A 30-year-old male presents with palpitations and dizziness. On physical examination, his pulse is irregularly irregular, and an S1Q3T3 pattern is noted on his ECG. A chest X-ray shows no significant abnormalities. What is the most likely diagnosis? a) Atrial fibrillation b) Wolff-Parkinson-White syndrome c) Ventricular tachycardia d) Atrial flutter e) Supraventricular tachycardia Answer: a) Atrial fibrillation Explanation: The patient's symptoms, irregularly irregular pulse, and ECG findings (S1Q3T3 pattern) are indicative of atrial fibrillation. Atrial fibrillation is characterized by disorganized and irregular atrial electrical activity, leading to an irregularly irregular ventricular response. The S1Q3T3 pattern on ECG can be seen in acute pulmonary embolism, but in the absence of significant abnormalities on chest X-ray, atrial fibrillation is more likely.
