Prevalence of illicit drug use in young sudden cardiac death patients; an Australian prospective cohort study

Background

Illicit drug use may accelerate coronary disease and cardiac hypertrophy or stimulate arrhythmias. Rates of illicit drug use in young sudden cardiac death (SCD) patients are uncertain.

Purpose

To identify rates of illicit drug use in young SCD patients in Australia.

Methods

A prospective multi-centre registry identified out of hospital cardiac arrest (OHCA) patients aged 1–50 years between April 2019 and April 2020. Clinical characteristics were compared between patients with and without illicit drug use (defined by toxicological results or reported regular use). Illicit drugs included stimulants such as amphetamine-type substances and cocaine, or non-stimulants such as heroin, cannabis and novel psychoactive substances (cathinones and synthetic cannabinoids).

Results

770 OHCAs occurred, with 555 patients undergoing forensic assessment. 287 patients had confirmed cardiac cause of OHCA, with 274 undergoing toxicological assessment and 79 (28.8%) having positive toxicology for illicit drugs (n=60) or reported regular drug use (n=19). An additional 121 patients experienced non-cardiac SCD due to illicit drug toxicity, resulting in a total of 200 patients (36.0% of OHCAs) with illicit drug use. Patients with SCD and illicit drug use were more commonly male (86.1% vs 72.3%, p=0.015), regular smokers (36.7% vs 21.5%, p=0.009), had cardiomegaly (76.5% vs 57.5%, p=0.007), and higher rates of coronary disease and cardiomyopathy (coronary disease 44.3% vs 33.3%, cardiomyopathy 30.4% vs 18.5%, p=0.003). Methamphetamines (n=42, 53.1%) were the most common illicit drug identified and polysubstance abuse occurred frequently (n=15, 19.0%).

Conclusion

Approximately one-third of young SCD patients use illicit drugs, with high rates of polysubstance abuse. Illicit drug use in SCD patients is associated with coronary disease and cardiomyopathy.

Funding Acknowledgement

Type of funding sources: None.

Prevalence of coronary artery anomalies in young sudden cardiac death: insights from a prospective state-wide registry

Background

Coronary artery anomalies (CAAs) have been previously implicated as a major cause of young sudden cardiac death (SCD), particularly in exercise-related SCD with a reported prevalence of up to 33%.

Methods

A state-wide prospective out-of-hospital cardiac arrest registry identified all patients aged 1–50 years who experienced an SCD and underwent autopsy from April 2019 to April 2021. Rates of normal anatomy, normal variants and CAAs were identified and circumstances and cause of death for patients with CAAs examined.

Results

Of 1,477 patients who experienced cardiac arrest during the study period, 490 underwent autopsy and were confirmed to have experienced SCD. Of these 490 patients, five (1.0%) had a CAA identified with three having anomalies of coronary origin and two having anomalies of coronary course. In no cases was the CAA deemed responsible for the SCD. In two cases, severe coronary disease and intra-coronary thrombus with histological evidence of acute myocardial infarction were identified, in the third critical coronary disease was found, the fourth had an unrelated thoracic aortic dissection and the fifth had cardiomegaly in the setting of illicit drug use. Of 27 patients who experienced their SCD during exercise, only one had a CAA identified (the patient with thoracic aortic dissection).

Conclusion

In this prospective cohort of consecutive young patients with SCD who underwent autopsy, CAAs occurred in 1.0% of patients and did not cause any deaths. The role of CAAs in causing young SCD appears to be less significant than previously hypothesised.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): NHMRC, NHF

Clinical and pathologic features of out-of-hospital cardiac arrest in pregnancy: insights from a state-wide registry

Background

Cardiovascular disease is the most common cause of indirect maternal mortality worldwide, and cardiac arrest occurs in up to 1 in 12,000 pregnancies.

Objective

To define rates, clinical and pathologic factors of out-of-hospital cardiac arrest (OHCA) in pregnant and post-partum females.

Methods

A prospective state-wide cardiac arrest registry combining ambulance, hospital and forensic data captured all OHCAs from 2019–2021. Clinical and pathological details for pregnant patients were identified.

Results

1,482 OHCAs occurred, including 376 females of child-bearing age of whom eight were pregnant or post-partum. OHCA incidence was lower in pregnant females compared to non-pregnant females of child-bearing age (5.2 OHCAs per 100,000 pregnant females vs 23.1 per 100,000 females of child-bearing age, p<0.0001). Seven patients (87.5%) died, with five (62.5%) having a cardiac cause of OHCA (unascertained = 2, cardiomyopathy = 2 (1 hypertrophic), ischemic heart disease = 1). Two patients had pre-existing cardiac risk factors, but none had a cardiac diagnosis pre-arrest. Compared to in-hospital cardiac arrests (IHCAs) in pregnancy, OHCAs are more likely to have a cardiac cause (odds ratio 3.81) and lower maternal survival (odds ratio 0.09).

Conclusion

Maternal OHCA affects approximately 1 in 20,000 pregnancies with high maternal mortality rates. OHCA occurs at one-quarter the rate in non-pregnant females of child-bearing age. Approximately two-thirds of maternal OHCAs had an underlying cardiac cause, but low rates of cardiac diagnosis pre-arrest. OHCAs differ markedly from IHCAs in pregnant females, requiring ongoing evaluation as to specific causes and preventability.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): NHMRC, NHF

Obesity in young sudden cardiac death: rates, clinical features, and insights into people with body mass index >50kg/m2

Background

Obesity is common in young sudden cardiac death (SCD) victims but it is unclear whether it is more common than in the general population. This study aimed to contextualize young SCD obesity rates, identifying clinical and pathologic features in WHO class II and III obesity.

Methods

A prospective state-wide out-of-hospital cardiac arrest registry included all SCDs in Victoria, Australia from 2019–2021. Body mass indices (BMIs) of patients 18–50 years were compared to age-referenced general population. Characteristics of SCD patients with WHO Class II obesity (BMI ≥30kg/m2) and non-obesity (BMI <30kg/m2) were compared. Clinical characteristics of people with BMI >50kg/m2 were assessed.

Results

504 patients were included. Obesity was strongly over-represented in young SCD compared to the age-matched general population (55.0% vs 28.7%, p<0.0001). Obese SCD patients more frequently had hypertension, diabetes and obstructive sleep apnoea (p<0.0001, p=0.009 and p=0.001 respectively), ventricular fibrillation as their arrest rhythm (p=0.008) and left ventricular hypertrophy (LVH) (p<0.0001). Obese patients were less likely to have toxicology positive for illicit substances (22.0% vs 32.6%, p=0.008) or significant alcohol history (18.8% vs 26.9%, p=0.030). Patients with BMI >50 kg/m2 represented 8.5% of young SCD. LVH (n=26, 60.5%) was their predominant cause of death and only 10 (9.3%) patients died from coronary disease.

Conclusion

Over half of young Australian SCD patients are obese, with all obesity classes over-represented compared to the general population. Obese patients had more cardiac risk factors. Almost two thirds of patients with BMI>50 kg/m2 died with LVH, with fewer than 10% dying from coronary disease.

Funding Acknowledgement

Type of funding sources: None.

Economic impact of sudden cardiac arrest

Background

Each year, there are approximately 5,000 out-of-hospital cardiac arrests (OHCAs) in the state of Victoria, Australia (population 6.4 million, state healthcare budget AUD$2.9 billion / €1.8billion). Mortality from OHCA approaches ninety percent. High mortality rates and survivors not returning to work is likely to have an adverse effect on the Victorian economy but this has not been previously investigated.

Purpose

To model the economic impact of OHCA mortality and survivors not returning to work.

Methods

Data on all OHCAs transported by Ambulance Victoria from July 2017- June 2018 in Victoria, Australia was collected, including age, gender, survival to hospital, survival to discharge, and survival to 12 months. Cases were excluded if arrest was precipitated by trauma, exsanguination, overdose, terminal illness, hanging, SIDS, electrocution, sepsis, respiratory causes, drowning, or neurological causes. Pre-arrest employment status of patients was modelled using the Australian Bureau of Statistics Economic Security dataset, which provides contemporary employment rates for gender-matched five-year cohorts for Australians aged 15–79 years. For survivors to 12 months, pre-arrest and post-arrest work status were confirmed. Economic impact was then calculated to a five year horizon utilizing a Markov model with probabilistic sensitivity analysis.

Results

4,934 arrests meeting the inclusion criteria were transported by Ambulance Victoria in twelve months, of whom 4,639 were determined to be cardiac arrests without any exclusion criteria as a precipitant. 695 patients survived to hospital (15.0%), and 325 to discharge (7.0%). At 12 months, 303 patients were alive (6.5% of overall cases, 93.2% of those discharged from hospital). Economic modelling of age and gender-matched data indicated that 1516 patients (35%) would have been employed pre-cardiac arrest, but only 216 survivors (4.7%) would be employed at five years post-arrest. Using Markov modelling incorporating estimated earnings and the pre-determined value of a statistical life, the annual economic burden of cardiac arrest approximated AUD$4 billion (€2.5 billion) at a five-year horizon.

Conclusion

The annual economic impact of cardiac arrest in Victoria, Australia is approximately AUD$4 billion (€2.5 billion) in a five-year horizon. As the annual Victorian state budget for all healthcare is AUD$2.93 billion (€1.8 billion), our data suggests that the economic impact of cardiac arrest is under-appreciated. Therefore, research in this area and providing state-of-the-art care for all cardiac arrest patients should be a healthcare priority.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): NHMRC/NHF Postgraduate Scholarship, RACP JJ Billings Scholarship