What Are Hyperacute T-Waves and What Do They Mean?

By Michael H. Crawford, MD, Editor

Synopsis: A retrospective study of emergency department patients suspected of having an acute coronary syndrome has shown that a computer system for determining a new quantitative high-amplitude electrocardiogram (ECG) T-wave score has a high specificity and reasonable sensitivity for identifying patients with acute coronary occlusion that performs as well as ECG ST-elevation myocardial infarction criteria.

Source: Meyers HP, Simancik F, Herman R, et al. Hyperacute T waves are specific for occlusion myocardial infarction, even without diagnostic ST elevation. JACC Adv. 2025; Aug 11. doi: 10.1016/j.jacadv.2025.102120. [Online ahead of print].

Current guidelines state that high-amplitude T-waves (HATW) are an ST-elevation myocardial infarction (STEMI) equivalent and are highly predictive of coronary occlusion (occlusion myocardial infarction; OMI). However, there is no objective definition or criterion for HATW provided. Thus, this international, multicenter study sought to derive and validate a quantitative definition of HATW in adults presenting to the emergency department (ED) with suspected acute coronary syndromes (ACS) in five centers: two in Europe, one in Lebanon, and two in the United States.

A total of 2,656 patients were included, 1,261 (mean age 57 years, 59% men) in the derivation cohort and 1,395 (mean age 64 years, 64% men) in the validation cohort. Excluded were patients with wide QRS (≥ 110 ms) and elevated troponin levels but no angiogram performed. Clinical information was derived by chart review. The diagnosis of OMI was by troponin level and coronary angiogram results. The first available electrocardiogram (ECG) before angiography was selected for this analysis.

A computer system (PMCardio) was used to measure ECG waves to derive T-wave (TW) magnitude (area under the TW from J-point to the end of the TW) relative to QRS amplitude and TW symmetry (time from J-point to peak TW vs. time from peak to end of TW). Leads aVR and V1 were excluded, since upright TW of sufficient amplitude to measure are not expected in these leads. Also, measurements were only made in any lead if the TW amplitude was ≥ 1 mm, the TW was positive (not inverted or biphasic), and the total duration of the TW (J-point to end) was ≥ 80 ms.

In the derivation group, it was determined that TW area relative to QRS amplitude (magnitude score; TWM) was superior to TW amplitude alone. The optimal TWM for ≥ 98% specificity was ≥ 0.7. TW symmetry in the validation cohort performed similarly, so the two measures were combined to derive the final HATW score. In the validation cohort, using two contiguous leads with a total score of ≥ 0.7, the sensitivity for diagnosing OMI was 97% and the specificity was 45%, which was similar to using ECG STEMI criteria (sensitivity 97%, specificity 41%). Also, in the 38 patients without STEMI ECG criteria, 84% with a positive HATW score had an OMI by angiography. The authors concluded that their HATW ECG score showed considerable clinical utility for the diagnosis of OMI in suspected ACS patients in the ED.

Commentary

To the authors’ knowledge, this is the first study to define a quantitative measure of HATW, which demonstrates significant clinical utility as an ECG criterion for OMI in potential ACS patients. In particular, their HATW score has a high specificity and positive predictive value with reasonable sensitivity to be an ECG STEMI equivalent. Unfortunately, simple TW amplitude is suboptimal for this purpose.

The HATW score uses measures of TW magnitude and symmetry that simply show that HATW are taller and more symmetric than normal TW. Two of the coauthors were deemed experts at ECG analysis and could detect these specific TW findings with reasonable accuracy, but this is not a skill that one could expect practitioners in the average ED to possess. Therefore, the authors suggested that this should be done by specific ECG software for this purpose.

Of interest, this study confirms the low sensitivity of STEMI ECG criteria for OMI (41%), which has been observed in other studies. Of course, the diagnosis of OMI involves other clinical features and is not solely dependent on the ECG. In addition, the notion that HATW is a precursor to the development of STEMI ECG findings was not supported by the researchers’ data. Thus, they advise that, in the appropriate clinical situation, the presence of HATW should occasion patient transfer to the invasive laboratory. Do not wait for STEMI ECG criteria to appear, since they may not.

There are limitations to this study. It is a retrospective chart review study with the inherent limitations of this type of study. The study population had a high prevalence of ACS with 11% OMI. So, it may not be applicable to a broader ED population. There was inconsistent race or ethnicity data available, but there likely were few Black patients in whom these ECG measurements may be different, based on other studies. Also, the study was not designed to capture de Winter T-waves, which have ST depression and HATW.

Overall, this study supports the guideline recommendation that HATW are a feature of ACS but recommends that a dedicated computer-based ECG analysis system be used to identify them.

Michael H. Crawford, MD, is Professor Emeritus of Medicine and Consulting Cardiologist, UCSF Health, San Francisco.