David L. Perschbacher

Arrhythmia rate distribution and tachyarrhythmia therapy in an ICD population: Results from the INTRINSIC RV trial

BACKGROUND Appropriate implantable cardioverter-defibrillator (ICD) therapy for ventricular tachycardia (VT) or ventricular fibrillation (VF) depends, in part, on the programming of tachycardia zones. OBJECTIVE We assessed events treated with ICD shocks or antitachycardia pacing (ATP) in the Inhibition of Unnecessary RV Pacing with AV Search Hysteresis in ICDs (INTRINSIC RV) trial. METHODS ATP and shock episodes from 1530 patients with dual-chamber ICDs were analyzed. RESULTS For episodes in which electrograms were stored and adjudicated, ATP was delivered for 763 episodes (182 patients), shock-only was delivered for 300 episodes (146 patients), and shock following ATP was delivered for 81 episodes (56 patients). ATP was delivered appropriately for 507 episodes (130 patients), with 93% success, and inappropriately for 256 episodes (89 patients). For ATP episodes, appropriate (VT: 170 ± 28 bpm) and inappropriate (not VT: 165 ± 21 bpm) rates did not differ (P = .16). When the initial therapy was shock, onset rates were higher for appropriate therapy than for inappropriate therapy (224 ± 46 bpm vs 187 ± 31 bpm; P <.001). Inappropriate ATP was more likely to be followed by a shock (odds ratio 2.49; 95% confidence interval 1.56-3.97; P <.001). Fifty-eight percent (225 of 381) of shocked episodes had rates <200 bpm. For episodes between 200 and 250 bpm, 20% (23 of 113) were polymorphic VT or VF, 59% were monomorphic VT, 19% were supraventricular, and <1% was artifact. For episodes >250 bpm, 37% were VF, 28% polymorphic VT, 23% monomorphic VT, 7% supraventricular, and 5% artifact. CONCLUSIONS In a general ICD population, ATP treated VT effectively or obviated the need for shock. Most ventricular arrhythmias <250 bpm were not VF. Proper zone programming may identify and treat VT without shock.

Survival After Rate-Responsive Programming in Patients With Cardiac Resynchronization Therapy-Defibrillator Implants Is Associated With a Novel Parameter: The Heart Rate Score.

Background— Rate-responsive pacing (DDDR) versus nonrate-responsive pacing (DDD) has shown no survival benefit for patients undergoing cardiac resynchronization therapy defibrillator (CRT-D) implants. The heart rate score (HRSc), an indicator of heart rate variation, may predict survival. We hypothesized that high-risk HRSc CRT-D patients will have improved survival with DDDR versus DDD alone. Methods and Results— All CRT-D patients in LATITUDE remote monitoring (2006–2011), programmed DDD, had HRSc calculated at first data upload after implant (median 1.4 months). Patients subsequently reprogrammed to DDDR 7.6 median months later were compared with a propensity-matched DDD group and followed for 21.4 median months by remote monitoring. Data were adjusted for age, sex, lower rate limit, percent atrial pacing, percent biventricular pacing, and implant year. The social security death index was used to identify deaths. Remote monitoring provided programming and histogram data. DDDR programming in CRT-D patients was associated with improved survival (adjusted hazard ratio =0.77; P<0.001). However, only those with baseline HRSc ≥70% (2308/6164) had improved HRSc with DDDR (from 88±9% to 78±15%; P<0.001) and improved survival (hazard ratio =0.74; P<0.001). Patients with a high baseline HRSc and significant improvement over time were more likely to survive (hazard ratio =0.63; P=0.006). For patients with HRSc <70%, DDDR reprogramming increased the HRSc from 46±11% to 50±15% (P<0.001); survival did not change. The HRSc did not change with DDD pacing over time. Conclusions— In CRT-D patients with HRSc ≥70%, DDDR reprogramming improved the HRSc and was associated with survival. Patients with lower HRSc had no change in survival with DDDR programming.

A Device Histogram-Based Simple Predictor of Mortality Risk in ICD and CRT-D Patients: The Heart Rate Score: DEVICE HISTOGRAM PREDICTOR OF MORTALITY

We hypothesized that survival in implantable cardioverter defibrillator (ICD) and cardiac resynchronization therapy defibrillator (CRT‐D) patients is predicted by baseline Heart Rate Score.

Addition of minute ventilation to rate-response pacing improves heart rate score more than accelerometer alone

BACKGROUND Heart rate score (HRSc) ≥70%, a novel parameter, predicts risk of mortality in patients with implantable cardioverter-defibrillators and identifies patients who have survival benefit with DDDR vs DDD pacing. OBJECTIVE The purpose of this study was to determine if DDDR pacing lowers HRSc, and a blended sensor with minute ventilation (MV) and accelerometer (XL) improves HRSc more than accelerometer (XL) alone in patients requiring pacemakers (PMs). METHODS HRSc, the percentage of all beats in the tallest 10-beat/min device histogram bin, was calculated. Data from the Limiting Chronotropic Incompetence for Pacemaker Recipients Study, a prospective randomized trial of PM patients, comparing XL to blended-sensor (XL + MV) rate-responsive pacing, were analyzed retrospectively for HRSc changes from baseline. The relationship of patient activity (sensor-detected from device memory) to HRSc was examined. RESULTS Of the 501 randomized patients, 215 (43%) patients had HRSc ≥70% during DDD pacing at baseline. In these patients, HRSc decreased after DDDR programming by 14.2%, while it increased by 0.4% in those with baseline HRSc <70% (n = 286) (HRSc ≥70% vs HRSc <70%; P < .01). No differences were detected between the 2 randomized sensor-based groups at baseline. Blended-sensor (MV + XL) programming reduced HRSc more than the XL sensor alone (MV + XL: 18% vs XL: 10%; P < .001). No correlation was observed between patient activity and HRSc (correlation = -0.14; P = .07). CONCLUSION HRSc improved (reduced) with rate-response (DDDR) programming in PM patients with high HRSc during DDD pacing. Blended sensors (MV + XL) improved HRSc more than XL alone. HRSc does not correlate with patient activity levels, suggesting that other patient factors determine this parameter. This programming approach needs to be investigated prospectively in a PM outcomes trial.