ST-Segment Elevation in a Woman With Out-of-Hospital Cardiac Arrest

Chang Kai-Chun; Lin Yi-Syuan; Lin Po-Chih

doi:10.1001/jamainternmed.2024.2886

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Challenges in Clinical Electrocardiography

September 16, 2024

ST-Segment Elevation in a Woman With Out-of-Hospital Cardiac Arrest

颁丑补苍驳听碍补颈-颁丑耻苍,听惭顿¹; 尝颈苍听驰颈-厂测耻补苍,听惭顿¹; 尝颈苍听笔辞-颁丑颈丑,听惭顿¹

Author Affiliations Article Information

¹Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan

JAMA Intern Med. 2024;184(10):1254-1255. doi:10.1001/jamainternmed.2024.2886

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A woman in her mid 70s presented to the emergency department following a sudden loss of consciousness during a meal. When paramedics arrived, the patient had a palpable pulse, but an out-of-hospital cardiac arrest (OHCA) developed in the ambulance. Cardiopulmonary resuscitation (CPR) was initiated, achieving return of spontaneous circulation (ROSC) after 19 minutes without a shockable rhythm. The reported medical history included hypertension. The patient underwent an electrocardiogram (ECG) on arrival (Figure, A).

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October 26, 2024

Shark fin pattern and Lambda waves are not synonomous

james coromilas, MD | Rutgers Robert Wood Johnson Medical School

Dr. Kai-Chun and colleagues presented a case of woman in her mid 70鈥檚 who presented with a cardiac arrest and was found to have "triangular" ST segment elevation described as a 鈥渢riangular QRS-ST-T waveform (TW)鈥�, 鈥済iant R wave pattern鈥�, 鈥渟hark-fin sign鈥� or 鈥渓ambda-wave pattern鈥�. While the first 3 are all markers of poor prognosis in STEMI, the lambda wave pattern is not related to STEMI.
The TW pattern is characterized by increased R wave amplitude, downsloping ST elevation and a merged ST-T wave that resembles an action potential. The TW was described to occur in 1-2% of acute STEMI and is associated with increased infarct size and increased risk for cardiogenic shock and VF. The study cited by the authors in 1961 revealed giant R waves and occasional action potential waveforms in experimental canine coronary occlusion but did not describe the shark-fin pattern. The name shark-fin was first used to describe a pattern similar to the TW pattern in 2015 (1). The shark-fin complexes are characterized by 鈥渂lurring together of QRS and T-wave as a result of extreme ST deviation (2).
The lambda wave was first coined by Gussak et al. to describe the ECG presented by Rivera et al in a case of a young man with history of syncope who had sudden death due to asystole following a brief run of VT (3,4). The shark-fin pattern is usually associated with STEMI whereas the lambda wave pattern is usually associated with non-coronary mechanisms of ST elevation although there may be occasional exceptions for both.
Many papers erroneously use lambda wave to describe a TW pattern. This is probably because the downsloping ST segment of the TW may has a similarity to part of the Greek letter lambda. However, this does not meet the initial description of the lambda wave as a 鈥渟lurry terminal portion of its ascending limb of the R wave and downsloping ST segment with a negative T wave鈥� (3).
Thus, shark-fin pattern and lambda waves are not synonomous. We need precise definitions of shark-fin pattern and lambda waves before we can determine if these descriptions are diagnostically and prognostically useful. Do we need to differentiate between shark-fin, TW and giant R wave patterns?
The authors conclude that the shark-fin and lambda wave ST elevations were due to subarachnoid hemorrhage. While the clinical decision to not do a coronary angiogram was reasonable, it is not possible to state unequivocally that subarachnoid hemorrhage and not coronary occlusion was the cause of the ST elevation in this case.

References
1. Smith SW. Giant R-waves. What are they? July 3, 2015
https://hqmeded-ecg.blogspot.com/2015/07/giant-r-waves-what-are-they.html

2. Galgi S and Smith SW. 鈥淪hark Fin:鈥� A deadly ECG sign that you must know. June 11, 2018. https://hqmeded-ecg.blogspot.com/2018/06/shark-fin-deadly-ecg-sign-that-you-must.html

3. Gussak I, Bjerregaard P, Kostis J. Electrocardiographic 鈥淟ambda鈥� Wave and Primary Idiopathic Cardiac Asystole: A New Clinical Syndrome? Journal of Electrocardiology; 37: 105-107, 2004

4. Riera ARP, Ferreira C, Schapachnik E, et al: Brugada syndrome with atypical ECG: Downsloping ST seg- ment elevation in inferior leads. Journal of Electrocardiology 37:101鈥�104, 2004

CONFLICT OF INTEREST: None Reported

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