ECG in a person with persistent anginal pain for the past several hours showing significant ST segment depression anterolateral leads along with sinus tachycardia. ST segment elevation is noted in aVR. Such a pattern is consistent with significant left main coronary artery stenosis. Clinical evaluation and X-Ray chest showed features of pulmonary edema. Angiography done after initial stabilisation with intensive medical management showed severe stenosis of distal left main coronary artery along with multiple lesions in all the three vessels, making a standard indication for an urgent coronary artery bypass grafting. A similar ECG pattern can also occur in severe proximal triple vessel disease. The previous ECG is given below for comparison, which shows minimal changes. But the ST segment elevation (minimal) in aVR is seen. This highlights the need for serial ECGs in acute coronary syndrome as initial ECGs may be normal even in those with severe disease.