The Use and Efficacy of FFR-CT: Real-World Multicenter Audit of Clinical Data With Cost Analysis.

BACKGROUND: Fractional flow reserve-computed tomography (FFR-CT) is endorsed by UK and U.S. chest pain guidelines, but its clinical effectiveness and cost benefit in real-world practice are unknown. OBJECTIVES: The purpose of this study was to audit the use of FFR-CT in clinical practice against England's National Institute for Health and Care Excellence guidance and assess its diagnostic accuracy and cost. METHODS: A multicenter audit was undertaken covering the 3 years when FFR-CT was centrally funded in England. For coronary computed tomographic angiograms (CCTAs) submitted for FFR-CT analysis, centers provided data on symptoms, CCTA and FFR-CT findings, and subsequent management. Audit standards included using FFR-CT only in patients with stable chest pain and equivocal stenosis (50%-69%). Diagnostic accuracy was evaluated against invasive FFR, when performed. Follow-up for nonfatal myocardial infarction and all-cause mortality was undertaken. The cost of an FFR-CT strategy was compared to alternative stress imaging pathways using cost analysis modeling. RESULTS: A total of 2,298 CCTAs from 12 centers underwent FFR-CT analysis. Stable chest pain was the main symptom in 77%, and 40% had equivocal stenosis. Positive and negative predictive values of FFR-CT were 49% and 76%, respectively. A total of 46 events (2%) occurred over a mean follow-up period of 17 months; FFR-CT (cutoff: 0.80) was not predictive. The FFR-CT strategy costs £2,102 per patient compared with an average of £1,411 for stress imaging. CONCLUSIONS: In clinical practice, the National Institute for Health and Care Excellence criteria for using FFR-CT were met in three-fourths of patients for symptoms and 40% for stenosis. FFR-CT had a low positive predictive value, making its use potentially more expensive than conventional stress imaging strategies.

When does the E/e' index not work? The pitfalls of oversimplifying diastolic function.

Since the E/e' ratio was first described in 1997 as a noninvasive surrogate marker of mean pulmonary capillary wedge pressure, it has gained a central role in diagnostic recommendations and a supremacy in clinical use that require critical reappraisal. We review technical factors, physiological influences, and pathophysiological processes that can complicate the interpretation of E/e'. The index has been validated in certain circumstances, but its use cannot be extrapolated to other situations-such as critically ill patients or children-in which it has either been shown not to work or it has not been well validated. Meta-analyses demonstrated that E/e' is not useful for the diagnosis of HFpEF and that changes in E/e' are uninformative during diastolic stress echocardiography. A similar ratio has been applied to estimate right heart filling pressure despite insufficient evidence. As a composite index, changes in E/e' should only be interpreted with knowledge of changes in its components. Sometimes, e' alone may be as informative. Using a scoring system for diastolic function that relies on E/e', as recommended in consensus documents, leaves some patients unclassified and others in an intermediate category. Alternative methods for estimating left heart filling pressures may be more accurate, including the duration of retrograde pulmonary venous flow, or contractile deformation during atrial pump function. Using all measurements as continuous variables may demonstrate abnormal diastolic function that is missed by using the reductive index E/e' alone. With developments in diagnostic methods and clinical decision support tools, this may become easier to implement.

Diagnosis of Heart Failure With Preserved Ejection Fraction: Machine Learning of Spatiotemporal Variations in Left Ventricular Deformation.

BACKGROUND: Stress testing helps diagnose heart failure with preserved ejection fraction (HFpEF), but there are no established criteria for quantifying left ventricular (LV) functional reserve. The aim of this study was to investigate whether comprehensive analysis of the timing and amplitude of LV long-axis myocardial motion and deformation throughout the cardiac cycle during rest and stress can provide more informative criteria than standard measurements. METHODS: Velocity, strain, and strain rate traces were measured from all 18 LV segments by echocardiographic myocardial velocity imaging at rest and during semisupine bicycle exercise in 100 subjects aged 69 ± 7 years, including patients with HFpEF and healthy, hypertensive, and breathless control subjects. A machine-learning algorithm, composed of an unsupervised statistical method and a supervised classifier, was used to model spatiotemporal patterns of the traces and compare the predicted labels with the clinical diagnoses. RESULTS: The learned strain rate parameters gave the highest accuracy for allocating subjects into the four groups (overall, 57%; for patients with HFpEF, 81%), and into two classes (asymptomatic vs symptomatic; area under the curve, 0.89; accuracy, 85%; sensitivity, 86%; specificity, 82%). Machine learning of strain rate, compared with standard measurements, gave the greatest improvement in accuracy for the two-class task (+23%, P < .0001), compared with +11% (P < .0001) using velocity and +4% (P < .05) using strain. Strain rate was also best at predicting 6-min walk distance as an independent reference criterion. CONCLUSIONS: Machine learning of spatiotemporal variations of LV strain rate during rest and exercise could be used to identify patients with HFpEF and to provide an objective basis for diagnostic classification.

Post pericardiocentesis low cardiac output syndrome in a patient with malignant thymoma.

We describe a case of transient biventricular failure after pericardiocentesis in a patient with malignant thymoma. Within 1 week the cardiac function returned to normal. The epidemiology and pathophysiology of the post pericardiocentesis low cardiac output syndrome is discussed.