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Background: Stress-only single-photon emission computed tomography myocardial perfusion imaging (SO SPECT MPI) is associated with similarly benign prognosis as stress-rest SPECT MPI. However, previous studies have used attenuation correction rather than prone imaging to increase the rate of SO studies., Objectives: To assess the prognosis of SO SPECT MPI performed with prone imaging., Methods: We performed a retrospective cohort analysis of all patients who underwent a Tc-99m gated SPECT MPI over a 58-month period., Results: Two thousand four hundred and sixty five patients were followed up. Of them, 1114 (45.2%) patients had a SO supine test, 388 (15.7%) underwent a SO supine and prone test, and the remaining 963 (39.1%) patients underwent a full stress-rest SPECT MPI. There was a similar annual mortality rate between the SO supine/prone group (1.3%), the SO supine (1.5%), and the stress-rest (1.5%) group (P = 0.47). Patients in the stress-rest group were significantly more likely to suffer from myocardial infarction (MI) as compared to the other two groups with an annual rate of 0.7% as compared to 0.4% (P = 0.049)., Conclusions: Normal supine-prone SO SPECT MPI is associated with a similarly benign prognosis as stress-rest SPECT MPI. The adjunction of prone imaging to the stress supine significantly increases the rate of SO SPECT MPI.

Background: Mechanical left ventricular dyssynchrony (MLVD) might contribute in the therapeutic decision-making in patients with heart failure (HF) prior to cardiac resynchronization therapy (CRT). Our aim was to assess MLVD in patients with HF prior to implantable cardioverter-defibrillator (ICD) compared to patients with CRT-D., Methods: In a prospective study, patients with LVEF ≤ 35% who were scheduled for ICD or CRT-D, underwent gated SPECT myocardial perfusion imaging with technetium 99m sestamibi within 3 months prior procedure. MLVD was measured by phase analysis., Results: The study cohort consisted of 143 patients, 71 with ICD and 72 with CRT-D. Age 68.3 ± 11 and LVEF 24 ± 6%. Phase standard deviation (SD) was 62.5 ± 18 and 59.7 ± 20 (P = NS), respectively. During follow-up of 23.7 ± 12.1 months, there were 10 vs 14 cardiac death in ICD and CRT-D, respectively (P = NS), hospitalization for HF, in 34 vs 53 (P < .001). In multivariate analysis, Phase SD was the independent predictor for cardiac death [HR 2.66 (95% CI 1.046-6.768), P = .04]. Kaplan-Meier curves of phase SD of 60° significantly identified ICD patients with and without cardiac deaths and hospitalization for HF exacerbation., Conclusions: MLVD by phase SD can identify patients with cardiac events and predict cardiac death in patients treated with ICD.

Background: Left ventricular (LV) dyssynchrony by phase analysis has been studied by myocardial perfusion imaging (MPI)-gated SPECT in patients with LV dysfunction in various clinical settings. We aimed to investigate the routine use of phase analysis with gated SPECT for predicting cardiac outcome., Methods: Patients referred to a tertiary medical center in 2010-2011 prospectively underwent a gated SPECT and phase analysis, and follow-up for cardiac events. The values of clinical variables, MPI, LV function, and LV dyssynchrony in predicting cardiac events were tested by univariate and multivariate analyses., Results: The study group included 787 patients (66.5 ± 11 years, 81% men) followed for a mean duration of 18.3 ± 6.2 months. There were 45 (6%) cardiac events defined as composite endpoint; cardiac death occurred in 26 patients, and the rest had new-onset or worsening heart failure and life-threatening arrhythmias. In multivariate analysis, it was shown that NYHA class, diabetes mellitus, and LVEF <50% were the independent predictors for composite endpoint. However, the independent predictors for cardiac mortality were NYHA class (for each increment in class) and phase standard deviation (SD) (for each 10° increment)., Conclusion: Gated SPECT with phase analysis for the assessment of LV dyssynchrony can successfully predict cardiac death together with NYHA class, in patients with LV dysfunction.

Background: We previously described the feasibility of performing myocardial perfusion imaging (MPI) with half the technetium (Tc-99m) activity using ordered-subset expectation maximization with resolution recovery (OSEM-RR) processing. This study sought to assess the accuracy of this technique by correlating the findings with coronary angiography., Methods: Of 290 patients who underwent MPI-gated SPECT using a half dose of Tc-99m sestamibi and OSEM-RR software in 2010-2012 at a tertiary medical center, 62 were referred for invasive coronary angiography within 90 days and formed the study group. Ischemia was defined as a summed difference score (SDS) of >3 on the MPI scan. Luminal stenosis of ≥70% on invasive coronary angiography served as the reference., Results: Mean Tc-99m activity per study was 23.9 ± 11.5 mCi and mean effective radiation dose was 7.2 ± 3.4 mSv. MPI revealed no abnormalities in 10 patients (16.2%), myocardial infarction only in 8 patients (12.9%), and ischemia in 44 patients (71.1%). Overall sensitivity, specificity, and positive and negative predictive values for MPI compared to invasive angiography were 89.1%, 75.0%, 91.1%, and 70.5%, respectively., Conclusions: MPI SPECT performed with a half dose of Tc-99m and OSEM-RR image processing correlates well with invasive angiography. (J Nucl Cardiol 2013).

Background: We previously described the feasibility of myocardial perfusion imaging (MPI) with nearly half the radiation dose using ordered-subset expectation maximization with resolution recovery (OSEM-RR) processing. This study sought to determine if the findings can be expanded to obese patients., Methods: Fifty obese patients (>100 kg) referred for MPI underwent stress-rest or rest-stress studies with a half dose of Tc-99m sestamibi in a 1-day protocol using OSEM-RR processing. Image quality and clinical results were compared with matched patients (by age, sex, weight, presence/probability of coronary artery disease) evaluated with standard "full-dose" Tc-99m sestamibi, mostly in a 2-day protocol. Dose activities were adjusted individually by weight., Results: Mean Tc-99m activity was 33.4 ± 13.9 mCi in the half-dose group and 60 ± 10 mCi in the full-dose group (P < .0001). Respective mean effective doses per study were 10 ± 4 and 18 ± 3 mSv (P < .0001). Overall image quality was good-to-excellent in 94% of the half-dose group and 80% of the full-dose group (P < .045). There was no between-group difference in rate or size of ischemia or infarction, except for stress left ventricular ejection fraction., Conclusions: MPI with half the radiation dose is feasible in obese patients. Image quality is better than for full-dose MPI, and the procedure can be performed in 1 day.

Objective: This study sought to assess the feasibility of performing myocardial perfusion imaging (MPI) with half the technetium activity using ordered-subset expectation maximization with resolution recovery (OSEM-RR), an iterative reconstruction software developed to improve count statistics and acquisition time., Methods: Two hundred eighteen patients referred for MPI were randomly allocated to undergo stress-rest or rest-stress protocols with standard full-dose (FD) injections of technetium (Tc)-99m sestamibi or half-dose (HD) injections and OSEM-RR processing. Dose activities were adjusted individually by weight. The groups were compared for image quality and clinical results., Results: The groups were similar for mean patient age, weight, and body mass index, sex distribution, pre-test probability of CAD and CAD prevalence. Mean Tc-99m activities for the low-dose and high-dose stages were as follows: FD group: 429 ± 85 MBq and 1132 ± 200 MBq; HD group: 263 ± 129 MBq and 629 ± 85 MBq (P < .0001 for both). Mean effective dose per study was 13.6 ± 1.4 mSv in the FD group and 7.7 ± 1.0 mSv in the HD group (P < .001). Over all image quality was good-to-excellent in 98% and 95% of the groups, respectively. However, when we analyzed the low-dose stage separately, image quality was slightly worse in the HD than the FD, though still within the good-to excellent range., Conclusions: MPI with nearly half the radiation dose is feasible with good image quality.

Background: To examine the yield of an ultra-low-dose computed tomography (CT) transmission module for attenuation-correction (AC) on a dedicated cardiac camera in evaluation of SPECT-myocardial perfusion imaging (MPI) in the diagnosis of CAD and for additional chest abnormalities., Methods: The study group included 150 patients with known or suspected CAD referred for technetium sestamibi SPECT MPI. CT transmission scanning (effective radiation 0.17 mSv) was performed after each gated SPECT scan. AC and non-corrected (NC) SPECT scans were evaluated on a 5-point scale using a 17-segment model, and the sum stress score (SSS) and sum rest score (SRS) were calculated for each condition. Overall image quality, sensitivity and normalcy rate (51 patients) and processing of 28 CT slices were screened for chest findings., Results: CT-based AC significantly improved image quality (P = .01). Mean SSS was 3.8 ± 5.8 with AC and 6.1 ± 7.1 with NC (P < .001); the respective SRS values were 2.6 ± 6.3 and 3.9 ± 7.7 (P < .001). The sensitivity of detecting ≥70% stenosis was 71% and 86% (P = NS) and the normalcy rate was 30% and 89% (P < .0001) in NC and AC SPECT MPI, respectively. Chest CT: lung abnormalities in 31%, aortic calcifications in 27%, and hiatus hernia in 5%., Conclusions: Ultra-low-dose CT for AC of SPECT-MPI improves image quality, diagnostic accuracy and suggests detection of chest findings.

Background: The prognostic value of myocardial perfusion imaging (MPI) in the very elderly population has not been addressed specifically. The aim of this study was to examine the characteristics of the octogenarian population referred for MPI and the prognostic value of the procedure in terms of patient gender., Methods: The study sample consisted of 162 consecutive patients (61 women, 101 men) of mean age 83 +/- 3 years (range, 80-90) who underwent stress MPI. The duration of follow-up was 45+/-12 months. Outcome measures were cardiac-related death, and nonfatal myocardial infarction (MI)., Results: Thirty-one major cardiac events (19%) were recorded, including 26 cardiac deaths and 5 MI events, in 6 of the 61 women (10%) and 25 of the 101 men (25%) (p < 0.03). The univariate predictors of cardiac death or MI, except of known coronary artery disease (CAD), were MPI variables: left ventricular (LV) dilatation, increased lung uptake, abnormal scan, and the presence and extent of myocardial ischemia. However, the only predictors for major cardiac events were: LV dilatation (OR = 6.9, 95% CI 2.7-17.4, p < 0.0001) and ischemia by scan (OR = 2.75, 95% CI 1.09-6.96, p < 0.03). The Kaplan Meier curve demonstrated significant differences in survival between patients with or without LV dilatation and patients with or without ischemia., Conclusions: LV dilatation and myocardial ischemia were useful predictors of cardiac death and MI in octogenarian patients with CAD or with suspicion of CAD.

Background: Left internal mammary artery (LIMA) grafting to the left anterior descending artery (LAD) is known to have long-term patency. However, myocardial ischemia in the territories supplied by LIMA to LAD is still demonstrated. The aim of this study is to examine the relationships between the extent, location, and clinical outcome of myocardial ischemia in LAD territories (ILAD) by use of myocardial perfusion imaging (MPI) and angiographic characteristics of such a bypass conduit., Methods and Results: We studied 38 consecutive patients with prior coronary artery bypass grafting who showed stress-induced ischemia in LIMA to LAD territories by MPI single photon emission computed tomography between the years 1996-2000. All patients underwent quantitative coronary angiography within 6 months of the nuclear study. Single photon emission computed tomography parameters of ILAD were assessed by location (septum, apex, anterior, and anterolateral) and included extension score (1-4 per patient), severity score (0-3 per territory), and total sum score. LIMA to LAD quantitative coronary angiography parameters included minimal lumen diameter, lesion length, reference diameter, and diameter stenosis (percentage). LAD and LIMA diameters and ratio (in normal segments) were determined within 10 mm proximal and distal to the anastomotic site. The study group was compared with 18 control subjects without ischemia or stenosis treated with LIMA to LAD. The patients were followed up for cardiac death at an interval of 3.2 +/- 1.5 years from the time of MPI testing. The patients' mean age was 66 +/- 12 years (31 men and 7 women); the mean period after surgery was 6.2 +/- 1.5 years. The ILAD distribution was as follows: septum, 12 (32%); apex, 20 (52%); anterior, 24 (63%); and anterolateral, 18 (47%). The mean extension score was 1.9 +/- 1.0, and the mean total sum score was 3.4 +/- 2.3. Of 38 patients with ILAD, only 17 (45%) had greater than 50% luminal stenosis (2 LIMA and 15 anastomosis or distal). Among clinical variables during stress testing, the prevalence of angina was significantly higher in the luminal stenotic patients versus patients without stenosis (P =.04). A significant correlation was found between anterior wall ischemia and reference diameter (r = -0.7, P =.002) and between total sum score and minimal lumen diameter (r = -0.48, P =.05). Of note, the LAD-to-LIMA ratio was significantly lower in patients with ILAD and without luminal stenosis compared with the control group (0.73 +/- 0.16 vs 0.87 +/- 0.15, P =.004). Cardiac death occurred in 8 patients (21%), 5 patients with luminal stenosis versus 3 patients without stenosis (P = not significant)., Conclusions: In patients with LIMA to LAD anastomosis, myocardial ischemia could occur even without angiographic luminal stenosis and apparently reflects a mismatch between LAD and LIMA diameters at distal anastomotic sites. Regarding the similar prevalence of cardiacdeath, invasive evaluation and aggressive treatment are recommended in all patients with ischemia in LIMA/LAD territories.

Background: Although the combination of increased pulmonary thallium uptake and ischemia has demonstrated prognostic utility, the value of pulmonary uptake independent of ischemia has not been evaluated critically. Accordingly, our purpose was to evaluate the prognostic utility of thallium lung uptake in patients who do not have stress-induced defects., Methods and Results: We studied 184 patients who were divided into three groups. Patients with increased pulmonary uptake were grouped into either the normal perfusion (n = 48) or fixed defect (n = 44) scan group and were compared with a third group (n = 92) of control patients who had normal scans and no lung uptake. During a mean follow-up of 23 +/- 13 months, there were 13 cardiac events (death or myocardial infarction) and the incidence per year was 0.6%, 2%, and 12% in the control, normal, and fixed defect groups, respectively (p < 0.00001). Life table analysis demonstrated greater event-free survival rates in the control and normal groups compared with the group with fixed defects. A Cox regression analysis showed that the number of fixed defects (infarct segments) was the most important independent prognostic factor (p < 0.00001) for future cardiac events., Conclusion: In patients with increased pulmonary thallium uptake and no stress perfusion defects, the prognosis is similar to that of control patients. However, patients with infarct segments and lung uptake have a significantly worse prognosis.