Cause of ST segment abnormality in ED chest pain patients.

The objective of this study was to determine the electrocardiographic diagnoses of chest pain patients with ST segment elevation (STE) on the 12-lead electrocardiogram (ECG). This study was a retrospective ECG review of adult chest pain patients in a university hospital emergency department (ED) over a 3-month period (January 1, 1996 to March 31, 1996). STE was determined if the ST segment was elevated >/=1 mm in the limb leads and >/=2 mm in the precordial leads in at least two anatomically contiguous leads. Results showed 902 patients who met entry criteria and of whom 202 (22.4%) had STE. Thirty-one (15%) patients had STE acute myocardial infarction (AMI) as the final hospital diagnosis which caused the STE; 171 (85%) patients with STE had non-AMI diagnosis responsible for the ST segment elevation, including left ventricular hypertrophy (LVH) 51 (25%), left bundle branch block (LBBB) 31 (15%), benign early repolarization (BER) 25 (12%), right bundle branch block 10 (5%), nonspecific bundle branch block 10 (5%), left ventricular aneurysm 5 (3%), acute pericarditis 2 (1%), ventricular paced rhythm 2 (1%), and undefined ST segment elevation 35 (17%). Forty-four patients had AMI as the final diagnosis of whom 31 showed STE on presentation to the ED. In 2 of 31 (6%) cases of STE AMI, the ST segment waveform was atypical for acute infarction. We concluded that AMI is not the most common cause of STE in ED chest pain patients. LVH is most often responsible for electrocardiographic STE followed by AMI and LBBB which occur at equal frequencies.