Invasive treatment may have better outcomes for some heart attack patients
Jun 15, 2005 - 3:21:38 PM
Invasive treatment including stenting may have better outcomes than conventional treatments for heart attack patients who arrive at the hospital more than 12 hours after symptoms began, according to a study in the June 15 issue of JAMA.
In patients with acute ST-segment elevation myocardial infarction (STEMI - a certain finding on an electrocardiogram, suggesting a heart attack), numerous studies have demonstrated that early reperfusion (restoration of blood flow) within 12 hours of symptom onset is associated with increased myocardial (heart muscle) salvage, preservation of left ventricular function, and improved survival, according to background information in the article. Due to time-dependent reduction in the efficacy of thrombolysis (administration of medications to help dissolve blood clots), the application of this reperfusion method after 12 hours from symptom onset of acute myocardial infarction (MI, heart attack) offers little or no benefit and may be even harmful. Between 8.5 percent to 40 percent of patients with acute MI present late after symptom onset, thus being no longer eligible for thrombolysis.
Despite efforts to reduce time to presentation, recent studies have demonstrated that time-to-arrival at the hospital after the onset of symptoms has not changed or has even increased. Several findings suggest that reperfusion therapy may be beneficial even among patients with acute MI who present late after symptom onset. Current guidelines do not recommend reperfusion treatment in these patients. No specifically designed studies have addressed the role of primary percutaneous coronary intervention (PCI) in patients with STEMI presenting more than 12 hours after symptom onset.
Albert Schömig, M.D., of Technische Universität, Munich, Germany, and colleagues conducted a study to assess whether an invasive strategy based on PCI with stenting is associated with reduction of infarct (dead tissue from lack of blood) size in patients with acute STEMI presenting more than 12 hours after the symptom onset, compared with a conventional conservative treatment strategy.
The study, conducted from May 23, 2001, to December 15, 2004, included 365 patients aged 18 to 80 years, without persistent heart attack symptoms admitted with the diagnosis of acute STEMI between 12 and 48 hours from symptom onset. Patients were randomized to receive either an invasive strategy (n=182) based predominantly on coronary stenting plus the intravenous medication abciximab or a conventional conservative treatment strategy (n=183), which included an intravenous infusion of heparin.
The researchers found that the final left ventricular infarct size was significantly smaller in patients assigned to the invasive group (median, 8.0 percent) vs. those assigned to the conservative group (median, 13.0 percent). The average difference in final left ventricular infarct size between the invasive and conservative groups was ?-6.8 percent. The outcomes of death, recurrent MI, or stroke at 30 days occurred in 8 patients in the invasive group (4.4 percent) and 12 patients in the conservative group (6.6 percent) (a 33 percent lower risk of these outcomes for patients in the invasive group).
"This finding increases the level of evidence in support of the invasive strategy and deserves consideration when current treatment guidelines for this category of patients will be reassessed," the researchers conclude.
In an accompanying editorial, Raymond J. Gibbons, M.D., and Cindy L. Grines, M.D., of Mayo Clinic and Foundation, Rochester, Minn.; and William Beaumont Hospital, Detroit, comment on the findings of Schömig et al, the BRAVE-2 trial.
"Should the next update of STEMI Clinical Practice Guidelines consider PCI to be generally indicated (a class I indication) for all patients presenting with STEMI after 12 hours? Probably not yet. Existing guidelines consider the presence of ongoing symptoms after 12 hours to be a class IIa indication for PCI. On the basis of BRAVE-2, it would seem appropriate to expand this class IIa indication. Although it seems reasonable to consider acute PCI in all patients with STEMI who present 12 hours or longer after the onset of chest pain, regardless of whether they have ongoing pain, this single small trial does not provide sufficient evidence to warrant a class I indication. Such an indication would require confirmation at least in a second small trial using infarct size as an end point or preferably in a larger trial using clinical end points."
"Should patients with STEMI presenting after 12 hours be considered 'medical emergencies' requiring acute mobilization of the catheterization laboratory in the middle of the night? Probably not. Although the BRAVE-2 investigators proceeded with urgent PCI in the patients who were included in this trial, the trial results do not reveal whether this urgency was justified."
"The BRAVE-2 trial results are a noteworthy challenge to existing dogma and an important contribution to current knowledge. However, the results do not yet justify a revolution in clinical practice," the authors conclude.
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