Researchers highlight possible ‘neglected risk factor’ for MI

Certain antiphospholipid antibodies were detected more often after heart attacks than for age-matched controls, suggesting the markers could be used to identify patients at high risk of myocardial infarction, according to a study published Oct. 22 in the Annals of Internal Medicine.

Researchers took blood samples of 805 patients six to 10 weeks after they were hospitalized for a first MI at one of 17 Swedish hospitals. They matched those individuals to non-MI participants by age, sex and region, and highlighted the following findings:

  • MI patients showed a higher incidence of immunoglobulin G (IgG) anti-2-glycoprotein I and/or IgG anticardiolipin than control individuals (11.1 percent versus 1.3 percent). The researchers classified people with these laboratory results as “antiphospholipid antibody (aPL) IgG positive.”
  • Upon multivariable analysis adjusted for traditional risk factors, aPL IgG positivity remained significantly associated with MI, with an odds ratio of 7.8. Current smoking carried an odds ratio of 2.6, while diabetes, hypertension and body mass index weren’t independently associated with that outcome.
  • There was a trend toward aPL IgG positivity being more common in women (26.1 percent versus 17.9 percent in men) and current smokers (33.7 percent versus 25.1 percent in nonsmokers).

“A strong and independent association between aPL IgG positivity and first-time MI may represent an important, but until now neglected, risk factor for MI in the general population,” wrote lead author Giorgia Grosso, MD, with Karolinska University Hospital in Stockholm, and colleagues. “If confirmed in long-term cohort studies, these findings may lead to improved management, treatment, and outcomes for many patients who have had or are at high risk for MI.”

The authors noted blood samples were taken just once six to 10 weeks after MI, so it remains unknown whether the antibodies were present before the MI and how long they remain in circulation.

“Persistent aPLs together with MI would indicate definite (antiphospholipid syndrome), for which current guidelines recommend indefinite warfarin treatment,” the authors wrote. “Transient aPLs might represent an immunologic reaction to myocardial damage during MI or an infection, and whether these aPLs are associated with enhanced risk for thrombosis is not known.”