The 1+1 Trial

Abstract

Background-The tachycardia detection interval (TDI) in implantable cardioverter/defibrillators (ICDs) is conventionally programmed according to the slowest documented ventricular tachycardia (VT), with a safety margin of 30 to 60 ms. With this margin, VTs above the TDI may occur. However, longer TDIs are associated with an increased risk of inappropriate therapy. We hypothesized that patients with slow VTs (Ͻ200 bpm) may benefit from a long TDI and a dual-chamber detection algorithm compared with a conventionally programmed single-chamber ICD. Methods and Results-Patients with VTs Ͻ200 bpm were implanted with a dual-chamber ICD that was randomly programmed to a dual-chamber algorithm and a TDI of Ն469 ms or to a single-chamber algorithm with a TDI 30 to 60 ms above the slowest documented VT cycle length and the enhancement criteria of cycle length variation and acceleration. The primary combined end point was the number of all inappropriate therapies, VTs above the TDI, and VTs with significant therapy delay (Ͼ2 minutes). After 6 months, a crossover analysis was performed. Total follow-up was 1 year. One hundred two patients were included in the study. The programmed TDI was 500Ϯ36 ms during the dual-chamber phase and 424Ϯ63 ms during the single-chamber phase. For the primary end point (inappropriate therapies, VTs above the TDI, or VTs with detection delay), a moderate superiority of the dual-chamber mode was found: Mann-Whitney estimatorϭ0.6661; 95% CI, 0.5565 to 0.7758; Pϭ0.0040. Conclusions-Dual-chamber detection with a longer TDI improves VT detection and does not increase the rate of inappropriate therapies despite a considerable increase in tachycardia burden.

2015 HRS/EHRA/APHRS/SOLAECE expert consensus statement on optimal implantable cardioverter-defibrillator programming and testing

“…However, VT can also present slower rates in the range of those of supraventricular tachyarrhythmias or even of sinus tachycardia. Therefore, any rate cutoff will always imply a tradeoff between maximizing sensitivity for ventricular tachyarrhythmia detection at the expense of inappropriate detection of fast supraventricular tachyarrhythmias and maximizing specificity at the expense of some slow VTs going undetected [103].…”

“…This includes patients with slower monomorphic VT, those at risk for AF with rapid ventricular rates, or those capable of exercising to sinus rates in the VT zonev [103,132]. In secondary prevention patients with slower VT, older discrimination algorithms reduced shocks for SVT compared with rate-only detection.…”

“…Any benefit of dual-chamber discrimination is likely restricted to specific patient groups [103,138]. For example, the Dual Chamber and Atrial Tachyarrhythmias Adverse Events (DATAS) trial of predominantly secondary prevention patients with slower VTs reported modest benefit from dual-chamber discrimination, while the recent Reduction and Prevention of Tachyarrhythmias and Shocks Using Reduced Ventricular Pacing with Atrial Algorithms (RAPTURE) trial of primary prevention patients programmed to a fast detection rate (4182 bpm) and long detection duration (30/40 intervals) did not [103,138,139]. Inappropriate therapy for SVT occurred in only 2% of the patients in each group.…”

“…Atrial lead-related complications were 1.3%, therapy was delivered from 170 bpm (VT) and 200 bpm (VF), and no difference in ventricular pacing percentage was noted [141]. Dual-chamber algorithms probably reduce the risk of underdetection compared with single-chamber algorithms because more than 80% of VTs with a ventricular rate greater than the atrial rate undergo no further analysis [103,124,125]. However, the rate of clinically significant underdetection with modern programming is so low that this difference is rarely of clinical significance.…”

Future Research Prioritization: Implantable Cardioverter-Defibrillator Therapy in Older Patients

“…While several studies have compared outcomes between single-chamber and dual-chamber ICDs, these investigations had major limitations, yielded conflicting results, and predated the evidence on optimal programming of ICDs. [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] Today's health care providers and patients, therefore, often struggle in making the critical decision of what device type to choose, and professional societies and policymakers are incapable of developing evidence-based recommendations and coverage decisions. 8,33 These issues are further compounded by the advent of subcutaneous ICDs, whose outcomes, especially in the elderly, are uncertain.…”