Optimal Programming to Improve Mechanical Indices, Symptoms and Exercise in Cardiac Resynchronization Therapy.

Cardiac resynchronization therapy (CRT) is primarily designed to synchronize the mechanical activity of the heart. While CRT is beneficial in average, a sizable proportion of patients do not clearly benefit from (respond to) CRT. Whether routinely optimizing the timing between the atria and ventricles (AV timing) and the timing between the left and right ventricles (VV timing) will significantly increase the likelihood of patients benefiting from (responding to) CRT is unknown.

The combination of simple and reliable measures of functional capacity (specific activity score [SAS] and 6-minute walk distance) with echocardiographic measures of left ventricular (LV) volume and ejection fraction (EF) is a practical way of defining response to CRT.

Based on surveys, most patients receiving CRT devices do not have formal optimization of AV and VV timing. This is largely because the usefulness of this is questionable and significant resources are required to perform detailed echo measurements.

A method for estimating optimal sensed AV (sAV), paced AV (pAV), and VV timing using intra-cardiac electrograms (I-EGM) has been developed (QuickOptTM) and offers a quick, simple and inexpensive means to optimize both CRT timing. However, the utility of QuickOptTM optimization is unproven.

Primary hypothesis. QuickOpt facilitated serial optimization of sAV, pAV, and VV timing in the initial 9 months following successful CRT will increase the rate of clinical response and structural remodeling at 12 months compared to usual care. Clinical response will be defined as a reduction in SAS of > 1 class or a 25% or larger improvement in 6 minute hall walk distance at 12 months versus baseline. Structural remodeling will be defined as a 15% or greater reduction in left LV end systolic volume or ≥ 5% absolute improvement in echo-derived LV EF at 12 months versus baseline.