Isolated posterior acute myocardial infarction presenting to an emergency department: diagnoses and emergent fibrinolytic therapy

Objectives: Isolated posterior acute myocardial infarction (AMI) is rare and possibly underdiagnosed. The incidence of misdiagnosis in the emergency department (ED) is unknown. Delayed diagnosis may prevent timely treatment, particularly emergent fibrinolytic therapy. We describe the experience of an urban ED on this rare condition. Methodology: A six years and seven months case series of isolated posterior AMI of, initial presentation (as identified by inpatient discharge/death ICD-9-CM diagnosis code) was studied. Patients not admitted from the ED, those who developed isolated posterior AMI only after admission and/or those with concomitant ST segment elevation AMI involving other anatomical locations of the heart (e.g. inferior or lateral walls), were excluded. Results: Eleven cases were included in the study. All the nine cases with electrocardiograms available for review demonstrated features consistent with isolated posterior AMI. Eight out of the eleven (72.7%) cases were correctly diagnosed as isolated posterior AMI in the ED. The other three cases were treated as non-ST elevation myocardial infarction (NSTEMI). Nevertheless, their lack of the typical symptoms of acute coronary syndrome and delayed presentation (more than 12 hours) precluded them from fibrinolytics. Three of the eleven cases received fibrinolytics (all streptokinase). All three cases survived to discharge and there were no haemorrhagic complications. None of the cases underwent emergent percutaneous coronary intervention. Conclusion: The majority of cases with isolated posterior AMI (72.7%) were diagnosed in the ED. Although three cases were interpreted as NSTEMI, the use of fibrinolytic reperfusion therapy was not affected.