Comparison between IEGM-based approach and echocardiography in AV/PV and VV delay optimization in CRT-D recipients (Quicksept study)

Abstract

Background: AtrioVentricular (AV) and InterVentricular (VV) delay optimization can improve ventricular function in Cardiac Resynchronization Therapy (CRT) and is usually performed by means of echocardiography. St Jude Medical has developed an automated algorhythm which calculates the optimal AV and VV delays (QuickOpt™) based on Intracardiac ElectroGrams, (IEGM), within 2 min. So far, the efficacy of the algorhythm has been tested acutely with standard lead position at right ventricular (RV) apex. Aim of this project is to evaluate the algorhythm performance in the mid- and long-term with RV lead located in mid-septum.

Methods: AV and VV delays optimization data were collected in 13 centers using both echocardiographic and QuickOpt™ guidance in CRTD implanted patients provided with this algorhythm. Measurements of the aortic Velocity Time Integral (aVTI) were performed with both methods in a random order at pre-discharge, 6-month and 12-month follow-up.

Results: Fifty-three patients were studied (46 males; age 68 ± 10y; EF 28 ± 7%). Maximum aVTI obtained by echocardiography at different AV delays, were compared with aVTI acquired at AV delays suggested by QuickOpt. The AV Pearson correlations were 0.96 at pre-discharge, 0.95 and 0,98 at 6- and 12- month follow-up respectively. After programming optimal AV, the same approach was used to compare echocardiographic aVTI with aVTI corresponding to the VV values provided by QuickOpt. The VV Pearson Correlation were 0,92 at pre-discharge, 0,88 and 0.90 at 6-month and 12- month follow-up respectively.

Conclusions: IEGM-based optimization provides comparable results with echocardiographic method (maximum aVTI) used as reference with mid-septum RV lead location.

Keywords: Cardiac resinchronization therapy; Echocardiographyc optimization; IEGM based algorythm; Mid-septum stimulation; Optimization algorythm.

Fig. 1

Correlation between aVTI (cm) calculated with optimal AV/PV intervals optimized by Echo and QuickOpt™ method’s at pre-discharge and at 12 month Follow up (upper line). The correlation between the two methods is always good.

Fig. 2

Correlation between aVTI (cm) calculated at the optimized VV intervals obtained by Echo and QuickOpt™ method’s at pre-discharge and at 12-month follow-up (upper line). The correlation between the two methods was always good.

Fig. 3

Bland-Altman plot of differences in optimal atrioventricular interval measured by echocardiography and by QuickOpt at Phd, 6 and 12-month follow-up. Grey zone indicate average, upper and lower limit of agreement (1.13 msec ± 31 msec; IC 95% −61 msec + 63 msec). Colored area indicates clinically acceptable margins of difference between the two tecniques (0 ± 30 msec). Although there was no statistical difference between the two methods, the clinically acceptable margins of difference between them (0 ± 30 msec) showed a low concordance (64%).

Fig. 4

Bland-Altman plot of differences in optimal VV interval measured by echocardiography and by QuickOpt at Phd, 6 and 12-month follow-up. Grey zone indicate average, upper and lower limit of agreement (25 msec ± 33 msec; IC 95% −40 msec + 90 msec). Colored area indicates clinically acceptable margins of difference between the two tecniques (0 ± 30 msec). Although there was no statistical difference between the two methods, the clinically acceptable margins of difference between them (0 ± 30 msec) showed a low concordance (56%).

Fig. 5

Correlation of optimal VV intervals measured with ECHO and QuickOpt method. In 50% of cases the ventricle paced first was different. In this analysis 13 patients with VV intervals equal to 0 msec as calculated by either method were excluded. Blue colored area represents the conflict zones between the two methods. In general the larger the advance of the left ventricle, the wider the error between the two methods.