NEW YORK (Reuters Health) – In patients with ST-segment elevation myocardial infarction (STEMI), substantial myocardial salvage and reduced infarct size can be achieved even when primary angioplasty is performed 12 to 72 hours after symptom onset, results of a Danish study indicate.

Current guidelines from the European and American societies of cardiology recommend primary angioplasty for STEMI only if symptoms have been present for less than 12 hours, Dr. Martin Busk of Aarhus University Hospital, Skejby and colleagues explain in the June issue of the European Heart Journal. “However, 8.5-40% of STEMI patients are late presenters with symptoms for more than 12 h on admission.”

The clinicians evaluated final infarct size and myocardial salvage in 341 early presenters (symptom onset < 12 hours) versus 55 late presenters (symptom onset 12 to 72 hours) undergoing primary angioplasty.

They performed myocardial perfusion imaging acutely to assess area at risk before angioplasty and again after 30 days to assess final infarct size (% of left ventricular myocardium), salvage index (% non-infarcted area at risk), and left ventricular ejection fraction (LVEF).

According to the investigators, late presenters, compared with early presenters, had larger median final infarct size (14% vs 7%; p = 0.005), lower salvage index (53% vs 69%; p = 0.05), and lower LVEF (48% vs. 53%; p = 0.04).

However, there was only a weak correlation between symptom duration and final infarct size, salvage index, and LVEF, they report.

“The key finding was that early presenters undergoing primary angioplasty achieved an increased myocardial salvage and a reduced final infarct size when compared with late presenters undergoing primary angioplasty,” Dr. Busk told Reuters Health.

However, “substantial myocardial salvage was observed beyond the 12-hour limit, even when the infarct related artery was totally occluded,” the researcher added.

In the 247 patients with TIMI-flow 0, late presenters had lower salvage index than early presenters (44% vs. 57%; p = 0.03), but substantial salvage (>50% of area at risk) was observed in 41% of late presenters despite total infarct-artery occlusion.

“Based on our study,” Dr. Busk noted, “the 12-hour cut-off point for offering primary angioplasty appears to be totally arbitrary.”

“It is unpredictable from the symptom duration as reported by the patient,” Dr. Busk said, “whether myocardial salvage can be achieved with primary angioplasty, even when the symptom duration is above 12 hours.”

Reference:
Euro Heart J 2009;30:1322-1330.