Postmortem ICD interrogation in mode of death classification

Forensic perspectives on postmortem CIED interrogation: A systematic review and meta-analysis

BACKGROUND

Cardiac implantable electronic devices (CIED) are a heterogeneous group of medical devices with increasingly sophisticated diagnostic capabilities, which could be exploited in forensic investigations. However, current guidelines are lacking clear recommendations on the topic. The first aim of this systematic review is to provide an updated assessment of the role of postmortem CIED interrogation, and to give practical recommendations, which can be used in daily practice. Secondly, the authors aim to determine the rates of postmortem CIED interrogation and autopsy investigations, the type of final rhythm detected close to death (with a focus on the significance of documented arrhythmias), as well as the role of postmortem CIED interrogation in the determination of final cause/time of death, and any potentially fatal device malfunctions.

METHODS

A systematic search in MEDLINE and Scopus aiming to identify reports concerning postmortem human CIED interrogation was performed, including a systematic screening of reference lists. Case reports, letters to the editors, commentaries, review articles or guidelines were excluded, along with studies related to cardiac devices other than CIED. All data were pooled and analyzed using fixed-effects meta-analysis models, and the I2 statistic was used to assess heterogeneity.

RESULTS

A total of 25 articles were included in the systematic review, enrolling 3194 decedent CIED carriers. Ten studies (40%) had a 100% autopsy rate, whereas in further 6 studies autopsy findings were variably reported; CIED interrogation was available from 22 studies (88%), and it was never performed prior to autopsy. The overall rate of successful postmortem CIED interrogation was 89%, with high heterogeneity among studies, mainly due to device deactivation/battery discharge. Twenty-four percent of CIED carriers experienced sudden cardiac death (SCD), whereas non-sudden cardiac and non-cardiac death (NSCD, NCD) were reported in 37% and 30% of decedents, respectively. Ventricular tachyarrhythmias were recorded in 34% of overall successfully interrogated CIED, and in 62% of decedents who experienced a SCD; of all ventricular tachyarrhythmias recorded, 40% was found in NSCD or NCD. A clear interpretation of the etiological role of recorded arrhythmias in the causation of death required integration with autopsy findings. Overall, potentially fatal device malfunctions were detected in 12% of cases.

CONCLUSIONS

Postmortem CIED interrogation is a valuable tool for the determination of the cause of death, and may complement autopsy. Forensic pathologists need to know the potential utility, pitfalls, and limitations of this diagnostic examination to make this tool as much reliable as possible.

Are arrhythmias the drivers of sudden cardiac death in heart failure with preserved ejection fraction? A review

In patients with heart failure with preserved ejection fraction (HFpEF), sudden cardiac death (SCD) accounts for approximately 25-30% of all-cause mortality and 40% of cardiovascular mortality in properly adjudicated large clinical trials. The mechanism of SCD in HFpEF remains unknown but thought to be driven by arrhythmic events. Apart from atrial fibrillation, which is prevalent in approximately 45% of HFpEF patients, the true burden of other cardiac arrhythmias in HFpEF remains undetermined. The incidence and risk of clinically significant advanced cardiac conduction disease with bradyarrhythmias and ventricular arrhythmias remain less known. Recommendations have been made for long-term cardiac rhythm monitoring to determine the incidence of arrhythmias and clarify mechanisms and mode of death in HFpEF patients. In animal studies, spontaneous ventricular arrhythmias and SCD are significantly elevated in HFpEF animals compared with controls without heart failure. In humans, these studies are scant, with a few published small-size studies suggesting an increased incidence of ventricular arrhythmias in HFpEF. Higher rates of clinically significant conduction disease and cardiac pacing are seen in HFpEF compared with the general population. Excepting atrial fibrillation, the predictive effect of other arrhythmias on heart failure hospitalization, all-cause mortality, and precisely SCD remains unknown. Given the high occurrence of SCD in the HFpEF population, it could potentially become a target for therapeutic interventions if driven by arrhythmias. Studies to address these knowledge gaps are urgently warranted. In this review, we have summarized data on arrhythmias and SCD in HFpEF while highlighting avenues for future research in this area.

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.

Sudden death in heart failure with preserved ejection fraction and beyond: an elusive target

Heart failure (HF) with preserved ejection fraction (HFpEF) represents half of HF patients, who are more likely older, women, and hypertensive. Mortality rates in HFpEF are higher compared with age- and comorbidity-matched non-HF controls and lower than in HF with reduced ejection fraction (HFrEF); the majority (50-70%) are cardiovascular (CV) deaths. Among CV deaths, sudden death (SD) (~ 35%) and HF-death (~ 20%) are the leading cardiac modes of death; however, proportionally, CV deaths, SD, and HF-deaths are lower in HFpEF, while non-CV deaths constitute a higher proportion of deaths in HFpEF (30-40%) than in HFrEF (~ 15%). Importantly, the underlying mechanism of SD has not been clearly elucidated and non-arrhythmic SD may be more prominent in HFpEF than in HFrEF. Furthermore, there is no specific strategy for identifying high-risk patients, probably due to wide heterogeneity in presentation and pathophysiology of HFpEF and a plethora of comorbidities in this population. Thus, the management of HFpEF remains problematic due to paucity of data on the clinical benefits of current therapies, which focus on symptom relief and reduction of HF-hospitalization by controlling fluid retention and managing risk-factors and comorbidities. Matching a specific pathophysiology or mode of death with available and novel therapies may improve outcomes in HFpEF. However, this still remains an elusive target, as we need more information on determinants of SD. Implantable cardioverter-defibrillators (ICDs) have changed the landscape of SD prevention in HFrEF; if ICDs are to be applied to HFpEF, there must be a coordinated effort to identify and select high-risk patients.