Novel Precordial Mid-T-Wave Inversion: A Pulsation Artifact Mimicking Myocardial Ischemia and Proposed Mechanisms

Background : Electrocardiographic (ECG) artifacts mimicking acute coronary syndrome (ACS) pose a significant risk of misdiagnosis and unnecessary invasive procedures. While arterial pulsation artifacts are known to cause limb-lead ST-T changes adhering to the "single-limb lead exemption principle," their potential to induce specific repolarization abnormalities in precordial leads remains unreported. Case presentation: A 66-year-old woman presented with chest tightness. The initial ECG showed ST-segment elevation in leads III and aVF, depression in I and aVL, and a previously undescribed pattern of isolated mid-portion T-wave inversions in precordial leads V2–V6, with preserved initial T-wave morphology. Suspected ACS was reconsidered after a senior physician noted atypical features. The diagnosis of artifact was confirmed after repositioning the limb electrodes, which resulted in complete normalization of all ECG abnormalities. Coronary computed tomography angiography revealed only mild atherosclerosis, ruling out acute ischemia. Conclusion : This case is the first to describe a unique pulsation artifact pattern featuring isolated mid-portion T-wave inversions in precordial leads. We elucidate its mechanism via propagation of limb-derived interference currents through the Wilson Central Terminal, which perturbs the vulnerable mid-repolarization phase. This novel sign, especially when combined with the limb lead exemption principle (spared lead II localizing the source to the left arm), suggests a potential electrocardiographic sign for differentiating artifact from true pathology. We propose a simple diagnostic algorithm integrating lead-specific analysis and dynamic electrode repositioning to prevent misdiagnosis and unnecessary interventions in clinical practice.