An observational cohort study of 7937 ED visits by patients presenting with chest pain or ‘ischemic equivalent’ (shortness of breath for which ACS was considered a possible cause) was done to examine the relationship between left bundle branch block (LBBB) on the ECG and the incidence of acute myocardial infarction (AMI). No difference was observed in the rates of AMI in patients with new or presumed new LBBB, old LBBB, and no LBBB. The authors suggest that this large cohort of undifferentiated ED patients may be more reflective of the true prevalence of AMI in LBBB (7.3% in this study) and question the appropriateness of a liberal fibrinolytic strategy for such patients. Another argument for primary PCI?
Lack of association between left bundle-branch block and acute myocardial infarction in symptomatic ED patients
Am J Emerg Med. 2009 Oct;27(8):916-21
Plasma levels of adrenaline and noradrenaline increased signficantly in patients with acute coronary syndrome during ambulance transportation – a finding in keeping with studies on normal volunteers. I wonder how much more of an effect helicopter retrieval might have?
Emergency ambulance transport induces stress in patients with acute coronary syndrome
Emerg Med J. 2009 Jul;26(7):524-8.
Hyperoxia may reduce coronary artery blood flow, increase systemic vascular resistance, and decrease cardiac output. This paper argues that if the baseline arterial oxygen saturations are >90%, high concentration oxygen does not increase oxygen transport, as the reductions in cardiac output are in excess of the increase in oxygen content. The balance of the limited evidence that exists suggests that the routine use of oxygen in uncomplicated MI (no failure or shock) may increase infarct size and possibly increase the risk of mortality, owing to its haemodynamic effects, including a reduction in coronary blood flow.
Routine use of oxygen in the treatment of myocardial infarction: systematic review
Heart. 2009 Mar;95(3):198-202