Background: Percutaneous coronary intervention (PCI) is now a favorable treatment for acute ST elevation myocardial infarction (STEMI). However, in non-official hours (non-OH), this modality of treatment has a questionable outcome because of the treatment delay.

Objective: To compare the outcomes of PCI during official hours (OH) with non-OH in acute STEMI patients.

Material and Method: A prospective consecutive registry of PCI in acute ST-elevation MI patients at King Chulalongkorn Memorial Hospital from May 1999 to December 2003 were analyzed. Kaplan Meier survival analysis was used to determine the in-hospital mortality. Multivariate analysis was used to determine the prognostic factors for in-hospital mortality.

Results: Two hundred and fifty six consecutive patients (OH-107, non-OH-149) who underwent PCI for acute STEMI were enrolled. Their mean age (61.9±12.2 vs. 60.6±12.8 y, p = ns), male gender (73.8% vs. 73.2%, p = ns), history of diabetes (30.2% vs. 33.8%, p = ns), severity of the patients (percent of patients in Killip IV – 22.4 vs. 21.5, p = ns), ejection fraction (48.7±15.1 vs. 45.9±14.7, p = ns), cardiopulmonary resuscitation prior PCI (15.0% vs. 14.2%, p = ns), anterior MI (55.1% vs. 51.0%, p = ns) were similar in both groups. Hypertension was slightly less common (39.6% vs. 52.7%, p = 0.04) but smoking was more common (62.6% vs. 49.0%, p = 0.03) in OH group. Door to balloon time and decision to balloon time were significantly shorter in the OH group than the non-OH group (67.9±47 vs. 119.6±83 min, p<0.001 and 60.8±35 vs. 98.3 min, p<0.001). However, the total delayed time was not statistically significantly different (402±316 vs. 424±215, p = 0.55). Angiographic success rate was achieved in 98.1% for the OH group and 94.7% in the non-OH group (p = ns). In-hospital mortality rate was 10.3% and 10.7% respectively.

Conclusion: The door to balloon time for PCI in acute STEMI patients in the non-OH group was longer than the OH group; however, the total delayed time was not different. The in-hospital mortality rate was similar.

Keywords: Primary percutaneous coronary intervention, ST-elevation myocardial infarction, Official hours, Non-official hours