الفهرس 
Arrhythmogenicity of Anti-Tachycardia Pacing (ATP) in Patients with Implantable Cardioverter Defibrillator (ICD) and Cardiac Resynchronization Therapy (CRT-D)
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Abstract
Anti-tachycardia pacing therapy(ATP)has shown comparable efficacytoshock therapy in ventricular tachycardia (VT) termination with better quality of life. However, some ATPs may lead to VT acceleration or degeneration to ventricular fibrillation (VFs), which will result in more ICD shocks. Few studied the predictors of that acceleration.
Objective:
The aim of this study was to investigate the predictors of VT acceleration by ATP therapy.
Methods:
We retrospectively reviewed 488 monomorphic VT episodes thatrequired ATP therapy in 60 patients with structural heart diseases implanted with ICD or CRTD. The clinical data of the patients and the episodes’ details were evaluated.
Results:
Patients with a higher ejection fraction (EF)were more likely to be cardioverted by ATP therapy (P: 0.024). VT acceleration was more frequent in patients with lower EF (mean 31.24 ±4.08, P: 0.016), The percentage of accelerated episodes was 8.5%. VT episodes with a mean cycle length (CL)< 310 msec are more likely to accelerate (sensitivity 76.3%, specificity 67.7%, PPV value 45%, NPV 86%, and AUC 0.790). There was a statistically significant difference in theaccelerated VT episodes as compared to non-accelerated episodes regarding the number of ATP bursts(mean 3.66±2.22 vs 1.76±1.35, P:< 0.001), ramp(23.7% vs 4.2%, P: < 0.001),scanning (55.3 % vs 31.3%, P: 0.003) and shorter burst adaptive cycle length(mean 83.55±2.92 vs 84.64±2.61, P: 0.016).In a multivariate analysis, the VT CL, number of ATP bursts and ramp pacing predicted VT acceleration by ATP therapy.
Conclusion:
Fast VTs with a CL less than 310 msec are more likely to acceleratewith ATP therapy.The number of ATP bursts, and ramp had a significant effect on VT acceleration. To avoid VT acceleration by ATP therapy, ramp pacing better be avoided especially in fast VTs and lesser number of bursts should be delivered.