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Keywords:

  • implantable cardioverter defibrillator;
  • antitachycardia pacing;
  • ventricular tachycardia;
  • ventricular fibrillation;
  • sudden cardiac death;
  • shock reduction;
  • PROVIDE study

ICD Programming for Shock Reduction

  1. Top of page
  2. ICD Programming for Shock Reduction
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Limitations
  8. Conclusion
  9. References
  10. Supporting Information

Background

Shock therapy delivery by implantable cardioverter-defibrillators (ICD) can be painful and may have adverse consequences. Reducing shock burden for patients with ICDs would be beneficial.

Methods

PROVIDE was a prospective, randomized study of primary prevention ICD patients. Patients in the experimental group received a combination of programmed parameters with higher detection rates, longer detection intervals, empiric antitachycardia pacing (ATP), and optimized supraventricular tachycardia (SVT) discriminators, while those in the control group were programmed with conventional parameters. Shock therapy and arrhythmic syncope were compared.

Results

Of 1,670 patients enrolled (846 in the experimental group, 824 in the control group) and monitored over a follow-up of 530 ± 241 days, 202 patients received shock therapy for any cause (82 in the experimental group and 120 in the control group). The median time to first shock was significantly prolonged (13.1 vs 7.8 months, hazard ratio [HR]: 0.62, 95% confidence interval [CI]: 0.47 to 0.82, P = 0.0005) and the 2-year shock rate significantly reduced (12.4% vs 19.4%, P < 0.001) in the experimental group compared to the control group. There was no increase in arrhythmic syncope (HR: 1.64, 95% CI: 0.69 to 3.90, P = 0.26), while the overall mortality was reduced (HR: 0.7, 95% CI: 0.50 to 0.98, P = 0.036) in the experimental group compared to the control group.

Conclusion

A combination of programmed parameters utilizing higher detection rate, longer detection intervals, empiric ATP, and optimized SVT discriminators reduced ICD therapies without increasing arrhythmic syncope and was associated with reduction in all-cause mortality among ICD patients.


Introduction

  1. Top of page
  2. ICD Programming for Shock Reduction
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Limitations
  8. Conclusion
  9. References
  10. Supporting Information

Implantable cardioverter-defibrillators (ICD) improve survival in patients with reduced left ventricular systolic function by terminating life-threatening ventricular arrhythmias.[1-4] Although effective at treating ventricular tachycardia (VT) and ventricular fibrillation (VF), shock therapy can be painful, and repetitive shocks have the potential to impact quality of life and decrease overall survival.[5-7] As a result, a variety of programming strategies aimed at reducing unnecessary shocks and thereby reducing overall shock burden have been proposed.[8-12] These approaches, selected from a large array of possible programmable parameters, are designed not only to reduce inappropriate shocks, but also to avoid shocks for nonsustained ventricular arrhythmias.

The Programming Implantable Cardioverter Defibrillators in Patients with Primary Prevention Indication to Prolong Time to First Shock (PROVIDE) study was designed to test the hypothesis that a combination of higher detection rates,[9, 10, 12] prolonged detection intervals,[10, 12] optimized SVT discriminators,[13-15] and empiric ATP therapy[8, 11] compared to conventional parameters will prolong time to first shock without increasing incidence of arrhythmia-related syncope in patients receiving an ICD for primary prevention of sudden cardiac death.

Methods

  1. Top of page
  2. ICD Programming for Shock Reduction
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Limitations
  8. Conclusion
  9. References
  10. Supporting Information

Study Design

PROVIDE was a prospective, randomized, multicenter study that enrolled patients who met primary prevention criteria for ICD or cardiac resynchronization therapy defibrillator (CRT-D) implantation[15] and were implanted with a St. Jude Medical ICD/CRT-D (Current™, Promote™, Unify™, and Fortify™). The complete study design, including randomization, data collection, and device programming has been published earlier and readers are referred to it for details.[16]

The primary exclusion criteria included (1) history of spontaneous sustained VT or VF prior to the implant, (2) inducible sustained VT at a rate below 181 bpm during an electrophysiology test, or (3) presence of ICD or CRT-D device prior to the currently implanted device. Patients were enrolled within 30 days of device implantation. All patients provided informed consent, and the institutional review committee of each participating center approved the study.

Randomization and Data Collection

Randomization was assigned in a 1:1 ratio between the control and experimental arm at the enrollment visit and was stratified according to cardiac disease classification (i.e., ischemic or nonischemic etiology) and implanted device type (i.e., single chamber, dual chamber, or CRT-D). Tachycardia detection and treatment parameters were programmed according to the patient's assigned randomization as outlined in the Device Programming section. Programmable parameters not specified in the protocol were left to the individual investigator's discretion.

Follow-up visits were conducted in-clinic or remotely at 3 months, 6 months, 9 months, 12 months, and every 3 months thereafter until study closure. A minimum of 1 in-clinic follow-up per year was required. During in-clinic and remote follow-up visits, device data, including stored electrograms and episode diagnostics, were collected. Information about syncopal episodes, hospitalization, death, and device-related adverse events was collected by direct patient interview by a health care provider at each in-clinic visit and after each remote follow-up. Based on history of events surrounding a syncopal event, and intracardiac electrograms corresponding to the event, each syncopal episode was classified into arrhythmic or nonarrhythmic by the Data and Safety Monitoring Board.

Device Programming

Control group

All patients randomized to the control group were programmed to similar detection criteria and therapy zones as those programmed in the PROVE study[11] and reflect the empiric programming of a primary prevention patient. Specifically, a monitor only zone was programmed for rates between 150 and 180 bpm. A VT therapy zone was set between 180 bpm and 214 bpm, with 2 rounds of ATP followed by high-output defibrillation shocks. SVT discriminators at nominal values were activated for the VT therapy zone. A VF zone was set for all rates above 214 bpm, where all therapies were maximum-output shocks. For both the VT and VF zones, a total of 12 beats were required for detection and delivery of therapy (Fig. 1).

image

Figure 1. Overview of programmed therapy. Device programming including the therapy zones and respective rate cut-offs. Each zone lists the therapy available (e.g., monitor, ATP, or shocks), the use of SVT discriminators and the number of beats to detection. VT = ventricular tachycardia; VF = ventricular fibrillation; ATP = anti-tachycardia pacing; and SVT = supraventricular tachycardia.

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Experimental group

In the experimental group patients, 2 VT zones were programmed: a slow VT zone from 180 to 214 bpm, where 2 rounds of ATP were attempted prior to high-output shocks, and a fast VT zone from 214 to 250 bpm, where 1 round of ATP was attempted prior to high-output shocks. The slow VT zone required 25 beats for detection and had aggressive SVT discriminator settings.[13, 14] The fast VT zone required 18 beats for detection and did not employ SVT discriminators. A VF therapy zone was programmed for all rates above 250 bpm, where 12 beats were required for detection and all therapies were maximum-output shocks (Fig. 1).

Data Analysis

The primary analyses were conducted according to the principles of intent-to-treat. The primary endpoint was all-cause time to first shock and was compared between control and experimental groups using a log-rank test. Occurrence of first shock, occurrence of any shock and occurrence of all shocks were also compared between 2 groups using continuity adjusted chi-square test. The mean numbers of episodes between the 2 groups were compared using negative binominal models. Shock rates at 1 year and 2 years were calculated using the Kaplan–Meier method. Episodes resulting in ATP or shock therapy were classified into appropriate or inappropriate based on determination of underlying arrhythmia by an adjudication committee. Therapy was deemed appropriate if VT or VF was the cause of ATP or shock. Any other reason for therapy in the absence of VT or VF was considered inappropriate. Inappropriate therapies were further classified into arrhythmic (atrial tachycardia, atrial fibrillation, atrial flutter, supraventricular tachycardia, or sinus tachycardia) or nonarrhythmic (oversensing, device-related, or lead issues).

The main safety endpoint was freedom from arrhythmic syncopal events. All episodes of syncope were evaluated for correlation to arrhythmias based on device diagnostics. Other safety endpoints included device related adverse events, hospitalizations, and deaths. Freedom from arrhythmic syncopal events, device-related adverse events, hospitalizations and mortality were compared between the control and experimental groups using a log-rank test. The Cox proportional-hazards regression model was used to compare the risk of first shock, syncope, and all-cause mortality among the 2 groups.

Demographic continuous variables are reported by mean, standard deviation, and range, and categorical variables are reported by count and percentage. Demographic variables were compared between the 2 groups. Continuous variables were compared using a 2-sample t-test if normally distributed and using the Wilcoxon rank sum test if not normally distributed. Categorical variables were compared using a Pearson chi-square test. Statistical tests with probability values less than 0.05 were considered statistically significant.

Sample Size

The sample size was calculated to achieve an 80% power to detect a 30% increase in the time to first shock at the 5% significance level.[17] Assuming a patient accrual period of 2 years and a follow-up time of 1 year, the total number of patients required to achieve 226 first shocks was 1400. Assuming an overall attrition of approximately 15%, the total number of patients required to be enrolled was 1600 patients (800 per group).

Data and Safety Monitoring Board

A Data and Safety Monitoring Board (DSMB) was formed, comprising 2 cardiac electrophysiologists and 1 statistician who were independent of the study and the study sponsor. The DSMB met quarterly in order to evaluate adverse events related to the protocol. The DSMB reviewed syncopal episodes to classify the episodes as arrhythmic or nonarrhythmic by reviewing patient records, device electrograms, and episode logs for each episode. The DSMB periodically reviewed the available data and provided recommendations regarding continuing the trial based on the safety and efficacy data.

Adjudication Committee

The adjudication committee consisted of 3 cardiac electrophysiologists. Stored electrograms from individual patient's devices were downloaded at each follow-up visit and remote interrogation. Episodes which resulted in delivery of ATP or shock therapy were de-identified and reviewed independently by 2 cardiac electrophysiologist members of the adjudication committee. When both reviewers agreed on the diagnosis, the episode was not reviewed further. Upon a disagreement, a third cardiac electrophysiologist reviewed and classified the episode.

Results

  1. Top of page
  2. ICD Programming for Shock Reduction
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Limitations
  8. Conclusion
  9. References
  10. Supporting Information

Study Population

A total of 1,670 patients were enrolled and randomized at 97 centers in the United States between November 2008 and September 2010. All patient demographic variables (Table 1) were similar between the experimental and control groups except for the history of unstable angina (P = 0.04). The age of the patients was 64 ± 13 years with a left ventricular ejection fraction of 27 ± 9%. All patients received an ICD for a primary prevention indication with 59.5% receiving single-chamber or dual-chamber devices and 40.5% receiving CRT-D devices. The patients randomized to the control group were followed for a mean of 515 ± 240 days (2–1,005) versus a mean of 545 ± 242 days (1–1,019) in the experimental group (P = 0.01).

Table 1. Baseline Demographic and Clinical Characteristics
 Control (N = 824)Experiment (N = 846)P Value
  1. SD = standard deviation; NYHA = New York Heart Association; LVEF = left ventricular ejection fraction; MI = myocardial infarction; CABG = coronary artery bypass grafting; COPD = chronic obstructive pulmonary disease; ARB = angiotensin receptor blocker.

Age, years, mean ± SD64 ± 1264 ± 13ns
Gender, n599 (73%)620 (73%)ns
NYHA class, n   
I33 (4%)46 (5%)ns
II264 (32%)256 (30%) 
III381 (46%)401 (48%) 
IV8 (1%)18 (2%) 
Unknown138 (17%)125 (15%) 
LVEF,%, mean ± SD27 ± 927 ± 10ns
QRS duration, milliseconds, mean ± SD123 ± 31124 ± 33ns
Cardiomyopathy, n   
Ischemic510 (62%)530 (63%)ns
Nonischemic314 (38%)316 (37%) 
Cardiac history, n   
Prior MI412 (50%)412 (48%)ns
Unstable angina76 (9%)104 (12%)0.05
CABG258 (31%)261 (31%)ns
PTCA/stents/atherectomy313 (38%)326 (39%)ns
Other medical conditions, n   
Diabetes300 (36%)300 (36%)ns
COPD115 (14%)105 (12%)ns
Hyperlipidemia497 (60%)508 (60%)ns
Hypertension607 (74%)606 (72%)ns
Peripheral vascular disease80 (10%)70 (8%)ns
Renal disease105 (13%)86 (10%)ns
Valvular disease115 (14%)112 (13%)ns
Cardiac medications, n   
Beta blocker734 (89%)748 (88%)ns
ACE inhibitor504 (61%)511 (60%)ns
ARB148 (18%)157 (19%)ns
Antiarrhythmic, class I10 (1%)9 (1%)ns
Antiarrhythmic, class III73 (9%)82 (10%)ns
Anticoagulant227 (28%)264 (31%)ns
Antiplatelet564 (68%)561 (66%)ns
Arrhythmia history, n   
Atrial fibrillation210 (25%)233 (28%)ns
Atrial flutter27 (3%)29 (3%)ns
Sinus tachycardia25 (3%)29 (3%)ns
Atrial tachycardia5 (0.6%)8 (0.9%)ns

Of the 1,670 patients enrolled in the study, 1,668 patients (99.9%) were programmed according to protocol at the time of enrollment. Of the 202 patients receiving at least 1 shock, 173 (86%) were programmed according to the protocol at the time of the first shock (83% for the control group versus 90% for the experimental group, P = 0.12).

Shock Therapy

At the end of the study follow-up, a total of 202 patients had received shock therapy for any cause (82 in the experimental group and 120 in the control group). The median time to first shock was significantly longer in the experimental group (13.1 months) than it was in the control group (7.8 months; hazard ratio [HR]: 0.62, 95% confidence interval [CI]: 0.47 to 0.82, P = 0.0005), as illustrated in Figure 2. After adjusting for gender, age, previous AF and cardiomyopathy (ischemic) effects, the hazard ratio was 0.59 (95% CI: 0.45 to 0.78). The proportions of patients receiving ≥1 shock after 1 year and 2 years were significantly reduced in the experimental group (7.23% and 12.23%) compared to the control group (12.23% and 18.25%, P < 0.001 and P < 0.001).

image

Figure 2. First shock by treatment group.

Kaplan–Meier curves depicting the percentage of patients in each treatment group receiving first shock during follow-up.

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Adverse Events

A total of 22 patients experienced 24 arrhythmic syncopal events. There were 10 arrhythmic syncopal events among 8 patients in the control group and 14 events among 14 patients in the experimental group. One patient in the control group had 3 arrhythmic syncopal events. The freedom from arrhythmic syncopal events was not significantly different between 2 groups (HR: 1.64, 95% CI: 0.69 to 3.90, P = 0.26). The arrhythmic syncopal event rate was not significantly different between the experimental and control groups (control: 0.012 events/patient vs treatment: 0.017 events/patient, P = 0.49) (Table 2). A total of 65 patients experienced 68 all-cause syncopal events (31 in the control group and 37 in the experimental group). The freedom from all-cause syncopal events was not significantly different between the 2 groups (HR: 1.25, 95% CI: 0.76 to 2.04, P = 0.37).

Table 2. Adverse Events in the PROVIDE Study Patients
 Control (N = 824)Experiment (N = 846)P Value
  1. Device-related adverse events include: bleeding/hematoma, elevated pacing thresholds, infection, lead dislodgement, lead damage, loss of capture, loss of sensing, oversensing, pacemaker mediated tachycardia, extracardiac stimulation, and undersensing.

  2. a

    P value was calculate from negative binominal regression model;

  3. b

    P value was calculated based on log-rank test.

Arrhythmic Syncope (n)10140.49a
Device-related Adverse Events (n)1711500.30a
Hospitalizations (n)2652690.93a
Total Deaths (n)78600.036b

Patients in both groups experienced similar rates of device related adverse events (control: 0.21 events/patient, vs treatment: 0.18 events/patient, P = 0.30) and hospitalizations (control: 0.32 events/patient vs treatment: 0.32 events/patient, P = 0.93), but the patients in the experimental group had fewer deaths than the control group (21% vs 26.8%; HR: 0.7, 95% CI: 0.50 to 0.98, P = 0.036) (Table 2). The cumulative probability of death over study duration according to treatment group is depicted in Figure 3.

image

Figure 3. Mortality by treatment group.

Kaplan–Meier curves depicting all-cause mortality in each treatment group during follow-up.

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Appropriate and Inappropriate Therapy

Appropriate shocks for ventricular arrhythmias accounted for 75 of the first shocks, and inappropriate shocks accounted for 127 of the first shocks. Most of the inappropriate shocks were due to atrial flutter, atrial tachycardia, or atrial fibrillation (n = 105, 82.7%). Figure 4 displays the occurrence of appropriate and inappropriate shocks among the 2 groups based on the rate of underlying arrhythmia (details of arrhythmias resulting in inappropriate shocks are shown in online Fig. S1). There was considerable overlap between the ventricular rates of supraventricular and ventricular arrhythmias. The majority of inappropriate shocks in the control group occurred in the rates between 181 and 213 bpm. The time to first appropriate shock was not different between the 2 groups (HR: 1.10, 95% CI: 0.70 to 1.74, P = 0.68); however, the time to first inappropriate shock was markedly prolonged in the experimental group (HR: 0.44, 95% CI: 0.30 to 0.63, P < 0.0001), as shown in Figure 5. Also, first occurrence of inappropriate shocks, any occurrence of inappropriate shocks, and total occurrence of inappropriate shocks were significantly reduced in the experimental group compared to the control group, while for appropriate shocks these were not significantly different (any occurrence of inappropriate shocks denotes number of patients who received inappropriate shocks at any time during study period, while total occurrence of inappropriate shocks denotes all episodes of inappropriate shocks received by patients in each treatment arm).

image

Figure 4. Distribution of first shock based on rate of arrhythmia. First shock episodes in each treatment group are plotted based on the cycle length of initial arrhythmia. Each bar is shaded to depict proportion of appropriate and inappropriate shock therapy. The majority of shock reduction in the experimental group is achieved in VT-1 zone (181–213 bpm).

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image

Figure 5. First shock for appropriate and inappropriate therapies. Kaplan–Meier curves depicting the percentage of patients in each treatment group receiving first shock during follow-up based on initial arrhythmia. (A) Appropriate shock therapy for VT/VF. (B) Inappropriate shock therapy for reasons other than VT/VF, mostly AF/AT/AFL. VT = ventricular tachycardia; VF = ventricular fibrillation; AF = atrial fibrillation; AT = atrial tachycardia; AFL = atrial flutter.

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Overall, there were significantly fewer instances of ATP therapy delivery in the experimental group compared to the control group. This was true for all the situations in which ATP was delivered inappropriately. On the other hand, appropriate delivery of ATP therapy was significantly reduced in the experimental group only for first occurrence and any occurrence, but not for total occurrence. Table 3 summarizes the occurrence of appropriate and inappropriate ATP and shock therapies according to treatment group and type of therapy.

Table 3. Details of Delivered Therapy by Treatment Group
 ControlExperimentalP Value
  1. Patient percentage of the first occurrence of therapy and any occurrence of therapy were compared using the continuity adjusted chi-square test. The mean numbers of episodes with occurrence of therapy were compared using negative binominal models. ATP = anti-tachycardia pacing.

  2. a

    P value was calculated based on chi-square test.

  3. b

    P value was calculate based on negative binominal regression model.

First Occurrence of Therapy-N Patients (%)
ATP216 (26.2%)89 (10.5%)<.0001a
Appropriate116 (14.1%)35 (4.1%)<.0001a
Inappropriate100 (12.1%)54 (6.4%)<.0001a
Shock120 (14.6%)82 (9.7%)0.0029a
Appropriate34 (4.1%)41 (4.8%)0.5537a
Inappropriate86 (10.4%)41 (4.8%)<.0001a
Any Occurrence of Therapy-N Patients (%)
ATP255 (30.9%)101 (11.9%)<.0001
Appropriate136 (16.5%)44 (5.2%)<.0001a
Inappropriate119 (14.4%)57 (6.7%)<.0001a
Shock132 (16%)91 (10.7%)0.0029a
Appropriate42 (5.1%)46 (5.4%)0.8402a
Inappropriate90 (10.9%)45 (5.3%)<.0001a
Total Occurrence of Therapy-N Episodes
ATP9765270.0004b
Appropriate3983060.2124b
Inappropriate578221<.0001b
Shock3361940.0029b
Appropriate135960.2234b
Inappropriate201980.0011b

Device Type

As intended by the study design, the proportion of single-chamber, dual-chamber, and CRT-D devices implanted were similar between the control and experimental groups (P = 0.97). There was no difference in shock rate between single-chamber versus dual-chamber/CRT-D devices in the control group. Patients with dual-chamber and CRT-D devices were less likely to get a first shock in the experimental group compared to the control group (HR: 0.56, 95% CI: 0.40 to 0.79, P < 0.001), while patients with single-chamber devices had no statistical difference in the rate of receiving a first shock between the 2 groups (HR: 0.78, 95% CI: 0.46 to 1.32, P = 0.35). Stated differently, patients in the control group experienced similar rates of first shock irrespective of the device type (HR of dual chamber and CRT-D devices vs single chamber: 0.81, 95% CI: 0.54 to 1.23, P = 0.33), while the programming parameters in the experimental group resulted in a favorable reduction in first shock among patients with dual-chamber and CRT-D devices but not in patients with single-chamber devices (HR of dual chamber and CRT-D devices vs single chamber: 0.57, 95% CI: 0.36 to 0.91, P = 0.017).

Discussion

  1. Top of page
  2. ICD Programming for Shock Reduction
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Limitations
  8. Conclusion
  9. References
  10. Supporting Information

The PROVIDE trial results show that by utilizing a combination of specific programming parameters, ICD therapies can be significantly reduced without compromising the effectiveness of the ICD therapy in patients with an ICD implanted for primary prevention of sudden cardiac death. Moreover, the decrease in ICD therapies was associated with a 30% relative reduction in all-cause mortality.

There is some evidence that reducing ICD therapies may improve survival among patients with an ICD. In the MADIT-RIT (Multicenter Automatic Defibrillator Implantation Trial-Reduce Inappropriate Therapy) trial, the high-rate group experienced a reduction in inappropriate ICD therapies and a decrease in mortality.[12] In the PROVIDE trial, we also observed a similar reduction in ICD therapies and improved survival among patients randomized to the experimental group. Even though the mechanism and causation of this effect remains unclear,[18] our results add to the growing body of evidence showing that avoiding inappropriate ATP and shocks can favorably affect the outcome of ICD recipients.

A marked decrease in inappropriate shocks contributed to the overall reduction in ICD shock therapy in the experimental group. The majority of inappropriate shocks were due to SVTs, mainly atrial fibrillation and atrial tachycardia. Shocks due to T-wave oversensing, device malfunction, and lead issues constituted a very small percentage of the total inappropriate shocks. Overall, the appropriate shock rate was low and not significantly different between the 2 groups. This is similar to results of MADIT-RIT in which the high-rate and delayed-therapy groups showed a significant reduction only in inappropriate shock rate, while the appropriate shock rate was not statistically different as compared to the conventional programming group.[12]

Even though the trial was not designed to reduce ATP therapy, we found a significant reduction in both appropriate and inappropriate ATP therapy in the experimental group compared to the control group. This was likely related to the programming of higher detection rates and longer detection intervals in the experimental group. Although empiric ATP therapy is highly effective in terminating VT, it carries a small risk of accelerating VT,[11] inducing SVT or converting SVT to VT.[19, 20] Therefore, an overall reduction in both appropriate and inappropriate ATP therapy may be desirable. Based on our data we cannot rule out the possibility that excessive ATP therapy might have contributed to some of the increase in adverse events seen in the control group.

There is a tradeoff between avoidance of ICD therapies and risk of arrhythmic syncope. In the PROVIDE trial, the arrhythmic syncope was not significantly different between the 2 groups and was relatively rare, occurring in 1.7% of the experiment group patients over a 2-year follow-up period.  In comparison, in the PREPARE (Primary Prevention Parameters Evaluation) trial, arrhythmic syncope occurred in 1.6% of the patients in the preselected programming group but over only a 1-year follow-up period.[10] In addition, PREPARE reported 1 patient death due to prolonged ventricular arrhythmia. This could be explained by the fact that the ICD programming in the PREPARE trial used a relatively high number of beats for detection (30/40 beats in FVT/ VF zone). In contrast, the PROVIDE trial utilized a tiered strategy for the beats to detection (25 beats for slow VT zone, 18 beats for fast VT zone, and 12 beats for VF zone) in order to reduce the risk of arrhythmic syncope.  This may have resulted in a favorable reduction in arrhythmic syncope seen in our study as compared to the PREPARE trial.

It is interesting to speculate as to which of the individual programming parameters contributed most to the shock reduction in the experimental group. The largest percentage reduction in shocks in the experimental group occurred in the slow VT zone (between 181 bpm and 214 bpm), while the benefit in the fast VT zone (between 215 bpm and 249 bpm) and the VF zone (above 250 bpm) was relatively low. Also, patients with dual-chamber and CRT-D devices received fewer therapies than patients with single-chamber devices. This suggests that optimized SVT discriminators, which are more robust in dual-chamber devices and were only applied in the slow VT zone, as opposed to empiric ATP and longer detection intervals, which were applied in all the zones, may have contributed more to the overall reduction of shocks. In higher rate zones, ATP becomes less effective and arrhythmias tend to be more sustained, which could explain the reduction in benefit of experimental programming at higher rates.

Limitations

  1. Top of page
  2. ICD Programming for Shock Reduction
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Limitations
  8. Conclusion
  9. References
  10. Supporting Information

Differential effect of programming changes observed in single-chamber versus dual-chamber/CRT-D devices may be related to SVT discriminator algorithms in SJM devices and may not be applicable to all manufacturers.[21]

Conclusion

  1. Top of page
  2. ICD Programming for Shock Reduction
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Limitations
  8. Conclusion
  9. References
  10. Supporting Information

In this randomized study, a strategy utilizing a combination of programming parameters with higher detection rates, longer detection intervals, empiric ATP, and optimized SVT discriminators resulted in lower ICD therapies, and was associated with improved survival without any increase in arrhythmic syncope among patients with ICD.

References

  1. Top of page
  2. ICD Programming for Shock Reduction
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Limitations
  8. Conclusion
  9. References
  10. Supporting Information
  • 1
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  • 2
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  • 4
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  • 5
    Schron EB, Exner DV, Yao Q, Jenkins LS, Steinberg JS, Cook JR, Kutalek SP, Friedman PL, Bubien RS, Page RL, Powell J: Quality of life in the antiarrhythmics versus implantable defibrillators trial. Impact of therapy and influence of adverse symptoms and defibrillator shocks. Circulation 2002;105:589-594.
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    Irvine J, Dorian P, Baker B, O'Brien BJ, Roberts R, Gent M, Newman D, Connolly SJ: Quality of life in the canadian implantable defibrillator study (CIDS). Am Heart J 2002;144:282-289.
  • 7
    Carrol D L, Hamilton GA: Quality of life in implanted cardioverter defibrillator recipients: The impact of a device shock. Heart Lung 2005;34,:169-178.
  • 8
    Wathen MS, DeGroot PJ, Sweeney MO, Stark AJ, Otterness MF, Adkisson WO, Canby RC, Khalighi K, Machado C, Rubenstein DS, Volosin KJ: Prospective randomized multicenter trial of empirical antitachycardia pacing versus shocks for spontaneous rapid ventricular tachycardia in patients with implantable cardioverter-defibrillators: Pacing Fast Ventricular Tachycardia Reduces Shock Therapies (PainFREE Rx II) trial results. Circulation 2004;110:2591-2596.
  • 9
    Wilkoff BL, Ousdigian KT, Sterns LD, Wang ZJ, Wilson RD, Morgan JM: A comparison of empiric to physician-tailored programming of implantable cardioverter-defibrillators: Results from the prospective randomized multicenter EMPIRIC trial. J Am Coll Cardiol 2006;48:330-339.
  • 10
    Wilkoff BL, Williamson BD, Stern RS, Moore SL, Lu F, Lee SW, Birgersdotter-Gre UM, Wathen MS, Van Gelder IC, Heubner BM, Brown ML, Holloman KK: Strategic programming of detection and therapy parameters in implantable cardioverter-defibrillators reduces shocks in primary prevention patients: Results from the PREPARE (Primary Prevention Parameters Evaluation) study. J Am Coll Cardiol 2008;52:541-550.
  • 11
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Supporting Information

  1. Top of page
  2. ICD Programming for Shock Reduction
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Limitations
  8. Conclusion
  9. References
  10. Supporting Information

Disclaimer: Supplementary materials have been peer-reviewed but not copyedited.

FilenameFormatSizeDescription
jce12273-sup-0001-suppmat.tif1649KFigure S1. First shock episodes in each treatment group are plotted based on the cycle length of initial arrhythmia. Each bar is color coded to represent proportion of supraventricular and ventricular arrhythmias within that particular therapy zone.

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