Ultrasound’s arrhythmia localization surpassed ECG’s accuracy



– A new type of echocardiography that uses a high frame rate to track tissue motion allowed researchers to noninvasively map the source of cardiac arrhythmias in patients with significantly more precision than did standard 12-lead ECG recordings in a pilot, single-center study with 55 patients.

Electromechanical wave imaging (EWI) correctly identified the arrhythmia source in 53 of 55 (96%) patients scheduled to undergo arrhythmia ablation, whereas only 39 of the same 55 patients (71%) were correctly mapped using recordings from a standard 12-lead ECG read by several trained electrophysiologists. The findings from this pilot study suggested that EWI performed with noninvasive ultrasound can provide useful, added information to 12-lead ECG tracings to localize cardiac arrhythmias of various types prior to invasive procedures, Elaine Y. Wan, MD, said at the annual scientific sessions of the Heart Rhythm Society.

She cautioned, however, that future studies must still establish that adding EWI to standard preprocedural assessment can benefit patients by, for example, reducing their radiation dosages or shortening their procedure times.

Patients at Columbia University Medical Center in New York scheduled to undergo ablation for a cardiac arrhythmia first had noninvasive assessment with EWI and 12-lead ECG. Patients averaged 56 years old; 45% had an atrial flutter, 22% had Wolff-Parkinson-White syndrome accessory pathways, 20% had premature ventricular complexes, and 13% had an atrial tachycardia. The researchers used 3D electroanatomic arrhythmia mapping performed during ablation as the arrhythmia-localization standard against which they compared both the EWI and ECG results.

EWI can map cardiac electromechanical activity in all four heart chambers by tracking, with high temporal and spatial resolution, transient tissue deformations that occur in response to local electrical activation of cardiac myocytes, the depolarizations in cardiac muscle that produce tissue movement. The technique captures 2,000 image frames per second, creating a “video of tissue movement that lets us see where the movement started,” explained Dr. Wan, a cardiac electrophysiologist at Columbia.

Dr. Wan and associates previously reported use of EWI to successfully map accessory pathways in all 14 children with Wolff-Parkinson-White syndrome they tested versus success in 11 of these 14 patients (79%) when using expert interpretation of 12-lead ECG recordings (JACC Clin Electrophysiol. 2019 Apr;5[4]:427-37).

The new study is the first report on using EWI in adults, Dr. Wan noted. Advantages of EWI over 12-lead ECG include its lack of dependence on correct lead placement, and EWI does not share the inherent limitation of 12-lead ECG for localizing arrhythmias on the heart’s posterior wall, she said in a video interview.

SOURCE: Wan EY et al. Heart Rhythm 2019, Abstract S-LCT04-03.

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