ST segment elevation differs depending on the method of measurement.
OBJECTIVE
The literature seldom specifies the location or method of measurement of ST segment elevation (STE) for determining eligibility in reperfusion trials. The objective of this study was to assess if different methods of measurement of STE in precordial leads of patients with anterior acute myocardial infarction due to left anterior descending occlusion result in significantly different scores.


METHODS
This was a retrospective review of diagnostic electrocardiograms (ECGs) of consecutive patients presenting to our emergency department with acute myocardial infarction who had emergent primary percutaneous coronary intervention, left anterior descending occlusion, and no bundle branch block. STE was measured at the J point and at 60 milliseconds after the J point, relative to the PR segment, in leads V1-V6. STE by the two methods was compared for each lead, as were ST scores (sum of STE in leads V1-V6) and the sum of the STE in V2-V4. Eligibility for reperfusion therapy using 1-mm and 2-mm STE criteria in two consecutive anterior leads, as well as ST scores and the sum of the STE in V2-V4, were evaluated.


RESULTS
Thirty-seven ECGs were analyzed. Mean ST measurements in every lead were significantly lower when measured at the J point versus 60 milliseconds after the J point, as were ST scores (9.7 +/- 2.14 mm vs. 14.9 +/- 2.69 mm; p < 0.00001). Fewer ECGs met enrollment criteria when based on STE at the J point versus at 60 milliseconds after the J point. Fewer ECGs met an ST score of 6 mm when measured at the J point (70% vs. 88%).


CONCLUSIONS
In anterior STE myocardial infarction, STE measurements produce different results depending on the method of measurement. Future clinical trials should specify the method of measurement.
Department of Emergency Medicine, Hennepin County Medical Center, Minneapolis, MN 55415, USA. smith253@umn.edu
Stephen W
SW
Smith
D015906:Angioplasty, Balloon, Coronary; D023921:Coronary Stenosis / Q000175:diagnosis*; D004562:Electrocardiography / Q000379:methods*; D006801:Humans; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000628:therapy; D018579:Patient Selection; D015203:Reproducibility of Results; D012189:Retrospective Studies