Time to nearest PCI hospital determines reperfusion strategy in STEMI

The majority of ST-segment elevation myocardial infarction (STEMI) patients in the Midwest live within an hour of their nearest percutaneous coronary intervention (PCI)-capable hospital and are able to undergo primary PCI within two hours of an MI, researchers reported in the American Journal of Cardiology this month.

Primary PCI is the preferred reperfusion strategy for STEMI patients when they present to the hospital within 90 minutes of MI, lead author Hedvig B. Andersson, MD, and colleagues at the University of Michigan Medical Center in Ann Arbor, Michigan, wrote in AJC. In the case that a patient arrives at the hospital outside of that specified window, the American College of Cardiology Foundation, American Heart Association and European Society of Cardiology all recommend a pharmacoinvasive approach to treatment using fibrinolysis followed by either rescue PCI or routine early PCI.

“Whereas a pharmacoinvasive strategy can be initiated in any prehospital system, primary PCI can only be delivered at PCI-capable hospitals,” the authors wrote, noting recent observational studies have seen similar outcomes for primary PCI and fibrinolysis. “Geographic factors might therefore impact the choice of reperfusion strategy for STEMI, although this has not been studied in detail.”

For their study, Andersson and her team enrolled 27,205 STEMI patients undergoing PCI in Michigan between 2010 and 2016. Of those patients, 95 percent underwent primary PCI, while 5 percent were treated with a pharmacoinvasive strategy.

The majority of patients—96 percent—lived within an hour of a hospital with PCI capability, according to the analysis. Using Google Maps API (Application Programming Interface) to calculate pre-hospital transport times, the researchers found a patient’s distance to the nearest PCI site could predict their physician’s choice of reperfusion strategy for STEMI.

Primary PCI was used in 97 percent of patients with an estimated pre-hospital transport time of less than an hour, the authors said, though those patients’ average travel time was just 12 minutes. In contrast, just 48 percent of those with an average travel time of an hour or longer were treated with primary PCI.

“As expected, the probability of receiving primary PCI decreased with longer estimated pre-hospital transport times to the nearest PCI-capable hospital,” Andersson et al. wrote. “Whereas primary PCI was the treatment strategy of choice in almost all patients who lived within one hour from a PCI-capable hospital, primary PCI was only used in approximately half of the patients with longer pre-hospital transport times.”

As a whole, patients treated with primary PCI versus rescue PCI saw similar rates of post-procedural bleeding, in-hospital mortality and additional complications, the researchers said. Access site bleeding was the most common bleeding complication in both patients treated with primary PCI and those treated with a pharmacoinvasive strategy, while intracerebral hemorrhage was rare in both groups.

The authors said their study is limited in the fact that it doesn’t account for patients’ actual mode of transportation or any possible delays. They also estimated times based on patients’ zip codes rather than their home addresses, which would have produced more accurate results.

“Several factors other than estimated transport time can influence the decision on reperfusion strategy for STEMI,” Andersson and co-authors said. “For example, traffic delays and bad weather conditions can further prolong pre-hospital transport delays and favor the use of a pharmacoinvasive strategy. A pharmacoinvasive strategy is also more likely to be chosen in patients presenting to a hospital without PCI capability or outside of normal working hours.”

The researchers did say they noted a decline in the use of pharmacoinvasive treatments over their study period, though the dip was “for reasons unknown.” They said regional differences in transportation and PCI care also need to be explored in future work.