EP News: Pediatric and Congenital Electrophysiology

  • Elizabeth V. Saarel
    Address reprint requests and correspondence: Dr Elizabeth V. Saarel, 520 S. Eagle Rd, Suite 2204, Meridian, ID 83642.
    Department of Pediatric Cardiology, St. Luke’s Health System, Boise, Idaho; and Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio
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      Sugrue et al (J Am Coll Cardiol 2020;76:2834, PMID 33303072) reported a novel echocardiographic measurement, the electromechanical window (EMW), that may predict serious life-threatening events in patients with long QT syndrome (LQTS). This retrospective study included 651 patients with LQTS (age 26 ± 17 years; 60% women; 158 symptomatic; 51% LQTS type 1; 33% LQTS type 2; 11% LQTS type 3; 5% multiple mutations) and 50 healthy controls. EMW was calculated as the difference between the interval from QRS onset to aortic valve closure midline, as derived for continuous-wave Doppler, and the electrocardiogram-derived QT interval for the same beat. Most patients with LQTS had a negative EMW, whereas most control patients had a positive EMW. In a multivariate model containing age, sex, genotype, corrected QT interval, and EMW, EMW was associated independently with symptomatic status. For every 10-ms decrease in EMW (more negative), there was 37% increased odds of potentially life-threatening symptoms (odds ratio per 10 ms 1.37; 95% confidence interval 1.27–1.48; P < .0001). The authors conclude that EMW outperformed heart rate–corrected QT interval as a predictor of symptomatic status and EMW is now a clinically validated risk factor in LQTS.
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