This study aimed to determine the prevalence and differences between Non-ST elevation Myocardial Infarction (NSTEMI) with an occluded culprit artery (NSTEMIOA) and NSTEMI with a patent culprit artery (NSTEMIPA).

We conducted a retrospective observational study on NSTEMI patients admitted between 01/01/2010 to 30/06/2010. The inclusion criteria were diagnosis of NSTEMI and inpatient coronary angiogram. Patients were followed up for 12 months. The primary endpoints of interest were the differentiating characteristics between NSTEMIOA and NSTEMIOA. The secondary endpoints of interest were clinical outcomes in 12 months and the effect of delay in percutaneous coronary intervention on the extent of myocardial damage.

Of 143 NSTEMI patients, 34 (24%) patients had NSTEMIOA. NSTEMIOA patients had higher rates of hypercholesterolaemia (85.3% vs. 64.2%, p=0.015), ST-depression abnormality on ECGs (32.4% vs. 11.9%, p=0.008), multi-vessel disease on coronary angiogram (76.5% vs. 48.6%, p=0.004) and LV dysfunction on echo (75% vs 48%, p=0.016). At 12 months post-discharge, there was a trend of higher heart failure rate in NSTEMIOA subgroup but otherwise no difference between the two cohorts in death, myocardial infarction, revascularisation, arrhythmia, and re-admission for angina. There was no correlation between the peak CK level and the timing of percutaneous revascularisation in both cohorts.

A quarter of NSTEMI patients had an occluded culprit coronary artery. They were more likely to have hypercholesterolaemia, ECG abnormalities, multi-vessel disease and LV dysfunction.