Abstract 18144: Morphology of Far-field Electrogram and Effectiveness of Antitachycardia Pacing Among Fast VTs Occurring in ICD Patients: a Multicenter Study
Since the cycle length (CL) is a negative predictor of antitachycardia pacing (ATP) effectiveness, fast ventricular tachycardias (FVT) are less suitable to be terminated by ATP and need shocks (SH) more frequently. Among FVT occurring in ICD patients, no information is available regarding the ability of the far-field electrograms morphology (Ff-M) in predicting the result of the subsequent ATP. We hypothesized that the Ff-M, as pseudo-unipolar signal and thus, as an indicator of the direction of propagation front, could be related to the ATP effectiveness.
Methods: In this multicenter study we analyzed 289 FVT (CL: 250-320 ms) occuring consecutively in 53 ICD patients with Medtronic devices and left ventricular dysfunction (LVEF: 37±6; pacing site: right ventricular apex). FVT programming was standardized, including a single ATP burst as initial therapy, and SH for unsuccessful ATP. Configuration of Ff-M was HVA vs. HVB. VTs were classified in Q-VT or non Q-VT according to the presence or absence of a negative initial deflection in the Ff-M.
Results: The mean CL was 291±24 ms. We observed 4 Ff-M: QS (n=14, 5%), QR (n=158, 55%), R (n=93, 32%) and RS (n=24, 8%). Q-VTs had a higher LC, ms (295±26 vs. 286±21; p=0.002) and were associated with a higher LVEF, % (38±7 vs 36±9; p=0,01) and a lower frequency of previous MI (37 vs. 59%; p<0.001). The ATP effectiveness was 80% (86% in QS, 85% in QR, 74% in R, 62% in RS) and 59 (20%). The frequency of successful ATP was higher in Q-VT: 86 vs. 71% (p=0.002). By logistic regression analysis -which included LVEF, CL, etiology, functional class, beta-blocker therapy (BB-t) and indication- the LVEF (OR=1.07; p=0.002), the BB-t (OR=6.3; p<0.001) and a Q-VT pattern (OR=2.3; p=0.015) were found to be as independent predictors of effective ATP. Non Q-VTs need more frequently SH to be terminated (39 vs. 19%; p=0.002). ATP was safer in Q-VTs, the frequencies of acceleration (5.1 vs 12.3%; p=0.02) and syncope (4.6 vs. 12.3%; p=0.01) being lower.
Conclusions: 1- Among FVT occurring in ICD patients, Q-VTs are more suitable for termination by ATP, independently of CL. 2-Non Q-VT -which are usually ischemic- are poorly tolerated and more frequently terminated by SH. 3- In order to avoid SH, the substrate of non Q-VTs may need a more intensive treatment.
- © 2012 by American Heart Association, Inc.