Beyond Coronary Artery Disease: Etiologies and Outcomes of the Shark-Fin ECG Pattern: A Systematic Review

The shark-fin sign (SFS) is a rare, high-risk electrocardiographic pattern reported in commonly linked with obstructive coronary artery disease (CAD). To characterize the electrocardiographic patterns, etiologies, and clinical outcomes associated with the SFS. We systematically reviewed PubMed, EMBASE, Scopus, and Cochrane from inception through May 20, 2026, including all studies with participant-level data. Eighty-five papers involving 104 patients were included; 66.3% had non-obstructive etiologies. The obstructive CAD patients were predominantly male (97.1%), while other etiologies were predominantly female (60.8%). Among CAD cases, the left main coronary artery (LMCA)/proximal left anterior descending artery (LAD) was the culprit in 75.0%, and SFS localization matched coronary anatomy in 91.4%. VT/VF and death each occurred in 37.1%, with adverse outcomes confined to those with LMCA/LAD lesions. Among other etiologies, Takotsubo syndrome (TTS, 31.7%), vasospasm (14.4%), myocarditis (6.7 %) and neurologic emergencies (4.8%) were the most frequently reported. VT/VF occurred in 43.4% and 27.5% died. Among patients with TTS, 63.6% experienced VT/VF or death, compared with ventricular arrhythmias in 66% of patients with vasospasm. SFS is a high-risk ECG pattern rather than a diagnosis and warrants urgent etiologic evaluation and cardiac monitoring. Most published data are derived from patients without established CAD. LMCA/LAD disease, TTS, and coronary vasospasm were associated with particularly high-risk hospitalizations. Primary non-cardiac causes should also be considered when clinically suspected.