Sepsis and use of stimulant drugs are important causes of heart attack among people living with HIV according to US research published in the Journal of Acquired Immune Deficiency Syndromes. Heart attacks with such causes, rather than attacks caused by hardening of the arteries, predominated among younger people living with HIV who experienced a heart attack.
But the study also showed that even younger people with HIV were having heart attacks due to arterial disease and that there were high rates of heart attacks due to either sepsis/drug use and hardening in older individuals.
Dr Heidi Crane of the University of Washington, Seattle, and co-investigators conducted the research.
The findings of the study are important because heart disease is an increasingly important cause of serious illness and death among people living with HIV. Moreover, there are several types of heart attack, each with differing underlying causes. Treatment strategies depend on the type of heart attack.
Type 1 heart attacks are due to arterial disease, especially the build up of cholesterol-related deposits or plaques in the arteries. Instability in these plaques can cause arterial blockages, obstructing blood supply to the heart resulting in heart attack.
In contrast, the causes of Type 2 heart attack include sepsis (a severe reaction to an infection), use of cocaine and hypoxia (low levels of oxygen).
Risk factors for both types of heart attack are common among people living with HIV. Lifestyle factors such as diet and use of some antiretroviral drugs can cause increases in cholesterol. But rates of recreational drug use are also high among people with HIV and using unsterile injecting equipment raises the risk of infections.
In the general population, Type 1 heart attacks predominate. But Dr Crane’s research team have previously shown that HIV-positive people have a differing heart attack profile, with approximately half of attacks classified as Type 2. They found that there is a greater risk of death after a Type 2 heart attack.
They wanted to take this research further and see whether heart attack type among people living with HIV differed by age. They hypothesised that the causes associated with Type 2 heart attack would mean that it would predominate among younger people. But the investigators also hypothesised that Type 1 heart attacks would also be occurring among younger people living with HIV at a measurable rate.
Their research involved adults who received specialist HIV care in six US cities between 2000 and 2019. Potential heart attacks were identified from medical records. Two physicians reviewed each case to determine heart attack type. Incidence of each type was calculated according to age (in decades).
The total study population consisted of 28,741 people living with HIV. Of these, 875 had a heart attack. Their median age was 51 years, 79% were men, 50% were African American and 79% were taking antiretroviral therapy. Median CD4 cell count at the time of heart attack was 355.
Just over half (53%) of heart attacks were Type 1, the other 47% were Type 2 events.
Individuals experiencing a Type 1 heart attack were more likely than those with a Type 2 event to be aged 40 and over, male (85% vs 72%), White (49% vs 26%), on statins (49% vs 25%), taking antiretroviral therapy (84% vs 72%) and to have higher total and LDL (or ‘bad’) cholesterol. Average CD4 cell count also differed according to myocardial infarction type (Type 1, 423 vs Type 2, 253).
Type 1 type attacks occurred in people living with HIV of all ages, including among the under 30s (one event among 2254 individuals, rate 0.31 per 1000 person-years). Their frequency increased with age, with incidence among those aged 70 and older reaching 9 cases per 1000 person-years of follow-up.
Type 2 events were observed in all age groups (five events in the under 30s, rate 1.31 per 1000 person-years) and their frequency also increased with age (five events among the 573 people aged 70 and older, incidence 8.88 per 1000 person-years).
However, Type 1 events were more common than Type 2 events in people aged between 50 and 69, whereas Type 2 events were more common in those under the age of 40. The rate of Type 2 events among the under 30s was significantly higher (IRR = 10.0; 95% CI, 2.43-88.24, p < 0.001).
Common causes of Type 2 events were sepsis (36%), use of cocaine or other stimulant drugs (11%) and respiratory failure (10%).
“These results highlight that Type 1 myocardial infarctions and Type 2 myocardial infarctions represent distinct clinical entities and require different approaches to prevention and treatment,” comment the authors. “A key finding of this study is that people living with HIV with a Type 2 myocardial infarction were younger than those with a Type 1 myocardial infarction.”
“Common causes of Type 2 events were sepsis, use of cocaine or other stimulant drugs, and respiratory failure.”
They note that this is in contrast to the general population where Type 2 events are rare and generally occur in older individuals. Dr Crane and her colleagues suggest that this discrepancy was likely driven by the high frequency of sepsis-related heart attacks they observed. In the general population this accounts for 10% of Type 2 events but among people living with HIV it was the most common risk factor for a heart attack of this type, present in between 27 and 50% of individuals (depending on age).
“We found that among people living with HIV, Type 1 myocardial infarctions occurred in adults of all ages. Type 2 myocardial infarctions accounted for almost half of all myocardial infarctions…and occurred at a higher rate…until the age of 40,” conclude the investigators. “A better understanding of these important comorbidities, who is impacted, when, and why, is needed to further comprehend the underlying mechanisms and successfully intervene to improve long-term outcomes for older people living with HIV as the population in care continues aging.”