Patients with HIV who have used abacavir within the previous 6 months have a significantly increased risk for myocardial infarction (MI), according to a recent study published by the Journal of Acquired Immune Deficiency Syndromes.
The study analyzed inpatient and outpatient medical records for 8265 adults who initiated antiretroviral therapy (ART) for HIV between January 1, 2001, and December 31, 2013. Patients who experienced MI at or before exposure to ART were excluded from the analysis, which was adjusted for confounders such as age, race, sex, smoking status, kidney disease, and other factors that could contribute to the risk for MI. The data utilized were taken from the North American Cohort Collaboration on Research and Design, the largest consortium of HIV cohorts in Canada and the United States.
The study investigators found an increased risk for MI among patients treated with abacavir in the previous 6 months, and this increase persisted with the stratification of outcomes according to MI type. After adjusting for time-varying confounders and potential channeling biases, the data revealed that patients with recent abacavir exposure had an 84% higher risk for MI than those without recent abacavir exposure (adjusted hazard ratio=1.84; 95% CI, 1.17-2.91). The investigators acknowledge that despite their rigorous ascertainment, diagnostic, and adjudication procedures, confounding is still possible. A range of variables exist that may not only potentially increase the prevalence of MI but also the likelihood of abacavir prescription.
The exact mechanisms by which abacavir use increases MI risk remain speculative. The study investigators theorize that the effect of abacavir could enhance a pre-existing vulnerability to MI from systemic inflammation, coronary atherosclerosis, or immune dysregulation. This enhancement may appear early on in abacavir use or could be an ongoing, cumulative effect.
Despite the uncertain mechanics, however, the investigators believe the study results suggest that current MI risk-screening practices for HIV adults could be inadequate. They conclude by stating, “Future work may focus on identifying the best subset of patients who can benefit from abacavir with the least amount of risk.”
Elion RA, Althoff KN, Zhang J, et al. Recent abacavir use increases risk for types 1 and 2 myocardial infarctions among adults with HIV [published online February 6, 2018]. J Acquir Immune Defic Syndr. doi: 10.1097/QAI.0000000000001642