Normalized Echocardiographic Values From Guideline-Directed Dedicated Views for Cardiac Dimensions and Left Ventricular Function.

BACKGROUND: Continuous technologic development and updated recommendations for image acquisitions creates a need to update the current normal reference ranges for echocardiography. The best method of indexing cardiac volumes is unknown. OBJECTIVES: The authors used 2- and 3-dimensional echocardiographic data from a large cohort of healthy individuals to provide updated normal reference data for dimensions and volumes of the cardiac chambers as well as central Doppler measurements. METHODS: In the fourth wave of the HUNT (Trøndelag Health) study in Norway 2,462 individuals underwent comprehensive echocardiography. Of these, 1,412 (55.8% women) were classified as normal and formed the basis for updated normal reference ranges. Volumetric measures were indexed to body surface area and height in powers of 1 to 3. RESULTS: Normal reference data for echocardiographic dimensions, volumes, and Doppler measurements were presented according to sex and age. Left ventricular ejection fraction had lower normal limits of 50.8% for women and 49.6% for men. According to sex-specific age groups, the upper normal limits for left atrial end-systolic volume indexed to body surface area ranged from 44 mL/m2 to 53 mL/m2, and the corresponding upper normal limit for right ventricular basal dimension ranged from 43 mm to 53 mm. Indexing to height raised to the power of 3 accounted for more of the variation between sexes than indexing to body surface area. CONCLUSIONS: The authors present updated normal reference values for a wide range of echocardiographic measures of both left- and right-side ventricular and atrial size and function from a large healthy population with a wide age-span. The higher upper normal limits for left atrial volume and right ventricular dimension highlight the importance of updating reference ranges accordingly following refinement of echocardiographic methods.

Deep Learning for Improved Precision and Reproducibility of Left Ventricular Strain in Echocardiography: A Test-Retest Study.

AIMS: Assessment of left ventricular (LV) function by echocardiography is hampered by modest test-retest reproducibility. A novel artificial intelligence (AI) method based on deep learning provides fully automated measurements of LV global longitudinal strain (GLS) and may improve the clinical utility of echocardiography by reducing user-related variability. The aim of this study was to assess within-patient test-retest reproducibility of LV GLS measured by the novel AI method in repeated echocardiograms recorded by different echocardiographers and to compare the results to manual measurements. METHODS: Two test-retest data sets (n = 40 and n = 32) were obtained at separate centers. Repeated recordings were acquired in immediate succession by 2 different echocardiographers at each center. For each data set, 4 readers measured GLS in both recordings using a semiautomatic method to construct test-retest interreader and intrareader scenarios. Agreement, mean absolute difference, and minimal detectable change (MDC) were compared to analyses by AI. In a subset of 10 patients, beat-to-beat variability in 3 cardiac cycles was assessed by 2 readers and AI. RESULTS: Test-retest variability was lower with AI compared with interreader scenarios (data set I: MDC = 3.7 vs 5.5, mean absolute difference = 1.4 vs 2.1, respectively; data set II: MDC = 3.9 vs 5.2, mean absolute difference = 1.6 vs 1.9, respectively; all P < .05). There was bias in GLS measurements in 13 of 24 test-retest interreader scenarios (largest bias, 3.2 strain units). In contrast, there was no bias in measurements by AI. Beat-to-beat MDCs were 1,5, 2.1, and 2.3 for AI and the 2 readers, respectively. Processing time for analyses of GLS by the AI method was 7.9 ± 2.8 seconds. CONCLUSION: A fast AI method for automated measurements of LV GLS reduced test-retest variability and removed bias between readers in both test-retest data sets. By improving the precision and reproducibility, AI may increase the clinical utility of echocardiography.

Variability of echocardiographic measures of left ventricular diastolic function. The HUNT study.

OBJECTIVE: Investigate variability related to image acquisition and reading process for echocardiographic measures of left ventricular (LV) diastolic function, and its influence on classification of LV diastolic dysfunction (LVDD). METHODS: Forty participants (19 women) mean age 62 (28-88) years underwent echocardiographic examinations twice by different echocardiographers and blinded analyses by four readers in a cross-sectional design. Measurements included quantification of two- (2D) and three-dimensional (3D) recordings of the left atrium (LA) (maximal) volume (LAVmax ) and spectral Doppler blood flow and tissue velocities for assessment of LV diastolic function. Variability and reproducibility measures were calculated using variance component analyses and Kappa statistics. RESULTS: Image acquisition influenced variability more than image reading (mean 24% and 4% of variance, respectively), but variability from image reading was especially important for 2D LAVmax (16% of variance) compared to 4% for 3D LAVmax , which was reflected in better agreement for 3D measures. The variability of measures used in classification of LVDD had clinical significance, and agreement across the four raters in classification using current recommendations was only fair (Kappa 0.42), but the agreement improved when using 3D LAVmax (Kappa 0.58). Agreement and reliability measures were reported for all measures. CONCLUSION: Performing a new image acquisition influenced variability more than a introducing a new image reader, but there were differences across the different measures. LAVmax by 3D is superior to 2D with respect to lower variability. The variability of diastolic measures influences the reliability of LVDD classification, and this should be taken into account in the everyday clinic.

ß-Blocker Doses and Heart Rate in Patients with Heart Failure: Results from the National Norwegian Heart Failure Registry.

BACKGROUND: Use of ß-blockers and titration to the highest tolerated dose are highly recommended by the European Society of Cardiology (ESC) guidelines for treatment of chronic heart failure (HF) with a reduced ejection fraction (HFrEF), but little attention has been paid to the achieved heart rate (HR) during this treatment. OBJECTIVES: The aim of the present study was to examine the achieved HR in relation to the use of ß-blockers in these patients. METHODS: All of the patients (n = 2,689) in the National Norwegian Heart Failure Registry as part of the Norwegian Cardiovascular Disease Registry with a sinus rhythm and left ventricular ejection fraction (LVEF) <40% at stable follow-up visiting specialised hospital outpatient HF clinics in Norway were included. The ß-blocker doses were calculated as a percent of the target dose according to ESC HF guidelines. Differences between baseline variables according to the achieved HR were analysed by the Student's t test for continuous variables and Pearson's χ2 test for categorical variables. Linear regression was used to determine the predictors of HR ≥70 beats/min (bpm) in the multivariate analysis. RESULTS: One third of the patients had a resting HR ≥70 bpm. Of the patients with an HR ≥70 bpm, 72.3% used less than the target dose of ß-blocker; they were younger and had a higher NYHA class, more diabetes mellitus and chronic obstructive pulmonary disease (COPD), and higher N-terminal pro-B type natriuretic peptide (NT-proBNP) levels and estimated glomerular filtration rates compared to the patients with an HR <70 bpm. The 1-year mortality was 3.1, 3.7, 5.8, and 9.1% among the patients with an HR <70, 70-79, 80-89, and >89 bpm, respectively. Only 2 patients used ivabradine. CONCLUSIONS: In patients with HFrEF and sinus rhythm, an HR ≥70 bpm was associated with worse clinical variables and outcomes. A high proportion of the patients who had an HR ≥70 bpm was not treated with or/did not tolerate the target dose of a ß-blocker, although the ß-blocker dose was higher than in patients with an HR <70 bpm. This may suggest that increased efforts should be made to further increase the ß-blocker dose, and treatment with ivabradine could be considered among patients with an HR ≥70 bpm.

6 min walk test is a strong independent predictor of death in outpatients with heart failure.

AIMS: The aim of this study was to examine the prognostic value of the 6 min walk test (6MWT) in a large cohort of outpatients with heart failure. METHODS AND RESULTS: A total of 5519 outpatients with heart failure from the National Norwegian Heart Failure Registry (NNHFR), which is part of the Norwegian Cardiovascular Disease Registry, were included in this analysis. The NNHFR recommended the use of the 6MWT for prognostic assessment of all patients included in the registry. Patients were categorized according to the 6MWT: Category 1 walked the longest and Category 3 the shortest. During a median (25th-75th percentiles) follow-up of 24 (14-36), 12.9% of the patients died. Patients in Category 3 had the overall worst outcome than had patients in Categories 1 and 2. 6MWT used as a continuous variable was a highly significant independent predictor for mortality in a multivariate Cox regression model adjusted for 16 other variables with a hazard ratio of 0.979 [(95% confidence interval 0.972-0.986), P < 0.001]. The four most important predictors for mortality were active cancer in the last 5 years, age, 6MWT, and natriuretic peptides (all P < 0.001). CONCLUSIONS: 6MWT is a strong independent predictor of mortality in outpatients with HF. The findings support the use of the 6MWT in the prognostic assessment of patients with HF irrespective of HF aetiology.

Automatic quantification of left ventricular function by medical students using ultrasound.

BACKGROUND: Automatic analyses of echocardiograms may support inexperienced users in quantifying left ventricular (LV) function. We have developed an algorithm for fully automatic measurements of mitral annular plane systolic excursion (MAPSE) and mitral annular systolic (S') and early diastolic (e') peak velocities. We aimed to study the influence of user experience of automatic measurements of these indices in echocardiographic recordings acquired by medical students and clinicians. METHODS: We included 75 consecutive patients referred for echocardiography at a university hospital. The patients underwent echocardiography by clinicians (cardiologists, cardiology residents and sonographers), who obtained manual reference measurements of MAPSE by M-mode and of S' and e' by colour tissue Doppler imaging (cTDI). Immediately after, each patient was examined by 1 of 39 medical students who were instructed in image acquisition on the day of participation. Each student acquired cTDI recordings from 1 to 4 patients. All cTDI recordings by students and clinicians were analysed for MAPSE, S' and e' using a fully automatic algorithm. The automatic measurements were compared to the manual reference measurements. RESULTS: Correct tracking of the mitral annulus was feasible in 50 (67%) and 63 (84%) of the students' and clinicians' recordings, respectively (p = 0.007). Image quality was highest in the clinicians' recordings. Mean difference ± standard deviation of the automatic measurements of the students' recordings compared to the manual reference was - 0.0 ± 2.0 mm for MAPSE, 0.3 ± 1.1 cm/s for S' and 0.6 ± 1.4 cm/s for e'. The corresponding intraclass correlation coefficients for MAPSE, S' and e' were 0.85 (good), 0.89 (good) and 0.92 (excellent), respectively. Automatic measurements from the students' and clinicians' recordings were in similar agreement with the reference when mitral annular tracking was correct. CONCLUSIONS: In case of correct tracking of the mitral annulus, the agreement with reference for the automatic measurements was overall good. Low image quality reduced feasibility. Adequate image acquisition is essential for automatic analyses of LV function indices, and thus, appropriate education of the operators is mandatory. Automatic measurements may help inexperienced users of ultrasound, but do not remove the need for dedicated education and training.