NEW YORK (Reuters Health) – Patients with ST-elevation myocardial infarction (STEMI) who present 12 to 24 hours after onset of symptoms should be considered for reperfusion by primary percutaneous coronary intervention (PCI), researchers from Poland suggest in the December 31st online American Journal of Cardiology.

“Even if the time window for treatment of STEMI has been missed, probably your patient could benefit from invasive treatment,” Dr. Marek Gierlotka from Medical University of Silesia, Zabrze, Poland told Reuters Health by email.

Optimal management for these late presenters remains uncertain, the investigators say, but some recent studies have suggested that reperfusion by PCI can benefit patients when performed just after 12 hours from symptom onset.

Dr. Gierlotka and colleagues used data from the Polish Registry of Acute Coronary Syndromes (PL-ACS) to assess the current use of invasive treatment and mechanical reperfusion by primary PCI in patients with STEMI arriving at a hospital 12 to 24 hours after onset of symptoms.

Among 2036 such patients without cardiogenic shock or pulmonary edema and not perfused by thrombolysis, 1126 received conservative treatment and 910 were assigned to invasive treatment, including coronary angiography and primary PCI.

Fifteen percent of patients assigned to conservative treatment also underwent coronary angiography (beyond 24 hours after symptom onset), and 12% of patients in the conservative group (compared with 92% in the invasive group) underwent primary PCI.

Patients assigned to invasive treatment had approximately half the mortality of the conservative group at 30 days and 12 months. Rates of recurrent myocardial infarction in hospital, death in hospital, and 6 month mortality were also significantly lower in the invasive treatment group than in the conservative treatment group.

The reduced 12-month mortality in the invasive treatment group persisted in a subgroup of patients matched by propensity score.

The authors did not find any specific subgroup of patients for whom an invasive approach could be potentially harmful.

“The major limitation is some important measurements such as status of ongoing ischemia on admission and detailed reasons for choosing an invasive or conservative strategy in a particular case,” the researchers observe. “Even after propensity-score matching, the groups are likely to be biased by potentially important parameters that are not available in the registry.”

“Therefore,” the authors note, “the reported significant mortality decrease after adjustment should be interpreted with caution

Based on these findings, should late presenters undergo primary PCI? “I think yes, probably most of them should benefit from invasive treatment,” Dr. Gierlotka concluded. “Usually these patients are not referred to coronary angiography, but I think they should be.”

“It is difficult to perform a randomized trial on this issue, but I will try,” Dr. Gierlotka added.

Am J Cardiol 31 December 2010.