Rates of stroke following acute MI drop as treatments improve

Risk of ischemic stroke within one year of acute MI dropped by 20 percent over a 10-year span in the general Swedish population in a study published online Sept. 18 in Stroke.

Incidence rates of stroke within one year of acute MI observed by the research team were nearly double those seen in earlier meta-analyses. However, Anders Ulvenstam, MD, of Östersund Hospital in Frösön, Sweden, and colleagues noted that their data likely was more indicative of actual population rates.

The data, culled from the Register of Information and Knowledge about Swedish Heart Intensive Care Admissions (RIKS-HIA) allowed Ulvenstam et al to look at the 173,233 patients with AMI between 1998 and 2008.

They found that 4.1 percent of patients registered with AMI had a stroke within one year between 1998 and 2008. However, rates of stroke decreased over time. Between 1998 and 2000, stroke following acute MI occurred in 4.5 percent of patients. Between 2001 and 2002, the rate of stroke post MI dropped to 4.4 percent. In the 2003 to 2004 time point, the rate went down to 4.1 percent. it dropped to 3.9 percent in 2005 to 2006 and fell further to 3.8 percent in 2007 to 2008.

Rates of congestive heart failure and atrial fibrillation also dropped during the 10-year period.

Ulvenstam et al credited the use of PCI reperfusion and improved pharmacological treatments such as statins, aspirin and P2Y12-inhibitors for reductions in risk. PCI offered the greatest reduction in risk, they wrote, as medication with aspirin, beta-blockers and ACE inhibitors were used with consistency in both patients who did and did not experience a follow-up stroke, although with increasing frequency as the study progressed.

The most obvious risk factor they found for an ischemic stroke following acute MI was history of prior ischemic stroke (hazard ratio 2.56). Other factors that increased risks included age, atrial fibrillation, female sex, diabetes, heart failure during hospitalization and STEMI. The decreased rates in heart failure and atrial fibrillation, they posited, may have also influenced the overall decrease in ischemic stroke seen in the population.

“The observed risk reduction coincides with the improved outcome after AMI during the past decades and with the increased use of evidence-based treatment,” Ulvenstam et al wrote.