P552
Predictors of pacing induced left ventricular dysfunction and cardiomyopathy assessed by three-dimensional echocardiography and speckle tracking strain

Alexandria EPS Unit

During recent years there was a focus on the negative effects associated with long term right ventricular (RV) pacing. It was shown in both experimental and clinical studies that RV pacing leads to ventricular dyssynchrony, similar to that of left bundle branch block (LBBB) with subsequent electrical, mechanical and anatomical changes leading to detrimental effects on left ventricular structure and function. During the last two decades, 3D echocardiography developed from a time-consuming method to a routine clinical approach. At present, evidence suggested that 3D echocardiography provided improved accuracy and reproducibility over 2D methods for LV volume and function calculation. There is a growing number of literature signifying that speckle tracking strain is able to identify left ventricular (LV) dysfunction even before any reduction in LV ejection fraction (LVEF).

This was an observational study of fifty consecutive patients without structural heart disease and preserved ejection fraction (LVEF > 50%) presented with high grade atrioventricular block for permanent pacing. Complete 2D and a full volume 3D echocardiography was done before implantation, one-week and 6-months after implantation together with global longitudinal strains analysis (GLS). Patients were followed for 6 months to detect the incidence of PIVD (defined as a reduction in LVEF >10 percentage points but still above 50%) and PICMP (defined as a decrease in LVEF by 10 percentage points from baseline in the absence of other known causes of cardiomyopathy resulting in EF < 50%). PIVD and PICMP predictors and risk factors were analyzed over a 6-month period.

At six months, 25 (50%) patients developed PIVD; of these, 6 (12%) developed PICMP. Pre-implantation, GLS was significantly lower in the 6 patients who subsequently developed PICMP, compared to those who developed PIVD and the preserved EF group (mean GLS -15.50 vs. -21.0, -20.0 respectively; p = 0.005, 0.033 respectively). At one week, GLS was significantly lower in the 25 patients who subsequently developed PIVD, compared to those who did not (GLS -13.0 vs. -18.0 respectively; p = 0.002). A reduction of baseline GLS by 15% or more at one week was associated with the development of PIVD and PICMP (p = <0.001). A wider native QRS complex was associated with the development of PIVD and PICMP (p = 0.008, 0.018 respectively). The other predictors (Age, Sex, HTN, D.M, Post-pacing QRS width and axis, presence of native BBB, Pacemaker type and lead site) were found non-significant.

PICMP may be more common than previously reported and it may occur shortly after implantation. This rise in its incidence is due to the application of new sensitive tools like 3D echocardiography and speckle tracking strain. Pre-implantation GLS is a sensitive parameter for the development of PICMP. One-week GLS is an early predictor for the development of PICMP and PIVD before any reduction in EF develops.