Circ: Downloadable software reduces inappropriate ICD shocks by 50%
Software downloaded during a routine office visit cuts the risk of inappropriate shocks caused by lead fractures by almost 50 percent for patients with implantable cardioverter-defibrillators (ICDs) compared to conventional impedance monitoring, according to a study published in the Sept. 27 issue of Circulation.
“Downloadable software upgrades are common in consumer electronics but not in implantable medical devices,” the authors wrote.
Although all leads can fracture, the most widely sold model—the Sprint Fidelis (Medtronic), used with many different defibrillator designs and removed from the market in October 2007—had a much higher rate of breaks and inappropriate shocks.
Downloadable Lead Integrity Alert (LIA) software (Medtronic) monitors Fidelis leads for evidence of suspicious electrical signals, alerting the patient and recalibrating the device to make a shock less likely if a fracture is suspected, said lead author Charles D. Swerdlow, MD, of the Cedars-Sinai Heart Institute in Los Angeles.
In the prospective study, Swerdlow and colleagues compared the experience of patients prior to their undergoing surgery to replace fractured leads, including 213 who had received standard daily monitoring and 213 monitored with the addition of the downloadable LIA.
The LIA system is triggered by high impedance or rapid oversensing and responds by delaying detection of ventricular fibrillation and initiating a patient alert every four hours. Conventional daily impedance measurements respond with a daily alert.
The primary endpoint used during the study was the percentage of patients who received at least one inappropriate shock caused by a lead-related oversensing prior to in-person ICD analysis.
Those in the LIA arm had a 46 percent reduction in risk of one or more inappropriate shocks: 38 versus 70 percent in the control group.
Patients in the LIA arm had a 50 percent reduction in risk of experiencing five or more inappropriate shocks: 25 versus 50 percent in the control group.
Also, 72 percent of the patients in the LIA arm did not receive an inappropriate shock or had at least three days or more warning prior to the shock, compared to 50 percent of those without the software.
There was a higher number of patients in the LIA group who experienced alerts that were triggered without shocks or before shocks compared to the control group, 86 percent versus 58 percent, respectively.
The authors noted that there were 38 aborted shocks in 25 patients after the LIA warnings occurred. These shocks would have been delivered with the nominal NID.
LIA “is the first downloadable software designed to enhance the performance of nominally functioning ICDs and the first ICD monitoring feature that triggers real-time changes in ICD programming,” the authors said.
LIA “is most valuable when patients and physicians respond rapidly to alerts. LIA is the first downloadable software developed to upgrade almost all presently implanted, nominally functioning ICDs from one manufacturer,” the authors concluded.
“It may set a precedent for downloadable upgrades of implanted electronic devices to improve patient care.”
Medtronic funded the study.
“Downloadable software upgrades are common in consumer electronics but not in implantable medical devices,” the authors wrote.
Although all leads can fracture, the most widely sold model—the Sprint Fidelis (Medtronic), used with many different defibrillator designs and removed from the market in October 2007—had a much higher rate of breaks and inappropriate shocks.
Downloadable Lead Integrity Alert (LIA) software (Medtronic) monitors Fidelis leads for evidence of suspicious electrical signals, alerting the patient and recalibrating the device to make a shock less likely if a fracture is suspected, said lead author Charles D. Swerdlow, MD, of the Cedars-Sinai Heart Institute in Los Angeles.
In the prospective study, Swerdlow and colleagues compared the experience of patients prior to their undergoing surgery to replace fractured leads, including 213 who had received standard daily monitoring and 213 monitored with the addition of the downloadable LIA.
The LIA system is triggered by high impedance or rapid oversensing and responds by delaying detection of ventricular fibrillation and initiating a patient alert every four hours. Conventional daily impedance measurements respond with a daily alert.
The primary endpoint used during the study was the percentage of patients who received at least one inappropriate shock caused by a lead-related oversensing prior to in-person ICD analysis.
Those in the LIA arm had a 46 percent reduction in risk of one or more inappropriate shocks: 38 versus 70 percent in the control group.
Patients in the LIA arm had a 50 percent reduction in risk of experiencing five or more inappropriate shocks: 25 versus 50 percent in the control group.
Also, 72 percent of the patients in the LIA arm did not receive an inappropriate shock or had at least three days or more warning prior to the shock, compared to 50 percent of those without the software.
There was a higher number of patients in the LIA group who experienced alerts that were triggered without shocks or before shocks compared to the control group, 86 percent versus 58 percent, respectively.
The authors noted that there were 38 aborted shocks in 25 patients after the LIA warnings occurred. These shocks would have been delivered with the nominal NID.
LIA “is the first downloadable software designed to enhance the performance of nominally functioning ICDs and the first ICD monitoring feature that triggers real-time changes in ICD programming,” the authors said.
LIA “is most valuable when patients and physicians respond rapidly to alerts. LIA is the first downloadable software developed to upgrade almost all presently implanted, nominally functioning ICDs from one manufacturer,” the authors concluded.
“It may set a precedent for downloadable upgrades of implanted electronic devices to improve patient care.”
Medtronic funded the study.