Background: “ST-T changes in the ECG!!” These words are enough to get the emergency doctor to spring into action. These changes can be diffuse and/or non-specific but we should rule out all emergent and urgent causes before shifting the patient to the specialist. To err on the side of dangerous etiology is the dictum. Introduction: Out of all emergency department (ED) patients with undifferentiated chest pain, 7% will have ECG findings consistent with acute ischemia or infarction, and 6–10% of those in whom cardiac markers are ordered will have initially positive results. Of all patients with the possible acute coronary syndrome (ACS), 5–15% ultimately prove to have ACS.¹ Shortness of breath with chest pain mostly has a cardiac origin in the presence of dynamic ECG changes. We had managed a patient with rapidly evolving ECG changes, chest pain, palpitations, and grade III–IV dyspnea. In the chaotic environment of a busy ED, the most probable diagnosis here will be ACS. Comorbid conditions like diabetes mellitus, hypertension, and prior coronary artery disease (CAD) are commonly enquired. However, other long-standing illnesses like myasthenia gravis (MG), as in our patient can be easily missed if a patient is not forthcoming with history. We experienced a similar confusion when in the cacophony of chest pain, dyspnea, and T wave inversions with bundle branch blocks, ACS protocol was initiated and a simple diagnosis was missed. The significance of the alternating bundle branch block (ABBB) will be presented to the readers.