Importance of delayed perfusion with primary angioplasty on short-term mortality in acute myocardial infarction patients.

Background: Early primary coronary interventions (PCI) in acute ST elevation myocardial infarction (STEMI) is associated with improved outcome and mortality rate but delayed reperfusion especially after 6 hours is still doubtful in terms of clinical benefits because most myocardial muscle are infarcted after 6 hours of onset of chest pain.

Objective: The aim of the present study was to compare the mortality rate of patients treated with PCI within 6 hours of symptom onset to those treated between 6 to 24 hours after the onset of STEMI.

Material And Method: The present study included consecutive patients from the data of the Fast Track Registry of King Chulalongkorn Hospital from June 1, 1999 to October 31, 2003 to compare the thirty-day mortality of patients treated with early or delayed PCI (0-6 hours vs. 6-24 hours after symptom of chest pain) for STEMI.

Results: Two hundred and sixteen patients who underwent PCI were enrolled. Male gender (82% vs. 64.9%, p = 0.03) and history of smoking (72.1% vs. 50%, p = 0.04) were predominant in the early treatment group (ETG) vs. the delayed treatment group (DTG). Mean age (60.5% vs. 61.03%, p = 0.11), diabetes (31.4% vs. 29.7%, p = 0.82), hypertension (64.0% vs. 54.1%, p = 0.20), dyslipidemia (58.1% vs. 60.8%, p = 0.73), and ejection fraction < 40% (22.8% vs. 32.0%, p = 0.625) were similar in both groups. There were no differences in angiographic finding and hospital management. Door to balloon and total delay time were 124.13 +/- 143.27 min and 407.94 +/- 268.183 min, respectively. The thirty-day mortality (9.01% vs. 12.76%, p = 0.379) and I year mortality (12.4% vs. 16 9%, p = 0.532) were not significantly determined by Log rank test in both groups. As for cardiogenic shock, ETG tended to have a lower thirty-day mortality than DTG but no statistically significant difference (12.5% vs. 50.0%, p = 0.0809).

Conclusion: The delayed PCI up to 24 hours in STEMI does not increase short-term mortality at thirty days; therefore, it may still have benefit in STEMI patients. However it tended to have higher short-term mortality than early PCI especially in cardiogenic shock but showed no statistical significance.