Homelessness and Incidence and Causes of Sudden Death: Data From the POST SCD Study.

Importance: Over 580 000 people in the US experience homelessness, with one of the largest concentrations residing in San Francisco, California. Unhoused individuals have a life expectancy of approximately 50 years, yet how sudden death contributes to this early mortality is unknown. Objective: To compare incidence and causes of sudden death by autopsy among housed and unhoused individuals in San Francisco County. Design, Setting, and Participants: This cohort study used data from the Postmortem Systematic Investigation of Sudden Cardiac Death (POST SCD) study, a prospective cohort of consecutive out-of-hospital cardiac arrest deaths countywide among individuals aged 18 to 90 years. Cases meeting World Health Organization criteria for presumed SCD underwent autopsy, toxicologic analysis, and medical record review. For rate calculations, all 525 incident SCDs in the initial cohort were used (February 1, 2011, to March 1, 2014). For analysis of causes, 343 SCDs (incident cases approximately every third day) were added from the extended cohort (March 1, 2014, to December 16, 2018). Data analysis was performed from July 1, 2022, to July 1, 2023. Main Outcomes and Measures: The main outcomes were incidence and causes of presumed SCD by housing status. Causes of sudden death were adjudicated as arrhythmic (potentially rescuable with implantable cardioverter-defibrillator), cardiac nonarrhythmic (eg, tamponade), or noncardiac (eg, overdose). Results: A total of 868 presumed SCDs over 8 years were identified: 151 unhoused individuals (17.4%) and 717 housed individuals (82.6%). Unhoused individuals compared with housed individuals were younger (mean [SD] age, 56.7 [0.8] vs 61.0 [0.5] years, respectively) and more often male (132 [87.4%] vs 499 [69.6%]), with statistically significant racial differences. Paramedic response times were similar (mean [SD] time to arrival, unhoused individuals: 5.6 [0.4] minutes; housed individuals: 5.6 [0.2] minutes; P = .99), while proportion of witnessed sudden deaths was lower among unhoused individuals compared with housed individuals (27 [18.0%] vs 184 [25.7%], respectively, P = .04). Unhoused individuals had higher rates of sudden death (incidence rate ratio [IRR], 16.2; 95% CI, 5.1-51.2; P < .001) and arrhythmic death (IRR, 7.2; 95% CI, 1.3-40.1; P = .02). These associations remained statistically significant after adjustment for differences in age and sex. Noncardiac causes (96 [63.6%] vs 270 [37.7%], P < .001), including occult overdose (48 [31.8%] vs 90 [12.6%], P < .001), gastrointestinal causes (8 [5.3%] vs 15 [2.1%], P = .03), and infection (11 [7.3%] vs 20 [2.8%], P = .01), were more common among sudden deaths in unhoused individuals. A lower proportion of sudden deaths in unhoused individuals were due to arrhythmic causes (48 of 151 [31.8%] vs 420 of 717 [58.6%], P < .001), including acute and chronic coronary disease. Conclusions and Relevance: In this cohort study among individuals who experienced sudden death in San Francisco County, homelessness was associated with greater risk of sudden death from both noncardiac causes and arrhythmic causes potentially preventable with a defibrillator.

Heart Failure Burden by Autopsy, Guideline-Directed Medical Therapy, and ICD Utilization Among Sudden Deaths.

BACKGROUND: Studies of heart failure with reduced ejection fraction (HFrEF) and preserved ejection fraction (HFpEF) report high sudden cardiac death (SCD) rates but presume cardiac cause. Underlying causes, guideline-directed medical therapy (GDMT), and implantable cardioverter-defibrillator (ICD) use in community sudden deaths with heart failure (HF) are unknown. OBJECTIVES: This study aims to assess the burden of HF, GDMT, and ICD use among autopsied sudden deaths in the POST SCD (Postmortem Systematic Investigation of Sudden Cardiac Death) study, a countywide postmortem study of all presumed SCDs. METHODS: Incident WHO-defined (presumed) SCDs for individuals of ages 18 to 90 years were autopsied via prospective surveillance of consecutive out-of-hospital deaths in San Francisco County from February 1, 2011, to March 1, 2014. Sudden arrhythmic deaths (SADs) had no identifiable nonarrhythmic cause (eg, pulmonary embolism), and are thus considered potentially rescuable with ICD. RESULTS: Of 525 presumed SCDs, 100 (19%) had HF. There were 85 patients with known HF (31 HFpEF, 54 HFrEF) and 15 with subclinical HF (postmortem evidence of cardiomyopathy and pulmonary edema without HF diagnosis). SADs comprised 56% (293 of 525) of all presumed SCDs, and 69% (69 of 100) of HF SCDs. The rates were similar in HFrEF (40 of 54 [74%]) and HFpEF (19 of 31 [61%], P = 0.45). Four SAD patients (4%) had ICDs, 3 of which experienced device failure. Twenty-eight SCDs had ejection fraction ≤35%: 22 (79%) with arrhythmic and 6 (21%) with noncardiac causes. Of the 22 SAD patients, 8 (36%) had no identifiable barrier to ICD referral. Complete use of GDMT in HFrEF was 6%. CONCLUSIONS: One in 5 community sudden deaths had HF; two-thirds had autopsy-confirmed arrhythmic causes. ICD prevention criteria captured only 8% (22 of 293) of all SAD cases countywide; GDMT and ICD use remain important targets for HF sudden death prevention.

Cardiac arrhythmia spot light: Detection of ventricular fibrillation-Not all ICDs are created equal.

Intracardiac device electrograms demonstrating differing VF sensing performance between two manufacturer ICD generators.

Factors Predisposing to Survival After Resuscitation for Sudden Cardiac Arrest.

BACKGROUND: In the POST SCD study, the authors autopsied all World Health Organization (WHO)-defined sudden cardiac deaths (SCDs) and found that only 56% had an arrhythmic cause; resuscitated sudden cardiac arrests (SCAs) were excluded because they did not die suddenly. They hypothesized that causes underlying resuscitated SCAs would be similarly heterogeneous. OBJECTIVES: The aim of this study was to determine the causes and outcomes of resuscitated SCAs. METHODS: The authors identified all out-of-hospital cardiac arrests (OHCAs) from February 1, 2011, to January 1, 2015, of patients aged 18 to 90 years in San Francisco County. Resuscitated SCAs were OHCAs surviving to hospitalization and meeting WHO criteria for suddenness. Underlying cause was determined by comprehensive record review. RESULTS: The authors identified 734 OHCAs over 48 months; 239 met SCA criteria, 133 (55.6%) were resuscitated to hospitalization, and 47 (19.7%) survived to discharge. Arrhythmic causes accounted for significantly more resuscitated SCAs overall (92 of 133, 69.1%), particularly among survivors (43 of 47, 91.5%), than WHO-defined SCDs in POST SCD (293 of 525, 55.8%; p < 0.004 for both). Among resuscitated SCAs, arrhythmic cause, ventricular tachycardia/fibrillation initial rhythm, and white race were independent predictors of survival. None of the resuscitated SCAs due to neurologic causes survived. CONCLUSIONS: In this 4-year countywide study of OHCAs, only one-third were sudden, of which one-half were resuscitated to hospitalization and 1 in 5 survived to discharge. Arrhythmic cause predicted survival and nearly one-half of nonsurvivors had nonarrhythmic causes, suggesting that SCA survivors are not equivalent to SCDs. Early identification of nonarrhythmic SCAs, such as neurologic emergencies, may be a target to improve OHCA survival.

Sex and Racial Differences in Autopsy-Defined Causes of Presumed Sudden Cardiac Death.

[Figure: see text].

Association of QT-Prolonging Medications With Risk of Autopsy-Defined Causes of Sudden Death.

Importance: QT-prolonging medications (QTPMs) are a reported risk factor for sudden cardiac death (SCD) when defined by consensus criteria that presume an arrhythmic cause. The effect of QTPM on autopsy-defined sudden arrhythmic death (SAD) is unknown. Objective: To evaluate the association between QTPM and autopsy-defined SAD vs nonarrhythmic cause of sudden death. Design, Setting, and Participants: This prospective countywide case-control study included World Health Organization-defined (presumed) SCD cases who underwent autopsy as part of the San Francisco Postmortem Systematic Investigation of Sudden Cardiac Death Study (POST SCD) to determine arrhythmic or nonarrhythmic cause, and control deaths due to trauma (hereinafter referred to as trauma controls) in San Francisco County, California, from February 1, 2011, to March 1, 2014. Multivariate regression was used to evaluate the association of QTPM with the risk of presumed SCD, autopsy-defined SAD, and non-SAD compared with trauma controls. Medication exposure, determined by prescription lists and postmortem toxicologic findings, was used to calculate a summative QTPM exposure score (range, 0-20). Data were analyzed from September 1, 2018, to June 15, 2019. Exposure: QT-prolonging medication exposure, as measured by QTPM score (1 indicated low; 2-4, moderate; and >4, high). Main Outcomes and Measures: Death due to trauma, presumed SCD, and autopsy-defined non-SAD and SAD with no postmortem findings of extracardiac cause. Results: A total of 629 patients (mean [SD] age, 61.4 [15.7] years; 439 men [69.8%]) were included, 525 with presumed SCDs and 104 traumatic death controls. Individuals with presumed SCDs had higher exposure and were more likely to be taking any QTPM (291 [55.4%] vs 28 [26.9%]; P < .001) than trauma controls. Use of QTPMs was associated with increased risk of presumed SCD in low (odds ratio [OR], 2.25 [95% CI, 1.03-4.96]; P = .04) and high (OR, 6.70 [95% CI, 1.47-30.67]; P = .01) exposure groups. After autopsy adjudication, use of QTPMs was associated with increased risk of non-SAD (low-risk OR, 2.88 [95% CI, 1.18-6.99; P = .02]; moderate-risk OR, 2.62 [95% CI, 1.20-5.73; P = .02]; and high-risk OR, 14.22 [95% CI, 2.91-69.30; P = .001]) but not SAD in all exposure groups. This association was attenuated by the exclusion of occult overdose non-SADs in the highest exposure group. Conclusions and Relevance: These findings confirm the association between QTPMs and presumed SCD; however, after autopsy, this risk was specific for nonarrhythmic causes of sudden death. Studies using consensus SCD criteria may overestimate the association of QTPMs with the risk of SAD.