid AS (OR: 1.82, 95%: 1.1 to 3.1, p = 0.027; OR: 1.25, 95% CI: 1.10 to 1.38, p = 0.003).ConclusionMS length, which was significantly shorter in bicuspid AS compared with tricuspid AS, aortic valve calcification, and device implantation deeper than MS length predict PPMI or LBBB in bicuspid AS after TAVR.     

Prognostic value of stress myocardial perfusion single photon emission computed tomography imaging in patients with left bundle branch block

Background. Left bundle branch block (LBBB) may occur with or without structural heart disease. In patients with coronary artery disease the presence of LBBB is associated with an increased risk of cardiovascular events.Methods and Results. This study examined the outcome of 293 medically treated patients with LBBB and symptoms who were undergoing stress thallium-201 single photon emission computed tomography imaging. One hundred seventy-three men and 120 women with an age range of 67 ± 9 years and a pretest probability of coronary artery disease of 77% ± 28% were studied. During a mean follow-up of 33 months 58 hard cardiac events (death or nonfatal myocardial infarction) and 112 total events (hard events, coronary angioplasty, coronary bypass surgery, or cardiac transplantation) occurred. Univariate and multivariate Cox survival analysis with clinical, stress, hemodynamic, and single photon emission computed tomography variables identified the perfusion defect size (chi SQUARE = 27, p = 0.0001) and increased lung thallium uptake as the most important independent predictors of hard or total cardiac events. The hard event-free survival rate was 91% in patients with no or small defects (<15% of left ventricular myocardium) and 72% in patients with large defects (p = 0.0001, RR = 3.2, 95% CI 1.7 to 5.9). The total event-free survival rate was 81% in patients with small defects and 48% in patients with large defects (p = 0.0001, RR = 2.7, 95% CI 1.9 to 4.0). The total event rate was 54% in patients with large perfusion defects and increased lung uptake and 17% in patients with no or small abnormality and normal lung thallium uptake (p = 0.0001).Conclusion. Single photon emission computed tomography perfusion imaging is useful in predicting outcome in patients with LBBB and intermediate pretest probability of coronary artery disease. The size of perfusion abnormality and lung thallium uptake stratified patients into high and low risk groups with a threefold difference in hard and total cardiac events.     

Predictive variables for hard cardiac events and coronary revascularization in patients with normal left ventricular myocardial perfusion and systolic function

Background

The objective of this study was to investigate the impact of clinical, electrocardiographic and stress testing variables in predicting hard cardiac events (HE) and coronary revascularization (CR) in patients with normal stress–rest gated SPECT.

Materials and methods

Included in the study were 2,004 patients (63.5?±?12.5 years, 41.6 % men) with normal myocardial perfusion and left ventricular ejection fraction (LVEF) >50 % on gated SPECT who were followed for HE (cardiovascular death or acute myocardial infarction) and CR.

Results

During a follow-up of 4.3?±?2.4 years, 33 patients (1.6 %; 0.4 %/year) had HE and 50 patients (2.5 %; 0.6 %/year) underwent CR. In a univariate analysis, age ≥65 years, insulin-dependent diabetes mellitus (IDDM), left bundle branch block (LBBB), and pharmacological stress were associated with HE. Independent predictors of HE were age ≥65 years (p?<?0.001; HR 6.9), IDDM (p?=?0.014; HR 3.4), and LBBB (p?=?0.002; HR 4.6). In the univariate analysis, male gender, LVEF, known coronary artery disease (CAD), LBBB, and a positive stress test were associated with CR. Independent predictors of CR were known CAD (p?=?0.016; HR 2.1), and a positive stress test (p?=?0.006; HR 2.3).

Conclusion

Age ≥65 years, IDDM, and LBBB are HE-independent predictors in patients with normal myocardial perfusion and normal LVEF on gated SPECT. The presence of known CAD or a positive stress test significantly increases the probability of CR during follow-up.     

Thallium-201 myocardial SPECT in left bundle branch block: Diagnosis of myocardial ischemia with a disease-specific reference database

Background  The aim of this study was to assess the value of a myocardial perfusion single photon emission computed tomography (SPECT) reference file for patients with left bundle branch block (LBBB). Methods and Results  Tl-201 stress-redistribution myocardial perfusion SPECT studies of patients with complete, permanent LBBB were reviewed retrospectively. To develop a reference database, 18 patients with a low likelihood of coronary artery disease (CAD) were selected. Left ventricular regional average and standard deviation (SD) values of the reference file images were calculated. The diagnostic performance was tested on perfusion images of 49 patients with LBBB, undergoing both scintigraphic and coronary angiographic evaluation, and was compared with a commercial quantitative analysis system using a general reference database. The LBBB reference file performed significantly better in detecting epicardial CAD than did the general reference database (receiver operating characteristic area under the curve 0.835 ± 0.06 vs 0.580 ± 0.08, p < .01). Disease localization also was improved significantly in the territory of the left anterior descending and of the right coronary arteries. Conclusions  The use of a reference file of patients with LBBB and a low likelihood of CAD aids the detection and the localization of myocardial ischemia on Tl-201 myocardial SPECT images of this patient group. The authors thank Professor Mátyás Keltai MD and István Szilvási MD for valuable discussions. The authors also thank József Turák (Mediso Ltd., Budapest, Hungary) for providing technical information on the Interview image processing system.