EFFICACY OF PACEMAKER TACHYCARDIA TERMINATION ALGORITHMS - IS ELECTROPHYSIOLOGICAL TESTING ALONE ADEQUATE

Selection of an optimal pacemaker tachycardia reversion algorithm is g enerally performed utilizing programmed electrical stimulation (PES). Multiple tachycardias are induced and various tachycardia termination protocols are tested for reversion success. However, PES may induce no nclinical tachycardia and result in an inaccurate assessment of subseq uent reversion effectiveness for spontaneous tachycardia. To investiga te this question, we compared tachycardia reversion protocol success f or PES-induced tachycardia versus spontaneously occurring tachycardia in 16 patients with atrially placed Intermedics 262-12 antitachycardia pacemakers. The pacemaker has tachycardia response counters, and the reversion success was calculated from these counters. This was perform ed by comparing the percent of time 1-degrees versus 2-degrees modalit y use occurred; crossover to the 2-degrees modality implied failure of the 1-degrees modality to convert the tachycardia. PES was used to in duce multiple episodes of tachycardia and spontaneous episodes of tach ycardia were recorded over time by pacemaker counters. The pacemaker 1 -degrees modality success was then compared for spontaneous and induce d arrhythmias. Results: A total of 53 discrete data comparisons of PES versus spontaneous tachycardia counters were performed in the 16 pati ents. PES reversion success occurred 85% +/- 22% of the time versus a spontaneous reversion success of 88% +/- 22%. However, the Spearman ra nk correlation coefficient test demonstrated nonsignificant overall co rrelation (P < 0.1), and Pearson correlation on an individual patient basis varied widely (r value from < 0.1 to 1.0). Conclusions: When uti lizing the same termination algorithm, the percentage conversion of ta chycardias occurring spontaneously and induced by PES is similar but d oes not correlate well overall. This suggests that PES may not be a go od linear predictor of the long-term success of antitachycardia pacing algorithms.