The “shark fin” sign encompasses the morphological patterns of the lambda wave and the triangular QRS-ST-T pattern. It is an uncommon electrocardiographic pattern, but it predicts a high risk of ventricular fibrillation (VF) and death.

ECG Criteria

  • Giant R wave ≥ 10 mm resulting from the fusion of the QRS complex, ST segment, and T wave, showing a positive “triangular” morphology in the leads facing an ischemic region

ECG in the Shark Fin Sign

Electrocardiogram showing the shark fin sign

Shark fin sign. The QRS complex takes on a triangular shape as it merges with the ST segment and the T wave. Note the ST-segment elevation with triangular morphology in the anterior wall. It is a rare sign, but one of greater severity in acute myocardial infarction.

References

  1. Cipriani A, D’Amico G, Brunello G, Perazzolo Marra M, et al. The electrocardiographic “triangular QRS-ST-T waveform” pattern in patients with ST-segment elevation myocardial infarction: Incidence, pathophysiology and clinical implications. J Electrocardiol. 2018;51(1):8–14.
  2. Cipriani A, D’amico G, Brunetti G, Vescovo GM, et al. Electrocardiographic predictors of primary ventricular fibrillation and 30-day mortality in patients presenting with st-segment elevation myocardial infarction. J Clin Med. 2021;10(24).
  3. Fujii T, Ikari Y. Clinical outcomes of ST-elevation myocardial infarction patients who present special forms of ST-segment elevation. J Electrocardiol. 2023;81:80–4.