Introduction
Diastolic dysfunction (DD) is an alteration of relaxation, filling, and/or distensibility of the left ventricle [1]. DD can lead to diastolic heart failure and increases the risk of readmission rates and in-hospital mortality [2]. The increased prevalence of DD has led to growing interest in early detection in acute care settings [3, 4].
The American Society of Echocardiography (ASE) guidelines outline a detailed algorithm for the diagnosis of DD which includes (1) spectral pulsed wave Doppler of transmitral inflow; (2) pulsed wave Doppler profile of pulmonary venous flow; (3) mitral annulus downward velocity measurements (eʹ) using tissue Doppler imaging (TDI) at the septum (eʹS) and lateral wall (eʹL); and (4) left atrial (LA) volumes [5]. Obtaining these multiple measurements may be time-consuming and difficult for the average EP.
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Average peak mitral annulus velocity by TDI (eʹA = [eʹS + eʹL]/2) has been described as an acceptable single-step method for assessing LV relaxation, using eʹA < 9 cm/s as a threshold [6‐9]. TDI measurements can be obtained in 30 s with nearly 100% success rate, even with poor echocardiographic windows [10, 11]. This simplified approach may be more suitable for use by EPs with limited experience in echocardiography.
The purpose of this study was to ascertain inter-rater agreement in DD determination between eʹA < 9 cm/s measured by EPs and cardiologist interpretation of LBEs following the ASE guidelines.
Methods
Study design
Study protocol and measurements
LBEs were performed based on research staff availability by EPs (two emergency ultrasound fellowship-trained faculties and one emergency ultrasound fellow) who had performed at least 100 LBEs through routine clinical care and who underwent training and demonstrated proficiency in diastology with a board-certified cardiologist. A sonosite M-Turbo ultrasound system equipped with a harmonic 4.0-MHz variable-frequency phased-array transducer was used to obtain images and measurements. Studies were digitally archived for cardiologist review.
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EPs utilized electrocardiogram (EKG) rhythm strips to time diastole. EPs determined eʹA by averaging eʹS and eʹL measurements. EPs considered an eʹA < 9 cm/s as evidence of DD without adjustment for age or other risk factors. A board-certified cardiologist with an ASE level III echocardiography certification independently reviewed LBE images while blinded to EP interpretation. The cardiologist rated the images in accordance to the 2009 ASE guidelines [8] and upon reviewing digital recordings of the following: parasternal long view for determination of LV wall thickness, apical four-chamber view for estimation of LA size, E and A measurements, eʹS and eʹL, E/eʹ ratios to assess LA pressure, estimation of LA size, and the EKG rhythm strip (see Table 1 for comparison of data interpretation).
Table 1
Comparison of data utilized by emergency physician vs. cardiologist for determination of diastolic dysfunction
Interpretation by | Data collected | Interpretation |
|---|---|---|
Emergency physician | TDI measurements mitral annulus (i.e., eʹS and eʹL) | Average TDI velocities at mitral annulus (i.e., eʹA) |
Sinus EKG rhythm strip | Timing of early and late diastole | |
Cardiologist | Clip of PSL view | LV wall thickness estimation |
Clip of apical 4-chamber view | LA diameter | |
Mitral valve inflow velocities measurements (i.e., E and A) | E/A ratio | |
E/eʹ to estimate LA pressure | ||
TDI measurements mitral annulus (i.e., eʹS and eʹL) | E/eʹ to estimate LA pressure | |
Sinus EKG rhythm strip | Timing of early and late diastole |
Data analysis
EPs and cardiologist indicated DD present, DD absent, or indeterminate for each LBE study. A 3 × 3 contingency table provided a summary of agreement. Inter-rater reliability between EPs and the cardiologist was determined using an unweighted kappa with 95% confidence interval (CI) coefficient using Stata Release 15, StataCorp.
Results
Forty-eight studies were submitted to the cardiologist for review. Cardiologist and EP agreement are summarized in Table 2. Agreement was reached in 41 out of 48 cases (85.4%). The unweighted kappa coefficient was 0.74 (95% CI 0.57–0.92).
Table 2
Agreement between emergency physicians and cardiologist interpretation
Emergency physicians | Cardiologist | ||
|---|---|---|---|
DD present | DD not present | Indeterminatea | |
DD present | 18 | 0 | 1 |
DD not present | 2 | 22 | 4 |
Indeterminateb | 0 | 0 | 1 |
Discussion
Diastolic dysfunction is prevalent and delays in diagnosis can lead to increased morbidity and mortality. EPs with focused training in diastology may identify diastolic dysfunction with high sensitivity compared to a cardiologist trained in echocardiography. Previous studies have demonstrated that EPs can identify DD with high sensitivity, but either did not include TDI as part of their assessment [14] or reported only moderate agreement with cardiologist interpretation [4]. One study showed that EPs who met minimum requirements for LBEs based on American College of Emergency Physicians guidelines demonstrated high inter-rater agreement in the assessment of DD using primarily TDI, but failed to compare EP to a cardiologist interpretation [15]. Our study addresses the limitations of previous evidence by demonstrating that by following a more simplified approach using eʹA alone, EPs can identify DD with high level of agreement compared to a cardiologist following the ASE guidelines.
Limitations
Our sample size and convenience sampling may have introduced selection bias thus preventing a definitive correlation between eʹA and DD. EPs did not screen for regional wall motion abnormalities. Because wall motion abnormalities of the left ventricular basal segments can influence mitral annulus TDI diastolic velocities, this may have led to an overestimation of DD prevalence. Moreover, comparison was limited to cardiologist interpretation of LBE images, which may not be representative of typical exams obtained by a technician or specialist. A larger, multi-center study comparing EP assessment of eʹA against performance of a comprehensive echocardiogram can help establish external validity.
Conclusions
This study highlights a promising simplified approach for identifying DD by EPs. Relying on eʹA alone achieved good agreement for determination of DD compared to LBE interpretation by cardiologist. Future studies should further investigate this simplified approach as a one-step method of screening for LV DD in the emergency department.
Authors’ contributions
All authors have contributed to both the collection of data and the writing of the article. All authors read and approved the final manuscript. The authors would like to acknowledge the Research Open Access Publishing (ROAAP) Fund of the University of Illinois at Chicago for financial support towards the open access publishing fee for this article.
Competing interests
The authors declare that they have no competing interests.
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Availability of data and materials
This manuscript adhered to institutional policies regarding ultrasonography image collection and research. For access to full dataset, please contact corresponding author by e-mail.
Consent for publication
All patients gave written consent to participation in the study and the publication of the results.
Ethics approval and consent to participate
The University of Illinois at Chicago Institutional Review Board approved the study protocol.
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