Longer ICD Detection Window Reduces Inappropriate Shocks

BOSTON – Tweaking implantable cardioverter defibrillator settings to lengthen the detection window is safe and significantly reduces inappropriate antitachycardia pacing and shocks, an investigator said at the annual meeting of the Heart Rhythm Society.

Patients with ICDs programmed with a number of intervals to detect (NID) of 30/40 beats had a 37% reduction in ventricular therapies (antitachycardia pacing and shocks), compared with patients with ICDs programmed with an NID of 18/24 beats, with no significant differences in syncope or deaths between the groups, reported Dr. Maurizio Gasparini of Istituto Clinico Humanitas IRCCS, Milan.

"This strategy is demonstrated to be safe and effective in reducing unnecessary ICD therapy, and increasing consequently the quality of life of these patients," Dr. Gasparini said on behalf of coinvestigators in the randomized ADVANCE III (Avoid Delivering Therapies for Nonsustained Arrhythmias in ICD Patients III) trial.

In a previous trial, Dr. Gasparini and colleagues showed that 66% of ventricular fibrillation (VF) episodes, and 91% of fast ventricular tachycardia (FVT) episodes terminated spontaneously within 30 beats (Eur. Heart. J. 2009;30:2758-67), yet two major ICD manufacturers still have nominal (in-the-box) settings of only 2-3 seconds for a VF detection window, potentially leading to unpleasant and unnecessary shocks, he said.

The ADVANCE III investigators enrolled 1,902 patients from 94 centers with single-chamber, dual-chamber, or cardiac resynchronization therapy-defibrillator (CRT-D) ICDs. In all, 891 of those assigned to NID 18/24 programming with antitachycardia pacing (ATP) during charging and 876 patients assigned to NID 30/40 with ATP had available clinical data for the primary end point: a 20% or greater reduction in ATP and shocks for spontaneous arrhythmia with a cycle length of 320 ms or less.

The patients were predominantly male (84% in each arm) with a mean age of 65. Nearly half of patients in each group had New York Heart Association class III or IV heart failure, and 60% had coronary artery disease. The mean left ventricular ejection fraction in each group was 30%.

The devices were implanted for primary prevention in about 75% of patients in each arm. About 40% had CRT-Ds, 31% had dual-chamber devices, and 29% had single-chamber ICDs.

At a median follow-up of 12 months in an intention-to-treat analysis, 97 patients assigned to NID 30/40 had experienced 346 therapies (ATP or shock deliveries), compared with 149 patients and 557 therapies in those assigned to NID 18/24 (incidence rate ratio [IRR] 0.63, P less than .001), meeting the primary end point.

A Kaplan-Meier analysis also showed that the longer detection window was significantly better at keeping patients therapy free over 12 months.

There were no significant differences in syncopal events, which occurred in 1.5% of patients in the 30/40 group, compared with 0.8% in the 18/24 group, or in deaths, which occurred in 5.1% of patients randomized to the 30/40 strategy, and 5.9% of those assigned to 18/24.

The results suggest that "in many cases the nominal ICD settings are probably too conservative," Dr. Gasparini said.

Session comoderator Dr. Christine M. Albert, director of the center for arrhythmia prevention at Brigham and Women’s Hospital in Boston, challenged the safety findings, noting that the incidence of syncope in both treatment arms was extremely low.

Dr. Gasparini agreed, but noted that in each arm of the study population, about 20% of participants had experienced one or more syncopal episodes prior to device implantation.

"This was a population that theoretically may have a high incidence of syncope; nonetheless, we did not observe very high incidence of it," he said.

The study was supported by Medtronic. Dr. Gasparini reported having no conflicts of interest. Two of the study coauthors are Medtronic employees. Dr. Albert has previously received research support from St. Jude Medical and was a consultant to Novartis.

BOSTON – Tweaking implantable cardioverter defibrillator settings to lengthen the detection window is safe and significantly reduces inappropriate antitachycardia pacing and shocks, an investigator said at the annual meeting of the Heart Rhythm Society.

Patients with ICDs programmed with a number of intervals to detect (NID) of 30/40 beats had a 37% reduction in ventricular therapies (antitachycardia pacing and shocks), compared with patients with ICDs programmed with an NID of 18/24 beats, with no significant differences in syncope or deaths between the groups, reported Dr. Maurizio Gasparini of Istituto Clinico Humanitas IRCCS, Milan.

"This strategy is demonstrated to be safe and effective in reducing unnecessary ICD therapy, and increasing consequently the quality of life of these patients," Dr. Gasparini said on behalf of coinvestigators in the randomized ADVANCE III (Avoid Delivering Therapies for Nonsustained Arrhythmias in ICD Patients III) trial.

In a previous trial, Dr. Gasparini and colleagues showed that 66% of ventricular fibrillation (VF) episodes, and 91% of fast ventricular tachycardia (FVT) episodes terminated spontaneously within 30 beats (Eur. Heart. J. 2009;30:2758-67), yet two major ICD manufacturers still have nominal (in-the-box) settings of only 2-3 seconds for a VF detection window, potentially leading to unpleasant and unnecessary shocks, he said.

The ADVANCE III investigators enrolled 1,902 patients from 94 centers with single-chamber, dual-chamber, or cardiac resynchronization therapy-defibrillator (CRT-D) ICDs. In all, 891 of those assigned to NID 18/24 programming with antitachycardia pacing (ATP) during charging and 876 patients assigned to NID 30/40 with ATP had available clinical data for the primary end point: a 20% or greater reduction in ATP and shocks for spontaneous arrhythmia with a cycle length of 320 ms or less.

The patients were predominantly male (84% in each arm) with a mean age of 65. Nearly half of patients in each group had New York Heart Association class III or IV heart failure, and 60% had coronary artery disease. The mean left ventricular ejection fraction in each group was 30%.

The devices were implanted for primary prevention in about 75% of patients in each arm. About 40% had CRT-Ds, 31% had dual-chamber devices, and 29% had single-chamber ICDs.

At a median follow-up of 12 months in an intention-to-treat analysis, 97 patients assigned to NID 30/40 had experienced 346 therapies (ATP or shock deliveries), compared with 149 patients and 557 therapies in those assigned to NID 18/24 (incidence rate ratio [IRR] 0.63, P less than .001), meeting the primary end point.

A Kaplan-Meier analysis also showed that the longer detection window was significantly better at keeping patients therapy free over 12 months.

There were no significant differences in syncopal events, which occurred in 1.5% of patients in the 30/40 group, compared with 0.8% in the 18/24 group, or in deaths, which occurred in 5.1% of patients randomized to the 30/40 strategy, and 5.9% of those assigned to 18/24.

The results suggest that "in many cases the nominal ICD settings are probably too conservative," Dr. Gasparini said.

Session comoderator Dr. Christine M. Albert, director of the center for arrhythmia prevention at Brigham and Women’s Hospital in Boston, challenged the safety findings, noting that the incidence of syncope in both treatment arms was extremely low.

Dr. Gasparini agreed, but noted that in each arm of the study population, about 20% of participants had experienced one or more syncopal episodes prior to device implantation.

"This was a population that theoretically may have a high incidence of syncope; nonetheless, we did not observe very high incidence of it," he said.

The study was supported by Medtronic. Dr. Gasparini reported having no conflicts of interest. Two of the study coauthors are Medtronic employees. Dr. Albert has previously received research support from St. Jude Medical and was a consultant to Novartis.

BOSTON – Tweaking implantable cardioverter defibrillator settings to lengthen the detection window is safe and significantly reduces inappropriate antitachycardia pacing and shocks, an investigator said at the annual meeting of the Heart Rhythm Society.

Patients with ICDs programmed with a number of intervals to detect (NID) of 30/40 beats had a 37% reduction in ventricular therapies (antitachycardia pacing and shocks), compared with patients with ICDs programmed with an NID of 18/24 beats, with no significant differences in syncope or deaths between the groups, reported Dr. Maurizio Gasparini of Istituto Clinico Humanitas IRCCS, Milan.

"This strategy is demonstrated to be safe and effective in reducing unnecessary ICD therapy, and increasing consequently the quality of life of these patients," Dr. Gasparini said on behalf of coinvestigators in the randomized ADVANCE III (Avoid Delivering Therapies for Nonsustained Arrhythmias in ICD Patients III) trial.

In a previous trial, Dr. Gasparini and colleagues showed that 66% of ventricular fibrillation (VF) episodes, and 91% of fast ventricular tachycardia (FVT) episodes terminated spontaneously within 30 beats (Eur. Heart. J. 2009;30:2758-67), yet two major ICD manufacturers still have nominal (in-the-box) settings of only 2-3 seconds for a VF detection window, potentially leading to unpleasant and unnecessary shocks, he said.

The ADVANCE III investigators enrolled 1,902 patients from 94 centers with single-chamber, dual-chamber, or cardiac resynchronization therapy-defibrillator (CRT-D) ICDs. In all, 891 of those assigned to NID 18/24 programming with antitachycardia pacing (ATP) during charging and 876 patients assigned to NID 30/40 with ATP had available clinical data for the primary end point: a 20% or greater reduction in ATP and shocks for spontaneous arrhythmia with a cycle length of 320 ms or less.

The patients were predominantly male (84% in each arm) with a mean age of 65. Nearly half of patients in each group had New York Heart Association class III or IV heart failure, and 60% had coronary artery disease. The mean left ventricular ejection fraction in each group was 30%.

The devices were implanted for primary prevention in about 75% of patients in each arm. About 40% had CRT-Ds, 31% had dual-chamber devices, and 29% had single-chamber ICDs.

At a median follow-up of 12 months in an intention-to-treat analysis, 97 patients assigned to NID 30/40 had experienced 346 therapies (ATP or shock deliveries), compared with 149 patients and 557 therapies in those assigned to NID 18/24 (incidence rate ratio [IRR] 0.63, P less than .001), meeting the primary end point.

A Kaplan-Meier analysis also showed that the longer detection window was significantly better at keeping patients therapy free over 12 months.

There were no significant differences in syncopal events, which occurred in 1.5% of patients in the 30/40 group, compared with 0.8% in the 18/24 group, or in deaths, which occurred in 5.1% of patients randomized to the 30/40 strategy, and 5.9% of those assigned to 18/24.

The results suggest that "in many cases the nominal ICD settings are probably too conservative," Dr. Gasparini said.

Session comoderator Dr. Christine M. Albert, director of the center for arrhythmia prevention at Brigham and Women’s Hospital in Boston, challenged the safety findings, noting that the incidence of syncope in both treatment arms was extremely low.

Dr. Gasparini agreed, but noted that in each arm of the study population, about 20% of participants had experienced one or more syncopal episodes prior to device implantation.

"This was a population that theoretically may have a high incidence of syncope; nonetheless, we did not observe very high incidence of it," he said.

The study was supported by Medtronic. Dr. Gasparini reported having no conflicts of interest. Two of the study coauthors are Medtronic employees. Dr. Albert has previously received research support from St. Jude Medical and was a consultant to Novartis.