Predictors of nonsimultaneous interventricular delay at cardiac resynchronization therapy optimization

Cardiac resynchronization is a well tolerated and effective therapy for heart failure, but 30% of patients still do not respond to biventricular pacing. Optimization of device settings, in particular interventricular delay value, represents a plausible target for improving these results, but available literature is discordant. We aimed our study at the identification of the best suitable candidates to interventricular delay optimization.

A total of 77 consecutive patients with optimized drugs therapy underwent clinical, echocardiographic and electrocardiographic evaluation before and after 6 months from implantation of a biventricular defibrillator in accordance to current guidelines. In each patient, atrioventricular and interventricular delay values were optimized at predischarge with echocardiogram.

The only predictor of an optimized interventricular delay value different from simultaneous (i.e. standard shipment setting), at both univariate and multivariate analyses, was a QRS duration greater than 160 ms (odds ratio 22.958; P = 0.003) with a sensitivity of 70.9%.

Candidates to cardiac resynchronization therapy with a basal QRS greater than 160 ms have a higher chance of requiring echo-guided tailoring of interventricular delay value. A strategy based on these data can potentially improve device programming, reducing by one-third the need for optimization, according to our findings, and at the same time avoid unnecessary time-consuming procedures.