Circumflex artery related myocardial infarction: Less reperfusion therapy and large infarct size

Pre-hospital risk assessment in suspected non-ST-elevation acute coronary syndrome: A prospective observational study

Background:

Pre-hospital risk stratification of non-ST-elevation acute coronary syndrome (NSTE-ACS) by the complete HEART score has not yet been assessed. We investigated whether pre-hospital risk stratification of patients with suspected NSTE-ACS using the HEART score is accurate in predicting major adverse cardiac events (MACE).

Methods:

This is a prospective observational study, including 700 patients with suspected NSTE-ACS. Risk stratification was performed by ambulance paramedics, using the HEART score; low risk was defined as HEART score ⩽ 3. Primary endpoint was occurrence of MACE within 45 days after inclusion. Secondary endpoint was myocardial infarction or death.

Results:

A total of 172 patients (24.6%) were stratified as low risk and 528 patients (75.4%) as intermediate to high risk. Mean age was 53.9 years in the low risk group and 66.7 years in the intermediate to high risk group ( p<0.001), 50% were male in the low risk group versus 60% in the intermediate to high risk group ( p=0.026). MACE occurred in five patients in the low risk group (2.9%) and in 111 (21.0%) patients at intermediate or high risk ( p<0.001). There were no deaths in the low risk group and the occurrence of acute myocardial infarction in this group was 1.2%. In the high risk group six patients died (1.1%) and 76 patients had myocardial infarction (14.4%).

Conclusions:

In suspected NSTE-ACS, pre-hospital risk stratification by ambulance paramedics, including troponin measurement, is accurate in differentiating between low and intermediate to high risk. Future studies should investigate whether transportation of low risk patients to a hospital can be avoided, and whether high risk patients benefit from immediate transfer to a hospital with early coronary angiography possibilities.

Comparison of Outcomes and Intervention Among Patients With Non-ST-Segment Elevation Acute Myocardial Infarction of Those With a Left Circumflex Versus Those With a Non-Left Circumflex-Related Coronary Artery (From the ELISA-3 Trial)

Previous studies found that patients with an acute coronary syndrome (ACS) due to occlusion of the left circumflex (LC) coronary artery often present without ST-elevation, leading to a delay in diagnosis and revascularization, a larger infarct size, and a worse prognosis. In this subgroup analysis of the ELISA-3 study (early or late intervention in high-risk non-ST-segment elevation acute coronary syndromes [NSTE-ACS]) incidence, characteristics and prognosis of LC-related NSTE-ACS was investigated, and the outcome of early versus late invasive strategy was compared. In 383 of 542 patients the culprit vessel could be identified, with the LC artery in 112 (29%) of them. Patients with LC-related ACS had more often single vessel disease and underwent percutaneous coronary intervention more and CABG less frequently. The primary end point of the combined incidences of death, myocardial infarction, and recurrent ischemia at 30-day follow-up occurred in 9.0% of LC versus 16.5% of non-LC-related ACS (p = 0.057). Enzymatic infarct size and incidence of bleeding were comparable. Of patients with LC-related ACS, 62 were assigned to an early and 50 to a late invasive treatment with a median time from admission to angiography of 5.5 and 65.7 hours, respectively. The primary end point occurred in 9.7% and 8.0%, respectively (p = 1.00) with comparable enzymatic infarct size and bleeding. In conclusion, no significant differences in outcome were found between patients with an LC- and a non-LC-related NSTE-ACS. In LC-related NSTE-ACS, angiography within 12 hours of admission is feasible but not superior to angiography after more than 48 hours.