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The article discusses the use of [15O]H2O PET/CT myocardial perfusion imaging to diagnose coronary artery disease, with a case study of a 74-year-old male who presented with symptoms of peripheral edema and orthopnea. While the patient's myocardial perfusion was normal, the imaging revealed subsegmental perfusion defects in the lower and middle lobes of the right lung, leading to a suspicion of pulmonary embolisms. The study highlights the importance of recognizing perfusion defects during PET/CT imaging as potential indicators of pulmonary embolism, even though PET/CT is not a primary diagnostic tool for this condition. [Extracted from the article]

Aims: The present study tested the hypothesis that metformin treatment may increase myocardial efficiency (stroke work/myocardial oxygen consumption) in insulin‐resistant patients with heart failure and reduced ejection fraction (HFrEF) without diabetes. Methods and results: Thirty‐six HFrEF patients (ejection fraction 37 ± 8%; median age 66 years) were randomised to metformin (n = 19) or placebo (n = 17) for 3 months in addition to standard heart failure therapy. The primary endpoint was change in myocardial efficiency expressed as the work metabolic index (WMI), assessed by 11C‐acetate positron emission tomography and transthoracic echocardiography. Compared with placebo, metformin treatment (1450 ± 550 mg/day) increased WMI [absolute mean difference, 1.0 mmHg·mL·m‐2·106; 95% confidence interval (CI) 0.1 to 1.8; P = 0.03], equivalent to a 20% relative efficiency increase. Patients with above‐median plasma metformin levels displayed greater WMI increase (25% vs. –4%; P = 0.02). Metformin reduced myocardial oxygen consumption (–1.6 mL O2·100 g‐1·min‐1; P = 0.014). Cardiac stroke work was preserved (–2 J; 95% CI –11 to 7; P = 0.69). Metformin reduced body weight (–2.2 kg; 95% CI –3.6 to –0.8; P = 0.003) and glycated haemoglobin levels (–0.2%; 95% CI –0.3 to 0.0; P = 0.02). Changes in resting and exercise ejection fraction, global longitudinal strain, and exercise capacity did not differ between groups. Conclusion: Metformin treatment in non‐diabetic HFrEF patients improved myocardial efficiency by reducing myocardial oxygen consumption. Measurement of circulating metformin levels differentiated responders from non‐responders. These energy‐sparing effects of metformin encourage further large‐scale investigations in heart failure patients without diabetes. [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is available in the text. Background: Myocardial utilization of 3-hydroxybutyrate (3-OHB) is increased in patients with heart failure and reduced ejection fraction (HFrEF). However, the cardiovascular effects of increased circulating plasma-3-OHB levels in these patients are unknown. Consequently, the authors' aim was to modulate circulating 3-OHB levels in HFrEF patients and evaluate: (1) changes in cardiac output (CO); (2) a potential dose-response relationship between 3-OHB levels and CO; (3) the impact on myocardial external energy efficiency (MEE) and oxygen consumption (MVO2); and (4) whether the cardiovascular response differed between HFrEF patients and age-matched volunteers. Methods: Study 1: 16 chronic HFrEF patients (left ventricular ejection fraction: 37±3%) were randomized in a crossover design to 3-hour of 3-OHB or placebo infusion. Patients were monitored invasively with a Swan-Ganz catheter and with echocardiography. Study 2: In a dose-response study, 8 HFrEF patients were examined at increasing 3-OHB infusion rates. Study 3 to 4: 10 HFrEF patients and 10 age-matched volunteers were randomized in a crossover design to 3-hour 3-OHB or placebo infusion. MEE and MVO2 were evaluated using 11C-acetate positron emission tomography. Results: 3-OHB infusion increased circulating levels of plasma 3-OHB from 0.4±0.3 to 3.3±0.4 mM (P <0.001). CO rose by 2.0±0.2 L/min (P <0.001) because of an increase in stroke volume of 20±2 mL (P <0.001) and heart rate of 7±2 beats per minute (bpm) (P <0.001). Left ventricular ejection fraction increased 8±1% (P <0.001) numerically. There was a dose-response relationship with a significant CO increase of 0.3 L/min already at plasma-3-OHB levels of 0.7 mM (P <0.001). 3-OHB increased MVO2 without altering MEE. The response to 3-OHB infusion in terms of MEE and CO did not differ between HFrEF patents and age-matched volunteers. Conclusions: 3-OHB has beneficial hemodynamic effects in HFrEF patients without impairing MEE. These beneficial effects are detectable in the physiological concentration range of circulating 3-OHB levels. The hemodynamic effects of 3-OHB were observed in both HFrEF patients and age-matched volunteers. 3-OHB may potentially constitute a novel treatment principle in HFrEF patients. [ABSTRACT FROM AUTHOR]

Background: Myocardial utilization of 3-hydroxybutyrate (3-OHB) is increased in patients with heart failure and reduced ejection fraction (HFrEF). However, the cardiovascular effects of increased circulating plasma-3-OHB levels in these patients are unknown. Consequently, the authors' aim was to modulate circulating 3-OHB levels in HFrEF patients and evaluate: (1) changes in cardiac output (CO); (2) a potential dose-response relationship between 3-OHB levels and CO; (3) the impact on myocardial external energy efficiency (MEE) and oxygen consumption (MVO2); and (4) whether the cardiovascular response differed between HFrEF patients and age-matched volunteers.Methods: Study 1: 16 chronic HFrEF patients (left ventricular ejection fraction: 37±3%) were randomized in a crossover design to 3-hour of 3-OHB or placebo infusion. Patients were monitored invasively with a Swan-Ganz catheter and with echocardiography. Study 2: In a dose-response study, 8 HFrEF patients were examined at increasing 3-OHB infusion rates. Study 3 to 4: 10 HFrEF patients and 10 age-matched volunteers were randomized in a crossover design to 3-hour 3-OHB or placebo infusion. MEE and MVO2 were evaluated using 11C-acetate positron emission tomography.Results: 3-OHB infusion increased circulating levels of plasma 3-OHB from 0.4±0.3 to 3.3±0.4 mM ( P<0.001). CO rose by 2.0±0.2 L/min ( P<0.001) because of an increase in stroke volume of 20±2 mL ( P<0.001) and heart rate of 7±2 beats per minute (bpm) ( P<0.001). Left ventricular ejection fraction increased 8±1% ( P<0.001) numerically. There was a dose-response relationship with a significant CO increase of 0.3 L/min already at plasma-3-OHB levels of 0.7 mM ( P<0.001). 3-OHB increased MVO2 without altering MEE. The response to 3-OHB infusion in terms of MEE and CO did not differ between HFrEF patents and age-matched volunteers.Conclusions: 3-OHB has beneficial hemodynamic effects in HFrEF patients without impairing MEE. These beneficial effects are detectable in the physiological concentration range of circulating 3-OHB levels. The hemodynamic effects of 3-OHB were observed in both HFrEF patients and age-matched volunteers. 3-OHB may potentially constitute a novel treatment principle in HFrEF patients. [ABSTRACT FROM AUTHOR]