A 45-year-old male with s...

A 45-year-old male presents to the emergency department with severe chest pain, shortness of breath, and sweating. He has a history of smoking, high cholesterol, and a family history of heart disease. The patient reports that the chest pain started suddenly and is radiating to his left arm. He also mentions feeling lightheaded and nauseous.

Upon examination, the patient appears pale and diaphoretic. His vital signs are as follows: blood pressure 150/90 mmHg, heart rate 110 bpm, respiratory rate 20 bpm, and oxygen saturation 95% on room air. Auscultation reveals bilateral crackles at the lung bases and a loud S4 gallop is heard on cardiac examination. An electrocardiogram (ECG) shows ST-segment elevation in leads II, III, and aVF.

Based on the patient's presentation and findings, what is the most likely diagnosis, and what further diagnostic tests or treatments should be considered?