ST-segment elevation MI (STEMI) patients are at their greatest risk for ischemic and bleeding events shortly after PCI, with both risks dropping significantly over time. However, ischemic events are more common between 30 days and one year, supporting the extended use of intensified antiplatelet therapy, according to a new study in the Journal of the American College of Cardiology.

Researchers studied 3,602 patients with STEMI and categorized all bleeding and ischemic events, including recurrent events, as acute (within 24 hours of PCI), subacute (one to 30 days) and late (30 days to one year). Patients were treated with aspirin and clopidogrel for the entire year.

Bleeding was defined as major and minor bleeding not related to coronary artery bypass grafting, while ischemic events included cardiac death, reinfarction and definite stent thrombosis.

More than 90 percent of the bleeding events occurred in the first 30 days. In contrast, 59.5 percent of ischemic events occurred within 30 days, with the other 40.5 percent occurring between 30 days and one year.

“The current findings support the use of potent platelet inhibition continuing through at least 1 year to prevent both primary and recurrent ischemic events, especially in patients without excessive bleeding risk,” wrote lead researcher Gennaro Giustino, MD, with Icahn School of Medicine at Mount Sinai, New York, and colleagues. “Implementation of bleeding avoidance strategies is also essential, especially in the acute and subacute phases after primary PCI.”

The authors said previous studies failed to quantify the relative rates of these events over time. Earlier research also focused mainly on the time to first event, rather than including all recurrent events.

“Conventional time-to-event analyses are limited by the fact that patients are censored after the occurrence of the first endpoint event,” they wrote. “This approach does not allow evaluation of multiple or recurrent events over time, and therefore it impedes full appreciation of the overall disease burden and effects of concomitant treatments.”

Giustino et al. reported being surprised to find bleeding and ischemic events were most often discrete from one another. They added further studies are warranted to determine which subgroups of patients are at relatively higher risk for ischemic versus bleeding events.

In an accompanying editorial, Derek P. Chew, MBBS, and Deepak L. Bhatt, MD, praised the researchers’ decision to quantify all events—including recurrent ones—in terms of daily risk.

“Patients are rightly concerned about the risk of the ‘next event’ and not only the event they have just sustained,” Chew and Bhatt wrote. “The evaluation of the daily hazard for bleeding and ischemic events offers a clearer appreciation of the dynamic nature of risks over time, specifically, the temporal nature of the relative balance of bleeding and ischemic risks.”

The challenge, according to the editorial authors, is integrating this knowledge into daily practice while adjusting care based on patient-specific risk factors.