In Case You Missed It: Echo Highlights From ACC.19
Echocardiography is an integral part of diagnostic and therapeutic cardiology. There has been tremendous growth in the field, as evidenced by the myriad of cutting-edge research recently presented at ACC.19 in New Orleans, LA.
Echocardiographic advancements span all areas of the field, including technology, our interpretation of the findings, how our findings correlate with other invasive and noninvasive measures of heart function, and the wave of the future – machine learning.
By no means a comprehensive summary, this article will review the highlights of echocardiographic research presented at ACC.19. The following presentations were curated based on their relevance to contemporary advancements in cardiology.
Diastolic function assessment continues to evolve. In 2016, the American Society of Cardiology released new guidelines on the assessment of diastolic dysfunction. The main purpose of these new guidelines was to take the salient points from the 2009 guidelines and create a simplified tool that any clinician could use to reliably and precisely grade diastolic dysfunction based on a few echo parameters.
In an effort to do so, many more people are characterized as having grade I diastolic dysfunction solely because of the presence of "myocardial disease." It emphasizes understanding the precise nature of left ventricular filling pressures defined by mean pulmonary capillary wedge pressure as estimated on echocardiography by the ratio of early mitral inflow velocities to the mitral annular tissue doppler velocities.
In a study published in the Journal of the American College of Cardiology (JACC), Katsuji Inoue, MD, et al., took the assessment of diastology and estimation of filling pressures to the next level with their use of strain.
The group in Norway performed a study of 31 middle-aged patients measuring left atrial reservoir function through strain imaging techniques at rest and with exercise, and compared this assessment to invasive hemodynamic assessment of the pulmonary capillary wedge pressure. Resting left atrial reservoir strain indirectly correlated with pulmonary capillary wedge pressure (r=0.85, p<0.001) during exercise.
This finding is important because accurate assessment of filling pressures at rest and during exercise may help elucidate the etiology for dyspnea on exertion for many patients.
In another JACC study, Riccardo M. Inciardi, MD, et al., analyzed left atrial function with assessment of the prognostic role on heart failure and cardiovascular death in patients with atrial fibrillation (AFib). This was a sub-study of the ENGAGE-AF TIMI 48 trial.
The researchers prospectively enrolled 971 subjects with a history of AFib, and assessed the prognostic value of left atrial emptying function and left atrial expansion index on the risk of hospitalization for heart failure and cardiovascular death compared to left atrial structure.
The study showed that aberrancies in left atrial function, more than left atrial structure, were associated with increased risk of adverse outcomes, even after adjusting for possible covariates including ejection fraction, history of heart failure and baseline cardiac rhythm.
This research highlights the importance of recognizing high-risk patients with left atrial dysfunction who might benefit from more intensive therapy to improve cardiovascular outcomes.
In the wake of PARTNER-3 and COAPT trial results, structural interventions continue to rapidly grow. Echocardiography is critical for assessment of complex valve disease. Shiying Liu, MD, et al., at Massachusetts General Hospital, performed a study examining the utility of direct planimetry of the left ventricular outflow tract (LVOT) by simultaneous biplane imaging.
Using computed tomography as the reference standard, they assessed whether planimetry with biplane imaging correctly identified the LVOT area. On average, the area obtained by biplane imaging was larger than standard transthoracic technique of using the LVOT diameter and calculating the area.
Additionally, when using the biplane LVOT area, the proportion of patients with severe aortic stenosis and discordant mean gradient decreased from 47 percent to 22 percent. Moreover, 33 percent of the patients initially thought to have severe aortic stenosis were reclassified to moderate aortic stenosis with the reclassification index being more pronounced in the paradoxical low gradient severe aortic stenosis group.
Having a method to more precisely calculate area with a noninvasive and ionizing radiation-free method will greatly improve diagnostic acumen and allow more effective patient triage.
While attending ACC.19, I found the most novel and exciting area of research in echocardiography to be machine learning. Previously, Sukrit Narula, BA, et al., proved that a machine learning framework incorporating speckle tracking echocardiographic data can differentiate physiologic vs. pathologic patterns of hypertrophy with reasonable sensitivity and specificity.
Also at ACC.19, Ashley Beecy, MD, et al., presented a study examining a novel deep learning model for right ventricular quantification on echocardiography. With use of cardiac magnetic resonance imaging as the gold standard, automated maximum annular displacement of a segmented point correlated with high overall performance with TAPSE and S' for the assessment of right ventricular function.
Multiple other exciting advancements in machine learning were also presented. Algorithms are in development to aid imaging acquisition in less experienced hands, optimize work flow and efficiency of image acquisition, minimize errors, improve precision in interpretation of images, and promote structured reporting for ease of interpretation and scholastic activity.
These highlights only scratch the surface of all the echocardiographic science presented at ACC.19. It will be exciting to see how ACC.20/World Congress of Cardiology will further broaden the horizons!
This article was authored by Dipika J. Gopal, MD (@dipikagopal), Fellow in Training (FIT) at the University of Pennsylvania in Philadelphia, PA, and Jeffrey B. Geske, MD, FACC, cardiologist at Mayo Clinic in Rochester, MN.