Objective To investigate the effects of laparoscopic sleeve gastrectomy(LSG)on the cardiac structure and function in obese patients with heart failure(HF)and compare the efficacy of LSG across obese patients with different HF types.Methods This study included 33 obese patients with HF who underwent LSG.The clinical indicators were compared between before operation and 12 months after operation.Repeated measures analysis of variance was employed to evaluate the changes in echocardiographic parameters before operation and 3,6,and 12 months after operation.Patients were allocated into a HF with preserved ejection fraction group(n=17),a HF with mildly reduced ejection fraction group(n=5)and a HF with reduced ejection fraction(HFrEF)group(n=11)based on left ventricular ejection fraction(LVEF)before operation for subgroup analyses of the effects of LSG on the cardiac structure and function of obese patients with HF.The paired samples t-test was conducted to assess the degree of cardiac structural and functional alterations after LSG.Results The 33 patients included 69.7% males,with an average age of(35.3±9.9)years,and a body mass index(BMI)of(51.2±9.8)kg/m².The median follow-up was 9.0(5.0,13.3)months.Compared with the preoperative values,the postoperative BMI(P=0.002),body surface area(BSA)(P=0.009),waist circumference(P=0.010),hip circumference(P=0.031),body fat content(P=0.007),and percentage of patients with cardiac function grades Ⅲ-IV(P<0.001)decreased.At the 12-month follow-up left atrial diameter(P=0.006),right atrial long-axis inner diameter(RAD1)(P<0.001),right atrial short-axis inner diameter(RAD2)(P<0.001),right ventricular inner diameter(P=0.002),interventricular septal thickness at end-diastolic(P=0.002),and left ventricular end-diastolic volumes(P=0.004)and left ventricular end-systolic volumes(P=0.003) all significantly reduced compared with preoperative values.Additionally,left ventricular fractional shortening and LVEF improved(both P<0.001).Subgroup analyses revealed that cardiac structural parameters significantly decreased in the HF with preserved ejection fraction,HF with mildly reduced ejection fraction,and HFrEF subgroups compared with preoperative values.Notably,the HFrEF group demonstrated the best performance in terms of left atrial diameter(P=0.003),left ventricular inner diameter at end-diastole(P=0.008),RAD1(P<0.001),RAD2(P=0.004),right ventricular inner diameter(P=0.019),left ventricular end-diastolic volume(P=0.004)and left ventricular end-systolic volume(P=0.001),cardiac output(P=0.006),tricuspid regurgitation velocity(P=0.002),and pulmonary artery systolic pressure(P=0.001) compared to preoperatively.Postoperative left ventricular fractional shortening(P<0.001,P=0.003,P<0.001)and LVEF(P<0.001,P=0.011,P=0.001)became higher in all the three subgroups than the preoperative values.Conclusions LSG decreased the body weight,BMI,and BSA,improved the cardiac function grade,reversed the enlargement of the left atrium and left ventricle,reduced the right atrium and right ventricle,and enhanced the left ventricular systolic function.It was effective across obese patients with different HF types.Particularly,LSG demonstrates the best performance in improving the structures of both atria and ventricles in obese patients with HFrEF.
Humans ; Male ; Female ; Gastrectomy/methods* ; Heart Failure/complications* ; Adult ; Obesity/physiopathology* ; Laparoscopy ; Middle Aged ; Heart/physiopathology* ; Stroke Volume

BACKGROUND: Angiotensin receptor neprilysin inhibitors (ARNIs), angiotensin-converting enzyme inhibitors (ACEIs), angiotensin receptor blockers (ARBs), β-blockers (BBs), and mineralocorticoid receptor antagonists (MRAs) are the cornerstones in treating heart failure with reduced ejection fraction (HFrEF). Sodium-glucose cotransporter 2 inhibitors (SGLT-2is) are included in HFrEF treatment guidelines. However, the effect of SGLT-2i and the five drugs on HFrEF have not yet been systematically evaluated. METHODS: PubMed, Embase, and the Cochrane Library were searched for randomized controlled trials (RCTs) from inception dates to September 23, 2022. Additional trials from previous relevant reviews and references were also included. The primary outcomes were changes in left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter/dimension (LVEDD), left ventricular end-systolic diameter/dimension (LVESD), left ventricular end-diastolic volume (LVEDV), and left ventricular end-systolic volume (LVESV), left ventricular end-systolic volume index (LVESVI), and left ventricular end-diastolic volume index (LVEDVI). Secondary outcomes were New York Heart Association (NYHA) class, 6-min walking distance (6MWD), B-type natriuretic peptide (BNP) level, and N-terminal pro-BNP (NT-proBNP) level. The effect sizes were presented as the mean difference (MD) with 95% confidence interval (CI). RESULTS: We included 68 RCTs involving 16,425 patients. Compared with placebo, ARNI + BB + MRA + SGLT-2i was the most effective combination to improve LVEF (15.63%, 95% CI: 9.91% to 21.68%). ARNI + BB + MRA + SGLT-2i (5.83%, 95% CI: 0.53% to 11.14%) and ARNI + BB + MRA (3.83%, 95% CI: 0.72% to 6.90%) were superior to the traditional golden triangle ACEI + BB + MRA in improving LVEF. ACEI + BB + MRA + SGLT-2i was better than ACEI + BB + MRA (-8.05 mL/m 2 , 95% CI: -14.88 to -1.23 mL/m 2 ) and ACEI + BB + SGLT-2i (-18.94 mL/m 2 , 95% CI: -36.97 to -0.61 mL/m 2 ) in improving LVEDVI. ACEI + BB + MRA + SGLT-2i (-3254.21 pg/mL, 95% CI: -6242.19 to -560.47 pg/mL) was superior to ARB + BB + MRA in reducing NT-proBNP. CONCLUSIONS: Adding SGLT-2i to ARNI/ACEI + BB + MRA is beneficial for reversing cardiac remodeling. The new quadruple drug "ARNI + BB + MRA + SGLT-2i" is superior to the golden triangle "ACEI + BB + MRA" in improving LVEF. REGISTRATION PROSPERO; No. CRD42022354792.
Humans ; Heart Failure/physiopathology* ; Stroke Volume/physiology* ; Angiotensin Receptor Antagonists/therapeutic use* ; Angiotensin-Converting Enzyme Inhibitors/therapeutic use* ; Sodium-Glucose Transporter 2 Inhibitors/therapeutic use* ; Randomized Controlled Trials as Topic ; Mineralocorticoid Receptor Antagonists/therapeutic use* ; Adrenergic beta-Antagonists/therapeutic use*

OBJECTIVES: To compare perioperative and mid-term results of multiple versus single arterial off-pump coronary artery bypass grafting (OPCABG) in patients with impaired left ventricular function. METHODS: This study was conducted among 86 patients with a left ventricular ejection fraction (LVEF) <50%, who underwent OPCABG at our hospital between January, 2018 and December, 2021. Of these patients, 22 underwent OPCABG with multiple arterial grafts (multiple graft group) and 64 received a single arterial graft in OPCABG (single graft group). The preoperative, intraoperative, and perioperative data were collected, and the patients were followed up for a mean of 29.28±14.84 months. The perioperative outcomes and follow-up results of the patients were compared, and the factors influencing major adverse cardiovascular events (MACE) were identified using logistic regression. Kaplan-Meier analysis was used to compare the postoperative survival rate without MACE. RESULTS: The patients in multiple graft group had a significantly younger age than those in single graft group (P<0.05), but the other baseline data were similar between the two groups (P>0.05). Perioperative mortality, 24-h postoperative drainage volume, length of ICU stay, intubation time, and the incidence of new-onset atrial fibrillation were all similar between the two groups (P>0.05), but the rate of postoperative hypotension was significantly higher in multiple graft group (34.78% vs 11.54%, P=0.009). No significant differences were found in the incidence of MACE or echocardiographic data during the follow-up. Logistic regression identified the female sex (OR: 0.191, 95% CI: 0.049-0.075) and creatinine level (OR: 1.016, 95% CI: 1.000-1.033) as factors affecting postoperative MACE occurrence. Kaplan-Meier analysis showed no significant difference in MACE-free survival rate between the two groups. CONCLUSIONS OPCABG with multiple arterial grafts does not increase severe perioperative complications or the risk of mid-term MACE in patients with impaired left ventricular function.
Humans ; Follow-Up Studies ; Postoperative Complications/epidemiology* ; Ventricular Dysfunction, Left/physiopathology* ; Coronary Artery Bypass, Off-Pump/adverse effects* ; Male ; Female ; Ventricular Function, Left ; Middle Aged ; Risk Factors ; Aged ; Perioperative Period ; Stroke Volume

OBJECTIVES: Patients with heart failure with reduced ejection fraction (HFrEF) often require diuretics during hospitalization to alleviate fluid retention and improve prognosis. However, the diuretic efficacy and renal impact of dapagliflozin in this population remain unclear. This study aims to investigate the effects of dapagliflozin on diuresis and renal function in hospitalized patients with HFrEF. METHODS: This retrospective analysis included clinical data from 200 hospitalized HFrEF patients treated at Xiangya Hospital of Central South University between January 2021 and September 2022. Patients were divided into 2 groups based on whether they received dapagliflozin: a standard treatment group (n=120) and a dapagliflozin treatment group (n=80). The following were compared between the 2 groups during hospitalization: The 24-hour average difference of liquid intake and output during the first 5 days, urine output, cumulative urine output, diuretic efficiency, estimated glomerular filtration rate (eGFR), N-terminal pro B-type natriuretic peptide (NT-proBNP), hospitalization costs, drug costs, and cost-effectiveness ratio (C/E). RESULTS: 1) Primary outcome: The 24-hour average difference of liquid intake and output during the first 5 days was significantly higher in the dapagliflozin treatment group than in the standard treatment group (P<0.05). 2) Secondary outcomes: The 24-hour average urine volume, cumulative urine volume and diuretic efficiency in the first 5 days of dapagliflozin treatment group were higher than those in the standard treatment group, and the differences were statistically significant (all P<0.05). Among patients with impaired renal function on admission [eGFR between 45 and 90 mL/(min·1.73 m²)], the change in eGFR after treatment was significantly smaller in the dapagliflozin treatment group (P<0.05). For patients with normal renal function on admission [eGFR >90 mL/(min·1.73 m²)], the difference in eGFR changes between 2 groups was not significant (P>0.05). NT-proBNP decreased more in the dapagliflozin treatment group than in the standard treatment group during hospitalization (P<0.05). 3) Other indicators: The length of hospital stay was longer in the dapagliflozin treatment group. However, discharge systolic blood pressure, drug costs, and hospitalization costs were all higher in the standard group, though differences were not statistically significant (all P>0.05). The C/E was more favorable in the dapagliflozin treatment group (425.36 vs. 476.67). CONCLUSIONS In hospitalized patients with chronic HFrEF, dapagliflozin treatment increased 24-hour average difference of liquid intake and output and total urine output, reduced NT-proBNP levels, and showed a milder decline in eGFR in those with pre-existing renal impairment. Discharge blood pressure, drug costs, and hospital stay were not significantly affected. While standard therapy may offer better short-term clinical benefits, dapagliflozin demonstrated a superior short-term cost-effectiveness profile.
Humans ; Benzhydryl Compounds/pharmacology* ; Glucosides/pharmacology* ; Retrospective Studies ; Male ; Female ; Heart Failure/physiopathology* ; Hospitalization ; Middle Aged ; Aged ; Glomerular Filtration Rate/drug effects* ; Diuretics/therapeutic use* ; Kidney/drug effects* ; Natriuretic Peptide, Brain/blood* ; Stroke Volume ; Peptide Fragments/blood* ; Diuresis/drug effects*

INTRODUCTION: Normal stress myocardial perfusion imaging (MPI) carries a favourable prognosis. Conversely, elevated coronary artery calcium (CAC) is associated with increased major adverse cardiovascular events (MACE). There is limited information on the prognosis and management of patients with elevated CAC and normal MPI. We aimed to assess the outcomes of patients with elevated CAC and normal MPI in relation to post-MPI statin use. METHODS: A retrospective review of normal MPI with CAC score >300 was performed between 1 March 2016 and 31 January 2017 in a Singapore tertiary hospital. Patients with known atherosclerotic cardiovascular disease or left ventricular ejection fraction <50% on MPI were excluded. Patient demographics, prescriptions and MACE (cardiac death, nonfatal myocardial infarction and/or ischaemic stroke) at 24 months after MPI were traced using electronic records. Binary logistic regression was used to evaluate for independent predictors of MACE. RESULTS: We included 311 patients (median age 71 years, 56.3% male), of whom 65.0% were on moderate to high-intensity statins (MHIS) after MPI. MACE was significantly lower in the post-MPI MHIS group (3.5% vs. 9.2%, P = 0.035). On univariate binary logistic regression, post-MPI MHIS use was the only significant predictor for MACE (odds ratio [OR] 0.355 [95% confidence interval (CI) 0.131-0.962], P = 0.042), even after multivariate adjustment (adjusted OR 0.363, 95% confidence interval 0.134-0.984, P = 0.046). CONCLUSION Post-MPI MHIS use is associated with lower MACE and is an independent negative predictor for 24-month MACE among patients with normal MPI and CAC >300.
Humans ; Male ; Aged ; Female ; Coronary Artery Disease ; Hydroxymethylglutaryl-CoA Reductase Inhibitors ; Myocardial Perfusion Imaging/methods* ; Calcium ; Stroke Volume ; Brain Ischemia ; Risk Factors ; Ventricular Function, Left ; Stroke ; Prognosis

Objective: To investigate the clinical features and long-term prognostic factors of diabetic patients with low or intermediate complexity coronary artery disease (CAD) post percutaneous coronary intervention (PCI). Methods: This was a prospective, single-centre observational study. Consecutive diabetic patients with SYNTAX score (SS)≤32 undergoing PCI between January and December 2013 in Fuwai hospital were included in this analysis. The patients were divided into two groups based on SS, namely SS≤22 group and SS 23-32 group. Multivariate Cox regression analysis was performed to identify independent factors related to poor 5-year prognosis. The primary outcomes were cardiac death and recurrent myocardial infarction, the secondary outcomes were all cause death and revascularization. Results: Of the 3 899 patients included in the study, 2 888 were men (74.1%); mean age was 59.4±9.8 years. There were 3 450 patients in the SS≤22 group and 449 patients in the SS 23-32 group. Compared with SS≤22 group, the incidence of revascularization was higher in SS 23-32 group (18.9% (85/449) vs. 15.2% (524/3450), log-rank P=0.019). There was no significant difference in all-cause death, cardiac death and recurrent myocardial infarction between the two groups (log-rank P>0.05). Multivariate Cox regression analysis showed that age (HR=1.05, 95%CI 1.02-1.08, P<0.001), chronic obstructive pulmonary disease (HR=3.12, 95%CI 1.37-7.07, P=0.007) and creatinine clearance rate (CCr)<60 ml/min (HR=3.67, 95%CI 2.05-6.58, P<0.001) were independent risk factors for 5-year cardiac death, while left ventricular ejection fraction (HR=0.94, 95%CI 0.91-0.96, P<0.001) was a protective factor. Previous PCI (HR=2.04, 95%CI 1.38-3.00, P<0.001), blood glucose level≥11.1 mmol/L on admission (HR=2.49, 95%CI 1.32-4.70, P=0.005) and CCr<60 ml/min (HR=1.85, 95%CI 1.14-2.99, P=0.012) were independent risk factors for 5-year recurrent myocardial infarction. The SS of 23-32 was independently associated with risk of revascularization (HR=1.54, 95%CI 1.09-2.16, P=0.014), after adjusting for residual SS. Residual SS was not a risk factor for 5-year prognosis. Conclusions: In diabetic patients with low-or intermediate complexity CAD, SS 23-32 is associated with increased risk of 5-year revascularization; the clinical characteristics of the patients are associated with the long-term mortality and recurrent myocardial infarction, but not related to revascularization.
Male ; Humans ; Middle Aged ; Aged ; Female ; Coronary Artery Disease/surgery* ; Stroke Volume ; Percutaneous Coronary Intervention ; Prospective Studies ; Treatment Outcome ; Ventricular Function, Left ; Prognosis ; Risk Factors ; Myocardial Infarction/etiology* ; Diabetes Mellitus

OBJECTIVE: To explore the cardioprotective effects of astragaloside IV (AS-IV) in heart failure (HF). METHODS: PubMed, Excerpta Medica Database (EMBASE), Cochrane Library, Web of Science, Wanfang Database, Chinese Bio-medical Literature and Retrieval System (SinoMed), China Science and Technology Journal Database (VIP), and China National Knowledge Infrastructure (CNKI) were searched from inception to November 1, 2021 for animal experiments to explore AS-IV in treating HF in rats or mice. The left ventricular ejection fraction (LVEF), left ventricular fractional shortening (LVFS), left ventricular end-diastolic dimension (LVEDD), left ventricular end-systolic dimension (LVESD), left ventricular weight-to-body weight (LVW/BW) and B-type brain natriuretic peptide (BNP) were recorded. The qualities of included studies were assessed by the risk of bias according to the Cochrane handbook. Meta-analysis was performed using Stata 13.0. RESULTS: Twenty-one articles involving 558 animals were considered. Compared with the control group, AS-IV improved cardiac function, specifically by increasing LVEF (mean difference (MD)=6.97, 95% confidence interval (CI)=5.92 to 8.03, P<0.05; fixed effects model) and LVFS (MD=7.01, 95% CI=5.84 to 8.81, P<0.05; fixed effects model), and decreasing LVEDD (MD=-4.24, 95% CI=-4.74 to -3.76, P<0.05; random effects model) and LVESD (MD=-4.18, 95% CI=-5.26 to -3.10, P<0.05; fixed effects model). In addition, the BNP and LVW/BW levels were decreased in the AS-IV treatment group (MD=-9.18, 95% CI=-14.13 to -4.22, P<0.05; random effects model; MD=-1.91, 95% CI=-2.42 to -1.39, P<0.05; random effects model). CONCLUSIONS AS-IV is a promising therapeutic agent for HF. However, this conclusion needs to be clinically validated in the future.
Animals ; Mice ; Rats ; Stroke Volume ; Ventricular Function, Left ; Heart Failure/drug therapy* ; Natriuretic Peptide, Brain

Heart failure with preserved ejection fraction (HFpEF) displays normal or near-normal left ventricular ejection fraction, diastolic dysfunction, cardiac hypertrophy, and poor exercise capacity. Berberine, an isoquinoline alkaloid, possesses cardiovascular benefits. Adult male mice were assigned to chow or high-fat diet with L-NAME ("two-hit" model) for 15 weeks. Diastolic function was assessed using echocardiography and noninvasive Doppler technique. Myocardial morphology, mitochondrial ultrastructure, and cardiomyocyte mechanical properties were evaluated. Proteomics analysis, autophagic flux, and intracellular Ca²⁺ were also assessed in chow and HFpEF mice. The results show exercise intolerance and cardiac diastolic dysfunction in "two-hit"-induced HFpEF model, in which unfavorable geometric changes such as increased cell size, interstitial fibrosis, and mitochondrial swelling occurred in the myocardium. Diastolic dysfunction was indicated by the elevated E value, mitral E/A ratio, and E/e' ratio, decreased e' value and maximal velocity of re-lengthening (-dL/dt), and prolonged re-lengthening in HFpEF mice. The effects of these processes were alleviated by berberine. Moreover, berberine ameliorated autophagic flux, alleviated Drp1 mitochondrial localization, mitochondrial Ca²⁺ overload and fragmentation, and promoted intracellular Ca²⁺ reuptake into sarcoplasmic reticulum by regulating phospholamban and SERCA2a. Finally, berberine alleviated diastolic dysfunction in "two-hit" diet-induced HFpEF model possibly because of the promotion of autophagic flux, inhibition of mitochondrial fragmentation, and cytosolic Ca²⁺ overload.
Male ; Mice ; Animals ; Heart Failure/drug therapy* ; Stroke Volume/physiology* ; Ventricular Function, Left/physiology* ; Berberine/therapeutic use* ; Disease Models, Animal ; Mitochondrial Dynamics ; Myocardium ; Homeostasis

INTRODUCTION: Despite the challenges related to His bundle pacing (HBP), recent data suggest an improved success rate with experience. As a non-university, non-electrophysiology specialised centre in Singapore, we report our experiences in HBP using pacing system analyser alone. METHODS: Data of 28 consecutive patients who underwent HBP from August 2018 to February 2019 was retrospectively obtained. The clinical and technical outcomes of these patients were compared between two timeframes of three months each. Patients were followed up for 12 months. RESULTS: Immediate technical success was achieved in 21 (75.0%) patients (mean age 73.3 ± 10.7 years, 47.6% female). The mean left ventricular ejection fraction was 53.9% ± 12.1%. The indications for HBP were atrioventricular block (n = 13, 61.9%), sinus node dysfunction (n = 7, 33.3%) and upgrade from implantable cardioverter-defibrillator to His-cardiac resynchronisation therapy (n = 1, 4.8%). No significant difference was observed in baseline characteristics between Timeframe 1 and Timeframe 2. Improvements pertaining to mean fluoroscopy time were achieved between the two timeframes. There was one HBP-related complication of lead displacement during Timeframe 1. All patients with successful HBP achieved non-selective His bundle (NSHB) capture, whereas only eight patients had selective His bundle (SHB) capture. NSHB and SHB capture thresholds remained stable at the 12-month follow-up. CONCLUSION Permanent HBP is feasible and safe, even without the use of an electrophysiology recording system. This was successfully achieved in 75% of patients, with no adverse clinical outcomes during the follow-up period.
Humans ; Female ; Middle Aged ; Aged ; Aged, 80 and over ; Male ; Bundle of His ; Follow-Up Studies ; Stroke Volume ; Retrospective Studies ; Treatment Outcome ; Cardiac Pacing, Artificial/adverse effects* ; Electrocardiography ; Ventricular Function, Left/physiology*

Objective: To evaluate the predictive value of the proportion of hibernating myocardium (HM) in total perfusion defect (TPD) on reverse left ventricle remodeling (RR) after coronary artery bypass graft (CABG) in patients with heart failure with reduced ejection fraction (HFrEF) by ^99mTc-methoxyisobutylisonitrile (MIBI) single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) combined with ¹⁸F-flurodeoxyglucose (FDG) gated myocardial imaging positron emission computed tomography (PET). Methods: Inpatients diagnosed with HFrEF at the Cardiac Surgery Center, Anzhen Hospital of Capital Medical University from January 2016 to January 2022 were prospectively recruited. MPI combined with ¹⁸F-FDG gated PET was performed before surgery for viability assessment and the patients received follow-up MPI and ¹⁸F-FDG gated PET at different stages (3-12 months) after surgery. Δ indicated changes (post-pre). Left ventricular end-systolic volume (ESV) reduced at least 10% was defined as RR, patients were divided into reverse remodeling (RR+) group and the non-reverse group (RR-). Binary logistic regression analysis was used to identify predictors of RR. Receiver operating characteristic (ROC) curve analysis was performed and the area under the curve (AUC) was calculated to assess the cut-off value for predicting RR. Additionally, we retrospectively enrolled inpatients with HFrEF at the Cardiac Surgery Center, Anzhen Hospital of Capital Medical University from January 2021 to January 2022 as the validation group, who underwent MPI and ¹⁸F-FDG gated PET before surgery. Echocardiography was performed before CABG and after CABG (3-12 months). In the validation group, the reliability of obtaining the cut-off value for the ROC curve was verified. Results: A total of 28 patients with HFrEF (26 males; age (56.9±8.7) years) were included in the prospective cohort. HM/TPD was significantly higher in the RR+ group than in the RR- group ((51.8%±17.9%) vs. (35.7%±13.9%), P=0.016). Binary logistic regression analysis revealed that HM/TPD was an independent predictor of RR (Odds ratio=1.073, 95% Confidence interval: 1.005-1.145, P=0.035). ROC curve analysis revealed that HM/TPD=38.3% yielded the highest sensitivity, specificity, and accuracy (all 75%) for predicting RR and the AUC was 0.786 (P=0.011). Meanwhile, a total of 100 patients with HFrEF (90 males; age (59.7±9.6) years) were included in the validation group. In the validation group, HM/TPD=38.3% predicted RR in HFrEF patients after CABG with the highest sensitivity, specificity and accuracy (82%, 60% and 73% respectively). Compared with the HFrEF patients in the HM/TPD<38.3% group (n=36), RR and cardiac function improved more significantly in the HM/TPD≥38.3% group (n=64) (all P<0.05). Conclusions: Preoperative HM/TPD ratio is an independent factor for predicting RR in patients with HFrEF after CABG, and HM/TPD≥38.3% can accurately predict RR and the improvement of cardiac function after CABG.
Male ; Humans ; Middle Aged ; Aged ; Stroke Volume ; Heart Failure ; Fluorodeoxyglucose F18 ; Retrospective Studies ; Reproducibility of Results ; Prospective Studies ; Coronary Artery Bypass ; Ventricular Dysfunction, Left ; Tomography, Emission-Computed, Single-Photon ; Perfusion ; Myocardium