This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: ECG and Arrhythmias 1, Subject name: Medicine
[{'content': 'What is the abnormality shown in the ECG? \nSelect and explain. \nA. Premature ventricular contractions, B. Sine wave pattern, C. ST segment depression, D. Electrical alternans', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The ECG shows presence of PVC- premature ventricular contractions which increase the risk of development of ventricular tachycardia due to R on T phenomenon. PVCs (bigeminal or trigeminal pattern) occurs due to electrolyte abnormalities (especially hypokalemia or hyperkalemia and hypomagnesemia), hypehyroidism, and occult hea diseases. VT or VF may occur due to the precipitation of a PVC just prior to the peak of the T wave on ECG.', 'role': 'assistant'}]