Researchers from the University of California San Francisco
looked at all sudden cardiac deaths and sudden arrhythmic deaths that occurred
outside a hospital setting in San Francisco County between 2011 and 2016. Autopsies
were carried out in all cases of out-of-hospital cardiac arrest. Sudden
arrhythmic deaths were autopsy-defined deaths where no extracardiac cause of
death could be identified.
They identified 47 out-of-hospital sudden cardiac deaths in
people with HIV and 505 in the HIV-negative population in the same period. Sudden
cardiac deaths occurred at a significantly younger age in people with HIV (54
years vs 63 in the general population, p < 0.001) and people with HIV who
suffered sudden cardiac death were more likely to have a previous history of heart
attack, to have a psychiatric diagnosis, current substance, alcohol and tobacco
use.
Approximately half of the deaths (47%) were sudden
arrhythmic deaths. Sudden arrhythmic deaths are cases which can be rescued by
use of a defibrillator.
Sudden cardiac death was more commonly due to occult
overdose (an overdose where drug overdose had not been immediately apparent) in
people with HIV. Just over one-third of all sudden cardiac deaths were judged
to be due to occult overdose in people living with HIV, compared to 13% in
HIV-negative people (p < 0.0001). Occult overdose was defined as a case where
no drug use was detected at the scene of death, only upon autopsy.
Sudden cardiac death due to kidney failure was more common
in people living with HIV (6% vs 1%, p = 0.003).
The incidence ratio of sudden cardiac death was approximately
86% higher in people living with HIV than HIV-negative people (1.86 for SCD,
95% CI 1.39-2.4, p < 0.0005) while the incidence of sudden arrhythmic death was
58% higher (1.58 for SAD, 95% CI 1.02-2.43, p = 0.006).
Although the incidence of sudden cardiac death and sudden
arrhythmic death were each higher in black people than in other demographic
groups, the incidence ratio did not differ significantly between HIV-positive and HIV-negative black people. In white people on the other hand, the incidence
of sudden cardiac death was approximately twice as high (p = 0.006).
The investigators noted a significantly higher prevalence of
cardiac fibrosis – abnormal thickening of the heart valves due to deposition of
collagen in the myocardium – in people living with HIV who suffered a sudden
cardiac death.
After controlling for
age, gender, heart disease and coronary artery disease, people with HIV who
suffered sudden cardiac death had 60% greater extent of interstitial fibrosis
at autopsy than HIV-negative people. Fibrosis occurs with ageing and is
associated with the development of heart failure.
“This might be the mechanism by which HIV increases the risk
for fatal arrhythmias,” said Dr Zian Tseng of University of California San
Francisco. But how fibrosis occurs is still unclear. “Is there chronic
inflammation, activated immune cells circulating? I think it’s controversial if
there is direct HIV infection of the myocardial cells,” he told a press
conference.
