Recent studies appear to suggest a correlation between timing to coronary angiography and clinical outcome among patients with acute coronary syndrome (ACS). We aim to study 12-month outcomes of ACS patients who are stratified according to early (≤24 hours), intermediate (>24 to <48 hours) and delayed (≥48 hours) coronary angiography. This is a prospective observational study of patients with ACS defined as either unstable angina pectoris or non-ST elevation myocardial infarction (MI) admitted between October 2008 and July 2009. Baseline clinical characteristics of age, gender, cardiovascular risk factors (diabetes mellitus, hypertension, dyslipidemia) and TIMI score were analyzed and adjusted for outcomes. The primary outcome was combined major adverse cardiovascular events (MACE) of death or non-fatal MI, as well as target vessel revascularization (TVR) up to 12 months. This study consisted of 642 patients (75% males, mean age 60±13) with median follow-up of 7 months and median TIMI score of 4. Over half (50.2%) were categorized as high-risk (TIMI score ≥4). 281 patients (43.5%) had early angiography, 170 (26.5%) had angiography between >24 to <48 hours and 191(30%) patients had delayed angiography ≥48 hours. In high-risk patients, the primary outcome occurred in 10.9% of patients in the early group, as compared with 13.2% in intermediate group and 23.9% in delayed group (p=0.015) at six months. However, in low-risk patients (TIMI scores <4), there was no significant difference between the groups (7.1% vs. 3.4% vs. 5.9%, p=0.316) at six months. Compared to the intermediate and delayed groups, patients in the early group had lower overall MACE at 12 months (21% vs. 14% vs. 10%, p=0.006) that was largely related to a lower frequency of death at 12 months (11% vs. 7% vs. 4.6%, p=0.03). There were no differences in rates of TVR between the groups (4% vs. 7% vs. 3.5%, p=0.14). In this observational analysis, an early strategy to coronary angiography was associated with improved survival at one year while an early to intermediate strategy benefitted the subgroup of high-risk patients with significant reductions in cardiovascular events at six months.
Keywords: Myocardial infarction, acute coronary syndrome, coronary angiography