Are Hyperacute T Waves a Reliable Early Sign of MI?

March 17, 2023

Written by Clark Strunk

Spoon Feed
Hyperacute T-waves, when defined by an absolute amplitude threshold greater than the 95^th percentile, were not helpful in diagnosing myocardial infarction.

Why does this matter?
Rapid identification of patients presenting to the emergency department who have an acute coronary occlusion allows for more timely initiation of reperfusion therapies and better patient outcomes. Hyperacute T-waves are thought to be one of the earliest signs on ECG of acute ischemia and have the potential to identify these patients earlier.

A new wave of thinking…
This was a post hoc analysis from a prospective study of patients presenting to the ED with chest pain who had an ECG recorded. Maximum T wave amplitudes were compared between patients diagnosed with and without myocardial infarction, which revealed no statistically significant difference in any of the 12 leads, although the T wave amplitudes mostly trended toward being higher in patients without myocardial infarction. The 95^th percentile T wave amplitude threshold was also determined and likelihood ratios for MI overlapped with 1 in all leads except aVF, III, aVR, and V1, the latter of which often had inverted T waves, making these findings likely to represent the presence of an upright T wave, as opposed to the study definition of a hyperacute T wave, and ultimately leading the authors to conclude that the presence of hyperacute T waves did not portend any useful diagnostic information.

Overall, this paper indicates to me that to effectively use hyperacute T-waves in clinical practice, we cannot simplify their identification to an absolute amplitude threshold. Perhaps, moving forward we should place more emphasis on T-wave morphology, comparison to other leads, comparison to prior ECG, and relative size compared to the preceding QRS complex (works cited) to see if this can help us capture one of the earliest ECG signatures of an acute coronary occlusion.

Another Spoonful
Dr. Smith ECG blog has over 60 posts on hyperacute T waves if you want to see examples. Also, ECGwaves has an excellent section on T waves (Wellen’s, de Winter, hyperkalemia, and hyperacute) you don’t want to miss.

Source
Hyperacute T Wave in the Early Diagnosis of Acute Myocardial Infarction. Ann Emerg Med. 2023 Feb 9:S0196-0644(22)01327-0. doi: 10.1016/j.annemergmed.2022.12.003. Epub ahead of print.

Works Cited
Electrocardiographic differentiation of early repolarization from subtle anterior ST-segment elevation myocardial infarction. Ann Emerg Med. 2012 Jul;60(1):45-56.e2. doi: 10.1016/j.annemergmed.2012.02.015. Epub 2012 Apr 19.

Editor’s Note: Don’t take away from this study that hyperacute T waves don’t matter. They do. They are just not identified based on an absolute amplitude > 95^th percentile. When you see them, they’re broad, tall, usually not pointy, and usually in several adjacent precordial leads. Amal Mattu teaches that often with hyperacute T waves, the QRS could ‘fit’ into the T waves, which is apt. ~Clay Smith