Algorithm-based reduction of inappropriate defibrillator shock: Results of the Inappropriate Shock Reduction wIth PARAD+ Rhythm DiScrimination-Implantable Cardioverter Defibrillator Study

Patients with an implantable cardioverter defibrillator at risk of poorer psychological health during 24 months of follow-up (results from the Danish national DEFIB-WOMEN study)

OBJECTIVE

Identify implantable cardioverter defibrillator (ICD) patients at risk of distress (i.e., depression, anxiety, and ICD concerns) and associated risk factors.

METHOD

First-time ICD patients (n = 1503) from the Danish national DEFIB-WOMEN study completed questionnaires at baseline, 3, 6, 12 and 24 months.

RESULTS

Of patients with low scores on distress, only 4%-7.2% experienced an increase in distress during 24 months of follow-up (FU), while 30.5%-52.5% with increased levels were likely to maintain increased levels at FU. Higher education, higher age, female sex, and good physical functioning at baseline were associated with less depression, anxiety and ICD concerns at FU. Previous psychological problems, smoking, Type D personality, NYHA class III-IV - all assessed at baseline - and shocks during FU were associated with depression, anxiety and ICD concerns.

CONCLUSIONS

Generally, patients' psychological health improved, but patients with increased baseline scores were more likely to have increased scores at FU. We need to be vigilant if patients report elevated distress, particularly if they have depression at baseline, as depression seems more persistent. Given the impact of depression on health-related quality of life and prognosis, they should be screened and monitored closely.

Postmortem Interrogation of Cardiac Implantable Electronic Devices: A 15-Year Experience

OBJECTIVES

This study sought to define the feasibility and utility of postmortem cardiac implantable electronic device (CIED) interrogation.

BACKGROUND

The diagnostic yield of routine postmortem interrogation of CIEDs including pacemakers, defibrillators, and implantable loop recorders has not been established.

METHODS

The study reviewed all CIED interrogations in deceased individuals undergoing medicolegal investigation of sudden or unexplained death by the Victorian Institute of Forensic Medicine between 2005 and 2020.

RESULTS

A total of 260 patients (68.8% male, median age 72.8 years [interquartile range: 62.7-82.2 years]) underwent CIED interrogation (202 pacemakers, 56 defibrillators, and 2 loop recorders) for investigation of sudden (n = 162) or unexplained (n = 98) death. CIEDs were implanted for median of 2.0 years (interquartile range: 0.7-5.0 years), with 19 devices at elective replacement indicator and 5 at end of life. Interrogation was successful in 256 (98.5%) cases. Potential CIED malfunction was identified in 20 (7.7%) cases, including untreated ventricular arrhythmias (n = 13) and lead failures (n = 3, 2 resulting in untreated ventricular arrhythmia). Interrogation directly informed cause of death in 131 (50.4%) cases. A total of 72 (27.7%) patients had abnormalities recorded in 30 days preceding death: nonsustained ventricular tachycardia (n = 26), rapid atrial fibrillation (n = 17), elective replacement indicator or end-of-life status (n = 22), intrathoracic impedance alarms (n = 3), lead issues (n = 3), or therapy delivered (n = 1). In 6 cases in which the patient was found deceased after a prolonged period, interrogation determined time of death. In 1 case, CIED interrogation was the primary means of patient identification.

CONCLUSIONS

Postmortem CIED interrogation frequently contributes important information regarding critical device malfunction, premortem abnormalities, mechanism, and time of death or patient identity. Device interrogation should be considered for select patients with CIEDs undergoing autopsy.

Potential of remote monitoring to prevent sensing and detection failures in implantable cardioverter defibrillators

BACKGROUND

Sensing malfunction and misinterpretation of intracardiac electrograms (IEGMs) in patients with implantable cardioverter defibrillators (ICDs) may lead to inadequate device activity such as inappropriate shock delivery or unnecessary mode-switching. Remote monitoring has the potential for early detection of sensing malfunction or misclassification and may thus prevent adverse device activity. Therefore, the authors analyzed the amount, nature, and distribution of misclassification in current ICD and cardiac resynchronization therapy defibrillator technology using the device transmissions of the IN-TIME study population.

METHODS

All transmitted tachyarrhythmic episodes in the 664 IN-TIME patients, comprising 2214 device-classified atrial fibrillation (DC-AF) episodes lasting ≥ 30 s and 1330 device-classified ventricular tachycardia or fibrillation (DC-VT/VF) episodes, were manually analyzed by two experienced cardiologists.

RESULTS

After evaluation of all DC-VT/VF episodes, a total of 300 VT/VF events (23.1%) were false-positive, with supraventricular tachycardia being the most frequent cause (51.7%), followed by atrial fibrillation (21.3%) and T‑wave oversensing (21.0%). A total of 15 patients with false-positive DC-VT/VF received inappropriate shocks. According to the inclusion criteria, 616 IEGMs with DC-AF were assessed. A total of 19.7% were false-positive AF episodes and R‑wave oversensing was the most common reason (55.9%).

CONCLUSIONS

Remote monitoring offers the opportunity of early detection of signal misclassification and thus early prevention of adverse device reaction, such as inappropriate shock delivery or mode-switching with intermittent loss of atrioventricular synchrony, by correcting the underlying causes.