Non-diagnostic 12-Lead Electrocardiogram (ECG) in an Acute Proximal-to-Mid Right Coronary Artery Occlusion: A Case of Isolated Right Ventricular Infarction

Proximal-to-mid right coronary artery (RCA) occlusion typically produces inferior ST-segment elevation, yet isolated right ventricular (RV) infarction may appear non-diagnostic on a standard 12-lead electrocardiogram (ECG). A 50-year-old man presented with two hours of chest pain and rising high-sensitivity troponin I levels. The admission 12-lead ECG showed sinus rhythm with left axis deviation and subtle anterior T-wave inversion without inferior ST-segment elevation. Transthoracic echocardiography revealed mild RV dilation and hypokinesis with preserved left ventricular (LV) function. Coronary angiography demonstrated a thrombotic proximal-to-mid RCA occlusion, and primary percutaneous coronary intervention (PCI) restored the Thrombolysis in Myocardial Infarction (TIMI) 3 flow with prompt symptom relief. This case highlights the diagnostic challenge of "ECG-silent" proximal RCA occlusion and emphasizes the role of right-sided leads and early invasive evaluation to avoid delayed reperfusion.