Sudden cardiac death: Mysteries persist despite new study

As this new study shows, sudden cardiac death syndrome often has no clear pathological mechanism or no obvious anatomical or toxicological basis


Results of a new study of sudden cardiac death suggest that some of the mysteries surrounding arrest-related fatalities are likely to remain unanswered for the foreseeable future and perhaps should simply be accepted as falling among unfortunate medical occurrences that often have no ready explanations. 

“Cases of SCD [sudden cardiac death] associated with altercation and restraint receive mass media attention especially when police [or] other governmental bodies are involved,” the research team notes. 

But their findings about this phenomenon beg the question posed by one independent expert: Is it fair to hold law enforcement to unrealistic standards of prevention when there are so few certainties about how and why sudden deaths occur proximate to arrest? 

Puzzle of Youth
The new study, reported in the journal Medicine, Science and Law, was conducted by four researchers associated with the medical school at Aristotle University in Greece and St. George’s Medical School in London. Their aim was to further clarify the “well-established association” between both chronic and acute psychological stress and heart problems that may contribute to SCD. 

In older subjects, they explain, underlying coronary artery disease is often identified as an influential factor. But SCD “is becoming increasingly recognized” among younger subjects, including those in the age range most commonly associated with police encounters. And in this group there “mainly [seems to be an] absence of coronary artery disease.” 

So what “associations and causes” may be driving stress-related SCD in this population? The researchers hoped to find out. 

Subject Particulars
From a database of 2,400 SCD cases maintained at a cardiac pathology center in England, they thoroughly examined 110 instances of sudden death. The majority (over 80 percent) of subjects were male, the more vulnerable and combative gender, and nearly 60 percent were under age 35. Findings: 

• Overall, about six in 10 “died instantaneously during [a] stressful event.” The rest succumbed within 30 minutes after the event, with their stressed condition noticeable in the interim. 

• “The main circumstances of SCD,” the team found, were altercation (over 45 percent), struggling during restraint (31 percent), and merely being in police custody (10 percent). Lesser stressors included “receiving bad news,” “exams/school/job stress,” and “collapsing after a minor car accident.” 

• In nearly half the cases, restraint was imposed by LEOs. But at about the same collective rate, restraint was applied by non-LE personnel: psychiatric staff, security staff, or friends. 

• For the most part (90 percent), toxicology reports for drugs and/or alcohol were negative. 

Why’d They Die?
The researchers report that 20 percent of the victims “had a psychiatric history and were on psychotropic drugs, and it is well established that such patients have a higher incidence of sudden death.” Indeed, psychiatric patients are believed to be five times more likely to experience SCD than people generally, and “exposure to antipsychotic drugs further exacerbates this risk even at low doses.” 

Still, specific causation, especially among younger victims, seems to remain unclear. One member of the team performed a pathological analysis of each subject’s heart. “The single most common finding”: 60 percent had a heart that was “normal,” including the majority of those younger than 35. Where abnormality of the heart muscle was discovered, this defect was concentrated predominately in older subjects. Similarly, all cases of coronary artery disease were in older subjects, with an average age of 60. 

Without drawing specific conclusions, the researchers describe several possible influences among youthful victims with normal hearts, including a genetic predisposition to disrupted heart rhythm in the presence of “intense adrenalin activation” and an overwhelmingly negative “connection between the heart and the brain” incited by a psychological reaction to acute stress (being “scared to death,” in effect). 

As to definitive cause, though, the researchers report only vaguely: “[T]he mechanism of sudden death under stress may be multifactorial, resulting from a cascade of predisposing risk factors, including underlying cardiac disease, obesity, mental health, alcohol and/or drug use as well as physical exertion.” 

In high-profile cases, they recommend a “thorough autopsy with toxicology” conducted by an expert in cardiac pathology as the best hope of establishing “the correct cause of death” and shielding police and/or medical personnel from unwarranted blame. 

An Expert's Observations
This study was brought to the attention of Force Science News by Dr. Mark Kroll, adjunct professor of biomedical engineering at the University of Minnesota and Cal Poly University in California, who lectured on the science of arrest-related deaths at the latest ILEETA annual training conference. Kroll offers some pertinent observations for law enforcement: 

• “Being arrested is a highly emotional event, and the exertion of a struggle is several fold greater than that seen with normal exercise. To drive home the ability of extreme emotional stress to cause sudden death, consider that 4 percent of the deaths studied were caused by receiving news of a loved one’s death, 7 percent were due to stress from examinations or a job, and 4 percent were from the stress of a minor car accident without major injuries”--events unrelated to any law enforcement involvement. 

• “Annually, there are about 800,000 cases in which force is used by law enforcement in North America and approximately 800 arrest-related deaths (ARDs), yielding a mortality rate of about 1:1000--remarkably low, given the risks and stress involved. This can be compared to an in-hospital death rate of 1:232 for treatment of a common heart disorder [ablation for atrial fibrillation] by medical professionals--far higher than that for ARDs.” 

• “No matter how careful LEOs are, there will continue to be occasional ARDs. It is not clear that anything can be done to significantly reduce the risk of this below the present low rate. Is it even fair to expect law enforcement to achieve mortality rates even further below those of common hospital procedures when dealing with subjects who are often violent, disturbed, and intoxicated?” 

• “An autopsy report by a medical examiner is often the primary factor in LEO discipline, termination, civil lawsuits, and criminal prosecutions. An individual ME will see an ARD every 10 years on average. Yet society expects MEs and coroners to always reach a cause and contribution to death conclusively. 

“This is impossible since numerous studies find that 25-53 percent of sudden deaths in children, military recruits, and athletes cannot be explained. As this new study shows, this syndrome often has no clear pathological mechanism or no obvious anatomical or toxicological basis. 

“Hopefully, someday society will accept the diagnosis of ‘arrest-related death syndrome’ without forcing the medical examiner to always find some deadly condition which is not necessarily there to be found.” 

False Theory Corrected
Kroll cites a “small weakness” in the new paper: The researchers mention “so-called compression/positional asphyxia as possibly contributing to restraint deaths.” This “dying, unscientific theory” has been thoroughly discredited by “a substantial number of peer-reviewed studies” showing that positioning of arrestees has little or no impact on a suspect’s ability to breathe, Kroll states. He and two colleagues have published a letter of correction in the journal.

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