NEW YORK (Reuters Health) – People with HIV have a rate of sudden cardiac death that is more than double that in the non-infected population, according to a new study of cases in San Francisco County in California.
But a closer look at those deaths using autopsy data and blood tests is showing that heart attacks are often not the cause. Fibrosis and drug overdoses appear to also underlie the problem, researchers report in the New England Journal of Medicine.
“We actually found that among the sudden deaths, the rate of prior heart attack and the rate of heart attacks we could detect by autopsy were not any higher than the general population,” chief author Dr. Zian Tseng of the University of California, San Francisco, told Reuters Health by phone.
“What we think accounts for this increased risk is the fibrosis,” he said.
In addition, his team found that a third of those deaths in the HIV-infected people resulted from a drug overdose that would otherwise have gone undetected if not for the thorough postmortem each body received.
Doctors have known for years that an HIV infection hikes the risk of heart failure, acute myocardial infarction and ischemic stroke.
The new prospective postmortem study, known as HIV POST SCD, offers a systematic look at the risk by following all out-of-hospital cardiac arrests occurring in in San Francisco County from 2011 through most of 2016, and doing a deep dive into their causes.
“Sudden cardiac death is a presumed diagnosis because it’s very, very difficult to get an autopsy. So traditionally when someone collapses and dies suddenly, it’s called a cardiac death,” said Dr. Tseng, a cardiac electrophysiologist and professor in the department of medicine at UCSF.
But coauthor Dr. Ellen Moffatt in the San Francisco medical examiners’ office did a post mortem on all the deaths and that’s when the fibrosis and unidentified drug overdoses came into play.
“These are cardiac arrests that the paramedics had called cardiac arrest. The medical examiner or investigator on the scene found no evidence for suspicion of drug overdose – so no needles, no pills, nothing. The only way we discovered the overdose was by toxicology,” Dr. Tseng said. “These findings shed a light into this phenomenon that would otherwise never be investigated.”
In all, the team logged 610 unexpected deaths among HIV-positive people, 109 were considered to be the result of out-of-hospital cardiac arrest. When they looked further, they found that 48 actually met the formal criteria for presumed sudden cardiac deaths.
They calculated that the rate of presumed sudden cardiac death was 53.3 per 100,000 person-years among HIV-infected people versus 23.7 among those without a known infection, a statistically significant difference.
The additional testing revealed that only 22 of these sudden deaths were found to be heart related, caused by arrhythmia, associated coronary artery disease, damaged or enlarged heart chambers, or pre-existing arrhythmic disease.
The rates for sudden death from arrhythmia, as determined by autopsy, were 25.0 per 100,000 with HIV and 13.3 per 100,000 respectively without.
Among the group that experienced a presumed sudden cardiac death, the rates of death due to occult drug overdose were 34% among people with a known HIV infection and 13% in the control group.
Overall, 3.5% of the deaths among HIV-infected people were due to presumed sudden cardiac deaths.
The prominence of the fibrosis in the HIV-positive group was not unexpected.
“We’ve recognized for a long time that HIV causes a chronic inflammatory state in the body, even in patients with undetectable viral loads,” Dr. Tseng said. “By our traditional assays, we can’t find the virus anywhere in the body. Now it’s been recognized that HIV is sequestering somewhere. The brain is one potential area. Lymph nodes are another. We think this chronic level of inflammation is what leads to this scarring. And this fibrosis is happening in the lymph nodes, in the guts and now in the liver and the heart. It seems to be part of that inflammatory state that HIV induces.”
Thus, kidney failure, hemorrhage, infection and diabetic ketoacidosis were also responsible for such sudden deaths where it was presumed that sudden cardiac death was the cause.
“Only 23% of presumed sudden cardiac deaths were due to coronary artery disease,” the researchers write. “Thus, although incidences of acute myocardial infarction and other structural heart disease may be elevated in the context of HIV infection, they do not appear to underlie the higher incidence of sudden deaths that we observed among HIV-positive patients.”
Dr. Tseng said that, based on the new findings, emergency responders should think about the possibility of an overdose when they arrive at the scene of a cardiac arrest. Doctors might want to be more aggressive at screening for arrhythmias in their infected patients and the threshold for using a defibrillator might need to be adjusted for such cases.
SOURCE: https://bit.ly/3iHu43C The New England Journal of Medicine, online June 16, 2021.
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