There are multiple reasons for ST-segment elevation, the most important of which is acute myocardial infarction. However, because the treatment difference between MI vs. other more benign causes is so important, one should keep in mind the following factors that strongly point toward the diagnosis of MI: 1. the presence of ST-segment depression in any lead aside from aVR or V1 2. ST elevation that is horizontal or convex upwards (like a tombstone) 3. ST or T-wave morphologies that change over time with serial testing 4. ST changes compared to old ECGs 5. the development of Q-waves 6. ST elevation that follows coronary anatomy (e.g. limited to inferior leads, anterior leads, or lateral leads)
