Noninvasive quantitation of myocardial blood flow in human subjects with oxygen-15-labeled water and positron emission tomography

AbstractNoninvasive measurement of myocardial blood flow in absolute terms (i.e., milliliters per gram per min) has been difficult to accomplish despite the intrinsically quantitative power of positron emission tomography because of the nonphysiologic nature of tracers that have been employed conventionally as well as the limited spatial resolution of currently available instruments. It was previously demonstrated that myocardial blood flow in animals can be quantitated accurately with the diffusible tracer oxygen-15-labeled water (112[50) when the arterial input function and myocardial radiotracer concentration were measured directly. To extend the approach for completely noninvasive measurement of blood flow, a parameter estimation procedure was developed whereby effects of limited tomographic spatial resolution and cardiac motion were compensated for within the operational flow model.In validation studies in 18 dogs, myocardial blood flow measured with positron emission tomography after intravenously administered 112'S0 correlated closely with flow measured with concomitantly administered radiolabeled microspheres over the range of 0.29 to 5.04 ml/g per min (r = 0.95). Although regional ischemia was clearly identifiable tomographically, absolute flow could not be determined accurately in ischemic regions in four dogs because of poor count statistics related to wall thinning. Subsequently, myocardial blood flow was measured in 11 normal human subjects. Flow was homogeneous throughout the myocardium, averaged 0.90 t 0.22 ml/g per min at rest and increased to 3.551.15 ml/g per min after intravenous administration of dipyridamole.Therefore, positron emission tomography with H215O and the approach developed permits noninvasive measurement of myocardial blood flow in absolute terms in humans and should facilitate objective assessment of interventions designed to enhance nutritive perfusion

Sex-Specific Differences in Heart Failure:Pathophysiology, Risk Factors, Management, and Outcomes

Heart failure (HF) is a leading cause of hospitalisation, morbidity, and mortality in Canada. There are sex-specific differences in the etiology, epidemiology, comorbidities, treatment response, and treatment adverse effects that have implications on outcomes in HF. Sex-specific analyses of some HF trials indicate that optimal doses of drug therapies and benefit of device therapies may differ between male and female patients, but the trials were not designed to test sex differences. The under-representation of female participants in HF randomised controlled trials (RCTs) is a major limitation in assessing the sex-specific efficacy and safety of treatments. To ensure that female patients receive safe and effective HF therapies, RCTs should include participants proportionate to the sex-specific distribution of disease. This review outlines the sex-specific differences in HF phenotype and treatment response, and highlights disparities in services and gaps in knowledge that merit further investigation

Need for better and broader training in cardio-obstetrics: A national survey of cardiologists, cardiovascular team members, and cardiology fellows in training

Background Team-based models of cardio-obstetrics care have been developed to address the increasing rate of maternal mortality from cardiovascular diseases. Cardiovascular clinician and trainee knowledge and comfort with this topic, and the extent of implementation of an interdisciplinary approach to cardio-obstetrics, are unknown. Methods and Results We aimed to assess the current state of cardio-obstetrics knowledge, practices, and services provided by US cardiovascular clinicians and trainees. A survey developed in conjunction with the American College of Cardiology was circulated to a representative sample of cardiologists (N=311), cardiovascular team members (N=51), and fellows in training (N=139) from June 18, 2020, to July 29, 2020. Knowledge and attitudes about the provision of cardiovascular care to pregnant patients and the prevalence and composition of cardio-obstetrics teams were assessed. The widest knowledge gaps on the care of pregnant compared with nonpregnant patients were reported for medication safety (42%), acute coronary syndromes (39%), aortopathies (40%), and valvular heart disease (30%). Most respondents (76%) lack access to a dedicated cardio-obstetrics team, and only 29% of practicing cardiologists received cardio-obstetrics didactics during training. One third of fellows in training reported seeing pregnant women 0 to 1 time per year, and 12% of fellows in training report formal training in cardio-obstetrics. Conclusions Formalized training in cardio-obstetrics is uncommon, and limited access to multidisciplinary cardio-obstetrics teams and large knowledge gaps exist among cardiovascular clinicians. Augmentation of cardio-obstetrics education across career stages is needed to reduce these deficits. These survey results are an initial step toward developing a standard expectation for clinicians\u27 training in cardio-obstetrics

Non-specific chest pain and subsequent serious cardiovascular readmissions

Background: The rates of readmission for serious cardiovascular events among patients admitted with a diagnosis of non-specific chest pain are unknown. Methods: A national retrospective cohort study in the United States was undertaken to evaluate the rates, trends and predictors of readmission for serious cardiovascular events (acute coronary syndrome (ACS), pulmonary embolism (PE) and aortic dissection (AD)) after an inpatient episode with a primary diagnosis of non-specific chest pain. Results: Among 1,172,430 patients with an index diagnosis of non-specific chest pain between 2010 and 2014, 2.4% were readmitted with an ACS, 0.4% with a PE and 0.06% with an AD within 6 months of discharge. Predictors of ACS readmissions were diabetes (OR 1.49 95% CI 1.17–1.32), coronary artery disease (OR 2.29 95% CI 2.15–2.44), previous percutaneous coronary intervention (OR 1.65 95% CI 1.56–1.75), previous CABG (OR 1.52 95% CI 1.43–1.61) and discharge against medical advice (OR 1.94 95% CI 1.78–2.12). Female patients (OR 0.82 95% CI 0.78–0.86) and patients in whom a coronary angiogram was undertaken (OR 0.48 95% CI 0.45–0.52) were less likely to be readmitted for ACS. For PE, predictors of readmission were pulmonary circulatory disorder (OR 2.20 95% CI 1.09–4.43), anemia (OR 1.62 95% CI 1.40–1.86) and cancer (OR 4.15 95% CI 3.43–5.02). Peripheral vascular disease (OR 8.63 95% CI 5.47–13.60), renal failure (OR 2.08 95% CI 1.34–3.24) were predictors of AD. Conclusions: Non-specific chest pain may not be a benign condition as readmissions for serious cardiovascular events occur in 3% of patients within 180 days. Research is needed to define measures that may mitigate readmissions among these patients

Outcomes by Gender in the African-American Heart Failure Trial

OBJECTIVES Previous trials testing isosorbide dinitrate/hydralazine (I/H) were performed in all-male study cohorts, and thus the efficacy of I/H in women was unknown; 40% of the A-HeFT (African-American Heart Failure Trial) cohort were women. We therefore compared outcomes by gender and treatment. BACKGROUND Fixed-dose combined I/H significantly reduced mortality and heart failure hospitalizations and improved quality of life in 1,050 black patients with heart failure treated with background neurohormonal blockade. Previous trials testing I/H were done in all-male study cohorts, and thus the efficacy of I/H in women was unknown. METHODS Baseline characteristics and medications were compared between men and women by I/H and placebo treatment. Survival, time to first heart failure hospitalization, change in quality of life, and event-free survival were compared by gender and treatment. RESULTS At baseline, women had lower hemoglobin and creatinine levels; less renal insufficiency; and higher body mass indexes, diabetes prevalence, and systolic blood pressures; but worse quality of life scores. All-cause mortality was lower in women than in men treated with I/H but without significant treatment interaction by gender. The primary composite score, which weighted mortality, first heart failure hospitalization, and change in quality of life at 6 months, was similarly improved by I/H in men and women. First heart failure hospitalization and event-free survival (time to death or first heart failure hospitalization) were similarly improved in both genders. CONCLUSIONS Fixed-dose I/H improved heart failure outcomes in both men and women in A-HeFT. The I/H significantly improved the primary composite score and event-free survival as well as reduced the risk of first heart failure hospitalizations similarly in both genders. The I/H had a slightly greater mortality benefit in women, but without a significant treatment interaction by gender