New Automatic Tools to Identify Responders to Cardiac Resynchronization Therapy

Abstract

Background: New echocardiographic parameters (apical rocking [AR], septal flash [SF]) are intended to detect patterns specific to responders to cardiac resynchronization therapy (CRT). The patterns are visually recognized and qualitatively described, requiring experience and training. Speckle-tracking echocardiography can reflect SF and AR by using newly developed, dedicated parameters, such as start systolic index (SSI) and peak longitudinal displacement (PLD). The aim of this study was to investigate whether SSI and PLD can identify potential CRT responders.

Methods: In 125 patients, echocardiograms from before and 9 ± 3 months after CRT were retrospectively analyzed with dedicated EchoPAC prerelease software. From speckle-tracking baseline images, color-coded bull's-eye displays of SSI and PLD were generated. Cutoff values for both parameters were derived from 25 randomly selected patients and applied to the remaining 100 patients to identify CRT response, defined as a decrease in end-systolic volume of ≥15% during follow-up. The performance of SSI and PLD was compared with the visual assessment of AR and SF by expert and novice readers.

Results: Expert readers detected 77 patients with AR, identifying CRT responders with sensitivity and specificity of 85 ± 2% and 82 ± 2%, respectively. Novice readers reached 74 ± 7% sensitivity and 55 ± 11% specificity, while the sensitivity and specificity of the quantitative analysis were 72 ± 3% and 84 ± 4% for SSI and 80 ± 1% and 75 ± 2% for PLD, respectively.

Conclusions: New speckle-tracking-based quantitative assessment of mechanical dyssynchrony by SSI and PLD performs comparably in identifying CRT responders as visual analysis by expert readers and performs significantly better than novice readers.

Keywords: Candidate selection; Cardiac resynchronization therapy; Speckle tracking.