Delayed PCI in Stable Patients with STEMI Still Beats Medical Therapy

Download this article's Factoid in PDF (& PPT for Gold Subscribers)

In stable patients with ST-segment elevation myocardial infarction (STEMI), delayed percutaneous coronary intervention (PCI) just outside the recommended window of symptom onset still results in better clinical outcomes than medical therapy, according to registry results published online July 23, 2012, ahead of print in the American Journal of Cardiology.

Myung-Ho Jeong, MD, PhD, of Chonnam National University Hospital (Gwangju, South Korea), and colleagues looked at 2,344 stable STEMI patients from the Korea AMI Registry from November 2005 to January 2008 who received either elective PCI (n = 1,889) or medical therapy (n = 455) after presenting 12 to 72 hours after symptom onset. The median time from arrival to PCI was 22 hours.

These patients, referred to as ‘early latecomers,’ showed lower death and death/MI rates at 30 days with PCI compared with medical therapy (table 1).

Table 1. Clinical Outcomes at 30 Days

These results were maintained at 12 months (table 2).

Table 2. Clinical Outcomes at 12 Months

After adjustment for propensity score, the reductions at 30 days in the PCI group for death (adjusted HR 0.29; 95% CI 0.18-0.47; P < 0.001) and death/MI (adjusted HR 0.30; 95% CI 0.19-0.48; P < 0.001) remained significant, as they did at 12 months for both death (adjusted HR 0.31; 95% CI 0.20-0.47; P < 0.001) and death/MI (adjusted HR 0.36; 95% CI 0.25-0.53; P < 0.001).

When separated by quintile of propensity to undergo PCI, 12-month death/MI rates were still lower for patients who underwent PCI than for those who did not, indicating that patients with the same probability of undergoing PCI were more likely to benefit if they actually underwent the procedure. These results were maintained across multiple subgroups defined by sex, age (cut-off of 65 years), chest pain at presentation, time to presentation (cut-off of 24 hours), Q-wave, TIMI risk score (cut-off of 5), creatinine level, and pre-PCI TIMI flow.

The study authors note that the clinical benefit of reperfusion in stable STEMI patients presenting 12 to 24 hours after symptom onset is controversial, as studies have shown conflicting results in this patient group, with benefit thought to be unrelated to myocardial salvage. However, it has also been suggested that the interval to salvage viable myocardium can extend to several days. In fact, later PCI may be especially beneficial in the presence of a patent infarct-related artery (IRA), the authors propose. In the current study, 47% of patients had a totally occluded IRA, with the benefits of PCI consistent regardless of patency.

Paper Supports Current Practice

In a telephone interview with TCTMD, Sorin J. Brener, MD, of Weill Cornell Medical College (New York, NY), noted that the study upholds what most US practitioners have adopted, despite a lack of data to support it. “Current guidelines reflect that, saying it’s very reasonable to continue to embark on an invasive strategy in patients who are stable more than 12 hours after an MI and I think that’s exactly right,” he said.

“Practitioners at small hospitals that don’t have a cath lab should view these data as an opportunity to [transfer] their patients to a cath lab even if they arrived at their hospital first,” he said. “I’m not sure it has to be done in the middle of the night, necessarily. These people are stable, so it’s reasonable to wait until morning and then you pick up the phone and say ‘send this guy over.’”

Exactly why late PCI is beneficial, however, remains somewhat of a mystery. Dr. Brener noted 3 theories as to why opening an IRA may help after the accepted window for salvaging myocardium:

• There is a peri-infarct zone that is still salvageable, and opening the IRA improves remodeling
• Potentially fatal arrhythmias may be prevented
• Collaterals will form to benefit potential future IRAs

“The problem was obviously OAT, which tested all of these hypotheses and found all of them to be absolutely false,” Dr. Brener said, referring to the Occluded Artery Trial, which found that routine late PCI for a totally occluded IRA failed to reduce major cardiovascular events during 4 years of follow-up.

Dr. Brener said he believes that remodeling is positively affected when an IRA is opened late after an acute MI, but other factors may also be involved. “What’s happening is that I think the time windows are all artificial and fairly meaningless, frankly. The patient could have had four more hours of complete ischemia while they were asleep. Or more often what happens is the pain is intermittent, which means the IRA is opening and closing,” he said. “It is possible that each time when that happens, the clock should begin ticking again, and that’s why there’s still viable myocardium.”

 

---

Source:
Sim DS, Jeong M-H, Ahn Y, et al. Benefit of percutaneous coronary intervention in early latecomers with acute ST-segment elevation myocardial infarction. Am J Cardiol. 2012;Epub ahead of print.

 

 

Related Stories:

• Primary PCI Still Beneficial Later Than 12 Hours After STEMI
• Late PCI After AMI Yields Modest Benefit at Major Cost 
• Survival Advantage for Late PCI Extends Out to Four Years