Guidelines and recommendations for digital echocardiography

Quantification of left ventricular ejection fraction and cardiac output using a novel semi-automated echocardiographic method: a prospective observational study in coronary artery bypass patients

BACKGROUND

Echocardiographic quantification of ejection fraction (EF) by manual endocardial tracing requires training, is time-consuming and potentially user-dependent, whereas determination of cardiac output by pulmonary artery catheterization (PAC) is invasive and carries a risk of complications. Recently, a novel software for semi-automated EF and CO assessment (AutoEF) using transthoracic echocardiography (TTE) has been introduced. We hypothesized that AutoEF would provide EF values different from those obtained by the modified Simpson's method in transoesophageal echocardiography (TOE) and that AutoEF CO measurements would not agree with those obtained via VTI_LVOT in TOE and by thermodilution using PAC.

METHODS

In 167 patients undergoing coronary artery bypass graft surgery (CABG), TTE cine loops of apical 4- and 2-chamber views were recorded after anaesthesia induction under steady-state conditions. Subsequently, TOE was performed following a standardized protocol, and CO was determined by thermodilution. EF and CO were assessed by TTE AutoEF as well as TOE, using the modified Simpson's method, and Doppler measurements via velocity time integral in the LV outflow tract (VTI_LVOT). We determined Pearson's correlation coefficients r and carried out Bland-Altman analyses. The primary endpoints were differences in EF and CO. The secondary endpoints were differences in left ventricular volumes at end diastole (LVEDV) and end systole (LVESV).

RESULTS

AutoEF and the modified Simpson's method in TOE showed moderate EF correlation (r = 0.38, p < 0.01) with a bias of -12.6% (95% limits of agreement (95%LOA): -36.6 - 11.3%). AutoEF CO correlated poorly both with VTI_LVOT in TOE (r = 0.19, p < 0.01) and thermodilution (r = 0.28, p < 0.01). The CO bias between AutoEF and VTI_LVOT was 1.33 l min^-1 (95%LOA: -1.72 - 4.38 l min^-1) and 1.39 l min^-1 (95%LOA -1.34 - 4.12 l min^-1) between AutoEF and thermodilution, respectively. AutoEF yielded both significantly lower EF (EF_AutoEF: 42.0% (IQR 29.0 - 55.0%) vs. EF_{TOE Simpson}: 55.2% (IQR 40.1 - 70.3%), p < 0.01) and CO values than the reference methods (CO_{AutoEF biplane}: 2.30 l min^-1 (IQR 1.30 - 3.30 l min^-1) vs. CO_{VTI LVOT}: 3.64 l min^-1 (IQR 2.05 - 5.23 l min^-1) and CO_PAC: 3.90 l min^-1 (IQR 2.30 - 5.50 l min^-1), p < 0.01)).

CONCLUSIONS

AutoEF correlated moderately with TOE EF determined by the modified Simpson's method but poorly both with VTI_LVOT and thermodilution CO. A systematic bias was detected overestimating LV volumes and underestimating both EF and CO compared to the reference methods.

TRIAL REGISTRATION

German Register for Clinical Trials (DRKS-ID DRKS00010666, date of registration: 08/07/2016).

Pitfalls of Echocardiographic Image Perception: How to Overcome Them?

In recent years, the significant development of echocardiography systems has led to a sharp improvement in echocardiographic images' quality. In parallel with this, computerized technologies are also going far forward, which today make it possible to ensure a high level of transmission, storage, and display of echocardiography studies. Despite this, many cardiologists are not familiar with modern computerized technologies' new possibilities and continue to use the old standards. That is why many echocardiography laboratories with the best echocardiography systems work following the old minimalist approach. In this paper, we will look at some of the most common mistakes that result from the improper transmission, storage, and demonstration of echocardiography studies, and describe possible ways to overcome these problems.

Ultrasound Core Laboratory for the Household Air Pollution Intervention Network Trial: Standardized Training and Image Management for Field Studies Using Portable Ultrasound in Fetal, Lung, and Vascular Evaluations

Ultrasound Core Laboratories (UCL) are used in multicenter trials to assess imaging biomarkers to define robust phenotypes, to reduce imaging variability and to allow blinded independent review with the purpose of optimizing endpoint measurement precision. The Household Air Pollution Intervention Network, a multicountry randomized controlled trial (Guatemala, Peru, India and Rwanda), evaluates the effects of reducing household air pollution on health outcomes. Field studies using portable ultrasound evaluate fetal, lung and vascular imaging endpoints. The objective of this report is to describe administrative methods and training of a centralized clinical research UCL. A comprehensive administrative protocol and training curriculum included standard operating procedures, didactics, practical scanning and written/practical assessments of general ultrasound principles and specific imaging protocols. After initial online training, 18 sonographers (three or four per country and five from the UCL) participated in a 2 wk on-site training program. Written and practical testing evaluated ultrasound topic knowledge and scanning skills, and surveys evaluated the overall course. The UCL developed comprehensive standard operating procedures for image acquisition with a portable ultrasound system, digital image upload to cloud-based storage, off-line analysis and quality control. Pre- and post-training tests showed significant improvements (fetal ultrasound: 71% ± 13% vs. 93% ± 7%, p < 0.0001; vascular lung ultrasound: 60% ± 8% vs. 84% ± 10%, p < 0.0001). Qualitative and quantitative feedback showed high satisfaction with training (mean, 4.9 ± 0.1; scale: 1 = worst, 5 = best). The UCL oversees all stages: training, standardization, performance monitoring, image quality control and consistency of measurements. Sonographers who failed to meet minimum allowable performance were identified for retraining. In conclusion, a UCL was established to ensure accurate and reproducible ultrasound measurements in clinical research. Standardized operating procedures and training are aimed at reducing variability and enhancing measurement precision from study sites, representing a model for use of portable digital ultrasound for multicenter field studies.

Pulmonary Hypertension in Central Australia: A Community-Based Cohort Study

BACKGROUND

The burden of pulmonary hypertension (PHT) in Central Australia has not been previously studied. Our aim is to characterise the prevalence, clinical classification, and long-term survival of individuals with PHT in Central Australia.

METHODS

A community-based cohort study of all individuals diagnosed with PHT in Central Australia between 2005 and 2016 was undertaken. We estimated PHT prevalence using population data, describe clinical PHT classification, and characterised long-term survival using Kaplan-Meier approaches.

RESULTS

A total of 183 patients were identified (mean age 52±16years, 63% female). Of these individuals, 149 (81.4%) were of Aboriginal and Torres Strait Islander (ATSI) descent. The prevalence per 100,000 of any PHT was significantly higher In ATSI (723 [95% CI 608-839] compared to non-ATSI individuals (126 [95% CI 84-168], p<0.001). Furthermore, ATSI individuals were diagnosed at younger ages compared to non-ATSI individuals (49±15 vs 64±16years, p<0.001). Median estimated pulmonary artery systolic pressure (ePASP) was higher in patients with pulmonary arterial hypertension (PAH) compared to other causes (62 [IQR 54-69] vs 50 [IQR 44-58] mmHg, p<0.01). The median survival rate from diagnosis was 9 years (IQR 7.2-13.2). Age and ePASP were significant predictors of mortality (HR 1.05 [95% CI 1.02-1.07] and HR 1.56 [95% 1.00-2.42] respectively).

CONCLUSIONS

In this community based study, we found a high burden of PHT in Central Australia. The prevalence of PHT is greater in ATSI individuals and is diagnosed at younger ages compared to non-ATSI individuals. Together with other cardiovascular diseases, PHT may be in-part contributing to the gap in life expectancy between ATSI and non-ATSI individuals.

Vector velocity imaging echocardiography to study the effects of submassive pulmonary embolism on the right atrium

OBJECTIVES

To assess the effects of submassive pulmonary embolism (SMPE) on right atrial (RA) anatomy and function.

BACKGROUND

Right ventricular dysfunction (RVD) is associated with adverse outcomes in SMPE. However, the effects of SMPE on the structure and function of the RA have received much less attention.

METHODS

Fifty patients with SMPE documented by CT angiography (SMPE group) and evidence of RVD on two-dimensional echocardiography were retrospectively identified and compared to 50 controls (control group). Both RA and RV areas, volumes and fractional area change (FAC) were measured. Pulmonary artery systolic pressures were estimated. RA and RV longitudinal strains were obtained using vector velocity imaging (VVI).

RESULTS

Compared with controls, RA and RV FACs were significantly reduced and associated with higher chamber volumes in the SMPE group. Global longitudinal RA strain was reduced in the SMPE group (29% + 11% vs 55% + 16%; P < .01), as was global RV longitudinal strain (-12% + 5% vs -20% + 5%, P < .01), when compared to the controls. A linear relationship existed between RV and RA strain in both groups; however, the curve was shifted downward among those with SMPE. Furthermore, ROC curve analysis suggests RA area performs better than RV area as a marker of SMPE.

CONCLUSIONS

RA structure and function are adversely affected in SMPE, similar to the effects observed in RV. Lower RA strain appears to be a novel quantitative indicator of SMPE, and RA area may be a more sensitive marker of this condition and may provide additional prognostic information in this condition.

Renal Allograft Function Is a Risk Factor of Left Ventricular Remodeling After Kidney Transplantation

BACKGROUND

Cardiovascular disease is the leading cause of morbidity and mortality in kidney transplantation (KT) patients. The prevalence of left ventricular hypertrophy increases with the progression of renal insufficiency.

METHODS

We investigated the association between the progression of renal insufficiency and left ventricular hypertrophy after KT. We reviewed KT patients at Seoul National University Hospital from January 1973 to December 2009. The creatinine elevation ratio (CER, the percentage change in the creatinine level from 1 month to 5 years after transplant) was calculated as follows: (creatinine level at 5 years minus creatinine level at 1 month)/creatinine level at 1 month × 100.

RESULTS

The study population was classified into a high-CER group (CER ≥25%) and low-CER group (CER <25%). Mean left ventricular mass index (LVMI) values were 135.7 and 134.7 g/m² before KT and 101.7 and 123.7 g/m² at 5 years after KT in the low-CER and high-CER groups, respectively. The LVMI before or 1 year after KT was not different between the 2 groups, but the LVMI at 5 years post-transplant was higher in the high-CER group than in the low-CER group. The LVMI increased after its initial decrease in the high-CER group, whereas its reduction was maintained in the low-CER group during the 5 years after KT (P = .009, repeated-measures analysis of variance).

CONCLUSIONS

These data suggest that deterioration of renal allograft function is associated with left ventricular remodeling after KT.

The prevalence of pulmonary hypertension in patients with obesity hypoventilation syndrome: a prospective observational study

BACKGROUND

One important cardiovascular morbidity that is associated with obesity hypoventilation syndrome (OHS) is the development of pulmonary hypertension (PH). However, few studies have assessed PH in OHS patients. Therefore, we prospectively assessed the prevalence of PH in a large sample of OHS patients.

METHODS

In this prospective observational study, all consecutive OHS patients referred to the sleep disorders clinic during the study period were included. All patients underwent overnight polysomnography (PSG), spirometry, arterial blood samples and thyroid tests. Transthoracic echocardiography was performed for patients who agreed to participate in the study. PH was defined as systolic pulmonary artery pressure (SPAP) >40 mmHg.

RESULTS

Echocardiographic data were available for 77 patients with a mean age of 60.5±11.7 years, a BMI of 43.2±10.4 kg/m², and an Epworth Sleepiness Scale (ESS) score of 11.4±5.5. SPAP was >40 mmHg in 53 patients (68.8%), with a mean SPAP of 64.1±17.1 mmHg. There were no differences between the OHS patients with PH and those with normal PAP in terms of age, BMI, presenting symptoms, comorbidities, arterial blood gasses (ABG), and spirometric and PSG parameters. Approximately 71.4% of women and 61.9% of men with OHS also had PH. SPAP was >40-55 mmHg in 19 (24.7%) patients (18 women), >55-70 mmHg in 15 (19.5%) patients (6 women) and >70 mmHg in 19 (24.7%) patients (16 women). Severe PH (SPAP >70 mmHg) was diagnosed in 28.6% of the women and 14.3% of the men.

CONCLUSIONS

PH is very common among patients with OHS who have been referred to sleep disorders clinics. PH should be considered in the regular clinical assessment of all patients with OHS.

Quality Markers in Cardiology. Main Markers to Measure Quality of Results (Outcomes) and Quality Measures Related to Better Results in Clinical Practice (Performance Metrics). INCARDIO (Indicadores de Calidad en Unidades Asistenciales del Área del Corazón): A SEC/SECTCV Consensus Position Paper

Cardiology practice requires complex organization that impacts overall outcomes and may differ substantially among hospitals and communities. The aim of this consensus document is to define quality markers in cardiology, including markers to measure the quality of results (outcomes metrics) and quality measures related to better results in clinical practice (performance metrics). The document is mainly intended for the Spanish health care system and may serve as a basis for similar documents in other countries.

Professional Education, Training and Role of the Cardiac Sonographer in Different Countries

Performing a good echocardiographic examination requires intensive training and highly qualified technical staff personnel, which, in many countries, is represented by the Cardiac Sonographer. Being an operator-dependent diagnostic method, a long debate has been held to help identifying the most appropriate curriculum for the training of this professional profile. Although guidelines for the education of the Cardiac Sonographers have been suggested by the American Society of Echocardiography (ASE) several years ago and many scientific publications have given credibility, trust and enhance to this professional profile in Italy, this figure is not yet recognized by the National Health System. It is encouraging that in the last decade, national authorities, such as the SIEC (Società Italiana di Ecografia Cardiovascolare), have expressed interest in recognizing the Cardiac Sonographers as professionals in our country. Per their guidelines, the Cardiocirculatory Physiopathology Cardiovascular Perfusion technicians (TFCPCs) seem to be, among the professionals, the most suitable, due to their educational training and the role they play. Taking inspiration from the positive experience of this professional figure in the USA and in the Anglo Saxon countries, it could aims to be a valid support in terms of cost and quality for the Italian health system.

Depressed atrial function in diastolic dysfunction: a speckle tracking imaging study

BACKGROUND

Two-dimensional speckle tracking imaging (STI) has recently been applied to the study of left atrial (LA) reservoir function. We utilized STI to analyze LA function in diastolic dysfunction (DD), hypothesizing that LA strain abnormality is part of the pathogenesis of diastolic dysfunction.

METHODS

We applied STI to 50 patients with Grade 1-2 DD, comparing these results to 100 normal controls. Complete Doppler analysis of filling was made using peak E, peak A and tissue Doppler e' velocities; E/e' was used as a surrogate for LA pressure and LA stiffness index was calculated.

RESULTS

In analysis of covariance, adjusting for age and gender, compared with controls, DD patients had higher E/e', greater LA volume and greater LA stiffness, but lower E/A ratio and global LA strain. LA strain appears to be inversely related to LA volume, but not to other indices of LV diastolic function. In subgroup analysis, LA strain was significantly lower, and stiffness significantly higher in DD, even after correction for differences in LA volume and E/A ratio. Analysis of ROC curves suggests that abnormal LA strain is a better marker for diastolic dysfunction than LA enlargement.

CONCLUSION

LA strain by STI is significantly reduced in early diastolic dysfunction and is related to higher LA stiffness and LA size. Reduction in LA strain is partially independent of LA volume; accordingly we hypothesize that reduced atrial strain indicates impaired atrial distensibility.

Pulmonary hypertension: prevalence and mortality in the Armadale echocardiography cohort

Background

Pulmonary hypertension (PHT) lacks community prevalence and outcome data.

Objective

To characterise minimum ‘indicative’ prevalences and mortality data for all forms of PHT in a selected population with an elevated estimated pulmonary artery systolic pressure (ePASP) on echocardiography.

Design

Observational cohort study.

Setting

Residents of Armadale and the surrounding region in Western Australia (population 165 450) referred to our unit for transthoracic echocardiography between January 2003 and December 2009.

Results

Overall, 10 314 individuals (6.2% of the surrounding population) had 15 633 echo studies performed. Of these, 3320 patients (32%) had insufficient TR to ePASP and 936 individuals (9.1%, 95% CI 8.6% to 9.7%) had PHT, defined as, ePASP>40 mm Hg. The minimum ‘indicative’ prevalence for all forms of PHT is 326 cases/100 000 inhabitants of the local population, with left heart disease-associated PHT being the commonest cause (250 cases/100 000). 15 cases of pulmonary arterial hypertension/100 000 inhabitants were identified and an additional 144 individuals (15%) with no identified cause for their PHT. The mean time to death for those with ePASP >40 mm Hg, calculated from the first recorded ePASP, was 4.1 years (95% CI 3.9 to 4.3). PHT increased mortality whatever the underlying cause, but patients with PHT from left heart disease had the worst prognosis and those with idiopathic pulmonary arterial hypertension receiving disease-specific treatment the best prognosis. Risk of death increased with PHT severity: severe pulmonary hypertension shortened the lifespan by an average of 1.1 years compared with mild pulmonary hypertension.

Conclusions

In this cohort, PHT was common and deadly. Left heart disease was the most common cause and had the worst prognosis and treated pulmonary arterial hypertension had the best prognosis.

ACCF/ASE/AHA/ASNC/HFSA/HRS/SCAI/SCCM/SCCT/SCMR 2011 Appropriate Use Criteria for Echocardiography. A Report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Society of Echocardiography, American Heart Association, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, Society of Critical Care Medicine, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance American College of Chest Physicians

The American College of Cardiology Foundation (ACCF), in partnership with the American Society of Echocardiography (ASE) and along with key specialty and subspecialty societies, conducted a review of common clinical scenarios where echocardiography is frequently considered. This document combines and updates the original transthoracic and transesophageal echocardiography appropriateness criteria published in 2007 (1) and the original stress echocardiography appropriateness criteria published in 2008 (2). This revision reflects new clinical data, reflects changes in test utilization patterns,and clarifies echocardiography use where omissions or lack of clarity existed in the original criteria.The indications (clinical scenarios)were derived from common applications or anticipated uses, as well as from current clinical practice guidelines and results of studies examining the implementation of the original appropriate use criteria (AUC).The 202 indications in this document were developed by a diverse writing group and scored by a separate independent technical panel on a scale of 1 to 9,to designate appropriate use(median 7 to 9), uncertain use(median 4 to 6), and inappropriate use (median 1 to 3). Ninety-seven indications were rated as appropriate, 34 were rated as uncertain, and 71 were rated as inappropriate. In general,the use of echocardiography for initial diagnosis when there is a change in clinical status or when the results of the echocardiogram are anticipated to change patient management were rated appropriate. Routine testing when there was no change in clinical status or when results of testing were unlikely to modify management were more likely to be inappropriate than appropriate/uncertain.The AUC for echocardiography have the potential to impact physician decision making,healthcare delivery, and reimbursement policy. Furthermore,recognition of uncertain clinical scenarios facilitates identification of areas that would benefit from future research.

Point-of-care ultrasound in the neonatal intensive care unit: international perspectives

To explore international variation in implementation of point-of-care ultrasound in the neonatal intensive care unit (NICU), contributions were invited from neonatologists and paediatric cardiologists in six countries. The contributors show variation in national implementation that ranges from almost total coverage through to a minority of NICUs having point-of-care ultrasound capability. To a varying degree in all systems the main barriers have been concerns from the consultative specialties that traditionally use ultrasound, relating to the risk of misdiagnosis but also involving different clinical needs, liability concerns and lack of outcome-based evidence. All contributors agreed that safe point-of-care ultrasound depends on close collaboration with the consultative specialties and also that there is a need to develop training and accreditation structures for neonatologists using ultrasound.

Atrial and ventricular function in thalassemic patients with supra-ventricular arrhythmias

The aims of this study were to evaluate through Color Doppler Myocardial Imaging (CDMI) echocardiography if atrial or ventricular myocardial alterations could be detectable in patients with thalassemia major (THAL) and if these alterations could be considered as predictive elements for supra-ventricular arrhythmic events. Twenty-three patients with THAL underwent clinical and electrocardiographic evaluation; patients were grouped in THAL1 (9 with supra-ventricular arrhythmias) and THAL2 (14 without arrhythmias); 12 healthy subjects were considered as control group (C). We examined through conventional 2D Color Doppler echocardiography some morphological and functional parameters regarding left ventricular (LV) systolic and diastolic function, and through CDMI the velocities at mitral annulus level, the regional LV and left atrial (LA) strain and strain rate. All THAL patients had LV dimension (p<0.05), LA area (p<0.01) and E/Em ratio (p<0.001) to be significantly higher than controls. The mitral annulus longitudinal velocities were significantly lower in THAL1 than in THAL2 (p<0.001); the E/Em ratio was higher in THAL1 than THAL2 (p<0.001). The THAL1 showed a lower systolic strain rate of atrial wall than THAL2 and C (p<0.05). The multiple regression highlighted a significantly inverse correlation among E/Em and atrial strain (p<0.02). CDMI showed both THAL subgroups had subtle systolic and diastolic left ventricular myocardial alterations, which could represent the onset of developing "iron cardiomyopathy" and are related to supra-ventricular arrhythmia. Monitoring these parameters in the THAL patients could contribute to decisions about follow-up and therapy.

Does point-of-care functional echocardiography enhance cardiovascular care in the NICU?

Although the last two decades have seen major advances in the care of sick, extremely premature newborns, the approach to cardiovascular assessment and monitoring remains suboptimal owing to an overreliance on poorly predictive clinical markers such as heart rate or capillary refill time. Point-of-care functional echocardiography (PCFecho) enables real-time evaluation of cardiac performance and systemic hemodynamics to characterize acute physiology, identify the exact nature of cardiovascular compromise and guide therapeutic decisions. In this article, we will review four clinical scenarios where bedside functional cardiac imaging enabled delineation of the real clinical problem and refinement of the therapeutic care plan with direct patient benefits.

Regression equations for calculation of z scores of cardiac structures in a large cohort of healthy infants, children, and adolescents: an echocardiographic study

BACKGROUND

Decision making in the care of pediatric patients with congenital and acquired heart disease remains reliant on detailed measurements of cardiac structures using 2-dimensional echocardiography. Calculated z scores are often used to normalize these measurements to the patient's body size. Existing normal data in the literature are limited by small sample size, small numbers of measured cardiac structures, and inadequate data for the calculation of z scores. Accordingly, we sought to develop normative data in a large pediatric cohort using modern echocardiographic equipment from which z scores could be calculated.

METHODS

Two-dimensional and M-mode echocardiography was performed in 782 patients ranging in age from 1 day to 18 years. Measurements were made of 21 individual cardiac structures. Regression equations were derived to relate the size of the various cardiac structures to body surface area. Data are presented graphically, and regression equations are derived relating cardiac dimension to body surface area.

CONCLUSION

The presented data will allow the calculation of z scores for echocardiographically measured cardiac structures. This information will be valuable for clinicians caring for infants and children with known or suspected cardiac disease.

John Sutton MG, Ferrari VA, Scott CH, Wiegers SE. Failure of digital echocardiography to accurately diagnose intracardiac shunts

BACKGROUND

Intravenous agitated saline injection during transthoracic echocardiography assists in the detection of right to left intracardiac and intrapulmonary shunts. Whether digital echocardiography offers comparable sensitivity and specificity to analog tape recording to assess shunts is unknown. Technical differences between methods could lead to significant differences in shunt detection.

METHODS

Agitated saline was injected intravenously at rest and with Valsalva in 189 consecutive patient studies (406 injections). Echocardiographers assessed presence and degree of left ventricle contrast on simultaneously recorded analog tape and digital echocardiography images in blinded fashion.

RESULTS

Digital echocardiography had low overall sensitivity (rest 0.50, valsalva 0.63, late 0.39) compared to analog tape. Longer clip lengths improved sensitivity for detection of late contrast passage (rest 0.50, valsalva 0.67, late 0.46).

CONCLUSION

Digital echocardiography saline contrast studies have poor sensitivity for assessment of intracardiac shunts versus analog tape, and increasing clip length only modestly increases sensitivity. Joint Photographic Experts Group digital compression losses may be an important cause of failure to detect intracardiac shunts, including patent foramen ovale.

Clinically Compressed Digital Echocardiography: A Patient-safe Alternative to Videotape Review

Introduction: Digital storage of echocardiographic data offers logistical advantages over videotape archival. However, limited information is available on the accuracy of clinically compressed digitised examinations, an important consideration for patient safety. Materials and Methods: Transthoracic echocardiograms of 520 consecutive patients were prospectively acquired digitally and on videotape. Two echocardiologists, in consensus, reported studies in both formats sequentially. Using the videotape as a reference, the significance of any reported differences was graded from both imaging and clinical standpoints, and the reasons for these differences identified. Results: From an imaging perspective, differences between digital and videotaped studies were absent or minor in 459 cases (88%), fairly significant in 55 (11%) and very significant in 6 (1%). The main reasons for the observed differences were inadequate acquisition of optimal views (59%), an insufficient number of acquired cardiac cycles (25%) and suboptimal image quality (9%). These differences were considered to be of possible or definite clinical importance in 21 (4%) and 8 (2%) cases, respectively. In multinominal logistic regression models, the only independent predictor of significant difference between digitised and videotaped images was study complexity. Regardless of case complexity, most diagnostic errors arising from digital review were attributable to technical failure rather than observer error. Conclusions: The potential for important errors arising from exclusive reporting of clinically compressed digital echocardiograms is small. Digital echocardiography, as practiced in a routine clinical setting, offers a patient-safe alternative to videotape review. Key words: Clinical implications, Digital echocardiography, Patient safety, Videotape

A Novel Two-Dimensional Echocardiographic Image Analysis System Using Artificial Intelligence-Learned Pattern Recognition for Rapid Automated Ejection Fraction

OBJECTIVES

We sought to test the hypothesis that a novel 2-dimensional echocardiographic image analysis system using artificial intelligence-learned pattern recognition can rapidly and reproducibly calculate ejection fraction (EF).

BACKGROUND

Echocardiographic EF by manual tracing is time consuming, and visual assessment is inherently subjective.

METHODS

We studied 218 patients (72 female), including 165 with abnormal left ventricular (LV) function. Auto EF incorporated a database trained on >10,000 human EF tracings to automatically locate and track the LV endocardium from routine grayscale digital cineloops and calculate EF in 15 s. Auto EF results were independently compared with manually traced biplane Simpson's rule, visual EF, and magnetic resonance imaging (MRI) in a subset.

RESULTS

Auto EF was possible in 200 (92%) of consecutive patients, of which 77% were completely automated and 23% required manual editing. Auto EF correlated well with manual EF (r = 0.98; 6% limits of agreement) and required less time per patient (48 +/- 26 s vs. 102 +/- 21 s; p < 0.01). Auto EF correlated well with visual EF by expert readers (r = 0.96; p < 0.001), but interobserver variability was greater (3.4 +/- 2.9% vs. 9.8 +/- 5.7%, respectively; p < 0.001). Visual EF was less accurate by novice readers (r = 0.82; 19% limits of agreement) and improved with trainee-operated Auto EF (r = 0.96; 7% limits of agreement). Auto EF also correlated with MRI EF (n = 21) (r = 0.95; 12% limits of agreement), but underestimated absolute volumes (r = 0.95; bias of -36 +/- 27 ml overall).

CONCLUSIONS

Auto EF can automatically calculate EF similarly to results by manual biplane Simpson's rule and MRI, with less variability than visual EF, and has clinical potential.